|
|
| Toxicology |
| The area
of toxicology involves testing for the use of illegal substances,
poisons and alcohol. Using samples from a suspect such as hair, a
toxicologist can confirm whether a person has used illegal drugs weeks
ago or only yesterday. Urine and blood tests can reveal alcohol levels
and whether someone was poisoned. |
|
Choose one of the topics below to read more:
--> Preliminary
testing
--> Chromatography
--> Toxins
in the body
|
| |
| Preliminary
Testing |
|
| Testing for drugs follows
a certain procedure. First, a simple test is done to determine whether
a chemical is present. If it is found that there is a chemical present,
more complex testing is conducted to measure the quantity and type
of illegal substance. The preliminary test involves an immunoassay
kit which changes colour when drugs in a sample of urine combine with
the antibodies
that are present in the kit test. |
| |
| Chromatography |
|
| Both drugs and alcohol are tested
using chromatography,
which involves separating chemicals based on the speed at which they
move in liquid and gas. The essential testing device in the toxicology
department is gas chromatography. Consisting of a narrow tube containing
loosely packed solid particles, a non-reactive gas, for example, nitrogen,
flows through the tube. When the sample to be tested is inserted,
every individual chemical passes through the tube at varying speeds.
Timing when each chemical arrives at the exit point identifies the
composition of any substance mixture. These results are then placed
on a computer database, where each substance appears as a peak on
a graph. The peaks that are identical to a known drug make a positive
result. Liquid chromatography involves the same process, substituting
gas for liquid. |
| |
| Toxins
In The Body |
|
| Chromatography, as mentioned
earlier, is used in identifying poisons, whether it was accidental,
suicidal or homicidal. The testing is this time done on the victim
using samples taken during the autopsy. The liver, as this is the
part of the body that filters out the body's toxins, and blood samples
are the most useful in testing for poisons, but other samples such
as bile,
which holds antidepressants, heroin and morphine are also used. Flammable
substances such as solvents are present in the lungs as a result of
poisoning and the victim's hair stores, a record of poisoning, as
lines along the strand of hair in
chronological order. These samples are analysed using immunoassay
and chromatography methods, the same as testing for substances in
living individuals. |
|
|