Chemical characterization of latent fingerprints by matrix-assisted laser desorption ionization, time-of-flight secondary ion mass spectrometry, mega electron volt secondary mass spectrometry, gas chromatography/mass spectrometry, X-ray photoelectron spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopic imaging: an intercomparison.

The first analytical intercomparison of fingerprint residue using equivalent samples of latent fingerprint residue and characterized by a suite of relevant techniques is presented. This work has never been undertaken, presumably due to the perishable nature of fingerprint residue, the lack of fingerprint standards, and the intradonor variability, which impacts sample reproducibility. For the first time, time-of-flight secondary ion mass spectrometry, high-energy secondary ion mass spectrometry, and X-ray photoelectron spectroscopy are used to target endogenous compounds in fingerprints and a method is presented for establishing their relative abundance in fingerprint residue. Comparison of the newer techniques with the more established gas chromatography/mass spectrometry and attenuated total reflection Fourier transform infrared spectroscopic imaging shows good agreement between the methods, with each method detecting repeatable differences between the donors, with the exception of matrix-assisted laser desorption ionization, for which quantitative analysis has not yet been established. We further comment on the sensitivity, selectivity, and practicability of each of the methods for use in future police casework or academic research.

Detection and identification of body fluid stains using antibody-nanoparticle conjugates.

Body fluids are considered one of the most important evidence types in forensic casework. The presence and location of blood, semen and saliva can provide crucial information to investigators. Current practice relies on an accurate visual examination followed by the use of presumptive tests to determine the identity of the body fluid type. Further laboratory based tests are required to unequivocally confirm the identity of a stain. Body fluid stains can be difficult to detect with the naked eye, particularly on dark backgrounds and hence vital evidence may be overlooked. Current methods are fluid-type specific, with a separate, and different, test required for each body fluid. The laborious nature of such analysis and the impossibility of being carried out at the crime scene, leads to a delay in the investigation process that could prove detrimental to the solving of the case. Hence, there is a need for sensitive, specific and direct methods which can simultaneously detect, differentiate, and locate human fluids on items of forensic evidence. Here, we describe the preparation of functionalized iron oxide nanoparticles conjugated to antibodies specific to blood and saliva components and their use in detecting small traces against non-contrasting substrates including glass, ceramic tile, paper and black fabric. The advantage of our technique is that it can simultaneously detect blood and saliva and can spatially locate and differentiate these body fluid types. Most importantly, our technology, which exploits the superparamagnetic properties of iron oxide nanoparticles, works in situ with no need to remove the body fluid stains for testing and with no washing steps and does not interfere with downstream DNA profiling. Thus, our technology represents a novel and effective alternative to existing methods.

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.

Hydrophilic stationary phases: a practical approach for the co-analysis of compounds with varying polarity in biological matrices.

The aim was to simultaneously extract, separate and detect not only the opioid methadone and its primary metabolites (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine and 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline), but also creatinine from urine, plasma and fingerprints. Creatinine is highly polar and analysis by RP chromatography using conventional stationary phases such as silica-bonded C8 and C18 is unsuitable. Hydrophilic stationary phases are increasingly being applied for the analysis of highly polar analytes, this chemistry being investigated as a suitable alternative. A hydrophilic interaction liquid chromatography phase column successfully retained creatinine and permitted the co-analysis of methadone and its metabolites by LC-MS/MS. Prior to analysis, an extraction protocol for urine and plasma was required but for fingerprint deposits this was not necessary. Alteration of sample pH, necessary to extract methadone, and its metabolites led to difficulties associated with the extraction of creatinine. This problem was addressed by first performing an SPE incorporating a hydrophilic interaction phase to extract creatinine, and the eluent then combined with the opioid extract from a mixed-mode cation exchange phase. The assay for creatinine, methadone and its primary phase I metabolites met validation criteria. LC-MS/MS analysis of creatinine and drug compounds together offers considerable advantages over traditional approaches that necessitate the quantification of creatinine using spectrophotometric approaches.

Synthesis, characterisation and intracellular imaging of PEG capped BEHP-PPV nanospheres.

Aqueous dispersions of poly(ethylene glycol) (PEG) capped poly[2-(2',5'-bis(2''-ethylhexyloxy)phenyl)-1,4-phenylene vinylene] (BEHP-PPV) nanospheres with an average particle diameter of 13 nm have been synthesised by a miniemulsion route and used in simple intracellular imaging experiments.

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.

The detection and quantification of lorazepam and its 3-O-glucuronide in fingerprint deposits by LC-MS/MS.

The use of fingerprints as an alternative biological matrix to test for the presence of drugs and/or their metabolites is a novel area of research in analytical toxicology. This investigation describes quantitative analysis for the benzodiazepine lorazepam and its 3-O-glucuronide conjugate in fingerprints following the oral administration of a single 2 mg dose of lorazepam to five volunteers. Creatinine was also measured to investigate whether the amount of drug relative to that of creatinine would help to account for the variable amount of secretory material deposited. Fingerprints were deposited on glass cover slips and extracted by dissolving them in a solution of dichloromethane/methanol, containing tetradeuterated lorazepam as an internal standard. The samples were evaporated, reconstituted with mobile phase and analysed by LC-MS/MS. Chromatography was achieved using an RP (C18) column for the analysis of lorazapem and its glucuronide, and a hydrophilic interaction column (HILIC) for the analysis of creatinine. Lorazepam and its glucuronide were only detected where ten prints had been combined, up to 12 h following drug administration. In every case, the amount of lorazepam glucuronide exceeded that of lorazepam, the peak amounts being 210 and 11 pg, respectively. Adjusting for creatinine smoothed the elimination profile. To our knowledge, this represents the first time a drug glucuronide has been detected in deposited fingerprints.

Chemical imaging of latent fingerprint residues.

In situ attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopic imaging has been used to obtain chemical images of fingerprints under controlled humidity and temperature. The distribution of lipid and amino acid components in the fingerprints from different donors left on the surface of the ZnSe crystal has been studied using an in situ FT-IR spectroscopic imaging approach under a controlled environment and studied as a function of time. Univariate and multivariate analyses were employed to analyze the spectroscopic dataset. Changes in the spectra of lipids with temperature and time have been detected. This information is needed to understand aging of the fingerprints. The ATR-FT-IR spectroscopic imaging offers a new and complementary means for studying the chemistry of fingerprints that are left pristine for further analysis. This study demonstrates the potential for visualizing the chemical changes of fingerprints for forensic applications by spectroscopic imaging.

Changes in the lipid composition of latent fingerprint residue with time after deposition on a surface.

The work described in this report was focused on generating increased knowledge of fingerprint chemistry, particularly the composition of a latent fingerprint at the time it is deposited, and the chemical changes in lipid components that occur over time. Fingerprints from five male donors (aged 25-34 years) were collected and aged under controlled conditions. The prints were then sampled at set intervals, solvent extracted with dichloromethane, co-derivatized with MSTFA and analyzed by gas chromatography-mass spectrometry (GC-MS). It was shown that there was loss of squalene from prints stored in the light or in the dark. Loss was more rapid in the light, with squalene in prints from some donors not detected after 9 days storage. For these same donors, squalene was still detected after 33 days storage in the dark, but at much lower levels than in fresh prints. For saturated fatty acids (tetradecanoic, palmitic and stearic acid) there was a trend towards an increase in levels of these substances during storage (up to about 20 days) followed by a decrease back to original levels or below. This was the case for samples stored in the light or in the dark. For palmitoleic acid, a similar trend was seen. For oleic acid, this trend was seen for samples stored in the dark. For samples stored in the light the general trend was a decrease in level over the storage period (up to 33 days).

Drug testing by chemical analysis of fingerprint deposits from methadone-maintained opioid dependent patients using UPLC-MS/MS.

Chemical analysis of fingerprint deposits from methadone-maintained opioid-dependent patients by UPLC-MS/MS show detectable levels of methadone and its metabolite, EDDP, demonstrating intake of the drug.

A novel fluorescence-based method in forensic science for the detection of blood in situ.

Full DNA profiles can be generated from just a few cells; however these profiles can be contaminated from other cell types present at the crime scene. We report here on the development of an immunofluorescent technique to spatially locate human-specific blood in situ and also on the ability of this technique to detect individual leukocytes and the DNA contained within them. Four monoclonal mouse anti-human antibodies were evaluated; anti-glycophorin A to detect erythrocytes and anti-CD45, anti-myeloperoxidase (MPO) and anti-histone H1 to detect the nucleated leukocytes. Each antibody was labeled with either Alexa Fluor 488 or 568 for direct application to blood smears which allowed the simultaneous detection of erythrocytes and leukocytes. Furthermore, because histones are DNA binding proteins, the application of anti-histone H1 allowed the detection of DNA within a blood smear. Importantly it was found that full DNA profiles could be achieved after using this method with similar peak area ratios compared to untreated cells. The fluorescent antibodies were found to be human-specific with the exception of anti-histone H1 due to its conserved sequence. However, used in combination with anti-CD45 or anti-MPO the location of DNA from human-specific leukocytes could be detected. The technique was also tested on older blood stains and was still found to be sensitive and cell-specific after 4 months. Following the optimization of the methodology, the fluorescent antibodies were applied to short lengths of black cotton fibres covered with human blood spots. Although the background fluorescence from the cotton was found to be high, erythrocytes and even individual leukocytes could easily be detected, indicating that this technique could be used to detect extremely minute amounts of blood. Used in combination with laser capture microdissection (LCM), this method could be used to pick off individual leukocytes for LCN DNA techniques.

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.