This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Which of the following is used for preservation of alcohol? 
Select and explain. 
A. Potassium acetate, B. Sodium sulphide, C. Sodium fluoride, D. Glycerine
C: Sodium fluoride
Answer: C: Sodium fluoride 
Explanation: (Sodium fluoride)

Sodium fluoride is a useful preservative in a suspected case of alcohol poisoning.
It is done with mixing 10 mL of blood with potassium oxalate & sodium fluoride (enzyme inhibitors)
for suspected alcohol poisoning.
A preservative (sodium fluoride, 0.5 -2% weight by volume) should be added after collecting a vitreous humour sample for ethanol analysis in postmortem toxicology cases.
Gastric contents can be stored in saturated salt solution.