The document discusses key concepts in gas chromatography including typical equipment, mobile and stationary phases, column efficiency measurements, separation factors, and common detectors such as the thermal conductivity detector. Gas chromatography is used to separate volatile compounds using an inert gas as the mobile phase and different stationary phases to achieve retention and selectivity of analytes. Key parameters that affect separation include temperature programming, column size and phase, carrier gas choice, and detector selection based on the compounds of interest.
Gas chromatography is a technique used to separate components of a mixture. It was invented in 1901 by Russian botanist Mikhail Tswett. Key developments include John Porter Martin developing the first gas-liquid chromatograph in the 1950s. Gas chromatography-mass spectrometry allows identification of separated components. The technique works by vaporizing a sample and carrying it by a carrier gas through a column coated with a stationary phase, separating components based on how they partition between the mobile and stationary phases.
A separation technique in which the mobile phase is a gas. Gas chromatography is always carried out in a column.
Separating mixtures of gases or volatile materials based primarily on their physical properties.
Flame emission spectroscopy and atomic absorption spectroscopy pptSachin G
This document provides information on flame emission spectroscopy (FES) and atomic absorption spectroscopy (AAS). It discusses the principles, instrumentation, interferences and applications of these techniques. The key points are:
- FES and AAS work by atomizing samples in a flame or furnace and measuring the absorption of light at characteristic wavelengths to determine elemental composition.
- Instrumentation includes burners/atomizers to vaporize samples, monochromators to select wavelengths, and detectors to measure absorption. Flames and electrothermal atomizers are commonly used.
- Applications include analysis of metals in materials, soils, waters and clinical/environmental samples. Calibration curves are used to determine unknown concentrations from measured absorb
Thermogravimetric analysis (TGA) measures the change in mass of a sample as it is heated or cooled over time. It works by precisely measuring and recording the weight of a sample as the temperature changes. TGA is useful for determining a material's thermal stability and its compositional components, as well as investigating decomposition reactions and absorbed moisture content. A TGA instrument consists of a microbalance, furnace, temperature controller, and recorder to plot weight changes against temperature or time. Heating rates, atmosphere, and sample characteristics can impact the resulting TGA curve. Common applications include measuring purity, stability, and phase changes.
Principle and application of dsc,dta,ftir and x ray diffractionBhavesh Maktarpara
The document discusses various thermal analysis techniques used in preformulation including DSC, DTA, FTIR, and X-ray diffraction. It describes the principles of each technique and provides examples of their applications in determining impurities, polymorphism, hydrates/solvates, crystallinity, drug-excipient compatibility, and more. These techniques are valuable tools for characterization during preformulation studies.
Gas chromatography is a technique used to separate and analyze compounds that can be vaporized. It works by partitioning samples between a gas mobile phase and liquid stationary phase in a column. The separation depends on how the compounds partition between the phases. Key components of a GC system include the carrier gas, sample introduction system, column for separation, and detection system such as FID or TCD. Common applications include analysis of aromatics, hydrocarbons, flavors, and other volatile organic compounds.
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.
Gas chromatography is a technique used to separate components of a mixture. It was invented in 1901 by Russian botanist Mikhail Tswett. Key developments include John Porter Martin developing the first gas-liquid chromatograph in the 1950s. Gas chromatography-mass spectrometry allows identification of separated components. The technique works by vaporizing a sample and carrying it by a carrier gas through a column coated with a stationary phase, separating components based on how they partition between the mobile and stationary phases.
A separation technique in which the mobile phase is a gas. Gas chromatography is always carried out in a column.
Separating mixtures of gases or volatile materials based primarily on their physical properties.
Flame emission spectroscopy and atomic absorption spectroscopy pptSachin G
This document provides information on flame emission spectroscopy (FES) and atomic absorption spectroscopy (AAS). It discusses the principles, instrumentation, interferences and applications of these techniques. The key points are:
- FES and AAS work by atomizing samples in a flame or furnace and measuring the absorption of light at characteristic wavelengths to determine elemental composition.
- Instrumentation includes burners/atomizers to vaporize samples, monochromators to select wavelengths, and detectors to measure absorption. Flames and electrothermal atomizers are commonly used.
- Applications include analysis of metals in materials, soils, waters and clinical/environmental samples. Calibration curves are used to determine unknown concentrations from measured absorb
Thermogravimetric analysis (TGA) measures the change in mass of a sample as it is heated or cooled over time. It works by precisely measuring and recording the weight of a sample as the temperature changes. TGA is useful for determining a material's thermal stability and its compositional components, as well as investigating decomposition reactions and absorbed moisture content. A TGA instrument consists of a microbalance, furnace, temperature controller, and recorder to plot weight changes against temperature or time. Heating rates, atmosphere, and sample characteristics can impact the resulting TGA curve. Common applications include measuring purity, stability, and phase changes.
Principle and application of dsc,dta,ftir and x ray diffractionBhavesh Maktarpara
The document discusses various thermal analysis techniques used in preformulation including DSC, DTA, FTIR, and X-ray diffraction. It describes the principles of each technique and provides examples of their applications in determining impurities, polymorphism, hydrates/solvates, crystallinity, drug-excipient compatibility, and more. These techniques are valuable tools for characterization during preformulation studies.
Gas chromatography is a technique used to separate and analyze compounds that can be vaporized. It works by partitioning samples between a gas mobile phase and liquid stationary phase in a column. The separation depends on how the compounds partition between the phases. Key components of a GC system include the carrier gas, sample introduction system, column for separation, and detection system such as FID or TCD. Common applications include analysis of aromatics, hydrocarbons, flavors, and other volatile organic compounds.
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.
Differential thermal analysis - instrumental methods of analysis SIVASWAROOP YARASI
Differential thermal analysis (DTA) is a thermal analysis technique that measures the temperature difference between a sample and an inert reference material as both are subjected to identical temperature changes. DTA can detect physical and chemical changes that occur in a sample as it is heated or cooled, such as melting, crystallization, and decomposition. The technique works by comparing the temperature of the sample to the reference over time as both are heated or cooled at a controlled rate. Any temperature differences between the sample and reference are plotted against temperature or time to produce a DTA curve, which can provide information about the sample's composition and phase transitions. Key factors that can affect DTA curves include the sample environment, instrumentation used, and characteristics of the sample
Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) is a type of atomic absorption spectroscopy that uses a graphite-coated furnace to vaporize samples. Small aliquots of up to 100 microliters of aqueous samples are placed into the graphite tube and heated to high temperatures to break chemical bonds and produce free ground-state atoms. The amount of light absorbed by these atoms is proportional to the concentration of the element of interest. GFAAS offers greater sensitivity and lower detection limits than flame atomic absorption spectroscopy due to the higher temperatures achieved in the graphite furnace. It has applications in analyzing low metal concentrations in water samples and quantifying elements like beryllium in blood and serum.
The document discusses validation criteria for analytical test procedures, including specificity, linearity and range, accuracy, precision (repeatability, intermediate precision), detection limit, and quantitation limit. It provides definitions and recommendations for establishing each criterion through studies involving spiked samples, calibration standards, and statistical analysis of results. Criteria validation helps demonstrate that an analytical procedure is suitable for its intended purpose of identifying, quantifying, or limiting substances within drug samples.
There are two theories that explain chromatography: plate theory and rate theory. Plate theory, developed in 1941, views the column as divided into theoretical plates where analytes completely equilibrate between the stationary and mobile phases. Rate theory, proposed in 1956, accounts for the dynamics of separation. Greater separation occurs with more theoretical plates and smaller plate height. The number of theoretical plates can be calculated using methods like half-height or USP, and depends on factors like column length, particle size, and retention time.
The document summarizes different types of gas chromatography detectors. It describes the ideal characteristics of detectors and classifies them as destructive or non-destructive. The flame ionization detector (FID), thermal conductivity detector (TCD), and barrier discharge ionization detector (BID) are explained in detail. The FID detects compounds containing carbon, the TCD detects all compounds except the carrier gas, and the BID can detect inorganic and organic compounds except helium and neon. Each detector's principle of operation, applications, detection limits, and advantages/disadvantages are provided.
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.
Theory of high performance liquid chromatography pptshweta more
This document provides an overview of the theory of high performance liquid chromatography (HPLC). It discusses key concepts such as the retention factor (k), which is a measure of how long a compound is retained on the column. Selectivity (α) refers to the ability to distinguish between sample components, and is calculated as a ratio of the k values. Resolution (Rs) is the most important measure of separation, and depends on factors like k, α, and the number of theoretical plates (N). N is a measure of column efficiency, and the height equivalent of a theoretical plate (HETP) describes efficiency. The document outlines how these parameters can be optimized to improve separation and resolution.
This document provides an introduction and overview of gas chromatography (GC). It discusses the basic principles of GC, which involves separating components of a mixture based on how they partition between a stationary and mobile phase. The key components of a GC system are described, including the injector where samples are introduced, the column where separation occurs, the oven that controls temperature, and various detectors. Different types of columns, stationary phases, temperature programs, and detectors are discussed to provide flexibility in GC analysis for a wide range of applications.
Gas chromatography is a technique used to separate gaseous or volatile substances. It works by passing a gas carrying the sample components through a column containing an adsorbent material. The components interact differently with the adsorbent based on properties like boiling point, and exit the column at different rates, allowing for separation. Key components of a gas chromatograph include the injection port, column, temperature control system, and detectors used to analyze the separated components as they exit the column. Common detectors include the flame ionization detector and electron capture detector.
Gas chromatography is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition.
The Nobel Prize in Chemistry 1952 was awarded jointly to Archer John Porter Martin and Richard Laurence Millington Synge for their invention of partition chromatography. They developed the plate theory of chromatography, which models a chromatographic column as being divided into theoretical plates with each plate representing equilibrium between the mobile and stationary phases. The number of theoretical plates is used to represent the efficiency and performance of the column.
Differential thermal analysis (DTA) is a thermal analysis technique that measures the temperature difference between a sample and an inert reference material as they are heated or cooled under a controlled temperature program. During physical and chemical changes in the sample, it may absorb or release more or less heat than the reference. The temperature difference is recorded as a function of time or temperature to produce a DTA curve. Key components of a DTA instrument include a furnace, sample and reference holders, temperature sensors and programmer, recorder, and cooling system. DTA is used for applications such as determining heats of reaction, thermal properties, and identifying materials and their phase changes.
This document discusses analytical chemistry and instrumentation methods. It introduces analytical chemistry as determining the chemical composition of samples through qualitative and quantitative analysis. It then describes common analytical approaches, including identifying problems, designing experiments, conducting experiments, analyzing data, and proposing solutions. The document outlines classical and instrumental analytical methods and key considerations for selecting methods. It also defines important figures of merit for methods and discusses calibration techniques like external standards, standard additions, and internal standards.
Thermal analysis techniques such as differential thermal analysis (DTA) measure the temperature difference between a sample and an inert reference material as they undergo identical thermal cycles. DTA provides information about physical and chemical changes in a material as it is heated, such as melting, crystallization, and decomposition, by detecting endothermic or exothermic reactions. The DTA instrument consists of sample and reference holders connected to thermocouples within a furnace. Changes in the sample are detected as differences in temperature compared to the unreactive reference. DTA is useful for characterizing materials like minerals, polymers, and pharmaceuticals.
1. It is one of the type of Hyphenated technique.
2. It is a combination of gas chromatographic technique and spectroscopic technique.
3. It is having a high resolution capacity.
4. It is used has volatile and Non-volatile compounds.
5. It is used for qualitative and quantitative analysis.
This document summarizes a seminar presentation on amperometric titration given by Kalyani S. Dalpe. It defines amperometric titration as a form of quantitative analysis where the equivalence point is determined by measuring the electric current produced during the titration. It describes the principle that the diffusion current is directly proportional to the concentration of electroactive material. It then discusses three types of titration curves depending on whether the titrand, titrant, or product are reducible. Finally, it lists some advantages such as higher accuracy and independence from capillary characteristics, and one disadvantage being potential inaccurate results.
1) Ion pair chromatography is a type of column chromatography that uses ion pairing agents to neutralize charged analytes and allow their separation on a reversed-phase column.
2) By adding counter ions with the opposite charge to the mobile phase, ion pairs form between the counter ions and analytes, neutralizing their charge and increasing their hydrophobicity.
3) The use of ion-pairing reagents as mobile phase additives allows the separation of ionic and highly polar substances that cannot otherwise be separated by reversed-phase chromatography.
The document discusses key concepts in gas chromatography including theoretical plates, resolution, retention time, retention volume, separation factor, height equivalent to a theoretical plate (HETP), peak asymmetry, stationary phases, and considerations for choosing stationary phases. It provides definitions and equations for these terms and concepts. Examples of common stationary phase materials and their applications are also presented.
The document discusses analytical method development for HPLC. It notes that method development requires selecting requirements, instrumentation type, and why. Existing methods may be unreliable, expensive, or time-consuming, necessitating new method development. Key steps in development include defining goals, establishing sample preparation, selecting detector and mode of separation, performing preliminary separations, optimizing conditions, and validating the method. Method development is informed by factors like number of analytes, sample matrix, and analyte properties.
The document discusses the principles of chromatography. It describes how chromatography separates components in a mixture based on differences in their interactions with mobile and stationary phases. It discusses how Michael Tswett first demonstrated chromatography in 1903 and the key aspects of how it works. These include how retention time, partition coefficients, selectivity factors and efficiency parameters like plate number and height equivalent to a theoretical plate are used to characterize chromatographic separations.
Ion exchange chromatography uses charged sites on a stationary phase to selectively retain ionized solutes from a mobile phase based on electrostatic attraction. Cation exchangers contain negatively charged groups that attract positively charged cations, while anion exchangers contain positively charged groups that attract negatively charged anions. Key factors that influence selectivity include ion charge, hydrated radius, and polarizability. Ion exchange chromatography has various applications including separation of ions, removal of interferents, water softening, and demineralization.
High Performance Liquid Chromatography (HPLC) is described. HPLC uses high pressure to force a mobile phase through a column at a fast rate, increasing resolution. It discusses the types of chromatography used in HPLC, including normal phase, reverse phase, ion-exchange, and size-exclusion. The instrumentation of HPLC is also summarized, including components like the pump, mixing unit, degasser, injector, column, and detector.
Differential thermal analysis - instrumental methods of analysis SIVASWAROOP YARASI
Differential thermal analysis (DTA) is a thermal analysis technique that measures the temperature difference between a sample and an inert reference material as both are subjected to identical temperature changes. DTA can detect physical and chemical changes that occur in a sample as it is heated or cooled, such as melting, crystallization, and decomposition. The technique works by comparing the temperature of the sample to the reference over time as both are heated or cooled at a controlled rate. Any temperature differences between the sample and reference are plotted against temperature or time to produce a DTA curve, which can provide information about the sample's composition and phase transitions. Key factors that can affect DTA curves include the sample environment, instrumentation used, and characteristics of the sample
Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) is a type of atomic absorption spectroscopy that uses a graphite-coated furnace to vaporize samples. Small aliquots of up to 100 microliters of aqueous samples are placed into the graphite tube and heated to high temperatures to break chemical bonds and produce free ground-state atoms. The amount of light absorbed by these atoms is proportional to the concentration of the element of interest. GFAAS offers greater sensitivity and lower detection limits than flame atomic absorption spectroscopy due to the higher temperatures achieved in the graphite furnace. It has applications in analyzing low metal concentrations in water samples and quantifying elements like beryllium in blood and serum.
The document discusses validation criteria for analytical test procedures, including specificity, linearity and range, accuracy, precision (repeatability, intermediate precision), detection limit, and quantitation limit. It provides definitions and recommendations for establishing each criterion through studies involving spiked samples, calibration standards, and statistical analysis of results. Criteria validation helps demonstrate that an analytical procedure is suitable for its intended purpose of identifying, quantifying, or limiting substances within drug samples.
There are two theories that explain chromatography: plate theory and rate theory. Plate theory, developed in 1941, views the column as divided into theoretical plates where analytes completely equilibrate between the stationary and mobile phases. Rate theory, proposed in 1956, accounts for the dynamics of separation. Greater separation occurs with more theoretical plates and smaller plate height. The number of theoretical plates can be calculated using methods like half-height or USP, and depends on factors like column length, particle size, and retention time.
The document summarizes different types of gas chromatography detectors. It describes the ideal characteristics of detectors and classifies them as destructive or non-destructive. The flame ionization detector (FID), thermal conductivity detector (TCD), and barrier discharge ionization detector (BID) are explained in detail. The FID detects compounds containing carbon, the TCD detects all compounds except the carrier gas, and the BID can detect inorganic and organic compounds except helium and neon. Each detector's principle of operation, applications, detection limits, and advantages/disadvantages are provided.
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.
Theory of high performance liquid chromatography pptshweta more
This document provides an overview of the theory of high performance liquid chromatography (HPLC). It discusses key concepts such as the retention factor (k), which is a measure of how long a compound is retained on the column. Selectivity (α) refers to the ability to distinguish between sample components, and is calculated as a ratio of the k values. Resolution (Rs) is the most important measure of separation, and depends on factors like k, α, and the number of theoretical plates (N). N is a measure of column efficiency, and the height equivalent of a theoretical plate (HETP) describes efficiency. The document outlines how these parameters can be optimized to improve separation and resolution.
This document provides an introduction and overview of gas chromatography (GC). It discusses the basic principles of GC, which involves separating components of a mixture based on how they partition between a stationary and mobile phase. The key components of a GC system are described, including the injector where samples are introduced, the column where separation occurs, the oven that controls temperature, and various detectors. Different types of columns, stationary phases, temperature programs, and detectors are discussed to provide flexibility in GC analysis for a wide range of applications.
Gas chromatography is a technique used to separate gaseous or volatile substances. It works by passing a gas carrying the sample components through a column containing an adsorbent material. The components interact differently with the adsorbent based on properties like boiling point, and exit the column at different rates, allowing for separation. Key components of a gas chromatograph include the injection port, column, temperature control system, and detectors used to analyze the separated components as they exit the column. Common detectors include the flame ionization detector and electron capture detector.
Gas chromatography is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition.
The Nobel Prize in Chemistry 1952 was awarded jointly to Archer John Porter Martin and Richard Laurence Millington Synge for their invention of partition chromatography. They developed the plate theory of chromatography, which models a chromatographic column as being divided into theoretical plates with each plate representing equilibrium between the mobile and stationary phases. The number of theoretical plates is used to represent the efficiency and performance of the column.
Differential thermal analysis (DTA) is a thermal analysis technique that measures the temperature difference between a sample and an inert reference material as they are heated or cooled under a controlled temperature program. During physical and chemical changes in the sample, it may absorb or release more or less heat than the reference. The temperature difference is recorded as a function of time or temperature to produce a DTA curve. Key components of a DTA instrument include a furnace, sample and reference holders, temperature sensors and programmer, recorder, and cooling system. DTA is used for applications such as determining heats of reaction, thermal properties, and identifying materials and their phase changes.
This document discusses analytical chemistry and instrumentation methods. It introduces analytical chemistry as determining the chemical composition of samples through qualitative and quantitative analysis. It then describes common analytical approaches, including identifying problems, designing experiments, conducting experiments, analyzing data, and proposing solutions. The document outlines classical and instrumental analytical methods and key considerations for selecting methods. It also defines important figures of merit for methods and discusses calibration techniques like external standards, standard additions, and internal standards.
Thermal analysis techniques such as differential thermal analysis (DTA) measure the temperature difference between a sample and an inert reference material as they undergo identical thermal cycles. DTA provides information about physical and chemical changes in a material as it is heated, such as melting, crystallization, and decomposition, by detecting endothermic or exothermic reactions. The DTA instrument consists of sample and reference holders connected to thermocouples within a furnace. Changes in the sample are detected as differences in temperature compared to the unreactive reference. DTA is useful for characterizing materials like minerals, polymers, and pharmaceuticals.
1. It is one of the type of Hyphenated technique.
2. It is a combination of gas chromatographic technique and spectroscopic technique.
3. It is having a high resolution capacity.
4. It is used has volatile and Non-volatile compounds.
5. It is used for qualitative and quantitative analysis.
This document summarizes a seminar presentation on amperometric titration given by Kalyani S. Dalpe. It defines amperometric titration as a form of quantitative analysis where the equivalence point is determined by measuring the electric current produced during the titration. It describes the principle that the diffusion current is directly proportional to the concentration of electroactive material. It then discusses three types of titration curves depending on whether the titrand, titrant, or product are reducible. Finally, it lists some advantages such as higher accuracy and independence from capillary characteristics, and one disadvantage being potential inaccurate results.
1) Ion pair chromatography is a type of column chromatography that uses ion pairing agents to neutralize charged analytes and allow their separation on a reversed-phase column.
2) By adding counter ions with the opposite charge to the mobile phase, ion pairs form between the counter ions and analytes, neutralizing their charge and increasing their hydrophobicity.
3) The use of ion-pairing reagents as mobile phase additives allows the separation of ionic and highly polar substances that cannot otherwise be separated by reversed-phase chromatography.
The document discusses key concepts in gas chromatography including theoretical plates, resolution, retention time, retention volume, separation factor, height equivalent to a theoretical plate (HETP), peak asymmetry, stationary phases, and considerations for choosing stationary phases. It provides definitions and equations for these terms and concepts. Examples of common stationary phase materials and their applications are also presented.
The document discusses analytical method development for HPLC. It notes that method development requires selecting requirements, instrumentation type, and why. Existing methods may be unreliable, expensive, or time-consuming, necessitating new method development. Key steps in development include defining goals, establishing sample preparation, selecting detector and mode of separation, performing preliminary separations, optimizing conditions, and validating the method. Method development is informed by factors like number of analytes, sample matrix, and analyte properties.
The document discusses the principles of chromatography. It describes how chromatography separates components in a mixture based on differences in their interactions with mobile and stationary phases. It discusses how Michael Tswett first demonstrated chromatography in 1903 and the key aspects of how it works. These include how retention time, partition coefficients, selectivity factors and efficiency parameters like plate number and height equivalent to a theoretical plate are used to characterize chromatographic separations.
Ion exchange chromatography uses charged sites on a stationary phase to selectively retain ionized solutes from a mobile phase based on electrostatic attraction. Cation exchangers contain negatively charged groups that attract positively charged cations, while anion exchangers contain positively charged groups that attract negatively charged anions. Key factors that influence selectivity include ion charge, hydrated radius, and polarizability. Ion exchange chromatography has various applications including separation of ions, removal of interferents, water softening, and demineralization.
High Performance Liquid Chromatography (HPLC) is described. HPLC uses high pressure to force a mobile phase through a column at a fast rate, increasing resolution. It discusses the types of chromatography used in HPLC, including normal phase, reverse phase, ion-exchange, and size-exclusion. The instrumentation of HPLC is also summarized, including components like the pump, mixing unit, degasser, injector, column, and detector.
DNA contains the genetic instructions used in the development and functioning of all known living organisms. It is made up of nucleotides containing deoxyribose, phosphate groups, and one of four nitrogenous bases (adenine, guanine, cytosine, thymine) that bond together in a double helix structure. DNA is found primarily in the cell nucleus where it is organized into structures called chromosomes that contain an organism's complete set of genes.
This power point presentation explains double helical structure of DNA as proposed by Watson and Crick (1953).Attempts have also been made to high light the valuable contributions made by Rosalind Franklin and Wilkins. Brief details of different types of DNA have also been included.
This document provides an overview of ion exchange chromatography. It describes the basic principles of how ion exchange chromatography separates ions and polar molecules based on their charge. The document outlines the different types of ion exchangers used as stationary phases in cation exchange chromatography and anion exchange chromatography. It also discusses several factors that can affect the separation process and provides some examples of applications for ion exchange chromatography.
The document discusses ion exchange chromatography, which separates charged molecules by exchanging them for ions attached to an insoluble matrix. It describes the principle of reversible ion exchange between oppositely charged molecules and the matrix. The document outlines the types of ion exchange resins used, including polystyrene and cellulose. It also discusses cation and anion exchangers, preparation of ion exchangers, factors affecting separation, and applications such as water softening and analyzing nucleic acids.
This document discusses the structure, properties, and functions of DNA. It describes DNA as a polymer composed of deoxyribonucleotides that carries the genetic information found in chromosomes, mitochondria, and chloroplasts. The basic structure of DNA involves two anti-parallel strands coiled around each other to form the familiar double helix structure, held together by hydrogen bonds between complementary nucleotide base pairs and base stacking interactions. DNA exists in various structural forms and undergoes compaction in the cell, ultimately forming chromatin through association with histone proteins. The primary function of DNA is to serve as the template for its own replication and transcription into RNA to direct protein synthesis.
This document provides an overview of chromatography techniques. It defines chromatography as a separation technique based on differences in how compounds interact with a mobile and stationary phase. It describes the basic components of a chromatography system and classifications based on mobile phase, stationary phase, and support material. Key concepts like retention time, capacity factor, separation factor, and resolution are explained. Different types of chromatography are outlined including thin layer chromatography. Applications and advantages of chromatography are also summarized.
1. This document discusses key concepts in chromatography including retention time, efficiency, theoretical plates, plate height, the van Deemter equation, separation factors, and resolution.
2. It explains the basic components of a gas chromatography system including the carrier gas, column, injector, and detectors. Common carrier gases are helium, nitrogen, and hydrogen while common column types are packed, capillary, and open tubular.
3. The three main types of stationary phases in chromatography are solid adsorbents, liquids coated on solid supports, and bonded stationary phases which are covalently attached to prevent bleeding over time. Key stationary phases include dimethylsiloxane, methyl phenyl siloxane,
Chromatography is an analytical technique used to separate, identify, and quantify components in complex mixtures. It involves a stationary phase and mobile phase. Components are carried through the stationary phase by the flow of the mobile phase, with separation occurring due to differences in migration rates. Key terms in chromatography include the plate height and number of theoretical plates, which reflect separation efficiency. The Van Deemter equation models how the plate height relates to factors like diffusion and mass transfer between phases, allowing optimization of separation conditions. Chromatography has applications in qualitative and quantitative analysis of sample components.
Okay, here are the steps to solve this problem:
1) Calculate the capacity factors (k') for each compound using k' = (tR - tM)/tM
2) Calculate the separation factor (α) using α = k'D/k'C
3) Calculate the resolution (Rs) using the given formula
4) Set Rs = 1.5 and solve for the required column length
C: k'C = (14.1 - 3.1)/3.1 = 3.87
D: k'D = (21.6 - 3.1)/3.1 = 5.87
α = k'D/k'C = 5.87/
Chromatography is a technique used to separate mixtures by distributing components between a stationary and mobile phase. Separation occurs as components interact differently with the phases and move through a column at different rates. Key terms include retention time, plate number, and resolution which characterize separation efficiency. Variables like particle size, temperature, flow rate, and column length affect efficiency by influencing how components partition between phases.
Principles and application of chromatography by asheesh pandeyAsheesh Pandey
Chromatography is a laboratory technique used to separate mixtures by exploiting differences in how compounds partition between a stationary and mobile phase. There are two main types - column chromatography where the stationary phase is within a tube, and planar chromatography like paper or thin layer chromatography where the stationary phase is on a flat surface. Key factors that affect separations include the properties of the stationary and mobile phases used and operating parameters like flow rate. Chromatography is widely applied in fields like pharmaceutical analysis to purify compounds and determine sample composition.
Liquid chromatography still striving for high efficiency2guest63ff7d
This document discusses approaches to improve the efficiency of liquid chromatography (LC). It summarizes that existing approaches include high temperature LC, monolithic stationary phases, fused-core particles, and sub-2-micron totally porous particles. Each approach aims to reduce band broadening and mass transfer resistance through various means like increased flow rates, reduced diffusion distances, or improved permeability. However, each also has limitations such as potential thermal or chemical degradation, limited stability, or very high back pressures. Overall miniaturization and smaller particle sizes indicate the future direction of LC development towards higher efficiency separations.
Chromatography is a separation technique based on differential partitioning between a stationary and mobile phase. There are various types of chromatography classified by the physical state of the mobile phase, including gas-liquid chromatography (GLC), gas-solid chromatography (GSC), and liquid chromatography (LC). The retention time of an analyte depends on factors like the partition coefficient K, number of theoretical plates N, and capacity factor k'. Column efficiency is indicated by the number of theoretical plates and can be improved by reducing band broadening effects. Resolution is improved by increasing selectivity α, retention k', and plate number N.
Presentation of chromatography by Shaiq AliShaiq Ali
This document provides an overview of chromatography presented by Mr. Muhammad Kamran and Mr. Shaiq Ali. It begins with a brief history of chromatography developed by Mikhail Tswett in 1906. Key developments in chromatography are then outlined from 1903 to 1965. The document defines chromatography as a separation technique based on differences in interactions between compounds and a mobile and stationary phase. Various types of chromatography are described including thin layer, paper, HPLC, gas, and column chromatography. Applications of chromatography in fields like forensics, research, and the pharmaceutical industry are highlighted. The document concludes with explanations of important chromatography concepts such as capacity factor, efficiency, number of theoretical plates, resolution, and the van Deemter equation.
Chromatography is a physical separation method that separates a mixture into its individual components. It works by distributing the analytes between a stationary and mobile phase. There are different types of chromatography defined by the mobile and stationary phases used, including gas chromatography (GC) which uses a gas as the mobile phase. GC is commonly used with capillary columns for high resolution separation of volatile organic compounds. It works by separating compounds based on their partitioning between the stationary phase coating on the column and the carrier gas mobile phase.
The document discusses chromatography and system suitability testing. It defines system suitability testing as verifying that the chromatographic system is suitable for the intended analysis. Key parameters of system suitability testing include precision, capacity factor, resolution, theoretical plates, and tailing factor. Tests are run at the beginning and end of analysis, or when changes are made to the equipment or reagents. Acceptance criteria for parameters like precision and tailing factor are provided.
Gas chromatography (GC) is an analytical technique used to separate mixtures by distributing components between two phases - a stationary phase and a mobile gas phase. The mixture is injected into a column containing a stationary phase, and each component interacts differently with the phases as they move through the column at different rates. This allows the components to elute from the column at different retention times, enabling their separation and detection. Key aspects of GC include the carrier gas, column, injector, oven, detectors, and quantification methods for qualitative and quantitative analysis of sample components.
The document discusses chromatography techniques. It explains that chromatography separates components of a sample mixture based on how they distribute between a stationary and mobile phase. There are two main forms: planar chromatography and column chromatography. High performance liquid chromatography is a type of column chromatography that uses smaller diameter stationary phase particles. The document goes into details about the chromatography process, parameters like retention time and resolution, and factors that influence separation efficiency.
Lec#3_Separation by Chromatography.pptShahinaPanah
This document provides an overview of analytical chemistry-II and gas chromatography. It discusses key concepts like selectivity factor, column efficiency, retention time, dead time, plate theory, and sources of band broadening. It also describes the basic instrumentation of gas chromatography including carrier gas systems, sample injection, column configurations, detectors, and factors that affect column efficiency like mobile phase flow rate and column type (packed vs. capillary).
Gas chromatography and high performance liquid chromatography are analytical techniques used to separate mixtures. Mikhail Tswett invented chromatography in 1901 to separate plant pigments using a glass column packed with calcium carbonate. Liquid chromatography was later refined using smaller packing materials and pumps to deliver solvents at high pressures, allowing for faster separations and the development of high performance liquid chromatography. Chromatography works by separating components in a mixture based on how they interact differently with a stationary and mobile phase as they flow through a column.
Department of Chemistry /College of Sciences/ University of Baghdad
Subject: Analytical Chemistry 4
Second stage
2nd semester
Dr. Ashraf Saad Rsaheed
2017-2018
Liquid chromatography still striving for high efficiencyguest63ff7d
The document discusses liquid chromatography and approaches to improve its efficiency. It provides an overview of the chromatographic process and factors that affect column efficiency such as mobile phase velocity, temperature, column length, particle size. Existing approaches to improve efficiency include high temperature liquid chromatography, monolithic stationary phases, fused-core particles, and sub-2-micron totally porous particles. Overall miniaturization shows potential for future efficiency gains in liquid chromatography.
The plate theory of chromatography models a chromatographic column as consisting of theoretical plates that establish equilibrium between the mobile and stationary phases. As the mobile phase passes through the column, analytes distribute between the two phases and are carried from plate to plate until they elute. Increasing the number of plates narrows peaks and improves resolution. The efficiency of a column is represented by the number of plates or the height equivalent to a theoretical plate (HETP).
This document discusses gas chromatography (GC), which separates compounds that can be vaporized without decomposing. It has two types depending on the stationary phase: gas-solid chromatography (GSC) and gas-liquid chromatography (GLC). The distribution of analytes between phases is expressed by the distribution constant K. Plate theory and rate theory, including the Van Deemter equation, are presented to describe column efficiency and factors influencing peak broadening such as eddy diffusion, longitudinal diffusion, and mass transfer under non-equilibrium conditions.
This document discusses concepts related to gas chromatography including band broadening, column efficiency, and theoretical plates. It explains that in gas chromatography, band broadening occurs as solutes move through the column and can be explained by rate theory involving the random transfer of solutes between phases or by plate theory involving the number and height of theoretical plates. It also provides an overview of the basic components of a gas chromatography instrument, including the carrier gas system, sample injection system, column configurations, temperature programming, and various detection systems.
Supercritical fluids have properties between gases and liquids. They can dissolve materials like liquids and diffuse through solids like gases. Carbon dioxide is commonly used as a supercritical fluid in supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC). In SFE, the supercritical fluid is used to extract analytes from samples, while in SFC it is used as the mobile phase to separate analytes chromatographically. Both techniques take advantage of how the density and solvent strength of the supercritical fluid can be tuned by adjusting the pressure and temperature.
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The document is an introduction to chromatography. It defines chromatography as a family of laboratory techniques used to separate mixtures by distributing components between a mobile and stationary phase over time. The key principle is that the partitioning of solutes between the mobile and stationary phases results in their separation as they travel through the system at different rates. Chromatography can be used for analytical or preparative purposes and is classified based on the mechanism of interaction between the solute and stationary phase or the type of phases used.
Analytical chemistry is a subdiscipline of chemistry that focuses on developing methods to understand the chemical composition of matter. It involves separating, identifying, and determining the components of samples. Analytical chemists play roles in both pure and applied science, developing concepts and applying techniques in fields like biomedical science, environmental monitoring, and forensics. Common analytical techniques taught in the course include various types of chromatography, liquid and solid extraction methods, electrophoresis, precipitation, and distillation. The overall goal is to separate sample components to make identification and quantification easier.
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Monitoring and Managing Anomaly Detection on OpenShift
Overview
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11. What is a Jupyter Notebook?
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12. Jupyter Notebooks with Code Examples
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5th LF Energy Power Grid Model Meet-up SlidesDanBrown980551
5th Power Grid Model Meet-up
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Power Grid Model
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gas chromatography (GC)
1. Some important points to remember!
1.) Typical response obtained by chromatography (i.e., a chromatogram):
Where:
tR = retention time
tM = void time
Wb = baseline width of the peak in time units
Wh = half-height width of the peak in time units
2. 2.) Solute Retention:
A solute’s retention time or retention volume in chromatography
is directly related to the strength of the solute’s interaction with
the mobile and stationary phases.
Retention on a given column pertain to the particulars of that
system:
- size of the column
- flow rate of the mobile phase
3. 3.) Efficiency:
Efficiency is related experimentally to a solute’s peak width.
- an efficient system will produce narrow peaks
- narrow peaks smaller difference in interactions in order to separate two
solutes
Efficiency is related theoretically to the various kinetic processes that are
involved in solute retention and transport in the column
- determine the width or standard deviation (σ) of peaks
Estimate σ from peak widths,
assuming Gaussian shaped peak:
Wh
Wb = 4σ
Wh = 2.354σ
Dependent on the amount of time that a solute spends in the column (k’ or tR)
4. Number of theoretical plates (N): compare efficiencies of a system for
solutes that have different retention times
N = (tR/σ)2
or for a Gaussian shaped peak
N = 16 (tR/Wb)2
N = 5.54 (tR/Wh)2
The larger the value of N is for a column, the better the column will be
able to separate two compounds.
- the better the ability to resolve solutes that have small differences
in retention
- N is independent of solute retention
- N is dependent on the length of the column
5. Plate height or height equivalent of a theoretical plate (H or HETP): compare
efficiencies of
columns with different lengths:
H = L/N
where: L = column length
N = number of theoretical plates for the column
Note: H simply gives the length of the column that corresponds to one theoretical
plate
H can be also used to relate various chromatographic parameters (e.g., flow rate,
particle size, etc.) to the kinetic processes that give rise to peak broadening:
Why Do Bands Spread?
a. Eddy diffusion
b. Mobile phase mass transfer
c. Stagnant mobile phase mass transfer
d. Stationary phase mass transfer
e. Longitudinal diffusion
6. Van Deemter equation: relates flow-rate or linear velocity to H:
H = A + B/µ + Cµ
where:
µ = linear velocity (flow-rate x Vm/L)
H = total plate height of the column
A = constant representing eddy diffusion &
mobile phase mass transfer
B = constant representing longitudinal
diffusion
C = constant representing stagnant mobile
phase & stationary phase mass
transfer
One use of plate height (H) is to relate these kinetic process to
band broadening to a parameter of the chromatographic system
(e.g., flow-rate).
This relationship is used to predict what the resulting effect would
be of varying this parameter on the overall efficiency
of the chromatographic system.
7. Plot of van Deemter equation shows how H changes with the linear velocity (flow-
rate) of the mobile phase
µ optimum
Optimum linear velocity (µopt) - where H has a minimum value and the
point of maximum column efficiency.
µopt is easy to achieve for gas chromatography, but is usually too small for
liquid chromatography requiring flow-rates higher than optimal to separate
compounds
8. 4.) Measures of Solute Separation:
separation factor (α) – parameter used to describe how well two solutes are
separated by a chromatographic system:
α = k’2/k’1 k’ = (tR –tM)/tM
where:
k’1 = the capacity factor of the first solute
k’2 = the capacity factor of the second solute,
with k’2 ~ k’
A value of α ~ 1.1 is usually indicative of a good separation
Does not consider the effect of column efficiency or peak widths, only retention.
9. Resolution (RS) – resolution between two peaks is a second measure of how
well two peaks are separated:
tr2 – tr1
RS = (Wb2 + Wb1)/2
where:
tr1, Wb1 = retention time and baseline width for the first eluting peak
tr2, Wb2 = retention time and baseline width for the second eluting peak
Rs is preferred over α since
both retention (tr) and column
efficiency (Wb) are considered
in defining peak separation.
Rs ~1.5 represents baseline
resolution, or complete
separation of two neighboring
solutes ideal case.
Rs ~1.0 considered adequate
for most separations.
10. Gas Chromatography
A.) Introduction:
Gas Chromatography (GC) is a chromatographic technique in which
the mobile phase is a gas.
GC is currently one of the most popular methods for separating and
analyzing compounds. This is due to its high resolution, low limits of
detection, speed, accuracy and reproducibility.
GC can be applied to the separation of any compound that is either
naturally volatile (i.e., readily goes into the gas phase) or can be
converted to a volatile derivative. This makes GC useful in the
separation of a number of small organic and inorganic compounds.
11. Gas Chromatography
B.) Equipment:
A simple GC system consists of:
1. Gas source (with pressure and flow regulators)
2. Injector or sample application system
3. Chromatographic column (with oven for temperature
control)
4. Detector & computer or recorder
12. A typical GC system used is shown below (a gas chromatograph)
Carrier gas: He (common), N2, H2
Pinlet 10-50 psig
Flow = 25-150 mL/min packed column
Flow = 1-25 mL/min open tubular column
Column: 2-50 m coiled stainless steel/glass/Teflon
Oven: 0-400 °C ~ average boiling point of sample
Accurate to <1 °C
Detectors: FID, TCD, ECD, (MS)
14. C.) Mobile Phase:
GC separates solutes based on their different interactions with the
mobile and stationary phases.
- solute’s retention is determined mostly by its vapor pressure
and volatility
- solute’s retention is controlled by its interaction with the
stationary phase
- gas mobile phase has much lower density
‚decreased chance for interacting with solute
‚increased chance that solid or liquid stationary phase
interacts with solute
15. Carrier gas – main purpose of the gas in GC is to move the solutes
along the column, mobile phase is often referred to as carrier
gas.
Common carrier gas: include He, Ar, H2, N2
16. Carrier Gas or Mobile phase does not affect solute retention, but
does affect:
1.) Desired efficiency for the GC System
- low molecular weight gases (He, H2) larger
diffusion coefficients
- low molecular weight gases faster, more efficient
separations
2.) Stability of column and solutes
- H2 or O2 can react with functional groups on solutes
and stationary phase or with surfaces of the
injector,
connections and detector
3.) Response of the detector
- thermal conductor requires H2 or He
- other detectors require specific carrier gas
17. D.) Stationary Phases:
Stationary phase in GC is the main factor determining the
selectivity and retention
of solutes.
There are three types of stationary phases used in GC:
Solid adsorbents
Liquids coated on solid supports
Bonded-phase supports
18. 1.) Gas-solid chromatography (GSC)
- same material is used as both the stationary phase and support material
- common adsorbents include:
‚ alumina
‚l molecular sieves (crystalline
aluminosilicates [zeolites] and clay)
‚ silica
‚ active carbon
Magnified Pores in activated carbon
19. Gas-solid chromatography (GSC):
advantages:
- long column lifetimes
- ability to retain and separate some compounds not easily
resolved by other GC methods
‚ geometrical isomers
‚ permanent gases
disadvantage:
- very strong retention of low volatility or polar solutes
- catalytic changes that can occur on GSC supports
- GSC supports have a range of chemical and physical
environments
‚ different strength retention sites
‚ non-symmetrical peaks
‚ variable retention times
20. 2.) Gas-liquid chromatography (GLC)
- stationary phase is some liquid coated on a solid support
- over 400 liquid stationary phases available for GLC
‚ many stationary phases are very similar in terms of
their retention properties
- material range from polymers (polysiloxanes, polyesters,
polyethylene glycols) to fluorocarbons, molten salts and liquid
crystals
21. Based on polarity, of the 400 phases available only 6-12 are needed for
most separations. The routinely recommended phases are listed below:
Chemical nature of Max. McReynolds’ constants
Name polysiloxane temp. x’ y’ z’ µ’ s’
SE-30 Dimethyl 350 14 53 44 64 41
Dexsil300 Carborane-dimethyl 450 43 64 111 151 101
OV-17 50% Phenyl methyl 375 119 158 162 243 202
Higher the
number the
OV-210 50% Trifluoropropyl 270 146 238 358 468 310
higher the
absorption.
OV-225 25% Cyanopropyl- 250 238 369 338 492 386
25% phenyl
Silar-SCP 50% Cyanopropyl- 275 319 495 446 637 531
50% phenyl
SP-2340 75% Cyanopropyl 275 520 757 659 942 804
OV-275 Dicyanoallyl 250 629 872 763 1106 849
McReynolds’ constants based on retention of 5 standard “probe” analytes
– Benzene, n-butanol, 2-pentanone, nitropropanone, pyridine
22. Preparing a stationary phase for GLC:
- slurry of the desired liquid phase and solvent is made
with a solid support
‚i
w solid support is usually diatomaceous
earth (fossilized shells of ancient aquatic
algae (diatoms), silica-based material)
- solvent is evaporated off, coating the liquid stationary
phase on the support
- the resulting material is then packed into the column
23. disadvantage:
- liquid may slowly bleed off with time
‚ especially if high temperatures are used
‚ contribute to background
‚ change characteristics of the column with
time
24. 3.) Bonded-Phase Gas chromatography
- covalently attach stationary phase to the solid support
material
- avoids column bleeding in GLC
- bonded phases are prepared by reacting the desired
phase with the surface of a silica-based support
reactions form an Si-O-Si bond between the stationary phase
and support
or
reactions form an Si-C-C-Si bond between the stationary phase
and support
25. - many bonded phases exist, but most separations can be formed with
the
following commonly recommended bonded-phases:
‚ Dimethylpolysiloxane
‚ Methyl(phenyl)polysiloxane
‚ Polyethylene glycol (Carbowax 20M)
‚ Trifluoropropylpolysiloxane
‚ Cyanopropylpolysiloxane
CH3 CH3 C6H5 H H
O Si O Si O Si HO C C O H
CH3
n CH3 C6H5 n
n m H H
advantages:
- more stable than coated liquid phases
- can be placed on support with thinner and more uniform
thickness than liquid phases
26. E.) Support Material:
There are two main types of supports used in GC:
Packed columns
‚ large sample capacity
‚ preparative work
Capillary (open-tubular) columns
‚ahigher efficiency
‚i smaller sample size
‚ analytical applications
27.
28. F.) Elution Methods:
A common problem to all chromatographic techniques is that in any one
sample there may be many solutes present, each retained by the
column to a different degree:
Best separation and limits
of detection are usually
obtained with solutes with
k’ values of 2-10
Difficult to find one
condition that elutes all
solutes in this k’ range
general elution problem
Gradient elution - change column condition with time which changes
retention of solutes to overcome general elution problem
29. Temperature Programming – changing the temperature on the column with time to
simulate gradient elution in GC since a solute’s retention in GC is related to its
volatility.
Comparison of a GC separation using isothermal conditions and temperature
programming is shown below
ISOTHERMAL
Column temp. 120oC
Programmed temp.
(30oC to 180oC) (5o/min)
Temperature programming is usually done either in a stepwise change, a linear change or a
combination of several linear changes. A single linear change or ramp is the most common
30. G.) GC Detectors:
The following devices are common types of GC detectors:
1. Thermal Conductivity Detector (TCD)
2. Flame Ionization Detector (FID)
3. Nitrogen-phosphorus Detector
4. Electron Capture Detector (ECD)
5. Mass Spectrometers (discussed later in the course)
The choice of detector will depend on the analyte and
how the GC method is being used (i.e., analytical or
preparative scale)
31. 1.) Thermal Conductivity Detector (TCD)
- katherometer or hot-wire detector
- first universal detector developed for GC
Process
- measures a bulk property of the mobile phase leaving the
column.
- measures ability to conduct heat away from a hot-wire (i.e.,
thermal conductivity)
- thermal conductivity changes with presence of other
components in the mobile phase
32. Design
- based on electronic circuit known as a Wheatstone bridge.
- circuit consists of an arrangement of four resistors with a fixed current applied to
them.
- thermal conductivity changes with presence of other components in the mobile
phase.
- the voltage between points (+) and (-) will be zero as long as the resistances in the
different arms of the circuit are properly balanced
-one resistor in contact with
mobile phase leaving
column
-another in contact with
reference stream of pure
mobile phase
as solute emerge from column:
change in thermal conductivity change in amount of heat removed from
resistor change in resistor’s temperature and resistance change in voltage
difference between points (+) and (-).
33. Considerations
- mobile phase must have very different thermal conductivity
then solutes being separated.
- most compounds separated in GC have thermal conductivity
of about 1-4X10-5.
- H2 and He are carrier gases with significantly different
thermal conductivity values.
- H2 reacts with metal oxides present on the resistors, so not
used
34. advantages:
- truly universal detector
‚ applicable to the detection of any compound in GC
- non-destructive
‚ useful for detecting compounds from
preparative-scale columns
‚ useful in combination with other types of GC
detectors
disadvantage:
- detect mobile phase impurities
- sensitive to changes in flow-rates
- limit of detection
‚ ~ 10-7 M
‚ much higher then other GC detectors
35. 2.) Flame Ionization Detector (FID)
- most common type of GC detector
- “universal” detector capable of measuring the presence of almost any
organic and many inorganic compound
Process
- measures the production of ions when
a solute is burned in a flame.
- ions are collected at an electrode to
create a current
36. advantages:
- universal detector for organics
‚ doesn’t respond to common inorganic
compounds
- mobile phase impurities not detected
- carrier gases not detected
- limit of detection: FID is 1000x better than TCD
- linear and dynamic range better than TCD
disadvantage:
- destructive detector
37. 3.) Nitrogen-Phosphorus Detector (NPD)
- used for detecting nitrogen- or phosphorus containing compounds
- also known as alkali flame ionization detector or thermionic detector
Process
Alkali Bead
- same basic principal as FID
- measures production of ions when a solute
is burned in a flame
- ions are collected at an electrode to
create a current
- contains a small amount of alkali metal
vapor in the flame
- enhances the formation of ions from
nitrogen- and phosphorus- containing compounds
38. 3.) Nitrogen-Phosphorus Detector (NPD)
advantages:
- useful for environmental testing
‚ detection of organophosphate pesticides
- useful for drug analysis
- ‚ determination of amine-containing or basic
drugs
- Like FID, does not detect common mobile phase impurities
or carrier gases
- limit of detection: NPD is 500x better than FID in detecting
nitrogen and phosphorus- containing compounds
- NPD more sensitive to other heterocompounds, such as
sulfur-, halogen-, and arsenic- containing molecules
disadvantage:
- destructive detector
- NPD is less sensitive to organic compounds compared to
FID
39. 4.) Electron Capture Detector (ECD)
- radiation-based detector
- selective for compounds containing
electronegative atoms, such as halogens
Process
- based on the capture of electrons by
electronegative atoms in a molecule
- electrons are produced by ionization of the
carrier gas with a radioactive source
‚ 3H or 63Ni
- in absence of solute, steady stream of
these electrons is produced
- electrons go to collector electrode where
they produce a current
- compounds with electronegative atoms
capture electrons, reducing current
40. advantages:
- useful for environmental testing
‚ detection of chlorinated pesticides or herbicides
‚ detection of polynuclear aromatic carcinogens
‚ detection of organometallic compounds
- selective for halogen- (I, Br, Cl, F), nitro-, and sulfur-
containing compounds
- detects polynuclear aromatic compounds, anhydrides
and conjugated carbonyl compounds
42. Gas Chromatography can only be used to
analyze volatile components (i.e. compounds
that can be volatilized at 250oC without
decomposition).
Non-volatile components have to be
derivatized before GC analysis.
43. Retention Times
Response
RT= 4.0 min on SE-30
Hexane
GC Retention Time on SE-30
Response
RT= 4 min on SE-30
Unknown compound
GC Retention Time on SE-30
44. TENTATIVE IDENTIFICATION OF UNKNOWN COMPOUNDS
Response
Mixture of known compounds
Octane
Decane
1.6 min = RT
Hexane
GC Retention Time on Carbowax-20 (min)
Response
Unknown compound may be Hexane
1.6 min = RT
Retention Time on Carbowax-20 (min)
45. SEMI- QUANTITATIVE ANALYSIS OF FATTY ACIDS
Detector Response
C18
Peak Area (cm2 )
C 16 10
8
C14 6
4
2
0.5 1.0 1.5 2.0 2.5 3.0
Retention Time Sample Concentration (mg/ml)
C4
1
The content % of C fatty acids =
14 1
∗0
0
C + C11
+ C 8
6
1
4
= the content % of C fatty acids
14
46. GLC ADVANTAGES
1. Very good separation
2. Time (analysis is short)
3. Small sample is needed - µl
4. Good detection system
5. Can be used for both qualitative
and quantitative analysis
47. DISADVANTAGES OF GAS
CHROMATOGRAPHY
Material has to be volatilized at 250oC
without decomposition. If not the analyte has
to be derivatized.
e.g. Fatty acids → Methyl esters
Phenols → Silanized
Sugars → Silanized
48. Fatty Acids Methylester
O O
R C OH + CH3 OH + H2 SO4 R C O CH3
Reflux Volatile in Gas
Chromatography
O
CH2 O C R
O CH3 ONa O
CH O C R + CH 3 OH 3 R C O CH3
Volatile in Gas
O
Chromatography
CH2 O C R