The document discusses gas chromatography, including the general design of gas chromatographs and key components like columns, injectors, and detectors. It provides details on:
- The design of gas chromatographs, including gas supplies, flow control, temperature zones, and data collection systems.
- The separation process in gas chromatography, where analytes partition between a mobile gas phase and stationary liquid phase.
- Types of columns like packed and capillary, and factors to consider when choosing a column like sample capacity and resolution.
- Injection types like on-column, splitless, and split injection and their applications.
- Common detectors like the flame ionization detector (FID), thermal conductivity detector (TCD), and
These slides give an introduction to gas chromatography, It also guides analyst to a proper selection of liner, column, and some main operating conditions.
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.
These slides give an introduction to gas chromatography, It also guides analyst to a proper selection of liner, column, and some main operating conditions.
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.
Gas chromatography and its instrumentationArgha Sen
Gas chromatography is an unique technology which helps us in separating volatile analytes. Its is an easy and reproduciple method for detecting residual solvents found in APIs.
Gas chromatography and its instrumentationArgha Sen
Gas chromatography is an unique technology which helps us in separating volatile analytes. Its is an easy and reproduciple method for detecting residual solvents found in APIs.
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Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
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.
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.
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These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
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.
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.
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
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.
3. Some of the design“details”
• Gas supplies usually have either in-line or instrument
mounted traps to remove any water, oxygen,
hydrocarbons or other “contaminants” from compressed
gases
• Gas flows can be controlled using either needle valves or
mass-flow controllers (electronic sensors)
• Instruments can have multiple injectors, detectors or
columns
• Injectors and detectors usually have their own
temperature controlled zones (small heaters)
• The GC oven has a large fan and a vent door to help with
rapid cooling of the oven
• Data collection (and integration) can be done using a chart
recorder, integrator or a computerized data system
4. Separation Processes in GC
• Gas Chromatography as it is usually performed is correctly called gas-
liquid chromatography
• the analyte is in the gas phase in the GC and partitions between the mobile
phase (carrier gas) and the liquid stationary phase that is coated on the
inside of an open-tubular capillary column or on particles inside a packed
column
• Some packed-column GC uses non-coated solid stationary phases, in
which case one is performing gas-solid adsorption chromatography
• Capillary, open-tubular (WCOT specifically) column GC is the primary
type of GC used in quantitative analysis:
• higher resolution = greater ability to discriminate between components
• smaller capacity of the column is not important as long as sufficient analyte is
available for detection
• pg/mL (ppt) to g/mL (ppm) concentration range for liquid analytes
5.
6. The Objective in
Chromatography (all types)
• Separate your analytes (resolution of 1.5 or better) in
the shortest amount of time possible and detect
them….
• How can we do this in GC?
• Use different columns for different analyte types
• stationary phase
• diameter of column, stationary phase thickness
• column length
• Use different injection types/temperatures to optimize the
process of loading the sample on the column
• Use different temperature (or pressure) programs for the
column
• Select and use a detector that is suitable for the analyte(s) of
interest
7. GC Columns (concentrating on open-tubular capillary
columns)
• Column “frame” constructed of fused silica tubing
• Polyamide coating on the outside gives it strength
• Liquid stationary phases coated or bonded to the inside of the
tubing
• 0.1 - 0.53 mm + ID, 5-100 meters in length, stationary phases
usually 0.10 to 1.5 m in thickness
• Mounted on a wire cage to make them easier to handle
• 5-150 meters long.
11. Choosing a GC Column…
• Is the column compatible with your analytes
• polar analytes require polar stationary phases so they will
spend some of their “time” in the stationary phase
• non-polar analytes require non-polar stationary phases
• You usually have to compromise on the stationary phase to
get a good column for your analytes (which are probably a
mix of polar and non-polar)
• DB-5, HP-5, EC-5, RTX-5 (5% dimethyl, 95% diphenyl
polysiloxane) most common general use column.
• Temperature range, solvent and carrier gas
compatibility
• Sample capacity versus resolution
• usually determines packed vs.. capillary
• GC’s usually setup for either packed or capillary
• Let’s say you choose a capillary column, there’s more
to think about!
12.
13.
14.
15.
16. For capillary GC columns….
Increased length = greater N, therefore a greater R
expense is possible band broadening if analytes are on the
column too long!
Increased length leads to longer separations. Do you have
the time?
Increased stationary phase thickness and column
diameter provides increased sample capacity and
can provide increased resolution
tradeoffs are a longer analysis time and more column bleed
with thicker stationary phases
Is the column compatible with the detector?
Thick stationary phases bleed more and will contaminate a
mass spectrometer.
For most analytical work, a best “compromise”
column is chosen and other variables (temp, etc.) are
altered to optimize the separation.
17.
18.
19. Capillary vs. Packed Columns
Capillary Columns:
Higher resolution (R)
Greater HETP and N
Shorter analysis time
Greater sensitivity
Most common in analytical
laboratory GC instruments
Smaller sample capacity
Higher cost/column
Columns more susceptible
to damage
Packed Columns
Greater sample capacity
Lower cost (can make your own)
More rugged
Most common in process labs or
separating/determining major
components in a sample (prep
GC)
Limited lengths reduces R and N
Not compatible with some GC
detectors
20. Temperature Programming in GC
The “simplest” way to alter the separation in GC is to
alter the temperature program in the oven. You can
also alter the pressure of the carrier gas, but this is
less common (much).
Isothermal = constant temperature
Gradient = varied temperature
By altering the temperature, you vary the rate of the
reaction for any analyte:
they spend more or less time in the stationary phase
the greater the difference in the times between analytes, the
better the separation!
Analyte
Analyte phase
stationary
phase
mobile
21.
22. The traps of temperature…
If your temperature at a given time is too high, you
can cause the peaks to co-elute
poor resolution vs but a faster separation
If your temperature at a given time is too low, you
can get still get a good separation
adequate resolution, but a separation that takes very
long
You have to choose a compromise temperature
program
23.
24. GC Carrier Gases (the mobile phase)
Usually “inert” gases (don’t react with analytes except
sometimes in the detector)
Purpose:
sweep sample through the column
protect column from oxygen exposure at temperature
assist with function of the detector
Most common:
Helium (available relatively pure without extensive purification after
it leaves a compressed gas cylinder)
Nitrogen (usually requires an oxygen and water trap)
Hydrogen
normally used only with flame ionization detectors (FID) since the FID
needs it as fuel for the flame
still rarely used due to safety concerns (and chromatographic ones)
25.
26. GC Injection….
Samples are injected through a septum:
keeps oxygen out of the column
provides a seal to keep the carrier gas pressure up at the
head of the column
carrier gas flow rate is determined by the pressure or the gas at
the opening of the column
Many different (mostly proprietary) materials
red rubber (bleeds at about 250 C)
Thermogreen (good up to about 300 C)
High-temperature blue (good a little over 300 C)
The injector is usually lined with a de-activated glass
liner
prevents metal injector-sample reactions that would alter
analytes or damage the metal of the injector
Can be cleaned/replaced regularly
30. On-Column Injection:
used widely in packed-column GC, less in capillary GC
sample is deposited directly on the column
Good for thermally unstable compounds
Good for quantitative analysis at low concentrations
all sample is available to travel to the detector
BUT, you can inject only a relatively small amount of sample in
capillary GC anyhow.
Splitless Injection:
Sample is vaporized in the injector itself and ALL of the
sample is swept onto the column by the carrier gas
Again, relatively small samples are injected (10 L or less in
capillary GC)
Sample spends a large amount of time in the injector
Best for trace (1 -100 ppm range) concentrations of high
boiling point analytes in low boiling point solvents
extra time in the injector helps volatilize the analytes.
31. Split Injection:
the injection is split, with only a portion of the
sample (usually 1% - 20%) actually making it to
the column
the most common method of injecting samples
onto small diameter, open-tubular columns.
Even if you inject 20 L, only a fraction (adjustable)
makes it on to the column
Not good for analytes with a wide range of
boiling points
some may be swept out the split vent before they are
volatilized
Modern capillary GCs come with a
Split/Splitless injectors standard
you switch between modes by changing the split
vent gas flow and using a different injection liner.
33. GC Detectors
A dozen or more varieties (some obscure)
Must be:
sensitive to the analytes of interest
compatible with the column, carrier gas, solvent, etc.
rugged enough to withstand general unattended used
I’ve run our new GC for 36 hours straight without touching it!
Should have a known linear range
if the detector response is very linear, you can use a response
factor instead of a calibration curve for quantitation!
Usually require separate gas supplies (other than the
carrier gas), have their own temperature control.
Measure nothing more than a voltage or a current.
39. Thermal Conductivity
(TCD)
The carrier gas has a known
thermal conductivity.
As the thermal conductivity of
the column eluent (gas flow in)
changes, the resistance of the
filament changes.
The presence of analyte
molecules in the carrier gas
alter the thermal conductivity of
the gas (usually He)
There is normally a second
filament to act as a reference
(the carrier gas is split)
Increased sensitivity with
decreasing temperature
(detector), flow rate and applied
current.
Filaments will burn out
(oxidized) in the presence of
oxygen if hot!
Non-destructive
40.
41. FID
Destructive, sample lost.
Analytes containing C burn
in a hydrogen-oxygen flame
and produce ions
CHO+ ions are collected on a
cathode and the current they
produce results in the signal
WILL NOT detect non-C
containing compounds!
Requires H2 supply (tank or
generator) and O2 supply
(compressed air)
H2 carrier gas can be used,
eliminating the need for a
supply for the detector
A makeup gas can also be
required!
-
Flame
O
,
H
e
CHO
O
CH
2
2
42.
43. ECD
Particularly sensitive to halogens nitriles,
carbonyls, nitro compounds
Analytes pass through a cell, in which
electrons are traveling between a 63Ni
electrode and a collector electrode
As analytes with “electron capturing
ability” pass through the cell, the flow of
electrons is interrupted.
The change in current, due to reduced
flow of electrons, is recorded.
EXTREMELY SENSITIVE TO
HALOGENS
could ruin detector with 1 ppm
hexachlorocyclohexane by contaminating it
with excess analyte
Widely used for the determination of
pesticides, herbicides and PCBs in
environmental samples.
Non-destructive