A rapid method to detect dried saliva stains swabbed from human skin usingfluorescence spectroscopy

Saliva on skin is important in forensic trace evidence. if areas where sali va is present can be outlined, this may lead to DNA analysis and identifica tion. This study describes a rapid and non-destructive method to detect dri ed saliva on the surface of the skin by fluorescence spectroscopy. Eighty-t wo volunteers deposited samples of their own saliva on the skin of their Ve ntral forearm. a control sample of water was deposited at three different s ites on the contralateral arm. Saliva and water control were then allowed t o air-dry. Swab samples were taken from dried saliva and control sites and were dissolved in 0.1 M KCl solution. Emission spectra were obtained from t he solution and were characterized by a principal maximum at 345-355 nm wit h excitation at 282 nm. The fluorescence emission intensity was greater tha n background readings obtained from the control swab site in 80 of 82 volun teers (similar to 97.6%). The fluorescence profile of saliva samples were s imilar to those obtained from aqueous samples of pure amylase and tryptopha n, an endogenous fluorophore in alpha-amylase. The presence of an emission peak at 345-355 nm with excitation at 282 nm could provide a strong presump tive indication of saliva deposition. (C) 2000 Elsevier Science Ireland Ltd . All rights reserved.