Polarographic technique is applied for the qualitative or quantitative analysis of electroreducible or oxidisable elements or groups.
It is an electromechanical technique of analyzing solutions that measures the current flowing between two electrodes in the solution as well as the gradually increasing applied voltage to determine respectively the concentration of a solute and its nature.
The principle in polarography is that a gradually increasing negative potential (voltage) is applied between a polarisable and non-polarisable electrode and the corresponding current is recorded.
Polarisable electrode: Dropping Mercury electrode
Non-polarisable electrode: Saturated Calomel electrode
From the current-voltage curve (Sigmoid shape), qualitative and quantitative analysis can be performed. This technique is called as polarography, the instrument used is called as polarograph and the current-voltage curve recorded is called as polarogram
It is an electrochemical method of analysis used for the determination or measurement of the electrical conductance of an electrolyte solution by means of a conductometer.
Electric conductivity of an electrolyte solution depends on :
Type of ions (cations, anions, singly or doubly charged
Concentration of ions
Temperature
Mobility of ions
The main principle involved in this method is that the movement of the ions creates the electrical conductivity. The movement of the ions is mainly depended on the concentration of the ions.
The electric conductance in accordance with ohms law which states that the strength of current (i) passing through conductor is directly proportional to potential difference & inversely to resistance.
i =V/R
content- Principle
Ilkovic equation
Construction and working of dropping mercury electrode and rotating platinum electrode
Applications
Polarography is a voltammetric technique in which chemical species (ions or molecules) undergo oxidation (lose electrons) or reduction (gain electrons) at the surface of a dropping mercury electrode (DME) at an applied potential. Polarography only applies to the DME.
Objective of polarography
Polarography is an electroanalytical technique that measures the current flowing between two electrodes in the solution (in the presence of gradually increasing applied voltage) to determine the concentration of solute and its nature respectively
Polarography is based upon the principle that gradually increasing voltage is applied between two electrodes, one of which is polarisable (dropping mercury electrode) and other is non-polarisable and current flowing between the two electrodes is recorded.
A sigmoid shape current-voltage curve is obtained from which half wave potential as well as diffusion current is calculated.
Diffusion current is used for determination of concentration of substance.
Half wave potential is characteristic of every element.
Ilkovic equation is a relation used in polarography relating the diffusion current (id) and the concentration of the non-polarisable electrode, i.e., the substance reduced or oxidised at the dropping mercury electrode (polarisable electrode).
Definitions of types of currents
1. Residual current (ir), 2. Migration current (im): , 3. Diffusion current (id) 4.Half wave potential 5. Limiting current (il)
Dropping mercury electrode- Dropping mercury electrode (DME) is a polarisable electrode and can act as both anode and cathode.
The pool of mercury acts as counter electrode,
i.e., anode if DME is cathode or
cathode if DME is anode.
The counter electrode is a non-polarisable electrode.
To the analyte solution, electrolyte like KCl is added i.e., 50-100 times of sample concentration.
Pure nitrogen or hydrogen gas is bubbled through the solution, to expel (remove) out oxygen.
Eg: If the analyte solution contains cadmium ions, then cadmium ions are discharged at cathode (-)
Cd2+ + 2e- → Cd
Then, gradually increasing voltage is applied to the polarographic cell and current is recorded.
Graph is plotted between voltage applied and current. This graph is called Polarograph and the apparatus is known as Polarogram.
The diffusion current produced is directly proportional to concentration of analyte and this is used in quantitative analysis.
The half wave potential is characteristic of every compound and this is used in qualitative analysis.
Graph is plotted between voltage applied and current. This graph is called Polarograph and the apparatus is known as Polarogram.
The diffusion current produced is directly proportional to concentration of analyte and this is used in quantitative analysis.
The half wave potential is characteristic of every compound
It is an electrochemical method of analysis used for the determination or measurement of the electrical conductance of an electrolyte solution by means of a conductometer.
Electric conductivity of an electrolyte solution depends on :
Type of ions (cations, anions, singly or doubly charged
Concentration of ions
Temperature
Mobility of ions
The main principle involved in this method is that the movement of the ions creates the electrical conductivity. The movement of the ions is mainly depended on the concentration of the ions.
The electric conductance in accordance with ohms law which states that the strength of current (i) passing through conductor is directly proportional to potential difference & inversely to resistance.
i =V/R
content- Principle
Ilkovic equation
Construction and working of dropping mercury electrode and rotating platinum electrode
Applications
Polarography is a voltammetric technique in which chemical species (ions or molecules) undergo oxidation (lose electrons) or reduction (gain electrons) at the surface of a dropping mercury electrode (DME) at an applied potential. Polarography only applies to the DME.
Objective of polarography
Polarography is an electroanalytical technique that measures the current flowing between two electrodes in the solution (in the presence of gradually increasing applied voltage) to determine the concentration of solute and its nature respectively
Polarography is based upon the principle that gradually increasing voltage is applied between two electrodes, one of which is polarisable (dropping mercury electrode) and other is non-polarisable and current flowing between the two electrodes is recorded.
A sigmoid shape current-voltage curve is obtained from which half wave potential as well as diffusion current is calculated.
Diffusion current is used for determination of concentration of substance.
Half wave potential is characteristic of every element.
Ilkovic equation is a relation used in polarography relating the diffusion current (id) and the concentration of the non-polarisable electrode, i.e., the substance reduced or oxidised at the dropping mercury electrode (polarisable electrode).
Definitions of types of currents
1. Residual current (ir), 2. Migration current (im): , 3. Diffusion current (id) 4.Half wave potential 5. Limiting current (il)
Dropping mercury electrode- Dropping mercury electrode (DME) is a polarisable electrode and can act as both anode and cathode.
The pool of mercury acts as counter electrode,
i.e., anode if DME is cathode or
cathode if DME is anode.
The counter electrode is a non-polarisable electrode.
To the analyte solution, electrolyte like KCl is added i.e., 50-100 times of sample concentration.
Pure nitrogen or hydrogen gas is bubbled through the solution, to expel (remove) out oxygen.
Eg: If the analyte solution contains cadmium ions, then cadmium ions are discharged at cathode (-)
Cd2+ + 2e- → Cd
Then, gradually increasing voltage is applied to the polarographic cell and current is recorded.
Graph is plotted between voltage applied and current. This graph is called Polarograph and the apparatus is known as Polarogram.
The diffusion current produced is directly proportional to concentration of analyte and this is used in quantitative analysis.
The half wave potential is characteristic of every compound and this is used in qualitative analysis.
Graph is plotted between voltage applied and current. This graph is called Polarograph and the apparatus is known as Polarogram.
The diffusion current produced is directly proportional to concentration of analyte and this is used in quantitative analysis.
The half wave potential is characteristic of every compound
ESTIMATION OF THE RATE OF REACTION WILL BE DONE BASED ON THE POTENTIAL DIFFERENCE BETWEEN REFERENCE AND INDICATOR ELECTRODE. THE POTENTIAL OF THE REFERENCE ELECTRODE IS STABLE WHERE AS THE POTENTIAL OF THE INDICATOR ELECTRODE VARIES WITH THE POTENTIAL OF THE SOLUTION IN WHICH IT IS PLACED
The earliest voltammetric technique
Heyrovsky invented the original polarographic method in 1922, conventional direct current polarography (DCP).
It employs a dropping mercury electrode (DME) to continuously renew the electrode surface.
Diffusion is the mechanism of mass transport.
When an external potential is applied to a cell
containing a reducing substance such as CdCl2,
The following reaction will occur:
Cd2+ + 2e + Hg = Cd(Hg)
The technique depends on increasing the applied
voltage at a steady rate and simultaneously
record photographically the current-voltage
curve (polarogram)
The apparatus used is called a polarograph .
When an external potential is applied to a cell
containing a reducing substance such as CdCl2,
The following reaction will occur:
Cd2+ + 2e + Hg = Cd(Hg)
The technique depends on increasing the applied
voltage at a steady rate and simultaneously
record photographically the current-voltage
curve (polarogram)
The apparatus used is called a polarograph .
Capillary tube about 10-15cm
Int. diameter of 0.05mm
A vertical distance being maintained betwwen DME and the solution
Drop time of 1-5 seconds
Drop diameter 0.5mm
The supporting electrolyte
is a solution of (KNO3, NaCl, Na3PO4) in which the sample (which must be electroactive) is dissolved.
Function of the supporting electrolyte
It raises the conductivity of the solution.
It carries the bulk of the current so prevent the
migration of electroactive materials to working
electrode.
It may control pH
It may associate with the electroactive solute as
in the complexing of the metal ions by ligands.
Amperometry refers to the measurement of current under a constant applied voltage and under these conditions it is the concentration of analyte which determine the magnitude of current.
In Amperometric titrations, the potential applied between the indicator electrode (dropping mercury electrode) and the appropriate depolarizing reference electrode (saturated calomel electrode) is kept constant and current through the electrolytic cell is then measured on the addition of each increment of titrating solution. It is a form of quantitative analysis.
Otherwise called as Polarographic or polarometric titrations.
IR SPECTROSCOPY, INTRODUCTION, PRINCIPLE, THEORY, FATE OF ABSORBED RADIATION, FERMI RESONANCE, FINGERPRINT REGION, VIBRATIONS, FACTORS AFFECTING ABSORPTION OF IR RADIATION, SAMPLING TECHNIQUES, APPLICATIONS OF IR SPECTROSCOPY.
This presentation includes the most important cell used in polarography Dropping Mercury Electrode. Its structure, uses/Advantages and limitations are explain here
ESTIMATION OF THE RATE OF REACTION WILL BE DONE BASED ON THE POTENTIAL DIFFERENCE BETWEEN REFERENCE AND INDICATOR ELECTRODE. THE POTENTIAL OF THE REFERENCE ELECTRODE IS STABLE WHERE AS THE POTENTIAL OF THE INDICATOR ELECTRODE VARIES WITH THE POTENTIAL OF THE SOLUTION IN WHICH IT IS PLACED
The earliest voltammetric technique
Heyrovsky invented the original polarographic method in 1922, conventional direct current polarography (DCP).
It employs a dropping mercury electrode (DME) to continuously renew the electrode surface.
Diffusion is the mechanism of mass transport.
When an external potential is applied to a cell
containing a reducing substance such as CdCl2,
The following reaction will occur:
Cd2+ + 2e + Hg = Cd(Hg)
The technique depends on increasing the applied
voltage at a steady rate and simultaneously
record photographically the current-voltage
curve (polarogram)
The apparatus used is called a polarograph .
When an external potential is applied to a cell
containing a reducing substance such as CdCl2,
The following reaction will occur:
Cd2+ + 2e + Hg = Cd(Hg)
The technique depends on increasing the applied
voltage at a steady rate and simultaneously
record photographically the current-voltage
curve (polarogram)
The apparatus used is called a polarograph .
Capillary tube about 10-15cm
Int. diameter of 0.05mm
A vertical distance being maintained betwwen DME and the solution
Drop time of 1-5 seconds
Drop diameter 0.5mm
The supporting electrolyte
is a solution of (KNO3, NaCl, Na3PO4) in which the sample (which must be electroactive) is dissolved.
Function of the supporting electrolyte
It raises the conductivity of the solution.
It carries the bulk of the current so prevent the
migration of electroactive materials to working
electrode.
It may control pH
It may associate with the electroactive solute as
in the complexing of the metal ions by ligands.
Amperometry refers to the measurement of current under a constant applied voltage and under these conditions it is the concentration of analyte which determine the magnitude of current.
In Amperometric titrations, the potential applied between the indicator electrode (dropping mercury electrode) and the appropriate depolarizing reference electrode (saturated calomel electrode) is kept constant and current through the electrolytic cell is then measured on the addition of each increment of titrating solution. It is a form of quantitative analysis.
Otherwise called as Polarographic or polarometric titrations.
IR SPECTROSCOPY, INTRODUCTION, PRINCIPLE, THEORY, FATE OF ABSORBED RADIATION, FERMI RESONANCE, FINGERPRINT REGION, VIBRATIONS, FACTORS AFFECTING ABSORPTION OF IR RADIATION, SAMPLING TECHNIQUES, APPLICATIONS OF IR SPECTROSCOPY.
This presentation includes the most important cell used in polarography Dropping Mercury Electrode. Its structure, uses/Advantages and limitations are explain here
This Power point presentation was prepared to describe in detail about the two main voltammetry techniques of electrochemistry which is polarography and voltammetry. In these slides, I discussed the working, instrumentation, various electrodes, advantages, disadvantages..etc. Hope you understand the topic.
Potentiometry, Electrochemical cell, construction and working of indicator an...Vandana Devesh Sharma
Potentiometry - Electrochemical cell -Construction and working of reference (Standard hydrogen, silver chloride electrode and calomel electrode)
Indicator electrodes (metal electrodes and glass electrode)
Methods to determine end point of potentiometric titration
and applications
Potentiometry is the method to find the concentration of solute in
A given solution by measuring the potential between two Electrodes
(reference and Indicator electrode) . Potentiometric titration involves
the measurement of the potential of the indicator electrode and
reference electrode.
In potentiometric titration reference and indicator electrodes are
immersed in the solution of particular analyte (titrand) and
potential of indicator electrode is measured with relation to
reference electrode.
Titrant is added in analyte (Titrand) and change in potential is noted
down.
At the end point there is sharp change in potential on indicator
electrode.
Graph is plotted between the indicator electrode potential and
volume of titrant added.
This method is used for determination of sharp end point.
Types of Potentiometric Titration
1. Acid-base titration 2. Redox Titration 3.Complexometric titration 4. Precipitation Titration
Herbal drugs / herbal medicines include
herbs, herbal materials, herbal preparations and
finished herbal products, that contain as active ingredients, part of plants, or other plant materials, or combinations.
Herbal medicines comprise of therapies employing plant based products.
It is an integral part of Ayurveda and some indigenous medical systems.
Herbal drugs are becoming more popular in the modern world for their application to cure variety of diseases with less toxic effects and better therapeutic effects
OSI Reference Model - internationally standardised network architecture.
OSI = Open Systems Interconnection: deals with open systems, i.e.systems open for communications with other systems.
Specified in ISO 7498.
Model has 7 layers.
Supercomputers...are used to process very large amounts of information including processing information to predict hurricanes, satellite images and navigation, and process military war scenarios
Mainframes...are used by government and businesses to process very large amounts of information.
Mini-Computers...are similar to mainframes...they are used by business and government to process large amounts of information.
Personal Computers (PC
The first computers used vacuum tubes for circuitry and magnetic drums for memory.
They were often enormous and taking up entire room.
First generation computers relied on machine language.
They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.
The UNIVAC and ENIAC computers are examples of first-generation computing devices.
Chromatography is an analytical method in which compounds are physically separated and measured.
The main purpose of chromatography is to separate and quantify the target sample.
The Chromatography technique used to separate a mixture of compounds in pharmaceutical sciences , analytical analytical Chemistry with the purpose of identifying, quantifying and purifying the individual components of the mixture.
The Hedgehog pathway was discovered in fruit fly (Drosophila) and is conserved in vertebrates (including humans)
The Hedgehog pathway is involved in cell growth and differentiation to control organ formation during embryonic development.
Hedgehog signalling regulates embryonic development, ensuring that tissues reach their correct size and location, maintaining tissue polarity and cellular content.
In the skin, the Hedgehog pathway is critical for regulating hair follicle and sebaceous gland development.
Germline mutations in components of the Hedgehog signalling pathway results in a number of developmental abnormalities.
Hedgehog signalling normally remains inactive in most adult tissues
Oxygen is highly reactive atom that is capable of becoming part
of potentially damaging molecule commonly called “free radical.”
Free radicals are capable of attacking cells of the body, causing
them to lose their structure and function.
Free radicals have been implicated in the pathogenesis of at
least 50 diseases.
Free radial formation is controlled naturally by various compounds
known as antioxidants.
It is when the ability of antioxidant is limited that this damage can
become cumulative and debilitating.
Following criteria should be considered while selecting an antioxidant.
It should be able to produce desire redox reaction.
It should be physiologically and chemically compatible.
It should be physiologically inert.
It should be non-toxic both in the reduced and oxidized forms.
It should be effective in low concentration.
It should provide prolonged stability to the formulation.
These are the substances which are added in the formulation along the therapeutic agent so as to impart specific qualities in the formulation.
These are have very little or no therapeutic value but are necessary in the manufacture of various dosage forms.
Purposes served by Additives:
Provide bulk to the formulation.
Facilitate drug absorption or solubility and other pharmacokinetic considerations.
Aid in handling of “API” during manufacturing .
Provide stability and prevent from denaturation etc
Exists without actions of humankind in the form of matter/energy which is available in the earth and get used by living thing.
Or exist as a separate entity such as fresh water, air and as well as a living organism such as a fish.
Or it may exist in an alternate form that must be processed to obtain the resource such as metal ores, petroleum, and most forms of energy.
Extraction is a process of separation or isolation of pharmaceutical active ingredients
from plant or animal drugs with the help of solvent.
On the basis of the physical nature of crude drug to be extracted i.e. liquid or solid ,the extraction process may be:
Liquid –Liquid Extraction Or
Solid –Liquid Extraction.
The solvent used for extraction is called as ‘Menstruum’ and the residue left after extracting desired constituents is called ‘Marc’.
Required Ideal Properties of Menstruum :
Should be inert and non –toxic
Should extract only the desirable constituent of the crude drug .
Should be cheap and easily available
Parkinson’s disease (PD) is the second most chronic, slowly progressive age associated
neurodegenerative disorder characterized by selective loss of dopaminergic neurons in the substantia nigra (SN) pars compacta, leads to deficiency or depletion dopamine (DA) in the striatum.
Idiopathic - (unknown cause)
Genetic - (clustering of early-onset pd in some families)
Drug induced (Anti-depressant, calcium channel blockers)
Toxins – (Environmental and Neurotoxins)
Head Trauma – (During accidental conditions)
Cerebral Anoxia
Histamine is an endogenous substance that is amine synthesized, stored and released by the various cells of the body: (a) Mast cells, which are abundant in the skin, GI, and the respiratory tract,
(b) Basophils in the blood, and (c) Some neurons in the CNS and peripheral NS.
It is an “Autocoid” that is secreted locally and regulate the activity of various near lying cells and neurons.
Huntington's disease is slowly progressive, rapidly growing hereditary brain disease that causes abnormal motor coordination, thinking, behavior and ultimately leads to dementia.
Its necessary to diagnosis earlier i.e. onset of movement disorder, particularly
with chorea and impaired voluntary movement.
Autosomal dominant inheritance with 2000 people are diagnosed each year.
No drug therapy is available
The worldwide prevalence of Huntington’s Disease is 5-10 cases per 10000 which affects men and women equally
SPECTROSCOPY is defined as the study of the interactions between radiations and matter as function of wavelength λ .
Interactions with particle radiation or a response of a material to an altering field
or varying frequency.
SPECTRUM : A plot of the response as a function of wavelength or more commonly frequency is referred to as spectrum.
SPECTROMETRY : It is measurement of these responses and an instrument which performs such measurements is a spectrophotometer or spectrograph, although
these terms are more limited in use to original field of optics from which the
concept sprang.
HPTLC is the improved method of TLC which utilizes the conventional technique of TLC in more optimized way.
It is also known as planar chromatography or Flat-bed chromatography.
Chromatography is a physical process of separation in which the components to be separated are distributed between 2 immiscible phases-a stationary phase which has a large surface area and mobile phase which is in constant motion through the stationary phase.
These are the organic products of natural or synthetic origin which are basic in
nature & contain one or more than one nitrogen atoms, normally of heterocyclic nature &
possess specific physiological actions on human or animal body, when used in small quantites.
The term is derived from the word ‘alkali-like’ & hence they resemble some of characters
of naturally occuring amines.
The term is derived from the word ‘alkali-like’ & hence they resemble some of
characters of naturally occuring amines.
A Ward round is a visit made by a medical practitioner, alone or with a team of health care professionals and medical students to hospital in-patients at their bedside to review and follow-up the progress in their health.
Usually at least one ward round is conducted
everyday to review the progress of each
patient outcome.
Pharmacist’s participating in medical ward
rounds promotes health care
Participation of the Pharmacists in ward
rounds in various practice settings helps to
provide rational drug use.
PHARMACOVIGILANCE
The World Health Organization (WHO) defines Pharmacovigilance as “the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other drug-related problem.”
ADVERSE DRUG REACTION
According to WHO “ADR is a response to a drug which is noxious and unintended, and which occurs at doses normally used in man for the prophylaxis, diagnosis, or therapy of disease, or for the modifications of physiological function.”
Have full fleged clinical trial data management systems which bring them a good amount of business and revenue.
CDM is a fundamental process which controls data accuracy of each trial besides helping the timelessness to be achieved.
It helps in linking clinical research co-ordinator = who monitor all the sites & collects the data.
it Links with biostatisticians = who analyze, interpret and report data in clinically meaningful way.
Pyrogens include any substance capable of eliciting a febrile (or fever) response upon injection or infection
Endotoxin is a subset of pyrogens that are strictly of gram- negative bacterial origin; they occur (virtually) nowhere else in nature.
Lipopolysaccharide (LPS)is a part of endotoxin, or, endotoxin is the natural complex of LPS occurring in the outer layer of the bilayered gram-negative bacterial cell
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
HOT NEW PRODUCT! BIG SALES FAST SHIPPING NOW FROM CHINA!! EU KU DB BK substit...GL Anaacs
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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.
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
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
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
1. Polarography
DR. RUPINDER KAUR
ASSOCIATE PROFESSOR
DEPT. OF PHARMACEUTICAL CHEMISTRY
ISF COLLEGE OF PHARMACY
WEBSITE: - WWW.ISFCP.ORG
EMAIL: RUPINDER.PHARMACY@GMAIL.COM
ISF College of Pharmacy, Moga
Ghal Kalan, GT Road, Moga- 142001, Punjab, INDIA
Internal Quality Assurance Cell - (IQAC)
2. Introduction
Polarographic technique is applied for the qualitative or quantitative analysis of
electroreducible or oxidisable elements or groups.
It is an electromechanical technique of analyzing solutions that measures the current
flowing between two electrodes in the solution as well as the gradually increasing
applied voltage to determine respectively the concentration of a solute and its nature.
created by: Jaroslav Heyrovsky
2
3. 3Principle
The principle in polarography is that a gradually increasing negative potential
(voltage) is applied between a polarisable and non-polarisable electrode and the
corresponding current is recorded.
• Polarisable electrode: Dropping Mercury electrode
• Non-polarisable electrode: Saturated Calomel electrode
From the current-voltage curve (Sigmoid shape), qualitative and quantitative analysis
can be performed. This technique is called as polarography, the instrument used is
called as polarograph and the current-voltage curve recorded is called as polarogram.
4. 4
The point of inflection in the current-
voltage curve is known as Half-wave
potential and is characteristic or typical for
every element or functional group –
Qualtitative aspect.
The diffusion current measured is
proportional to the concentration of that
particular compound- Quantitative aspect.
Thus, polarography can be used for both
qualitative and quantitative analysis of
compounds.
5. 5
Polarographic measurements are governed by ilkovic equation
Ilkovic Equation — The linear relationship between the diffusion current (id) and the
concentration of electroactive species is shown by the Ilkovic equation:
id = 607 nCD1/2m2/3t1/6,
id = diffusion current in microamperes;
n = number of electrons required per molecule of electroactive Substance,
D = diffusion coefficient, in square cm per second,
C = concentration, in millimoles per L,
m = mass of mercury flow from the DME, in mg per second,
t = drop time, in seconds.
Polarographic measurements
6. 6
Organic and inorganic samples can be analysed.
Even low concentrations of the samples can be detected (10-3 M to 10-4 M).
Rapidity of the technique.
Qualitative and quantitative analysis can be performed easily.
Mixture of compounds or elements could be analysed without seperation.
Advantages of Polarography
7. 7Mercury electrodes
In polarography, mercury is used as a working
electrode, because mercury is a liquid. The working
electrode is often a drop suspended from the end of
a capillary tube.
3 examples of electrodes:
• HMDE (Hanging mercury drop electrode)
• DME (dropping mercury electrode)- Most
commonly used electrode. Mercury drops form
at the end of the capillary tube as a result of
gravity. The optimum interval between drops
for most analysis is between 2 to 5 seconds.
• DSME (static mercury drop electrode)
•
8. 8
Hg yields reproducible current-potential data.
This reproducibility can be attributed to the continuous
exposure of fresh surface on the growing mercury drop.
With any other electrode (such as Pt in various forms), the
potential depends on its surface condition and therefore on
its previous treatment.
The vast majority of reactions studied with the mercury
electrode are reductions.
Why Dropping Mercury Electrode?
At a Pt surface, reduction of solvent is expected to compete with reduction of
many analyte species, especially in acidic solutions.
The high overpotential for H+ reduction at the mercury surface. Therefore, H+
reduction does not interfere with many reductions.
9. 9
A mercury electrode is not very useful for performing oxidations, because Hg is
too easily oxidized.
The electrode cannot be used over +0.4 V (vs S.C.E.), because Hg dissolves and
anodic wave is recorded. Lesser than -1.8 V, hydrogen is liberated.
The capillary is difficult to maintain since dust or other articulate matter can block
the capillary.
Problems with mercury electrode
10. 10
The polarographic apparatus consists of a
polarisable electrode (DME) and a reference
electrode (SCE).
Between these electrodes, the required potential
range (0 to -3 V) can be applied.
It consists of a sample cell made up of glass, in
which the sample solution t be analysed is kept.
The capillary is dipped into the solution to be
analysed and the height of the mercury
reservoir is adusted so that droptime of about 2-
7 sec is set.
Method of Analysis
11. 11
Supporting electrolytes like potassium chloride is added to the sample solution to
eliminate migration current.
The oxygen present in the sample solution is rremoved by passing Nitrogen or using
alkaline pyrogallol solution.
Maximum suppressors are added in the required concentration range.
When all these things are done, the initial and final potential is set in the instrument
and the current-voltage curve is recorded.
From the polarogram, half wave potential and diffusion current is determined and
thus qualitative and quantitative analysis is performed.
12. 12Polarographic Maxima
An increase of current above the limiting
value in the form of a maximum is often
noticed on polarographic waves known as
polarographic maxima.
The origin of the maximum is sometimes
connected with the mechanism of the
electrode process as in the case of catalytic
discharge of ions, while in many cases, it is
caused by the increased transport of the
depolarizer towards the electrode by a
streaming motion of the solution.
The presence of this reproducible polarographic maxima leads to error in
determining half wave potential and diffusion current.
13. 13Elimination of Polarographic maxima
Maximum suppressors which increases the viscosity eliminate the polarographic
maxima such as:
• Gelatin (0.002% to 0.01%)
• Dyes (methyl red)
• Surfactants (triton)
14. 14
Residual current (ir): It is the sum of the relatively larger condensor current and a very
small Faradic current. Condensor current is due to the formation of Helmholtz double
layer at the mercury surface and Faradic current is due to the traces of impurities.
Migration current (im): It is due to migration of cations from the bulk of the solution
towards cathode due to diffusive force, irrespective of concentration gradient.
Diffusion current (id): Diffusion current is due to the actual diffusion of
electroreducible ion from the bulk of the sample to the surface os the mercury droplet
due to concentration gradient.
Limiting current (id): Beyind a certain potential, the current reaches a steady value
called as the limiting current. At this point, the rate of diffusion of ions is equal to the
rate of reduction and the state of electrode is said to be concentration polarised.
Different types of current in polarography
15. 15Factors affecting Diffusion Current
Concentration: Diffusion current is directly proportional to the concentration of the
electroreducible ions.
Temperature: Diffusion current also varies with respect to temperature (directly
proportional).
Viscosity of the medium: Diffusion coefficient depends on the viscosity of the
medium. Hence, diffusion current also varies.
Capillary characteristics: The bore size of the capillary, drop time in seconds and
the pressure of the mercury will all affect the diffusion current as they alter the flow
characteristics of mercury droplet.
Presence of maximum suppressors: Maximum suppressors like gelatin, dye stuffs
and surfactants will affect the diffusion current.
16. 16
Dissolved oxygen and peroxides
Trace metals and metal –containing drugs
Antiseptics and insecticides
Vitamins
Hormones
Antibiotics
Alkaloids
Blood serum and cancer diagnosis
Pharmaceutical Applications
17. 17
Only small volume of sample is required.
Turbid and coloured solutions can be analyzed.
It can be used for the determination of substances, which are not electrochemical
active (indirect).
Prior separation of excepients is not required.
Its sensitivity is sufficient for the determination trace elements and toxic impurities.
High speed analysis which is important for QC
Advantages of Polarography