fluorometry is used in pharmaceutical fields.An analytic method for detecting and measuring fluorescence in compounds that uses ultraviolet light stimulating the compounds, causing them to emit visible light. An important topic studied in instrumental analysis.
a substance can absorb any visible light or external radiation and then again emit it. this called fluorescence and the process of reduction in fluorescence intensity is called quenching. this presentation is all about quenching of fluorescence.
Fluorescence is the phenomenon whereby a molecule, after absorption radiation, emits radiation of a longer wavelength.
A compound absorbs radiation in the UV-rgion and emits visible light.
Absorption of uv/visible radiation causes transition of electrons from ground state (low energy) to excited state (high energy).
This increase in wavelength is known as the Stokes shift.
a substance can absorb any visible light or external radiation and then again emit it. this called fluorescence and the process of reduction in fluorescence intensity is called quenching. this presentation is all about quenching of fluorescence.
Fluorescence is the phenomenon whereby a molecule, after absorption radiation, emits radiation of a longer wavelength.
A compound absorbs radiation in the UV-rgion and emits visible light.
Absorption of uv/visible radiation causes transition of electrons from ground state (low energy) to excited state (high energy).
This increase in wavelength is known as the Stokes shift.
In this slide contains principle, instrumentation, methodology, and application of gel chromatography.
Presented by: SATHEES CHANDRA (Department of pharmaceutical analysis).
RIPER, anantapur
spectrofluorometer is the instrument for recording fluorescence emission and absorption spectra When a beam of light is incident on certain substances they emit visible light or radiations. This is known as fluorescence. Fluorescence starts immediately after the absorption of light and stops as soon as the incident light is cut off. The substances showing this phenomenon are known as flourescent substances.
This presentation include the detailed explanation of various parts of a UV-Visible spectrophotometer and two types of UV-Visible spectrophotometers-Single beam and Doube beam. It also include the comparison between single beam and double beam spectrophotometers.
Fluorimetry is a technique used in analytical chemistry and biochemistry to measure the concentration of a substance in a sample by analyzing the fluorescence it emits when exposed to specific wavelengths of light. This technique is based on the principle of fluorescence, which is the emission of light (or photons) by a molecule when it absorbs photons at a shorter wavelength.
Here's how fluorimetry works:
Excitation: A sample is exposed to a specific wavelength of light, known as the excitation wavelength, which is typically in the ultraviolet or visible range. This excitation light is absorbed by the molecules of interest in the sample, causing them to move to higher energy states.
Emission: After absorbing the excitation light, the molecules return to their ground state by releasing energy in the form of fluorescent light at longer wavelengths. The emitted light is typically at a longer wavelength than the excitation light, and it is specific to the particular molecule or compound being analyzed.
Detection: A detector, such as a photomultiplier tube or a photodiode, is used to measure the intensity of the emitted fluorescent light. The detector is sensitive to the specific wavelength of light emitted by the target molecules.
Data Analysis: The intensity of the emitted fluorescent light is correlated with the concentration of the substance in the sample. By comparing the intensity of the emitted light to a calibration curve or standard, the concentration of the substance can be determined.
Fluorimetry has various applications in chemistry and biology. It is commonly used for quantifying the concentration of fluorescent dyes, proteins, nucleic acids (e.g., DNA and RNA), and other biomolecules. It is also employed in environmental analysis, drug discovery, and medical diagnostics.
One of the advantages of fluorimetry is its high sensitivity, which allows for the detection of very low concentrations of analytes. Additionally, it offers high selectivity because the emitted fluorescence is specific to the target molecule.
Overall, fluorimetry is a valuable analytical tool that helps researchers and scientists measure and analyze a wide range of substances with high precision and sensitivity
In this slide contains principle, instrumentation, methodology, and application of gel chromatography.
Presented by: SATHEES CHANDRA (Department of pharmaceutical analysis).
RIPER, anantapur
spectrofluorometer is the instrument for recording fluorescence emission and absorption spectra When a beam of light is incident on certain substances they emit visible light or radiations. This is known as fluorescence. Fluorescence starts immediately after the absorption of light and stops as soon as the incident light is cut off. The substances showing this phenomenon are known as flourescent substances.
This presentation include the detailed explanation of various parts of a UV-Visible spectrophotometer and two types of UV-Visible spectrophotometers-Single beam and Doube beam. It also include the comparison between single beam and double beam spectrophotometers.
Fluorimetry is a technique used in analytical chemistry and biochemistry to measure the concentration of a substance in a sample by analyzing the fluorescence it emits when exposed to specific wavelengths of light. This technique is based on the principle of fluorescence, which is the emission of light (or photons) by a molecule when it absorbs photons at a shorter wavelength.
Here's how fluorimetry works:
Excitation: A sample is exposed to a specific wavelength of light, known as the excitation wavelength, which is typically in the ultraviolet or visible range. This excitation light is absorbed by the molecules of interest in the sample, causing them to move to higher energy states.
Emission: After absorbing the excitation light, the molecules return to their ground state by releasing energy in the form of fluorescent light at longer wavelengths. The emitted light is typically at a longer wavelength than the excitation light, and it is specific to the particular molecule or compound being analyzed.
Detection: A detector, such as a photomultiplier tube or a photodiode, is used to measure the intensity of the emitted fluorescent light. The detector is sensitive to the specific wavelength of light emitted by the target molecules.
Data Analysis: The intensity of the emitted fluorescent light is correlated with the concentration of the substance in the sample. By comparing the intensity of the emitted light to a calibration curve or standard, the concentration of the substance can be determined.
Fluorimetry has various applications in chemistry and biology. It is commonly used for quantifying the concentration of fluorescent dyes, proteins, nucleic acids (e.g., DNA and RNA), and other biomolecules. It is also employed in environmental analysis, drug discovery, and medical diagnostics.
One of the advantages of fluorimetry is its high sensitivity, which allows for the detection of very low concentrations of analytes. Additionally, it offers high selectivity because the emitted fluorescence is specific to the target molecule.
Overall, fluorimetry is a valuable analytical tool that helps researchers and scientists measure and analyze a wide range of substances with high precision and sensitivity
Luminescence is the emission of light by a substance. It occurs when an electron returns to the electronic ground state from an excited state and loses its excess energy as a photon.
It is of 3 types.
Fluorescence spectroscopy.
Phosphorescence spectroscopy.
Chemiluminescence spectroscopy
Fluorescence spectroscopy. : When a beam of light is incident on certain substances they emit visible light or radiations. This is known as fluorescence. Fluorescence starts immediately after the absorption of light and stops as soon as the incident light is cut off. The substances showing this phenomenon are known as flourescent substances
Phosphorescence spectroscopy: When light radiation is incident on certain substances they emit light continuously even after the incident light is cut off.
This type of delayed fluorescence is called phosphorescence.
Substances showing phosphorescence are phosphorescent substances.
Chemiluminescence (also chemoluminescence) is the emission of light (luminescence) as the result of a chemical reaction. There may also be limited emission of heat
Fluorescence
Phosphorescence
Radiation less processes
Vibration relaxation
Internal conversion
External conversion
Intersystem crossing
Jablonski diagram is a graphical representation of the various transitions(electronic states, vibrational levels) that can occur after a molecule has been excited photochemically.
When a molecule is raised from its ground state to a higher state using light, photochemistry occurs.
The molecule in the excited state has a shorter lifetime and significantly more energy than the ground state from which it was formed.
As a result, molecules in the excited state are much more reactive.
A photochemical or photophysical process deactivates an excited state.
Therefore, the fate of the excited molecules is described by using the Jablonski diagram, which only focuses on the photophysical process occurring during the excitation and deactivation process.
Radiative transitions involve the absorption of a photon, if the transition occurs to a higher energy level, or the emission of a photon, for a transition to a lower level.
Nonradiative transitions arise through several different mechanisms, all differently labeled in the diagram. Relaxation of the excited state to its lowest vibrational level is called vibrational relaxation. This process involves the dissipation of energy from the molecule to its surroundings, and thus it cannot occur for isolated molecules. A second type of nonradiative transition is internal conversion (IC), which occurs when a vibrational state of an electronically excited state can couple to a vibrational state of a lower electronic state.
A third type is intersystem crossing (ISC); this is a transition to a state with a different spin multiplicity. In molecules with large spin-orbit coupling, intersystem crossing is much more important than in molecules that exhibit only small spin-orbit coupling. ISC can
Parkinsonism which is also called as movement disorder is a progressive neurodegenerative disorder. In this ppt we will discuss about it with its pathophysiology and antiparkinsons drugs. Parkinsonism was first described by James Parkinson in 1817.
Market segmentation is the practice of dividing your target market into approachable groups. Market segmentation creates subsets of a market based on demographics, needs, priorities, common interests, and other psychographic or behavioral criteria used to better understand the target audience. Splitting up an audience in this way allows for more precisely targeted marketing and personalized content.
Paper chromatography is an analytical method used to separate coloured chemicals or substances.It is now primarily used as a teaching tool, having been replaced in the laboratory by other chromatography methods such as thin-layer chromatography (TLC).
This ppt briefly summaries the major drugs used in the management of respiratory disease and are used in their treatment. We will also have a look at the moa, contraindications, pharmacokinetics of drugs used in their treatment.
Our body needs many minerals. A balanced diet usually provides all of the essential minerals. The ppt list minerals, what they do in the body their functions, and their sources in foods. It also included deficiencies and toxic effects.
The above PPT includes different methods of sterilization- Dry heat, Moist heat, Radiation and Chemical methods. It also includes the basic knowledge on sterilization and tests for sterility.
This presentation quotes various pharmaceuticals calculations with examples. The following aspects like percentage calculations, alcoholic dilutions, alligation method, proof spirits calculation, isotonicity adjustment.
Anti-fungal medication is used to treat to fungal infections. They most commonly affect our skin, hair and nails .Nowadays skin problems are found very often.
This ppt highlights the discussion pertaining to the drugs acting on endocrine system. This include the discussions on insulin, oral hypoglycemic agents and glucagon. This is based according to Vth semester syllabus.
Herb drug and herb food interaction ppt by nitesh kumarNITESH KUMAR
HERB DRUG AND HERB FOOD INTERACTION IS AN IMPORTANT CHAPTER IN HERBLA DRUG TECHNOLOGY IN THE SYLLABUS OF B.PHARMACY 6TH SEM. IT GIVES A BETTER UNDERTANDING OF HERB FOOD INTERACTION AND RELATED DRUGS.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
2. Fluorescence: It is a phenomenon of emission of radiation when
the molecules are excited by radiation at certain wavelength.
Fluorimetry: It is measurement of fluorescence intensity at a
particular
wavelength with the help of a filter fluorimeter or a
spectrofluorimeter.
Principle:
Molecule contains σ electrons, π electrons and nonbonding (n)
electron.
The electrons may be present in bonding molecular orbital. It is
called as highest occupied molecular orbital (HOMO). It has lest
energy and more stable.
When the molecules absorb radiant energy from a light source,
the bonding electrons may be promoted to anti bonding
molecular orbital (LUMO). It has more energy and hence less
stable.
3. Excitation - The process of promotion of electrons from HOMO to
LUMO with absorption of energy is called as excitation.
Singlet state: a state in which all the electrons in a molecule are
paired. (↓↑)
Doublet state: a state in which un paired electrons are present.
(↓or↑)
Triplet state: a state in which unpaired electrons of same spin
present. (↑↑ )
Singlet excited state: a state in which electrons are unpaired but
of opposite spin like (↑↓) (un paired and opposite spin)
HOMO - Highest Occupied Molecular Orbital
LOMO - Lowest Occupied Molecular Orbital
When light of appropriate wavelength is absorbed by a
molecule the electrons are promoted from singlet ground state
to singlet excited state. Once the molecule is in this excited
state, relaxation can occur via several processes by emission of
radiation
4. Factors affecting fluorescence intensity:
1. Concentration: Fluorescence intensity is proportional to
concentration of substance only when the absorbance is less
than 0.02.
2. Quantum yield of fluorescence (ϕ):
(ϕ) = number of photons emitted/number of photons
absorbed
It is always less than 1.0 since some energy is lost by
radiation less pathways (Collisional, Intersystem Crossing,
Vibrational Relaxation)
3. Intensity of incident light: Increase in the intensity of incident
light on the sample fluorescence intensity also increases.
4. Adsorption: Adsorption of sample solution in the container
may leads to a serious problem.
5. Oxygen: Oxidation of fluorescent species to a non-
fluorescent species, quenches fluorescent substance.
6. pH: Alteration of pH of a solution will have significant effect
on fluorescence
5. 7. Temperature and viscosity:
Temperature increases can increase the collisional de
activation, and reduce fluorescent intensity.
If viscosity of solution is more the frequency of collisions are
reduced and increase in
fluorescent intensity.
8. Photochemical decomposition:
Absorption of intense radiation leads to photochemical
decomposition of a fluorescent substance to less fluorescent or
non-fluorescent substance.
9. Quenchers:
Quenching is the reduction of fluorescence intensity by the
presence of substance in the sample other than the fluorescent
analyte.
Quenching is following types:
a. Inner fluorescent effect: Absorption of Incident (UV) light or
emitted (fluorescent) light by primary and secondary filters
leads to decrease in fluorescence intensity.
6. b. Self-quenching: At low concentration linearity is observed, at
high concentration of the same substance increase in
fluorescent intensity is observed. This phenomenon is called
self-quenching.
c. Collisional quenching: Collisions between the fluorescent
substance and halide ions leads to reduction in fluorescence
intensity.
d. Static quenching: This occurs because of complex
formation between the fluorescent molecule and other
molecules. Ex: caffeine reduces fluorescence of riboflavin.
10. Scatter: Scatter is mainly due to colloidal particles in solution.
Scattering of incident light after passing through the sample
leads to decrease in fluorescence intensity.
Instrumentation:
1) Source of light:
Mercury vapor lamp: Mercury vapor at high pressure give
intense lines on continuous background above 350nm.low
pressure mercury vapor gives an additional line at 254nm.it is
7. Xenon arc lamp: It give more intense radiation than mercury
vapor lamp. it is used in spectrofluorimeter.
Tungsten lamp: If excitation has to be done in visible region this
can be used. It is used in low cost instruments.
2) Filters and Monochromators:
Filters: These are nothing but optical filters work on the
principle of absorption of unwanted light and transmitting the
required wavelength of light. In inexpensive instruments
fluorimeter primary filter and secondary filter are present.
a. Primary filter: Absorbs visible radiation and transmit UV
radiation.
b. Secondary filter: Absorbs UV radiation and transmit visible
radiation.
Monochromators: They convert polychromatic light into
monochromatic light. They can isolate a specific range of
wavelength or a particular wavelength of radiation from a
source.
a. Excitation monochromators: Provides suitable radiation
for
excitation of molecule.
8. b. Emission monochromators: Isolate only the radiation emitted
by the fluorescent molecules.
3) Sample cells: These are meant for holding liquid samples.
These are made up of quartz and can have various shapes ex:
cylindrical or rectangular etc.
4) Detectors: Photometric detectors are used. They are
A. Barrier layer /photovoltaic cell:
It is employed in inexpensive instruments. For ex: Filter
Fluorimeter.
It consists of a copper plate coated with a thin layer of cuprous
oxide (Cu2O). A semitransparent film of silver is laid on this
plate to provide good contact.
When external light falls on the oxide layer, the electrons
emitted from the oxide layer move into the copper plate.
Then oxide layer becomes positive and copper plate becomes
negative.
Hence an emf develops between the oxide layer and copper
plate and behaves like a voltaic cell. So, it is called photovoltaic
cell.
9. A galvanometer is connected externally between silver film and
copper plate and the deflection in the galvanometer shows the
current flow through it.
The amount of current is found to be proportional to the
intensity of incident light.
B. Photomultiplier tubes (PMT):
These are incorporated in expensive instruments like
spectrofluorimeter. Its sensitivity is high due to measuring
weak intensity of light.
The principle employed in this detector is that, multiplication of
photoelectrons by secondary emission of electrons.
This is achieved by using a photo cathode and a series of
anodes (Dyanodes). Up to 10 dyanodes are used. Each
dyanode is maintained at 75 - 100V higher than the preceding
one.
At each stage, the electron emission is multiplied by a factor of
4 to 5 due to secondary emission of electrons and hence an
overall factor of 106 is achieved.
10. PMT can detect very weak signals, even 200 times weaker than
that could be done using photovoltaic cell. Hence it is useful in
fluorescence measurements.
PMT should be shielded from stray light in order to have
accurate results.
Instruments:
The most common types are:
Single beam (filter) fluorimeter
Double beam (filter) fluorimeter
Spectrofluorimeter (double beam)
Single beam (filter) fluorimeter
It contains tungsten lamp as a source of light and has an
optical system consists of primary filter.
The emitted radiations are measured at 900 by using a
secondary filter and detector.
Primary filter absorbs visible radiation and transmit UV radiation
which excites the molecule present in sample cell.
11. Instead of 90 if we use 180 geometry as in colorimetry
secondary filter has to be highly efficient otherwise both the
unabsorbed UV radiation and fluorescent radiation will produce
detector response and give false result.
Single beam instruments are simple in construction cheaper
and easy to operate.
Double beam fluorimeter
It is similar to single beam except that the two incident beams
from a single light source pass through primary filters
separately and fall on another reference solution.
Then the emitted radiations from the sample or reference
sample pass separately through secondary filter and produce
response combinedly on a detector.
Spectrofluorimeter:
In this primary filter in double beam fluorimeter is replaced by
excitation monochromator and the secondary filter is replaced
by emission monochromator.
Incident beam is split into sample and reference beam by using
beam splitter.
12.
13.
14. Applications:
Fluorimetric methods are not useful in qualitative analysis and
much used in quantitative analysis.
Determination of inorganic substances. Al3+, Li+, Zn2+
Determination of thiamine HCl.
Determination of phenytoin.
Determination of indoles, phenols, & phenothiazines
Determination of napthols, proteins, plant pigments and
steroids.
Fluorimetry, nowadays can be used in detection of impurities in
nanogram level better than absorbance spectrophotometer with
special emphasis in determining components of sample at the
end of chromatographic or capillary column.
Determination of ruthenium ions in presence of other platinum
metals.
Determination of boron in steel, aluminum in alloys, manganese
in steel.
Determination of boron in steel by complex formed with
benzoin.
Estimation of cadmium with 2-(2 hydroxyphenyl) benzoxazole in
presence of tartarate.
Respiratory tract infections