general review of toxicological samples in forensic medicine and the methods of sampling process

2. Poison is any substance that can harm or kill and
Toxicology is the study of it.
Forensic Toxicology study postmortem signs of the
poisoning.
The toxicity of a substance depends on the amount
ingested, as well as the age, weight and state of
health of the person who ingests it.
Poison can be administered by ingestion, injection,
inhalation or absorbed through the skin.

3. There are factors that frustrate or distort
proper analysis :
1. Unsuitable sample
2. inadequate amount
3. incorrect sampling site
4. poor containers
5. inadequate preservation method
6. delayed or unsatisfactory storage and transport
to the laboratory

4. *Is the most useful sample for identifying drugs or other
toxins and for quantitative analysis
*The most satisfactory way of obtaining venous blood sample
is vein puncture of femoral vein by direct puncture in the groin
*Preservatives can be added like KF or NaF for detection of
alcohol as they have anti- coagulation and anti- bacterial
effect
*The analysis of results is very important especially in drugs
because their concentration may reflect whether they are
used in a toxic ,therapeutic or fetal level

5. •OBTAINED by a catheter or suprapubic puncture at least 50m
The great advantages of using urine are :
*It is easy to obtained and the concentration of drug may be
about 100 times more than blood
*it is free from proteins
The disadvantage is that :
*Some drugs are excreted as metabolites which make proving
of the presence of this drugs difficult
* if death take place quickly then little or none of the drug
reaches the urine

6. * COLLECTED by doing gastric lavage which is
contraindicated in comatose patient because of the risk of
aspiration pneumonia
*Sometimes when open the stomach and find powder ,
capsule or tablet either added to main jar on placed in separate
container
•COMPARING the concentration of toxin or drug with that of
blood is important
IN BLOOD
IN BLOOD
IN STOMACH
IN STOMACH
suicidal
Criminal

7. Useful in postmortem decomposition as fluid of the eye
resist putrefaction longer than other body fluids
Useful for some drugs like morphine & chlorpromazine
which directed collection in to the bottle because the bile
is viscous to be sucked through needle
Collected by lumber puncture
Some tissue may be needed such as liver (250) gm for
detecting drugs, brain in solbent
abuse, kidneys in heavy metal poisons ,Sctissue and
muscles area surrounding site of injection ,hair and nails

8. THE ADVANTAGE of liver
THE DISADVANTAGE
•Drugs present in higher concentration in liver
• its large size make sample obtaining easy in
postmortem cases
• used in cases of decomposed or exhumed bodies
where blood sample id difficult to obtained
The sample may be contaminated with bile
Most probably used in postmortem cases

9. *The major purpose for using specific containers
are :
1. To prevent contamination
2. To prevent decmposition
3. Maintain sample in good condition
4. prevent loss of sample
The liquid sample is best placed in glass
container where as the solid samples in plastic
containers

10. •Samples for analysis are best sent in their original state but
other additives is required to maintain them in optimum
condition until they reach the laboratory
• sodium and potassium fluoride added to blood alcohol
because they inhibit alcohol dehyrogenase activity
• sodium citrate added leading to remain blood liquid and sterile
• fluride is added for analysis of drugs such as : cocaine ,
cyanide , and carbone monoxide
•Samples should be labeled with name and date with
permanent label & each container should be put in a bag to
ovoid contamination