Preservatives to be Used in Different Cases
In all poisons excluding acids but including carbolic acid
Saturated solution of common salt.
All acids except carbolic acid
Rectified spirit.
Blood for chemical analysis
Potassium oxalate +NaF. (with a layer of liquid paraffin above it in cases of carbon monoxide and other gas poisoning cases).
Bleaching powder or chlorine gas
Rectified spirit.
Blood for grouping
Equal volume of 5% sodium citrate + 0.25 ml. formalize.
Nails, bones, hair, swabs
No preservative needed (femur bone is preferred) CSF:
Na fluoride 250 mg/30 ml fluid.
CSF
Can be collected by cisternal puncture through the Atlanto Occipital membrane or by puncturing the ventricles through the exposed brain surface.
Vitreous humor
Stored in a refrigerator (4°C) upto 48 hours.
Additional materials to be preserved in poisoning due to
Alcohol
About 100 ml of blood from a peripheral vein and as much CSF as can be withdrawn.
Barbiturates
One half of the brain.
Carbon monoxide, coal gas, chloroform, cyanides
About 100 ml of blood from the heart and one half of the brain.
Heavy metals
About 10 cm. of shaft of long bone (femur), about 5 gms. of plucked scalp hair, all finger or toe nails (nails are entirely removed from their beds), skin of the back and a wedge of quadriceps muscles before opening the abdomen.
Injected poisons
Skin, subcutaneous tissue and muscle forming the injection track, bone deep and similar material from the opposite area as control.
Organ phosphorus, endrine, neurotic poisons
Brain, spinal cord. Also in certain special circumstances, the following material is to be preserved
- In addition to the routine viscera
- Criminal abortion: Vagina, cervix and uterus with adnexa and the contents.
- Firearm injuries: Skin around the entrance wounds.
- Hydrophobia: Brain for negri bodies (for pathologists).
For Histopathology
Sections of various internal organs and body tissues required to be histologically examined are to be preserved in 10% formal saline. Sections of tissues for histological examinations should not exceed 6 – 9 mm. (1/4 to 3/8 inches) in thickness.
For Microbiological investigations
Blood from the heart, smears from the throat, swabs from abscess cavities, fluid from cysts etc. may be collected for bacteriological and other examinations.
