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Wednesday, June 24, 2015

Outline of Methamphetamine

Methamphetamine 

 Class of drugs is sympathomimetic

 Has direct stimulant activity on the CNS and Myocardium

 It is widely used to treat obesity

 They are extensively abused by individuals who try to stay awake for long period of time





 the effects of Methamphetamine generally last 2-4 hours

 has a half-life of 9-24 hours in the body

 generally detectable in the urine for 3-5 days

 Confirmatory testing is performed using GCMS.

 the effects of Methamphetamine generally last 2-4 hours

 has a half-life of 9-24 hours in the body

 generally detectable in the urine for 3-5 days

 Confirmatory testing is performed using GCMS.

Screening Sample – Urine
Confirmatory Sample - Blood

Methods

1. Immunoassay Systems Screening procedure (Methamphetamine card test)

2. Liquid or gas chromatography

Precautions 

-Adulterants, such as bleach or other strong oxidizing agents.

- Clean container w/o any preservatives

- Store the urine specimen at 2-8 degrees C or freeze urine specimen (-20degrees C) for longer storage

Friday, June 19, 2015

Solving the weight of substances needed to produce molar and normal solutions





To be able to solve the weight of substances needed to prepare certain molar and normal solutions, you can use the general formulas:

For Normal solutions

N = GEW/L of solution

GEW = W/MW/v

N = (W/MW/v)/L of solution

Where:

GEW = Gram Equivalent Weight

L = Liter

W = weight in grams of substance

MW = Molecular Weight

v = valence


The short cut formula is:

W = DN X DV X EW (MW/v)

Where:

DN = Desired Normality
DV = Desired Volume
MW = Molecular weight
v = valence

Here’s a sample problem.

How much CaCl2 will you need in preparing 500 mL of a 0.5 N solution?
W = DN X DV X EW (MW/v)
W = 0.5 X 0.5 X (111/2)
W = 13.875 grams of CaCl2

To prepare the 0.5 N CaCl2 solution:

Weigh 13.875 grams of CaCl2 and dilute it to 500 mL of solution in  a volumetric flask. You can first dispense 250 ml of the distilled water to the flask, dissolve the 13.875 CaCl2, and then add the diluent up to the 500 mL mark of the volumetric flask.

Take note of the following:

1.    Volume must be always be converted to liters when using this formula, or if you don’t want to convert, divide your answer by 1,000.

2.    The powder must not be added to 500 ml or 0.5 L but diluted TO 500 mL to in a volumetric flask to get the exact volume. The resulting volume in your 500 ml flask after dissolving the CacL2 must not be more or less than 500 ml. This will ensure accuracy of your measured solution.


For Molar solutions

M = GMW/L of solution

GMW = Weight/MW

M = (W/MW)/L of solution

Where:

GMW = Gram Molecular Weight

L = Liter

W = weight in grams of substance

MW = Molecular Weight

v = valence


Hence for Molar solutions the formula is:

W = DM X DV X MW

Where:

DM = Desired Molarity
DV = Desired Volume
MW= Molecular Weight

If you're given the same data but asked to solve for the molarity this is the formula and substitution:


Here’s a sample problem.

How much CaCl2 will you need in preparing 500 mL of a 0.5 M solution?
W = DN X DV X MW
W = 0.5 X 0.5 X 111
W = 27.75 grams of CaCl2
 
The only difference from the Normal solution is the absence of valence. 


To prepare the 0.5 M CaCl2 solution:

Weigh 27.75 grams of CaCl2 and dilute it to 500 mL of solution in  a volumetric flask. 
You can first dispense 250 ml of the distilled water in the flask, dissolve the 27.75 CaCl2, and then add the diluent up to the 500 mL mark of the volumetric flask.


Saturday, June 13, 2015

Clinical Chemistry 1 - Lipids and Its Major Functions, Fatty Acids Powerpoint Presentation

Lipids are unique from other substances in the blood because they are non polar and insoluble in water, but soluble in organic solvents.

Lipids (fats) in food are more difficult to digest than proteins and carbohydrates. Lipids are present in the body through various forms, such as triglyceride (storage form of lipid), phospholipid (important parts of biomembranes), cholesterol (important component of steroid hormones),fatty acids (the simplest forms of lipids).

Lipids have crucial functions in the body that include the following:

1. Acts as a body insulator. So, it's true Virginia, that when you're fat, you have more "heat insulators" in your body, hence, will feel less susceptible to the cold weather,

2. Acts as biomembranes (protector) of vital organs, such as the brain and the lungs.

3. Acts as an enzyme in the form of prostaglandin.

4. Acts as the basic component of steroid hormones.

5. Acts as carrier proteins for non-polar substances.

6. Acts as a source of energy when there's a dysfunction of carbohydrate being converted to energy.

Below is a slide presentation submitted by a previous student that you can read to let you understand more about lipids.


Thursday, June 11, 2015

Review on Lab Instrumentation, Clinical Chemistry 1



Spectrophotometer

An instrument used for measuring the transmission or reflection of light by comparing various wavelengths of the light. It also makes use of the Beer-Lambert’s principle which is “Light transmitted is inversely proportional to the concentration, while the absorbance is directly proportional to it.”




Some of the precautions in this test:

1.    Never brush cuvettes because it will lead to scratches and give inaccurate results
2.    Use rather a clean soft cloth to wipe the cells before reading it
3.    Ideal amount of the sample is ¾ full so that the light will strike the given sample and not the empty space.
4.    Let the machine be warmed up first for about 10-15 min before use, so that fluctuation is avoided.

There are four essential parts of a spectrophotometer

            1. Light source
            2.  Monochromator or filter
            3.  Sample cell with holder
            4.  Detector

Turbidimetry

-      The determination of the quantity of insoluble suspended matter in a liquid by measuring the loss of intensity of light in the direction of propagation of the incident beam, with reference to a standard solution

Gravimetry

-      Gravimetric methods of analysis are used where weights of reactants and products of chemical reactions are reproducible, stable and reflect the presence of constituents which are important in the establishment of identity. 
-      Two important methods deal with the trapping and weighing of products in the solid and gaseous phases.

Osmometry

-      Measurement of the amount of osmotic pressure that a particular solution  exerts
-      Can be vapor pressure osmometry, freezing point depression osmometry or membrane osmometry

Emission Flame Photometry

A type of flame photometry in which molecules in a flame are volatilised to generate free atoms that are excited to higher energy levels. When these atoms return to the ground state, they produce a characteristic emission spectrum. These typically use a low-temperature, air-gas, laminar flame burner which is inherently subject to drift and therefore lithium (Li), which is not a normal serum constituent, is excited as a known added constituent to "standardize" the results despite the drifting of the flame output. This approach does not permit addition of Ca as a third determined constituent as the emission of the Ca at serum levels in the low-temperature flame is below measurable intensity; furthermore the Li would interfere optically with the Ca determination.           

Atomic Absorption Spectrophotometry

             Atomic Absorption Spectrophotometry is the measurement of the concentration of an element in a given sample. This technique can be done in three ways: Flame type, Electrothermal type, and Color Vapor type. In the flame type, gas and combustible substance are used to ignite the mixture of gases.
            The second type which is electrothermal makes use of electric current and slit width. On the other hand is the cold vapor method wherein a reducing agent is added and vaporized.

Volumetry

            Volumetry is t he measurement of volumes of liquids, solids, and gas.
-the quantitative analysis of an unknown chemical solution by determining the amount of reagent of known concentration necessary to effect a reaction in a known volume of the solution
Chromatography

            It is a broad range of physical methods used to separate and or to analyze complex mixtures. The components to be separated are distributed between two phases: a stationary phase bed and a mobile phase which percolates through the stationary bed.

  1. Thin Layer Chromatography
TLC is a simple, quick, and inexpensive procedure that gives the chemist a quick answer as to how many components are in a mixture. TLC is also used to support the identity of a compound in a mixture when the Rf of a compound is compared with the Rf of a known compound (preferably both run on the same TLC plate).
A TLC plate is a sheet of glass, metal, or plastic which is coated with a thin layer of a solid adsorbent (usually silica or alumina). A small amount of the mixture to be analyzed is spotted near the bottom of this plate. The TLC plate is then placed in a shallow pool of a solvent in a developing chamber so that only the very bottom of the plate is in the liquid. This liquid, or the eluent, is the mobile phase, and it slowly rises up the TLC plate by capillary action.

B.   Gas chromatography 

    specifically gas-liquid chromatography - involves a sample being vaporized and injected onto the head of the chromatographic column. The sample is transported through the column by the flow of inert, gaseous mobile phase. The column itself contains a liquid stationary phase which is adsorbed onto the surface of an inert solid.

C.   ‘High Performance Chromatography 

       High-performance liquid chromatography   (HPLC) is a form of liquid chromatography  to  separate compounds that are dissolved in solution. HPLC instruments consist of a reservoir of mobile phase, a pump, an injector, a separation column, and a detector. Compounds are separated by injecting a plug of the sample mixture onto the column. The different components in the mixture pass through the column at different rates due to differences in their partitioning behavior between the mobile liquid phase and the stationary phase.

Electrophoresis

Electrophoresis is a separations technique that is based on the mobility of ions in an electric field. Positively charged ions migrate towards a negative electrode and negatively-charged ions migrate toward a positive electrode. For safety reasons one electrode is usually at ground and the other is biased positively or negatively. Ions have different migration rates depending on their total charge, size, and shape, and can therefore be separated.

Instrumentation

An electrode apparatus consists of a high-voltage supply, electrodes, buffer, and a support for the buffer such as filter paper, cellulose acetate strips, polyacrylamide gel, or a capillary tube. Open capillary tubes are used for many types of samples and the other supports are usually used for biological samples such as protein mixtures or DNA fragments. After a separation is completed the support is stained to visualize the separated components. 
Resolution can be greatly improved using isoelectric focusing. In this technique the support gel maintains a pH gradient. As a protein migrates down the gel, it reaches a pH that is equal to its isoelectric point. At this pH the protein is neutral and no longer migrates, i.e., it is focused into a sharp band on the gel.


Saturday, June 6, 2015

Laboratory Instrumentation in Clinical Chemistry a Powerpoint Presentation

A powerpoint presentation in Clinical Chemistry about laboratory instrumentation. View the images to help you become familiar with these instruments. You can also print the lecture version as your guide on the topic. A quiz is given at the end of the powerpoint to determine if you have learned something from the presentation. Enjoy the slide and good luck with your clinical chemistry class.

Thursday, March 19, 2015

Why Serum is the best Specimen in most Clinical Chemistry Laboratory Tests

Serum is the supernatant fluid when clotted blood has been centrifuged. It is the best specimen for most clinical chemistry laboratory tests because of its specific characteristics. Here are the reasons why serum is the best specimen.





*Serum has less protein 

When blood clots, one of the proteins - fibrinogen - takes part in the clotting process; thereby removing it from the serum. The absence of fibrinogen would make the supernatant clearer, while in plasma, since the blood does not clot, the fibrinogen remains in the supernatant and could add to the turbidity of the plasma.

*Serum has no anticoagulant

Since serum does not have an anticoagulant, there are no other substances that could interact with your test. There are potential interferences coming from anticoagulants with certain tests.

One example is the interference of the anticoagulant ethylene diaminetetraacetic acid (EDTA) in the laboratory determination of calcium ions. EDTA chelates calcium; hence, decreasing inaccurately the concentration of calcium in the sample.

The presence of an anticoagulant could also dilute the specimen and unreliably lower the concentration of the substance being analyzed.

*Most reagents are more compatible with serum 

The optimum reaction of the reagent with the substance in the blood is very important to produce reliable results; results that are precise and accurate simultaneously.

When a result is precise, it means that you get almost the same results repeatedly. Accuracy on the other hand, means obtaining values close to the “true value.”

When a result or method is reliable, then you are certain of the results because you know they could be depended on. Laboratory results are the data that doctors could base their diagnosis on.

Together with the history of the patient, the other diagnostic results, doctors could now come up with a conclusive diagnosis.

*Serum can be more stable than plasma with certain substances 

Some research like the study done by O'Keane and Cunningham proved that serum is more stable for other substances than plasma.

This is most especially for serum extracted with a separator gel. Gel tubes proved to be stable for creatinine, potassium, and urea than in plasma.

This would specify that gel tubes are more stable that plain serum tubes. These are the reasons why serum is considered the best specimen.

This does not indicate though, that the other blood specimens could not be used. There are certain tests, which require, specifically a plasma sample or a whole blood sample.

Knowing what these tests are would help a lot in coming up with reliable results and a correct diagnosis by the doctor.

Wednesday, March 18, 2015

How Ethanol Production Wastes Corn

Ethanol is a type of alcohol that can be used as a motor fuel or fuel additive. It is also present in alcoholic beverages, scents, and is sometimes used as a recreational drug. Previous studies revealed that ethanol can be produced from lignocellulosic biomass of corn stovers.

The process was originally considered as promising. The use of supposedly “useless” agricultural by-products, like corn stovers, to produce an alternative source of motor fuel was a sensational discovery, considering the scarcity of gasoline available for worldwide consumption.



Further studies revealed however, that the production of ethanol from corn stover has been found out to waste corn because of the following reasons:

1. Ethanol combustion produces 2.14 times as much ground level ozone than gasoline The data was presented by the Clean Fuels Report about the comparison of fuel emissions between ethanol and gasoline.

The report further stated that ethanol contributes 1.7 to the pollution caused by smog, while gasoline contributes only 1.0.

2. Prices of corn increased Because of the increase need in the production of ethanol from corn stovers, the price of corn has actually increased in the market.

The reduced supply of corn as staple food has prompted the increase in its price, while the total cost of producing ethanol from corn has also increased. Either way, the consumers do not benefit in the end.

3. Processing of corn stovers to ethanol is costly Contrary to previous assumptions, the production of a liter of ethanol is more costly than 1 liter of gasoline.

This is because the process of hydrolysis needs large amounts of water, needs more money to deal with carbon emissions, and requires more energy for its processing. The sugars present in the corn stovers have also to undergo fermentation before they are converted to ethanol, adding more production costs.

4. Environmental friendliness of ethanol is in question Ethanol from corn is not altogether environmental friendly because it produces acetaldehyde and formaldehyde which are considered as harmful substances. These substances can cause cancer when persons are exposed continuously for a long period of time. They pollute the environment through the water that you drink, the air you breathe and the substances or food that you take in.

The US national budget for the production of ethanol from corn was recently slashed last June, 2011 by the US Senate because of some of these aforementioned reasons.

The corn prices have dropped since then, and with this development, the corn industry would go back to being one of the primary sources of food for humans and animals and not as a source of biofuel.

Saturday, July 19, 2014

The Analysis of Blood Gas



Blood gas analysis (BGA) is also known as arterial blood gas determination (ABG), and is considered a special test in the clinical laboratory. The commonly assayed parameters are partial pressure carbon dioxide (pCO2), hydrogen ion concentration (pH) and bicarbonate (HCO3). The determination of these substances helps in the evaluation of the acid-base status of a patient.

Image credit: Lara Enriquez


The following are certain precautions observed by medical technologists in the extraction of arterial blood for blood gas analysis.

1. The best specimen is arterial blood.

This is because arterial blood is more homogenous than venous blood. The blood could be collected in the following common arterial sites: the radial artery, the brachial artery, the femoral artery and the scalp artery.

The most ideal anticoagulant is dry heparin, and the preferable syringe is a glass syringe. Recently, new receptacles are manufactured which are specifically for BGA.

2. Collect the specimen anaerobically (without air).

Your specimen should be covered at all times to prevent the escape of carbon dioxide to the air. It should be transported immediately to the testing laboratory. If it is left uncovered, unreliable results will be obtained which will lead to a wrong diagnosis by the Clinician/physician.

3. Preserve in crushed ice, if not tested immediately.

The low temperature has to be maintained. An increase in temperature would cause the gas to evaporate. It must also be preserved properly to obtain reliable results, aside from making sure that it is covered.

The body naturally maintains a state of balance called homeostasis. In the case of blood pH, this is done by the lungs and the kidneys which act as compensatory organs for one another. When the lungs are dysfunctional just like in respiratory diseases (emphysema, TB, chronic bronchitis, etc), the kidneys respond by excreting or retaining bicarbonate (HCO3).

On the other hand, when the kidneys are dysfunctional, the lung will respond by the increase retention or excretion of carbon dioxide (CO2). Through these physiologic processes, the critical pH (acidity and alkalinity) of blood is maintained at 7.35 to 7.45. Any slight variation from this pH, whether an increase or decrease, will lead to coma and eventually death. It is therefore imperative that the body maintains this slightly alkaline pH of blood for good health.

The following are acid-base conditions and the corresponding compensatory mechanisms :

Values : pH - decreased , PCO2 normal, HCO3 - decreased

Condition - metabolic acidosis

Compensatory mechanism - hyperventilation , increase excretion of CO2

decreased retention of CO2

Values: pH increased, HCO3 - increased , PCO2-normal

Condition - metabolic alkalosis

Compensatory mechanism - hypoventilation, decreased excretion of CO2

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increased retention of CO2

Values : pH- increased , PCO2 - decreased , HCO3 -normal

Condition - respiratory alkalosis

Compensatory mechanism : increased retention of HCO3

decreased excretion of H+

Values: pH-decreased , PCO2 -increased, HCO3 -normal

Condition: respiratory acidosis

Compensatory mechanism : increased retention of HCO3,

increased excretion of H+

Clinical laboratory scientists or medical technologists solve for the pH of blood making use of the

Henderson-Hasselbalch Equation: (H & H equation). The formula for this is:

pH = 6.1 + log (HCO3)/DCO2

HCO = TCO2-DCO2

DCO2 = PCO2 X 0.031

Where: pH =indicates the acidity or alkalinity of a solution (hydrogen ion concentration.

HCO3 - bicarbonate

DCO2 - dissolved carbon dioxide

TCO2 - total carbon dioxide

Normal values are:

pH = 7.35-7.45

HCO3 = 22 - 26 mmol/L

PCO2 = 35 - 35 mmHg

TCO2 = 23-27 mmol/L

Arterial blood gas has very important clinical significances. It is crucial that the Medical Technologists know the precautions and perform the determination accurately. A well performed ABG signifies a patient well served.




This was published by http://voices.yahoo.com/the-analysis-blood-gas-2482704.html?cat=5.

Reference:

Calbreath, Donald F. Fundamentals of Clinical Chemistry

Wednesday, May 21, 2014

CLINICAL CHEMISTRY 3 FINAL EXAMS - TABLE OF SPECIFICATIONS



CLINICAL CHEMISTRY 3 FINAL EXAMS  - TABLE OF SPECIFICATIONS

TOPIC
PERCENT (%)
ITEMS





ENDOCRINOLOGY
48
55

TOXICOLOGY
31
35

DRUG TESTING
21
25

TOTAL
100%
115
Grand Total= 130 items
TRANSCRIPTION

15


TRANSCRIPTION = 15 POINTS FOR A GRAND TOTAL OF 130.

Please Bring:
Calculator (no borrowing of calculators)
Blue book ( 1 pc.)
Permits
Pencil lead 2 (2 pcs) for SCANTRON answer sheet

Type of test

1. MULTIPLE CHOICE (115 pts), which includes:
Matching type (3 pts.)
      Problem solving (3 pts)
      Case analysis (7 pts.)

II. TRANSCRIPTION (15 pts.)