Gas chromatography uses temperature control devices and detectors to separate and analyze mixtures. Temperature control is crucial as it affects retention times and resolution. Common temperature control devices include thermostatically stable ovens that can precisely control column temperature over a wide range and during both isothermal and temperature programmed runs. Common detectors include the flame ionization detector, thermal conductivity detector, and mass spectrometer, each with their own advantages and limitations for detecting different types of compounds. The document provides details on the principles, instrumentation, and operation of these temperature control devices and detectors.
Gas chromatography (GC) is a technique used to separate and analyze compounds that can be vaporized without decomposition. It works by carrying a gas sample mixture through a column via an inert carrier gas, separating the compounds based on their interactions with the column's stationary phase. The separated compounds then exit the column and are detected, allowing for qualitative and quantitative analysis. Key components of a GC system include an injection port, column housed in an oven, detector, and recorder. Common applications are separation of lipids, drugs, pollutants, and more.
This document provides an overview of gas chromatography. It discusses the basic principles and components of gas chromatography including the stationary and mobile phases, how samples are injected and separated in the column based on their partitioning properties. Key components like the carrier gas, temperature control, detectors, and columns are described. The document outlines some parameters used to evaluate chromatography performance and lists common applications of gas chromatography in fields like pharmaceutical analysis, food testing, and environmental analysis.
Gas chromatography is a technique used to separate and analyze mixtures of substances. It works by vaporizing the sample and carrying it by an inert gas through a column coated with a stationary liquid or solid phase. Components in the sample partition between the mobile and stationary phases and exit the column at different retention times, producing separated peaks that can be analyzed. Key aspects of gas chromatography include the carrier gas, injection system, columns, temperature control, detectors, and data recording systems. Common detectors include the thermal conductivity detector, flame ionization detector, and electron capture detector. Gas chromatography is useful for analyzing volatile and thermally stable compounds.
Gas chromatography is a technique used to separate and analyze volatile compounds. It works by injecting a sample into a column through which an inert gas flows, carrying the separated components out at different rates depending on their interactions with the stationary phase coating the column. The separated components are detected to produce a chromatogram showing peaks that can be analyzed to determine the identity and quantity of each component in the original sample.
Gas chromatography and high performance liquid chromatography are analytical techniques used to separate compounds in a mixture. GC uses an inert gas as the mobile phase to carry vaporized analytes through a column coated with a stationary phase for separation. HPLC forces a liquid mobile phase at high pressure through a column packed with porous particles to separate compounds based on interactions with the stationary phase. Both techniques separate components by differences in partitioning between the mobile and stationary phases, with detectors then identifying and quantifying the separated analytes.
This document provides an overview of chromatographic methods of analysis, focusing on gas chromatography (GC). It describes the basic principles of chromatography, including the mobile and stationary phases. It explains how chromatograms are used to represent separations. GC principles are covered, along with instrumentation components like the column, carrier gas, injector, detectors, and recorder. Common detectors discussed include TCD, FID, ECD, and NP. Factors affecting separations and advantages of GC are summarized. The document provides a high-level introduction to key aspects of chromatographic separation methods.
1. Gas chromatography is a technique used to separate mixtures by injecting a sample into a carrier gas and passing it through a column with a stationary phase. Components are separated based on their interactions and affinity for the stationary and mobile phases.
2. The sample is vaporized and carried by the mobile gas through the column where separation occurs. Components elute at different times depending on their partitioning between the phases.
3. A detector measures the eluting components and outputs signals to show separation as peaks on a chromatogram.
Gas chromatography (GC) is a technique used to separate and analyze compounds that can be vaporized without decomposition. It works by carrying a gas sample mixture through a column via an inert carrier gas, separating the compounds based on their interactions with the column's stationary phase. The separated compounds then exit the column and are detected, allowing for qualitative and quantitative analysis. Key components of a GC system include an injection port, column housed in an oven, detector, and recorder. Common applications are separation of lipids, drugs, pollutants, and more.
This document provides an overview of gas chromatography. It discusses the basic principles and components of gas chromatography including the stationary and mobile phases, how samples are injected and separated in the column based on their partitioning properties. Key components like the carrier gas, temperature control, detectors, and columns are described. The document outlines some parameters used to evaluate chromatography performance and lists common applications of gas chromatography in fields like pharmaceutical analysis, food testing, and environmental analysis.
Gas chromatography is a technique used to separate and analyze mixtures of substances. It works by vaporizing the sample and carrying it by an inert gas through a column coated with a stationary liquid or solid phase. Components in the sample partition between the mobile and stationary phases and exit the column at different retention times, producing separated peaks that can be analyzed. Key aspects of gas chromatography include the carrier gas, injection system, columns, temperature control, detectors, and data recording systems. Common detectors include the thermal conductivity detector, flame ionization detector, and electron capture detector. Gas chromatography is useful for analyzing volatile and thermally stable compounds.
Gas chromatography is a technique used to separate and analyze volatile compounds. It works by injecting a sample into a column through which an inert gas flows, carrying the separated components out at different rates depending on their interactions with the stationary phase coating the column. The separated components are detected to produce a chromatogram showing peaks that can be analyzed to determine the identity and quantity of each component in the original sample.
Gas chromatography and high performance liquid chromatography are analytical techniques used to separate compounds in a mixture. GC uses an inert gas as the mobile phase to carry vaporized analytes through a column coated with a stationary phase for separation. HPLC forces a liquid mobile phase at high pressure through a column packed with porous particles to separate compounds based on interactions with the stationary phase. Both techniques separate components by differences in partitioning between the mobile and stationary phases, with detectors then identifying and quantifying the separated analytes.
This document provides an overview of chromatographic methods of analysis, focusing on gas chromatography (GC). It describes the basic principles of chromatography, including the mobile and stationary phases. It explains how chromatograms are used to represent separations. GC principles are covered, along with instrumentation components like the column, carrier gas, injector, detectors, and recorder. Common detectors discussed include TCD, FID, ECD, and NP. Factors affecting separations and advantages of GC are summarized. The document provides a high-level introduction to key aspects of chromatographic separation methods.
1. Gas chromatography is a technique used to separate mixtures by injecting a sample into a carrier gas and passing it through a column with a stationary phase. Components are separated based on their interactions and affinity for the stationary and mobile phases.
2. The sample is vaporized and carried by the mobile gas through the column where separation occurs. Components elute at different times depending on their partitioning between the phases.
3. A detector measures the eluting components and outputs signals to show separation as peaks on a chromatogram.
Gas chromatography is a technique used to separate mixtures by distributing components between a stationary and mobile phase. It can separate volatile organic compounds without decomposition. There are two main types: gas-solid and gas-liquid chromatography. The instrument uses a carrier gas to move samples through a column where separation occurs based on partitioning between the column coating and gas. Detectors then produce signals for separated components. Common detectors include FID, TCD, ECD, and FPD. Gas chromatography finds applications in fields like food analysis and environmental monitoring due to its speed, sensitivity, and ability to separate complex mixtures both qualitatively and quantitatively.
This document discusses gas chromatography. It begins by defining chromatography and describing different chromatography techniques. It then focuses on gas chromatography, explaining that the mobile phase is a carrier gas and the stationary phase is a liquid or polymer coating inside a column. Key components of a gas chromatograph are described, including the carrier gas, injector, column, temperature control, stationary phases, and detectors. The document discusses how gas chromatography can be used for qualitative analysis of compounds and lists some advantages and disadvantages. It concludes by mentioning gas chromatography-mass spectrometry as a modern approach.
Gas chromatography (GC) is a technique used to separate and analyze compounds that can be vaporized without decomposition. The sample is injected into a heated injector port and carried by an inert gas through a long column containing a stationary liquid or solid phase. Components of the sample partition between the stationary and mobile phases and elute from the column at different retention times, allowing for separation. Common detectors measure properties like conductivity or combustion byproducts to identify separated components. GC is useful for analyzing volatile organic compounds like natural products, foods, drugs, and more.
This document provides an overview of gas chromatography. It describes the basic components and process of gas chromatography including the carrier gas, sample injection system, columns, temperature and pressure programming, and common detectors like the thermal conductivity detector and flame ionization detector. The goal of gas chromatography is to separate a mixture into individual components using a mobile gas phase and stationary column packing material over time based on differences in how components partition between the two phases.
ANALYSIS THROUGH chromatography techniques.pptxRashmiSanghi1
Chromatography is a technique used to separate chemical components in a complex mixture. It works by carrying components through a stationary phase at different rates using a mobile phase, usually liquid or gas. Liquid chromatography uses high pressure to push a liquid mobile phase through a column, while gas chromatography uses an inert gas and higher temperatures. Different detectors can be used to analyze the separated components as they exit the column. Common detectors measure properties like thermal conductivity, ionization, or light emission to identify the separated chemicals. Chromatography is a powerful analytical and preparative separation method.
This document describes different types of process analyzers and analysis techniques. It discusses destructive vs non-destructive analysis, online vs inline analysis, and specific analyzer types like tunable diode laser analyzers, oxygen analyzers, dust monitoring systems, gas chromatography, and the operating principles of thermal conductivity and flame ionization detectors. The key techniques covered are spectroscopy, magnetic susceptibility, infrared absorption, light scattering, gas partitioning behavior, and ion detection.
Principle and application of ptgc and isothermal programmingAthira39
Gas chromatography is the separation of gaseous and volatile substances which is achieved by employing gas as a mobile phase and moving it through a column containing stationary phase which could be a liquid or solid.
Two methods of temperature control are used during gas chromatography:
Isothermal operation and;
Temperature programming
This document provides an introduction and overview of gas liquid chromatography (GLC) and high performance liquid chromatography (HPLC). It defines chromatography as a technique that separates components of a mixture based on differences in affinity for a stationary and mobile phase. GLC uses an inert gas as the mobile phase and a liquid stationary phase, while HPLC uses high pressure to push a liquid mobile phase through a column. The document describes the basic instrumentation, principles, and applications of these techniques.
This document discusses the use of gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) for the analysis of active pharmaceutical ingredients (APIs). It begins with an overview of chromatography techniques and then focuses on gas chromatography. Key aspects of GC covered include qualitative and quantitative analysis, temperature programming, columns, detectors such as the flame ionization detector, and applications in the pharmaceutical industry such as residual solvent testing. The document emphasizes that GC is well-suited for pharmaceutical analysis due to its ability to simultaneously separate and identify sample components.
Gas chromatography is an analytical technique used to separate mixtures by vaporizing the components and passing them through a column with a mobile gas phase and a stationary liquid phase. It was pioneered in the 1940s and the first gas chromatograph was developed in 1951. A typical gas chromatography system consists of a gas inlet, injector, column inside an oven, detector, and data system. The sample is injected and separated in the column based on interactions between the phases, then detected and analyzed to produce a chromatogram showing the composition of the original mixture.
Gas chromatography-mass spectrometry (GC-MS) combines the separation capabilities of gas chromatography with the mass analysis capabilities of mass spectrometry. It allows unknown substances to be separated, quantified, and identified. The document discusses the principles and components of GC and GC-MS, including sample introduction, columns, detectors, interfaces between GC and MS, ionization methods in MS, and interpretation of chromatograms and spectra. GC separates components which are then analyzed by MS to produce a 3D graph allowing identification of each separated component.
Gas chromatography is a technique used to separate components of a vaporized sample mixture based on their differential partitioning between a mobile gaseous phase and a stationary liquid or solid phase. The sample is injected into a heated injector and vaporized before entering the chromatographic column containing the stationary phase. Components of the sample migrate through the column at different rates depending on their affinity for the stationary phase, resulting in separation. Common detectors include the flame ionization detector (FID), thermal conductivity detector (TCD), and electron capture detector (ECD).
This document provides an overview of gas chromatography. It discusses the basic components and principles of GC, including the mobile and stationary phases, instrumentation, and applications. The key points are:
- GC separates components in a sample using an inert gas mobile phase and either a solid or liquid stationary phase in the column.
- Common instrumentation includes the carrier gas, flow regulators, sample injector, temperature-controlled column oven, detectors, and recorders.
- Separation is based on how strongly components partition between the mobile and stationary phases.
- GC has wide applications in fields like pharmaceutical analysis, environmental analysis, forensics, and industrial quality control.
- Advantages are strong separation power,
Thermogravimetric analysis (TGA) measures the change in weight of a sample as it is heated or cooled. It involves heating a sample in a controlled atmosphere and measuring its mass change over time or temperature. TGA provides information about physical and chemical changes that occur as the sample is heated, such as decomposition, oxidation, and vaporization. The results are displayed as a TGA curve, which plots mass or percentage mass change against temperature or time. TGA is useful for determining various characteristics of materials such as polymers, foods, and pharmaceuticals.
This document discusses gas chromatography coupled with mass spectrometry (GC-MS). GC-MS is a versatile technique that can separate, quantify, and identify unknown organic compounds and gases. It combines the separating power of GC with the identification abilities of mass spectrometry. Key aspects covered include the fundamentals of GC and MS, how they are coupled, different ionization methods used, and applications of GC-MS analysis.
Gas-liquid chromatography (GLC) is a technique used to separate and analyze compounds that can be vaporized without decomposition. It involves a stationary phase, typically a liquid coated on an inert solid support inside a column, and a gaseous mobile phase such as helium. Samples are injected and carried by the mobile gas through the column where components elute at different rates depending on their interaction with the stationary phase. This allows for separation of components in the sample which are then detected and peaks recorded to identify the compounds present. GLC is widely used in applications like food and flavor analysis, forensic science, and environmental monitoring.
This document discusses gas chromatography (GC), a popular chromatography technique used to separate volatile compounds based on how they partition between a gaseous mobile phase and a stationary solid or liquid phase. GC was invented in 1901 by Russian botanist Mikhail Tswett to separate plant pigments. It works by vaporizing a sample and carrying it through a column with an inert carrier gas, where different compounds interact differently with the stationary phase and elute out at different retention times due to differences in their properties. The document outlines the basic principles and components of a GC system.
Gas chromatography, an introduction.pdfSherif Taha
This lecture presents an introduction to the beginner user on the usage of the gas chromatography technique. The main topics are; selecting the injection technique, suitable liner, column of separation, and developing an efficient temperature program.
This document provides information about chromatography and gas chromatography. It discusses the principles of separation in chromatography, which involves differential affinities of analyte components for the stationary and mobile phases. This determines the rates at which components move through the column. It also describes the parts and basic procedure of gas chromatography, including sample injection and vaporization, separation of components in the column based on their partitioning between the stationary and mobile phases, and detection of eluted components.
This document summarizes the key steps in DNA isolation: cell lysis to break open cells, protein removal to separate DNA from proteins, centrifugation to separate molecules by density, and DNA purification to isolate DNA from other cellular components. It defines DNA isolation as extracting DNA and discusses its importance in research. The four main methods of DNA isolation are listed as cell lysis, protein removal, centrifugation, and DNA purification.
- When a current flows through a conductor, it produces a magnetic field around it. The magnitude of the magnetic field depends on the current and distance from the conductor.
- According to Faraday's law of electromagnetic induction, a changing magnetic flux induces an electromotive force (emf) in any closed circuit. The induced emf opposes the change in flux according to Lenz's law.
- Transformers work on the principle of mutual induction to change the voltage of an alternating current (AC) while keeping the frequency the same. They have a primary coil and secondary coil with different numbers of turns.
Gas chromatography is a technique used to separate mixtures by distributing components between a stationary and mobile phase. It can separate volatile organic compounds without decomposition. There are two main types: gas-solid and gas-liquid chromatography. The instrument uses a carrier gas to move samples through a column where separation occurs based on partitioning between the column coating and gas. Detectors then produce signals for separated components. Common detectors include FID, TCD, ECD, and FPD. Gas chromatography finds applications in fields like food analysis and environmental monitoring due to its speed, sensitivity, and ability to separate complex mixtures both qualitatively and quantitatively.
This document discusses gas chromatography. It begins by defining chromatography and describing different chromatography techniques. It then focuses on gas chromatography, explaining that the mobile phase is a carrier gas and the stationary phase is a liquid or polymer coating inside a column. Key components of a gas chromatograph are described, including the carrier gas, injector, column, temperature control, stationary phases, and detectors. The document discusses how gas chromatography can be used for qualitative analysis of compounds and lists some advantages and disadvantages. It concludes by mentioning gas chromatography-mass spectrometry as a modern approach.
Gas chromatography (GC) is a technique used to separate and analyze compounds that can be vaporized without decomposition. The sample is injected into a heated injector port and carried by an inert gas through a long column containing a stationary liquid or solid phase. Components of the sample partition between the stationary and mobile phases and elute from the column at different retention times, allowing for separation. Common detectors measure properties like conductivity or combustion byproducts to identify separated components. GC is useful for analyzing volatile organic compounds like natural products, foods, drugs, and more.
This document provides an overview of gas chromatography. It describes the basic components and process of gas chromatography including the carrier gas, sample injection system, columns, temperature and pressure programming, and common detectors like the thermal conductivity detector and flame ionization detector. The goal of gas chromatography is to separate a mixture into individual components using a mobile gas phase and stationary column packing material over time based on differences in how components partition between the two phases.
ANALYSIS THROUGH chromatography techniques.pptxRashmiSanghi1
Chromatography is a technique used to separate chemical components in a complex mixture. It works by carrying components through a stationary phase at different rates using a mobile phase, usually liquid or gas. Liquid chromatography uses high pressure to push a liquid mobile phase through a column, while gas chromatography uses an inert gas and higher temperatures. Different detectors can be used to analyze the separated components as they exit the column. Common detectors measure properties like thermal conductivity, ionization, or light emission to identify the separated chemicals. Chromatography is a powerful analytical and preparative separation method.
This document describes different types of process analyzers and analysis techniques. It discusses destructive vs non-destructive analysis, online vs inline analysis, and specific analyzer types like tunable diode laser analyzers, oxygen analyzers, dust monitoring systems, gas chromatography, and the operating principles of thermal conductivity and flame ionization detectors. The key techniques covered are spectroscopy, magnetic susceptibility, infrared absorption, light scattering, gas partitioning behavior, and ion detection.
Principle and application of ptgc and isothermal programmingAthira39
Gas chromatography is the separation of gaseous and volatile substances which is achieved by employing gas as a mobile phase and moving it through a column containing stationary phase which could be a liquid or solid.
Two methods of temperature control are used during gas chromatography:
Isothermal operation and;
Temperature programming
This document provides an introduction and overview of gas liquid chromatography (GLC) and high performance liquid chromatography (HPLC). It defines chromatography as a technique that separates components of a mixture based on differences in affinity for a stationary and mobile phase. GLC uses an inert gas as the mobile phase and a liquid stationary phase, while HPLC uses high pressure to push a liquid mobile phase through a column. The document describes the basic instrumentation, principles, and applications of these techniques.
This document discusses the use of gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) for the analysis of active pharmaceutical ingredients (APIs). It begins with an overview of chromatography techniques and then focuses on gas chromatography. Key aspects of GC covered include qualitative and quantitative analysis, temperature programming, columns, detectors such as the flame ionization detector, and applications in the pharmaceutical industry such as residual solvent testing. The document emphasizes that GC is well-suited for pharmaceutical analysis due to its ability to simultaneously separate and identify sample components.
Gas chromatography is an analytical technique used to separate mixtures by vaporizing the components and passing them through a column with a mobile gas phase and a stationary liquid phase. It was pioneered in the 1940s and the first gas chromatograph was developed in 1951. A typical gas chromatography system consists of a gas inlet, injector, column inside an oven, detector, and data system. The sample is injected and separated in the column based on interactions between the phases, then detected and analyzed to produce a chromatogram showing the composition of the original mixture.
Gas chromatography-mass spectrometry (GC-MS) combines the separation capabilities of gas chromatography with the mass analysis capabilities of mass spectrometry. It allows unknown substances to be separated, quantified, and identified. The document discusses the principles and components of GC and GC-MS, including sample introduction, columns, detectors, interfaces between GC and MS, ionization methods in MS, and interpretation of chromatograms and spectra. GC separates components which are then analyzed by MS to produce a 3D graph allowing identification of each separated component.
Gas chromatography is a technique used to separate components of a vaporized sample mixture based on their differential partitioning between a mobile gaseous phase and a stationary liquid or solid phase. The sample is injected into a heated injector and vaporized before entering the chromatographic column containing the stationary phase. Components of the sample migrate through the column at different rates depending on their affinity for the stationary phase, resulting in separation. Common detectors include the flame ionization detector (FID), thermal conductivity detector (TCD), and electron capture detector (ECD).
This document provides an overview of gas chromatography. It discusses the basic components and principles of GC, including the mobile and stationary phases, instrumentation, and applications. The key points are:
- GC separates components in a sample using an inert gas mobile phase and either a solid or liquid stationary phase in the column.
- Common instrumentation includes the carrier gas, flow regulators, sample injector, temperature-controlled column oven, detectors, and recorders.
- Separation is based on how strongly components partition between the mobile and stationary phases.
- GC has wide applications in fields like pharmaceutical analysis, environmental analysis, forensics, and industrial quality control.
- Advantages are strong separation power,
Thermogravimetric analysis (TGA) measures the change in weight of a sample as it is heated or cooled. It involves heating a sample in a controlled atmosphere and measuring its mass change over time or temperature. TGA provides information about physical and chemical changes that occur as the sample is heated, such as decomposition, oxidation, and vaporization. The results are displayed as a TGA curve, which plots mass or percentage mass change against temperature or time. TGA is useful for determining various characteristics of materials such as polymers, foods, and pharmaceuticals.
This document discusses gas chromatography coupled with mass spectrometry (GC-MS). GC-MS is a versatile technique that can separate, quantify, and identify unknown organic compounds and gases. It combines the separating power of GC with the identification abilities of mass spectrometry. Key aspects covered include the fundamentals of GC and MS, how they are coupled, different ionization methods used, and applications of GC-MS analysis.
Gas-liquid chromatography (GLC) is a technique used to separate and analyze compounds that can be vaporized without decomposition. It involves a stationary phase, typically a liquid coated on an inert solid support inside a column, and a gaseous mobile phase such as helium. Samples are injected and carried by the mobile gas through the column where components elute at different rates depending on their interaction with the stationary phase. This allows for separation of components in the sample which are then detected and peaks recorded to identify the compounds present. GLC is widely used in applications like food and flavor analysis, forensic science, and environmental monitoring.
This document discusses gas chromatography (GC), a popular chromatography technique used to separate volatile compounds based on how they partition between a gaseous mobile phase and a stationary solid or liquid phase. GC was invented in 1901 by Russian botanist Mikhail Tswett to separate plant pigments. It works by vaporizing a sample and carrying it through a column with an inert carrier gas, where different compounds interact differently with the stationary phase and elute out at different retention times due to differences in their properties. The document outlines the basic principles and components of a GC system.
Gas chromatography, an introduction.pdfSherif Taha
This lecture presents an introduction to the beginner user on the usage of the gas chromatography technique. The main topics are; selecting the injection technique, suitable liner, column of separation, and developing an efficient temperature program.
This document provides information about chromatography and gas chromatography. It discusses the principles of separation in chromatography, which involves differential affinities of analyte components for the stationary and mobile phases. This determines the rates at which components move through the column. It also describes the parts and basic procedure of gas chromatography, including sample injection and vaporization, separation of components in the column based on their partitioning between the stationary and mobile phases, and detection of eluted components.
This document summarizes the key steps in DNA isolation: cell lysis to break open cells, protein removal to separate DNA from proteins, centrifugation to separate molecules by density, and DNA purification to isolate DNA from other cellular components. It defines DNA isolation as extracting DNA and discusses its importance in research. The four main methods of DNA isolation are listed as cell lysis, protein removal, centrifugation, and DNA purification.
- When a current flows through a conductor, it produces a magnetic field around it. The magnitude of the magnetic field depends on the current and distance from the conductor.
- According to Faraday's law of electromagnetic induction, a changing magnetic flux induces an electromotive force (emf) in any closed circuit. The induced emf opposes the change in flux according to Lenz's law.
- Transformers work on the principle of mutual induction to change the voltage of an alternating current (AC) while keeping the frequency the same. They have a primary coil and secondary coil with different numbers of turns.
This document summarizes key concepts from a lecture on electrostatics:
- Coulomb's law describes the force between two point charges, and depends on the quantities and distance between the charges.
- Electric fields are generated by charged objects and their intensity depends on the charge and distance. Electric field lines depict the direction of the field.
- Capacitors store electric charge and their capacitance depends on the geometry of the capacitor plates and any dielectric material between them. The capacitance determines how much charge can be stored at a given potential difference.
09 UNIT-9(Electronics and down of Modern Physics) (1).pptxFatimaAfzal56
The document summarizes key concepts from a lecture on electronics and modern physics:
- Rectification converts alternating current to direct current using diodes in half-wave or full-wave configurations. Full-wave rectification uses two diodes or a bridge rectifier circuit to rectify both halves of the input cycle.
- Blackbody radiation is electromagnetic radiation that follows Planck's law and depends on the temperature of the blackbody. The Stefan-Boltzmann law states that a blackbody's total emissive power is directly proportional to the fourth power of its thermodynamic temperature.
- Photoelectric effect experiments provided evidence that light behaves as quantized packets of energy called photons, as described by Einstein's photo
This document provides an overview of key concepts in electric current and circuits, including:
- Current is defined as the rate of flow of electric charge. It is measured in amperes.
- Ohm's law states that the current through a conductor is directly proportional to the voltage applied.
- Resistance depends on the material's resistivity, length, and cross-sectional area. It increases with temperature for most materials.
- Electrical power is equal to current times voltage or voltage squared over resistance. It is measured in watts.
- Components like bulbs connected in series or parallel affect how voltage and current are distributed in a circuit.
10 UNIT-10(Atomic spectra and Nuclear Physics) (1).pptxFatimaAfzal56
- Atomic spectra are classified as continuous, line, or band spectra depending on the frequencies absorbed or emitted. Bohr's model explains the line spectrum of hydrogen. [END SUMMARY]
The document summarizes key concepts about work and energy:
- Work is the product of the force component in the direction of displacement and the displacement distance. It can be positive, zero, or negative depending on the angle between the force and displacement vectors.
- Energy is the ability to do work and exists in various forms including mechanical, electrical, chemical, and others. Mechanical energy includes kinetic energy and potential energy.
- The work-energy principle states that work done on an object equals its change in kinetic energy. This allows calculating work from changes in speed or kinetic energy.
The document discusses waves, including:
1) Progressive waves transfer energy from one point to another through periodic disturbance. Transverse waves have particles vibrating perpendicular to propagation, while longitudinal waves have particles vibrating parallel.
2) Transverse waves produce crests and troughs. Longitudinal waves produce compressions and rarefactions.
3) Characteristics of waves include wavelength, time period, frequency, amplitude, and wave velocity which equals frequency multiplied by wavelength.
This document defines regeneration as the ability to regain or recover lost or injured body parts. It provides examples of regeneration in lobsters being able to regenerate their pincers, starfish regenerating from their central disk, earthworms' ability to regenerate, and sponges' regenerative properties. Salamanders, lizards regenerating their tails, bone fracture healing, skin wound healing, planaria, and plants' regenerative capacities are also listed as examples of regeneration.
Heavy metals such as lead, cadmium, copper, and arsenic can pollute water sources through industrial waste, erosion of natural deposits, and corrosion of plumbing systems. When consumed, heavy metals can cause health effects ranging from nausea and diarrhea to organ damage and cancer. Common sources of heavy metal water pollution include mining and pesticide operations, erosion of rocks and soils, and corrosion of pipes, faucets and water heaters containing metals like lead and zinc. Protecting water sources and updating aging infrastructure can help reduce heavy metal contamination.
The document summarizes the process of wastewater treatment. It describes how wastewater is collected from residences, commercial, and industrial sources and undergoes primary, secondary, and sometimes tertiary treatment stages to remove contaminants before being returned safely to the environment or reused. The primary stages involve physical separation processes like screening and sedimentation. Secondary biological treatment uses activated sludge or trickling filters to reduce organic matter with microbes. The treated effluent is then typically disinfected before discharge or reuse while sludge is processed further.
The chapter Lifelines of National Economy in Class 10 Geography focuses on the various modes of transportation and communication that play a vital role in the economic development of a country. These lifelines are crucial for the movement of goods, services, and people, thereby connecting different regions and promoting economic activities.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
Certified as an ISO/IEC 27001: Information Security Management Systems (ISMS) Lead Implementer, Data Protection Officer, and Cyber Risks Analyst, Denis brings a heightened focus on data security, privacy, and cyber resilience to every endeavor.
His expertise extends across a diverse spectrum of reporting, database, and web development applications, underpinned by an exceptional grasp of data storage and virtualization technologies. His proficiency in application testing, database administration, and data cleansing ensures seamless execution of complex projects.
What sets Denis apart is his comprehensive understanding of Business and Systems Analysis technologies, honed through involvement in all phases of the Software Development Lifecycle (SDLC). From meticulous requirements gathering to precise analysis, innovative design, rigorous development, thorough testing, and successful implementation, he has consistently delivered exceptional results.
Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
This presentation was provided by Rebecca Benner, Ph.D., of the American Society of Anesthesiologists, for the second session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session Two: 'Expanding Pathways to Publishing Careers,' was held June 13, 2024.
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
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This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
Healing is the body’s response to injury in an attempt to restore normal structure and functions.
Healing can occur in two ways: Regeneration and Repair
There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
Complications of wound healing like infection, hyperpigmentation of scar, contractures, and keloid formation.
Pengantar Penggunaan Flutter - Dart programming language1.pptx
Pollution
1.
2. Temperature Control Devices and Detectors
used in Gas Chromatography
Fatima Afzal
Msf1900026
MS CHEMISTRY
UE Township Campus
3. Contents:
• Definition of Gas Chromatography
• History
• Principle
• Stationary & Mobile phase
• Instrumentation and working of GC
• Temperature Control Devices
• Detectors used in GC
• Application of GC
4. Definition:
• Gas chromatography is a separation
technique based on partitioning analytes
between two immiscible phase: gaseous
mobile phase(carrier gas) and a stationary
solid or immobilized liquid phase.
• GC is also sometimes known as Vapor
Phase Chromatography or Gas-Liquid
Partition Chromatography.
• It is a process of separating components
from the given crude drug by using a
gaseous mobile phase.
5. History:
• German physical Chemist Erika Cremer in 1947
together with Austrian student in Fritz Prior
developed the theoretical foundations of GC
and built the first liquid –gas chromatography,
but her work was deemed irrelevant and was
ignored for a long times.
• Archer John Porter Martin was awarded the
Nobel prize for his work in developing liquid-
liquid chromatography and credited for the
foundation of gas chromatography.
6. Principle of GC:
• The principle of separation in GC is Partition.
• The mixture of components to be separated is converted to vapor and mixed with gaseous
mobile phase.
• The component which is more soluble in stationary phase travel slower and eluted later. The
component which is less soluble in stationary phase travels faster and eluted out first.
• No two components have same partition coefficient conditions. So the component are
separated according to their partition coefficient.
7. Partition
Coefficient:
• It is the ratio of concentration of analytes in
stationary phase to the concentration of analyte in
the mobile phase.
• Separation occurs between mixtures of analytes,
when each analyte has a different ratio of the
solubility in stationary and mobile phase.
• The partition coefficient (K) is the ratio of
concentration of analytes at equilibrium.
• This coefficient is constant for a compound.
• This coefficient describes the way in which a
compound distributes itself between two
immiscible phases.
8. Stationary
& Mobile
Phase:
• The separation of compounds is based on the
different strengths of interaction of the
compounds with the two phases:
• Mobile Phase which is composed of an inert
gas like helium , argon or nitrogen.
• Stationary Phase consist of a packed column in
which the packaging or solid support itself act
as stationary phase. It is a substance which
stay fixed inside a column.
9. Properties of
Stationary &
Mobile Phase:
• Stationary phase is that part of chromatographic
system where the mobile phase will flow and
distribute the solute between phases.
• Stationary phase plays a vital role in determining
the selectivity and retention of solutes in the
mixture.
• Mobile phase carries the components of the
mixtures through the medium being used.
• Mobile phase is the liquid or gas that flows
through chromatographic system moving the
material to be separated at different rates over the
stationary phase.
10. Instrumentation of GC:
• Gas Chromatography has following components:
1. Carrier Gas.
2. Gas flow regulator.
3. Sample injector.
4. Column.
5.Preheated Oven.
6. Detector.
12. Working of Gas
Chromatography:
• Fill the syringe with the sample.
• Record the setting that is column temperature,
injector port temperature and detector
temperature.
• Introduce sample into the injection port by
completely inserting the needle into the ribbon
septum. Note down the injection time.
• The sample gets vaporized due to higher
temperature of injection port and is swept into
column by carrier gas.
13. Working of
GC:
• The sample components now get distributed
between the gas and stationary liquid phase
depending upon their solubilizing tendencies.
• The component with minimal solubility moves
faster and those with maximum solubility
travels slowly.
• The components leaving the column activates
the detector and recorded to give a plot.
15. Temperature
Control
Devices used
in GC:
• In gas chromatography separations,
temperature is a primary variable used to
control the separation, and it acts in a similar
capacity as mobile-phase strength in LC. Most
workers are aware that the column
temperature can affect the retention time of
sample components in an LC separation.
16. Temperature
affect
resolution:
• The resolution is poor because either the
temperature and/or the flow rate is too high;
they should be lowered. ... Factors such oven
temperature, carrier gas flow rate, column
length and diameter, and the type of mobile
phase all influence retention times.
17. Thermostatically stable oven:
The oven is a fundamental component of the GC system. The oven temperature
must be controlled very accurately over a wide range of temperatures to assure
accurate isothermal temperature settings and temperature programming.
The most important role of the oven temperature is its effect on the partition
coefficient of the analytes between stationary and mobile phase. An increase in
temperature will result in decreased retention of analytes and vice versa.
Separation usually occurs at a higher temperature than the ambient temperature
of about 25°C. The temperature during an analysis should be high enough to
evaporate the sample components.
19. Requirement
for GC oven:
• Requirements for a GC oven:
• Temperature range: 5 - 450oC
• Temperature stability: about 0.1 degrees
• Programming rate: 0.1 - 50oC/minute
• Reproducability: < 1%
• Cooldown time: 350 to 50oC in less than 10 minutes.
• Since temperature is such an important parameter,
there is a high demand on the stability and
reproducibility of temperature settings.
20. Isothermal
Analysis and
Temperature
Programming
• If a sample contains components with closely
similar boiling points, adequate separation with
a short analysis time is obtained at one specific
oven temperature. This is called an isothermal
analysis.
• When the sample components have a wide range of
boiling points, efficient separation within a short
analysis time is not to be expected. Temperature-
programmed analysis is preferred for such samples.
Temperature programming ensures complete and
efficient (sharp peaks) separation of early as well as
late-eluting analytes within resonable analysis
times.
22. Explanation:
In the bottom experiment the
temperature is programmed to
increase in time and the
compounds with higher boiling
temperature show elute faster
and show higher peaks.
The optimum column
temperature is dependent
upon the boiling point of the
sample components.
23. Gas Chromatography Heaters:
Gas Chromatography heaters are designed to provide highly uniform temperature across the
length of the column. This precision allows the operator to capture sample data with
resolutions that are useable and repeatable from run to run.
Small changes in column temperature and unstable temperature gradients can have a
significant effect on elution times resulting in poor and unusable data.
Gas Chromatography heating elements are designed to ramp and hold the temperature of a
column within a very small margin of error.
25. Temperature effect Retention time:
Retention time is the amount of time a compound exists in the column.
A lack of column temperature uniformity will affect retention time.
After separation each compound is going to spend a different amount of time in the column,
hence the different peaks on a gas chromatogram.
No matter what heating method is used (ie. isothermal or programmed), any fluctuations along
the column during sample analysis are going to have a significant effect on retention times.
26. Heater-Column Assembly:
Another method uses a heater
that spans the length of the
column in very close proximity
to the column. The entire
heater/sensor/column assembly
is encased inside another tube
This can be very accurate but
also increases column
replacement cost as the column
and heater become inseparable.
Another version of this involves
the column being etched
into flat material. Heaters are
then attached. Still another
version combines the traditional
oven with the heater-column
assembly.
28. Detectors:
The detector is the device located at the end of the column which provides a quantitative measurement of
the components of the mixture as they elute in combination with the carrier gas.
Any property of the gaseous mixture that is different from the carrier gas can be used as a detection
method.
These detection properties fall into two categories: bulk properties and specific properties. Bulk
properties, which are also known as general properties, are properties that both the carrier gas and
analyte possess but to different degrees. Specific properties, such as detectors that measure nitrogen-
phosphorous content, have limited applications but compensate for this by their increased sensitivity.
29. Parts of Detector:
Each detector has two main parts that when used together they serve as transducers to convert the
detected property changes into an electrical signal that is recorded as a chromatogram.
Sensor: The first part of the detector is the sensor which is placed as close the column exit as
possible in order to optimize detection.
Electronic Equipment: The second is the electronic equipment used to digitize the analog signal so
that a computer may analyze the acquired chromatogram. The sooner the analog signal is converted
into a digital signal, the greater the signal-to-noise ratio becomes, as analog signal are easily
susceptible to many types of interferences.
30. An ideal detector:
An ideal GC detector is distinguished by several
characteristics which are as follow:
• Adequate sensitivity to provide a high resolution signal for all
components in the mixture.
• The sensitivities of the detectors are in the range of 10-8 to 10-15 g of
solute per second.
• The quantity of sample must be reproducible.
• An ideal column will also be chemically inert.
• The detector should be reliable, predictable and easy to operate.
31. Mass Spectrometry Detectors
Mass spectrometer(MS) detectors are most powerful of all gas chromatography detectors.
In a GC/MS system, the mass spectrometer scans the masses continuously throughout the separation. When
the sample exits the chromatography column, it is passed through a transfer line into the inlet of the mass
spectrometer . The sample is then ionized and fragmented, typically by an electron-impact ion source.
During this process, the sample is bombarded by energetic electrons which ionize the molecule by causing
them to lose an electron due to electrostatic repulsion. Further bombardment causes the ions to fragment.
The ions are then passed into a mass analyzer where the ions are sorted according to their m/z value, or mass-
to-charge ratio. Most ions are only singly charged.
32. Instrumentation
:
• One of the most common types of mass analyzer in GC/MS is
the quadrupole ion-trap analyzer, which allows gaseous anions
or cations to be held for long periods of time by electric and
magnetic fields.
• A simple quadrupole ion-trap consists of a hollow ring electrode
with two grounded end-cap electrodes Ions are allowed into the
cavity through a grid in the upper end cap.
• A variable radio-frequency is applied to the ring electrode and
ions with an appropriate m/z value orbit around the cavity. As
the radio-frequency is increased linearly, ions of a stable m/z
value are ejected by mass-selective ejection in order of mass.
• Ions that are too heavy or too light are destabilized and their
charge is neutralized upon collision with the ring electrode wall.
Emitted ions then strike an electron multiplier which converts
the detected ions into an electrical signal.
• This electrical signal is then picked up by the computer through
various programs. As an end result, a chromatogram is
produced representing the m/z ratio versus the abundance of
the sample.
34. Mass spectroscopy detectors:
Advantages
• GC/MS units are advantageous
because they allow for the
immediate determination of the
mass of the analyte and can be
used to identify the components
of incomplete separations.
Disadvantages
• The disadvantages of mass
spectrometry detectors are the
tendency for samples to
thermally degrade before
detection and the end result of
obliterating all the sample by
fragmentation.
35. Flame
Ionization
Detectors:
• Flame ionization detectors (FID) are the
most generally applicable and most widely
used detectors.
• In a FID, the sample is directed at an air-
hydrogen flame after exiting the column.
• At the high temperature of the air-
hydrogen flame, the sample undergoes
pyrolysis, or chemical decomposition
through intense heating.
• Pyrolized hydrocarbons release ions and
electrons that carry current. A high-
impedance picoammeter measures this
current to monitor the sample's elution.
36. Instrumentation:
• To detect these ions, two electrode are used to provide a potential difference.
The positive electrode doubles as the nozzle head where the flame is
produced. The other, negative electrode is positioned above the flame.
• When first designed, the negative electrode was either tear-drop shaped or
angular piece of platinum. Today, the design has been modified into a tubular
electrode, commonly referred to as a collector plate.
• The ions thus are attracted to the collector plate and upon hitting the plate,
induce a current. This current is measured with a high-impedance
picoammeter and fed into an integrator.
• The manner in which the final data is displayed is based on the computer and
software. In general, a graph is displayed that has time on the x-axis and total
ion on the y-axis.
• The current measured corresponds roughly to the proportion of reduced
carbon atoms in the flame. Specifically how the ions are produced is not
necessarily understood, but the response of the detector is determined by the
number of carbon atoms (ions) hitting the detector per unit time.
• This makes the detector sensitive to the mass rather than the concentration,
which is useful because the response of the detector is not greatly affected by
changes in the carrier gas flow rate.
38. Flame ionization detectors:
Advantages
• It is advantageous to use FID
because the detector is
unaffected by flow rate,
noncombustible gases and
water. These properties allow
FID high sensitivity and low
noise.
Disadvantages
• This technique does require
flammable gas and also destroys
the sample.
39. Thermal
Conductivity
Detectors:
• Thermal conductivity detectors (TCD) were one the earliest
detectors developed for use with gas chromatography
• The TCD works by measuring the change in carrier gas
thermal conductivity caused by the presence of the sample,
which has a different thermal conductivity from that of the
carrier gas
• Their design is relatively simple, and consists of an
electrically heated source that is maintained at constant
power
• The temperature of the source depends upon the thermal
conductivities of the surrounding gases. The source is
usually a thin wire made of platinum, r . The resistance
within the wire depends upon temperature, which is
dependent upon the thermal conductivity of the gas.
40. Instrumentation:
• The TCD consists of an electrically heated
filament in a temperature-controlled cell. Under
normal conditions there is a stable heat flow
from the filament to the detector body.
• When an analyte elutes and the thermal
conductivity of the column effluent is reduced,
the filament heats up and changes resistance.
• This resistance change is often sensed by a
Wheatstone bridge circuit which produces a
measurable voltage change.
• The column effluent flows over one of the
resistors while the reference flow is over a
second resistor in the four-resistor circuit.
42. Description:
• A schematic of a classic thermal conductivity
detector design utilizing a Wheatstone bridge
circuit .
• The reference flow across resistor 4 of the
circuit compensates for drift due to flow or
temperature fluctuations.
• Changes in the thermal conductivity of the
column effluent flow across resistor 3 will result
in a temperature change of the resistor and
therefore a resistance change which can be
measured as a signal.
43. Thermal conductivity detector:
Advantages
• The advantages of TCDs are the
ease and simplicity of use, the
devices' broad application to
inorganic and organic
compounds, and the ability of
the analyte to be collected after
separation and detection.
Disadvantages
• The greatest drawback of the
TCD is the low sensitivity of the
instrument in relation to other
detection methods, in addition
to flow rate and concentration
dependency.
44. Electron-capture Detectors:
Electron-capture detectors
(ECD) are highly selective
detectors commonly used
for detecting environmental
samples as the device
selectively detects organic
compounds with moieties
such as halogens,
peroxides, quinones and
nitro groups and gives little
to no response for all other
compounds.
Therefore, this method is
best suited in applications
where traces quantities of
chemicals such as pesticides
are to be detected and
other chromatographic
methods are unfeasible.
The simplest form of ECD
involves gaseous electrons
from a radioactive ? emitter
in an electric field. In the
absence of organic
compounds, a constant
standing current is
maintained between two
electrodes. With the
addition of organic
compounds with
electronegative functional
groups, the current
decreases significantly as
the functional groups
capture the electrons.
45. Instrumentation:
• This detector operates similar to proportional
counter used for X-ray measurement.
• this detector, the effluent from the column is
passed over a ß emitter (Ni-63). An electron from ß
emitter causes ionization of carrier gas and
production of a burst of electrons.
• In the absence of organic compounds, a constant
standing current between a pair of electrodes
results from this ionization process. However in
presence of organic compounds the current
decreases significantly.
• The response of this detector is nonlinear unless
the applied potential across the detector is pulsed.
47. Electron capture detectors:
Advantages
• The advantages of ECDs are
the high selectivity and
sensitivity towards certain
organic species with
electronegative functional
groups
Disadvantages
• However, the detector has a
limited signal range and is
potentially dangerous owing
to its radioactivity. In addition,
the signal-to-noise ratio is
limited by radioactive decay
and the presence of O2 within
the detector.
48. Atomic
Emission
Detectors:
• Atomic emission detectors (AED), one of the newest addition
to the gas chromatographer's arsenal, are element-selective
detectors that utilize plasma, which is a partially ionized gas,
to atomize all of the elements of a sample and excite their
characteristic atomic emission spectra.
• AED is an extremely powerful alternative that has a wider
applicability due to its based on the detection of atomic
emissions.
• There are three ways of generating plasma: microwave-
induced plasma (MIP), inductively coupled plasma (ICP) or
direct current plasma (DCP). MIP is the most commonly
employed form and is used with a positionable diode array to
simultaneously monitor the atomic emission spectra of
several elements.
49. Instrumentation:
• The components of the Atomic emission
detectors include:
• 1) an interface for the incoming capillary GC
column to induce plasma chamber.
• 2) a microwave chamber.
• 3) a cooling system.
• 4) a diffraction grating that associated optics.
• 5) a position adjustable photodiode array
interfaced to a computer.
51. Photoionization
Detectors:
• Another different kind of detector for GC is the
photoionization detector which utilizes the properties of
chemiluminescence spectroscopy.
• Photoionization detector (PID) is a portable vapor and gas
detector that has selective determination of aromatic
hydrocarbons, organo-heteroatom, inorganic species and
other organic compounds.
• PID comprise of an ultraviolet lamp to emit photons that are
absorbed by the compounds in an ionization chamber exiting
from a GC column.
• Small fraction of the analyte molecules are actually ionized,
nondestructive, allowing confirmation analytical results
through other detectors. In addition, PIDs are available in
portable hand-held models and in a number of lamp
configurations. Results are almost immediate.
52. Instrumentation:
• In a photoionization detector high-energy photons, typically in the vacuum
ultraviolet (VUV) range, break molecules into positively charged ions.
• As compounds enter the detector they are bombarded by high-energy UV
photons and are ionized when they absorb the UV light, resulting in ejection of
electrons and the formation of positively charged ions.
• The ions produce an electric current, which is the signal output of the detector.
The greater the concentration of the component, the more ions are produced,
and the greater the current.
• The current is amplified and displayed on an ammeter or digital concentration
display. The ions can undergo numerous reactions including reaction with oxygen
or water vapor, rearrangement, and fragmentation. A few of them may recapture
an electron within the detector to reform their original molecules; however only a
small portion of the airborne analytes are ionized to begin with so the practical
impact of this (if it occurs) is usually negligible
• . Thus, PIDs are non-destructive and can be used before other sensors in
multiple-detector configurations.
54. Photoionization Detectors:
Advantages
• PID is used commonly to detect
VOCs in soil, sediment, air and
water, which is often used to
detect contaminants in ambient
air and soil.
Disadvantages
• The disadvantage of PID is
unable to detect certain
hydrocarbon that has low
molecular weight, such as
methane and ethane.
55. Application
of GC:
Gas chromatography is a physical separation method in
where volatile mixtures are separated. It can be used in
many different fields such as pharmaceuticals,
cosmetics and even environmental toxins.
The samples have to be volatile, human breathe, blood,
saliva and other secretions containing large amounts of
organic volatiles can be easily analyzed using GC.
Knowing the amount of which compound is in a given
sample gives a huge advantage in studying the effects
of human health and of the environment as well.
56. Applications
of GC:
Air samples can be analyzed using GC. Most of the time,
air quality control units use GC coupled with FID in order
to determine the components of a given air sample.
GC/MS is also another useful method which can
determine the components of a given mixture using the
retention times and the abundance of the samples.
This method be applied to many pharmaceutical
applications such as identifying the amount of chemicals
in drugs.
Moreover, cosmetic manufacturers also use this method
to effectively measure how much of each chemical is used
for their products.
57. References:
• Skoog, D. A.; Holler, F. J.; Crouch, S. R. Principles of Instrumental Analysis. Sixth Edition, Thomson Brooks/Cole, USA,
2007.
• Krugers, J. Instrumentation in Gas Chromatography. Centrex Publishing Company-Eindhoven, Netherlands, 1968.
• Hubschmann, H. Handbook of GC/MS: Fundamentals and Applications. Wiley-VCH Verlag, Germany, 2001.
• Scott, R. P. W. Chromatographic Detectors: Design, Function, and Operation. Marcel Dekker, Inc., USA, 1996.
• J.N. Driscoll. REview of Photoionization Detection in Gas Chromatography: The first Decade. Journal of
CHromatographic Science , Vol 23. November 1985. 488-492.
• Boer, H. , "Vapour phase Chromatography", ed. Desty, D. H., 169 (Butterworths Sci. Pub., London, 1957).
• Dimbat, M. , Porter, P. E. , and Stross, F. H. , Anal. Chem., 28, 290 (1956). | Article | ISI | ChemPort .