Optimisation of choline testing using Florence Iodine reagent, including comparative sensitivity and specificity with PSA and AP tests

The detection of semen in forensic science is essential in cases of sexual assault but can be problematic in the absence of spermatozoa. Choline is known to occur in high concentrations in seminal fluid and the Florence Iodine test for its detection has been used in forensic science for many years, however very little is documented regarding its sensitivity and specificity in forensic casework. This paper describes the optimisation of the choline Florence Iodine test (FI) and investigates the sensitivity and specificity of the test against different body fluids, food and drink substances, cleaning products and laboratory chemicals. Comparative testing against Acid Phosphatase (AP) and Prostate Specific Antigen (PSA Seratec®) tests is described and shows that the FI test has greater specificity than the PSA test which cross reacts with a number of body fluids.