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Biomedical subjects

R D Blackledge

Publications and source records attributed to R D Blackledge.

6 recordsLinked to original sources
PubMed1999

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.

Condoms↗
PubMed1995

Viscosity comparisons of polydimethylsiloxane lubricants in latex condom brands via Fourier self-deconvolution of their FT-IR spectra.

Many brands of latex condoms use a polydimethylsiloxane lubricant. The lubricant viscosity in ten different brands was compared by determining the average chain length through the ratio of the dimethyl to trimethyl peak area obtained after applying the resolution enhancement technique of Fourier self-deconvolution to their diffuse reflectance FT-IR spectra in the area around 800 cm-1.

Condoms↗
PubMedDate not supplied

Identification of polydimethylsiloxane lubricant traces from latex condoms in cases of sexual assault.

A polydimethylsiloxane (PDMS) liquid is used as a lubricant by many condom manufacturers. Because the use of condoms in sex crimes is likely to increase, a protocol was developed that could extract PDMS and the spermicide nonoxynol-9 from evidence items and separately identify them by Fourier transform infrared spectroscopy. Additionally, at least some discrimination was provided by microscopically identifying insoluble lubricants such as corn starch, lycopodium, silica, and talc which are added to some brands. Desorption chemical ionization mass spectrometry was used to compare the PDMS used by different manufacturers and to detect as little as 20 ng. The protocol was successfully used in two actual cases, one in which the assailant wore a lubricated condom, and a second in which he did not, but claimed to have done so.

Adolescent↗
PubMedDate not supplied

A target glitter study.

A target study was conducted using four different pre-selected types of commercial glitter particles. Recipient areas in the general environment around San Diego, California were tested. Glitter particles were recovered using double-sided tape affixed to square plastic Petri dishes. White light microscopy was the only search/identification method used. Additionally, a test was performed of the transferability of cosmetic glitter. Glitter particles were found to readily transfer. Of a total of 48 tape lifts from the general environment, 23 were found to contain at least one glitter particle. But due to the wide variety of glitter particles in terms of colour, shape, size, and surface morphology, the likelihood of transfer of one or more specific target particles was small.

Journal Article↗