Multiplexed detection of metabolites of narcotic drugs from a single latent fingermark.

An immunoassay based technique is used for the detection of psychoactive substances in the sweat deposited within fingermarks of a narcotic drug user. Magnetic particles functionalized with antimorphine and antibenzoylecgonine antibodies were used for the detection of a metabolite of heroin (morphine) and a metabolite of cocaine (benzoylecgonine), respectively. The drug metabolites were detected individually as well as simultaneously from a single fingermark. The images of the fingermarks obtained using brightfield and fluorescence microscopy were of high evidential quality with resolution to enable identification of an individual in addition to providing information on drug usage.

Rapid detection of drug metabolites in latent fingermarks.

Magnetic particles functionalised with anti-cotinine antibody have been used to image latent fingermarks through the detection of the cotinine antigen in the sweat deposited within the fingerprints of smokers. The antibody-magnetic particle conjugates are readily applied to latent fingerprints while excess reagents are removed through the use of a magnetic wand. The results have shown that drug metabolites, such as cotinine, can be detected and used to image the fingermark to establish the identity of an individual within 15 minutes.

Identification of oxidation products of squalene in solution and in latent fingerprints by ESI-MS and LC/APCI-MS.

An investigation was carried out to identify oxidation products of squalene (SQ) in latent fingerprints. Oxidation products of SQ incubated in solution with Rose Bengal as a photooxidizer were isolated by semipreparative HPLC-UV and identified by direct infusion ESI-MS and flow injection APCI-MS. Squalene hydroperoxides ranging from squalene monohydroperoxide (SQ-[OOH]) to SQ-[OOH]5 were identified together with SQ epoxide. SQ-[OOH] was the main oxidation product. An LC/APCI-MS method was developed and used to monitor the fate of SQ in solution and in latent fingerprints and the formation of SQ-[OOH] and SQ epoxide. SQ-[OOH] and SQ epoxide were detected in freshly deposited prints but increased markedly after 1 day and continued to increase up to 5 days after print deposition. By day 7, these substances could no longer be detected in prints. SQ was rapidly depleted from prints such that by day 7 it was no longer detected. A similar pattern was seen for SQ stored in the light in dichloromethane but with a slower formation of SQ-[OOH] and SQ epoxide. The oxidation of SQ in solution in the presence and absence of photooxidizer was shown by TLC to proceed as follows: SQ-->SQ-[OOH]+SQ epoxide. SQ-[OOH]-->SQ-[OOH]2-->SQ-[OOH]3-->SQ-[OOH]4+SQ-[OOH]5, with oxidation being more rapid in the presence of photooxidizer. SQ-[OOH]4 and SQ-[OOH]5 could still be detected at 20 days in a solution of SQ aged in solution in the absence of photooxidizer. The oxidation products of SQ should make suitable targets for development of new reagents for visualizing latent fingerprints in forensic science.

A Critical Comparison of Four Test Methods for Determining Overall and Specific Migration from Microwave Susceptor Packaging.

Four approaches for testing for overall migration and specific chemical migration from microwave susceptors were evaluated. The methods used olive oil as a conventional liquid food simulant, a semisolid simulant of olive oil and water absorbed onto diatomaceous earth, Tenax™ as a dry simulant, and compositional analysis of the susceptor by ASTM methods. The different methods were tested on five susceptor types used for the packaging of pizza, potato chips (French fries), pasty, popcorn, and a curry. For the comparison, the susceptor materials were impregnated with model substances as migration markers covering a range of molecular weight, volatility and polarity. Levels of specific migration (SM) and overall migration (OM) were determined using the four test methods, which were then evaluated on the basis of their ease and reproducibility of use along with the agreement between specific migration levels into simulants compared with migration into foods. There were severe problems with olive oil as a conventional liquid simulant as it was absorbed by the susceptor and made SM and OM measurements difficult. Humidity conditioning the susceptor for OM was a further difficulty with olive oil. Oil absorption was also a problem using the semisolid simulant, with OM being untried using this approach. The ASTM methods were found to be time-consuming, although the results for SM were similar to those obtained for foods. Overall, however, using Tenax was the preferred method for migration testing of susceptors. It allowed easy measurement of both OM and SM. SM values were generally much higher than for foods, however, and a reduction factor would be required for control of regulated ingredients. For other substances, such as thermal degradation products, a threshold of regulation approach applied to the Tenax extract would be a simple and effective control measure.