Detection of the Spermicide Nonoxynol-9 Via GC-MS

Abstract

The spermicide nonoxynol-9 is actually a complex mixture of dozens of closely related amphiphilic compounds, and the chemical properties of this assortment significantly hamper its characterization by GC-MS. The inability to perform routine GC-MS testing on nonoxynol-9 has limited its evidentiary value in forensic casework, which relies heavily on this technique for analysis. A disturbing trend in sexual assault is the use of condoms by assailants, to avoid leaving behind DNA evidence that can connect a perpetrator to a victim. This observation necessitates the development of alternative methods for the analysis of trace evidence that can show causal links between a victim and a suspect. Detection of lubricants associated with sexual assault is one such way to establish this connection. The development of GC-MS methods that permit facile detection of both nonoxynol-9 alone and nonoxynol-9 extracted from other complex matrices that have potential as trace evidence in sexual assault is reported. A detection limit of 2.14 μg of nonoxynol-9 is demonstrated, and a detailed mass spectral profile that elaborates on what is known of its structure is provided.

Direct analysis in real time mass spectrometry for analysis of sexual assault evidence

“…The presence of nonoxynol‐9 has been used as a probative link in sexual assault cases . The DART‐MS spectrum of the spermicide is intricate but fully characteristic of the substance, as nonoxynol‐9 is actually a mixture of similarly structured nonylphenol ethoxylates that manifests as a series of peaks in the mass spectrum . The individual components of nonoxynol‐9 all have a core nonylphenol structure, with each having a poly(ethylene oxide) side chain.…”

“…The components of the mixture differ from one another by the length of the side chain and the branching of the nonyl substituent (Fig. , insert) . The various components that are resolvable based on this repeating [‐OCH 2 CH 2 ‐] side chain result in a series of peaks.…”

“…[14][15][16]18,29,31] The DART-MS spectrum of the spermicide is intricate but fully characteristic of the substance, as nonoxynol-9 is actually a mixture of similarly structured nonylphenol ethoxylates that manifests as a series of peaks in the mass spectrum. [32,33] The individual components of nonoxynol-9 all have a core nonylphenol structure, with each having a poly(ethylene oxide) side chain. The components of the mixture differ from one another by the length of the side chain and the branching of the nonyl substituent ( Fig.…”

“…3, insert). [19,[32][33][34] The various components that are resolvable based on this repeating [-OCH 2 CH 2 -] side chain result in a series of peaks. Each peak identified in the spectrum represents a single constituent of the mixture, having between four and fourteen repeats ( Another form of probative evidence is a fingerprint which, although informative in its own right, is now much more so due to the increasing use in forensic analysis of 'touch DNA'.…”

Analysis of sexual assault evidence by desorption electrospray ionization mass spectrometry

“…Shepard et al . reported the analysis of the spermicide nonoxynol‐9 (N‐9) via GC–MS . Each of these techniques requires the sample to be extracted with a solvent prior to analysis.…”