Electrospray and MALDI mass spectrometry in the identification of spermicides in criminal investigations

Electrospray ionization (ESI) and matrix-assisted laser desorption/ionizati on (MALDI) mass spectrometry have been used to examine evidence in a sexual assault investigation. Because condoms are being used increasingly by sexu al assailants and some condom brands include the spermicide nonoxynol-9 (no nylphenoxy polyethoxyethanol) in the lubricant formulation, the recovery, a nd identification of nonoxynol-9 from evidence items may assist in proving corpus delicti. A method was developed for the recovery of nonoxynol-9 from internal vaginal swabs and for its identification by reverse phase liquid chromatography/electrospray ionization mass spectrometry (LC ESI-MS), nanoe lectrospray ionization (nanoESI) mass spectrometry, and high resolution MAL DI Fourier transform mass spectrometry (MALDI-FTMS). The method was tested on extracts from precoitus, immediate postcoitus, and four-hours postcoitus vaginal swabs provided by a volunteer whose partner does not normally use condoms, but for this trial used a condom having a water-soluble gel-type l ubricant that includes 5% nonoxynol-9 in its formulation. Subsequently, LC ESI-MS was used to identify traces of nonoxynol-9 from the internal vaginal swab of a victim of a sexual assault.