This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Special topics, Subject name: Forensic Medicine
Which of the following is not used as a preservative in chemical analysis 
Select and explain. 
A. Glycerine, B. Formalin, C. Salt solution, D. Rectified spirit
B: Formalin
Answer: B: Formalin 
Explanation: Formalin is not used as preservative for chemical analysis because extraction of poison becomes diffcult. Preservatives:- * Saturated sodium chloride solution * Rectified spirit * 10 mg/ml of sodium or potassium fluoride for blood, urine, CSF * Glycerol is used for virological study. Ref:- Essentials of Forensic medicine, Dr KS narayana Reddy 33th Edition; Pg num:- 124