The sensitivity and specificity of red-starch paper for the detection of saliva.

The detection of saliva in forensic casework is extremely important in many types of cases. This study describes a relatively sensitive method, based on a red dye bound to starch, for the detection of amylase. The sensitivity and specificity of the method has been examined by testing over 50 household products, various body fluids and five laboratory chemicals. This study demonstrated for the first time that positive results can be obtained from certain washing powders as well as other household products. As well as detecting amylase in saliva, positive Red-Starch results were obtained from faeces and urine. The method was found to be suitable for the detection of mixtures of saliva and semen in conjunction with the Brentamine test for the detection of acid phosphatase.

The use of phosphate buffered saline for the recovery of cells and spermatozoa from swabs.

In the forensic science laboratory, the recovery of spermatozoa from vaginal swabs, or vaginal cells from penile swabs, can help determine if sexual intercourse may have taken place. There are several methods used to recover spermatozoa and cells from the swabs before visualisation on a microscope slide and most of these methods use water. Phosphate buffered saline (PBS) is a non-toxic solution used in many biological laboratories. Unlike water, PBS prevents cells rupturing or shrivelling up due to osmosis. This study demonstrates that PBS can be used for the extraction of spermatozoa and cells from swabs and that PBS does not affect subsequent DNA profiling.