Toxicology

5 04 2010

Q

There was a car accident. A car crashed into another car. The man who crashed into another car was a good man. He was a dilligent worker and a good father. The investigators want to know why the man did such thing. They are wondering if the man was drunk or on drugs. What should they do to find out if the man was drunk or on drugs?

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A

They should ask the toxicologist to analyze by doing head gas chromatography, elisa test, and gas chromatograph/mass spectrometer. Doing head gas chromatography will reveal the presence of alcohol, and elisa test and GC/MS will reveal the presence and the type of drugs.

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In the 16th century, Paracelsus realized that anything can kill a human if it is taken excessively. But forensic toxicology wasn’t invented until the 1840s. A chemist named Mathieu Orlifa proved in court that Marie LaFarge poisoned her husband with arsenic.

Toxicology is science concerned with nature, effects, and detection of poisons.Forensic toxicologists test human fluids and tissues to determine the presence of drugs and other chemical substances.

In order to carry out the test, toxicologists draw out 3 types of bodily fluids

  1. 2mL of vitreous humor
  2. 30mL of blood
  3. 30mL of urine

1. 2mL of virtreous humor

Virtreous humor is the clear fluid inside the eye that give the eye its shape. It is inside your eye balls! Virteous humor is used as a confirmation to confirm the results from the blood and urine, because if a drug is present in any of these fluids, it will be present in all three. The vitreous humor is collected using a syringe. The toxicologist pokes the syringe through the eye ball and extracts the fluid inside. I won’t upload a video, because it is a quite disgusting process to see :(

2. 30mL of blood

Blood transports oxygen, nutrients, and other chemicals throughout a person’s body. Hemoglobin is a well known protein in blood that transports oxygen. Most chemicals in the body will appear in a person’s blood stream. Once the drug enters the blood stream, it will spread all throughout the body.

3. 30mL of urine

Urine is the main way toxins and other chemicals exit the body. The toxicologist collects the urine postmortem from the bladder, again, using a syringe.

So why are three fluids examined? It is because looking at multiple fluids helps prevent error and contamination. If a drug is present in one part of the body, it should also be in others.

These are the sccening tests driven to determine the presence of alcohol/drugs.

  1. Headspace Gas Chromatography
  2. Elisa Test
  3. Gas Chromatograph/Mass Spectrometer

1. Headspace gas chromatography

Headspace gas chromatography is used to refer to the area between the sample and the top of the vial. The alcohol in the sample will evaporate into the headspace, where it can be analyzed.

2. Elisa Test

Elisa test is used to detect drugs in the sample. It can detect the presence of drugs, but it cannot definitely identify individual chemicals. All samples and controls are replicated twice the make sure no mistakes are made. The samples change color when a drug is detected. Positive and negative controls are used to ensure that the test is working correctly. The positive control purposefully have drugs, and the negative control doesn’t.

3. Gas chromatograph/Mass spectrometer

To find out the exact drug, gas chromatoraph/mass spectrometer, or GC/MS is used. It is only used if something shows up in the screening tests, because this is a very expensive test :(. GC/MS separates the chemicals in a specimen and identifies each one. It takes up to 20 minutes for the processing to complete. The chemicals in the sample separate from each other based on their properties. Then, the chemical gets a positive change in the ion source, and breaks into fragments. The analyzer sorts the fragments, again, by similar properties. The detector calculates the number of chemical fragments of each type. A graph is generated for each chemical. The graph is called mass spectrum. The chemicals broken into fragments are indicated as the peaks on the graph. Every chemical has its own unique pattern. The presence of drug is found by comparing the graph to other graphs of samples with different types of drug intake.

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One response

23 04 2010
Jenny

I like this post
It is very nicely written and organized
visit my blog too :)

http://jennyp12.wordpress.com/

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