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

Electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry have been used to examine evidence in a sexual assault investigation. Because condoms are being used increasingly by sexual assailants and some condom brands include the spermicide nonoxynol-9 (nonylphenoxy polyethoxyethanol) in the lubricant formulation, the recovery, and 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), nanoelectrospray ionization (nanoESI) mass spectrometry, and high resolution MALDI 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 lubricant 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.

Nanoelectrospray mass spectrometry and precursor ion monitoring for quantitative steroid analysis and attomole sensitivity.

Nanoelectrospray ionization (nanoESI) mass spectrometry was performed on naturally occurring steroid sulfates and unconjugated steroids derivatized to their sulfate esters using precursor ion monitoring. Initially, an extraction method was developed based on a combinatorial approach employed to obtain the most efficient liquid/liquid extraction protocol. The new method allowed unconjugated steroids and their sulfated analogues to be isolated separately in a two-step procedure using diethyl ether/hexane (90:10, v/v) in the first step to extract the unconjugated steroids and chloroform/2-butanol (50:50, v/v) in the second step to extract steroid sulfates. Precursor ion scanning performed with a triple-quadrupole mass spectrometer was used to examine quantitatively the extracted unconjugated and sulfated steroids, where the recovery efficiency averaged 70 and 87%, respectively. In addition, some steroids could be structurally elucidated by employing tandem mass spectrometry. The limit of detection for steroid sulfates from the biological matrix was 200 amol/microL (approximately 80 fg/microL) with only 1 microL of sample being injected. Endogenous levels of the unconjugated and sulfated steroids were detected and quantified from physiological samples including urine and blood. Internal standards, pregnenolone-d4 sulfate and dehydroepiandrosterone-d2 (DHEA), were used for quantitation. Extraction and nanoESI analyses were also performed on cerebrospinal fluid where the neurosteroid DHEA sulfate was detected. The small amount of material consumed (typically less than 20% of the injection volume) suggests that nanoESI has even greater potential for high sensitivity when combined with nanoLC approaches, especially for monitoring reproductive and adrenal steroids, as well as for the analysis of the less abundant neurosteroids.