Mass spectrometry imaging of latent fingerprints using titanium oxide development powder as an existing matrix.

Recent research has focused on increasing the evidentiary value of latent fingerprints through chemical analysis. Although researchers have optimized the use of organic and metal matrices for matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) of latent fingerprints, the use of development powders as matrices has not been fully investigated. Carbon forensic powder (CFP), a common nonporous development technique, was shown to be an efficient one-step matrix; however, a high-resolution mass spectrometer was required in the low mass range due to carbon clusters. Titanium oxide (TiO2 ) is another commonly used development powder, especially for dark nonporous surfaces. Here, forensic TiO2 powder is utilized as a single-step development and matrix technique for chemical imaging of latent fingerprints without the requirement of a high-resolution mass spectrometer. All studied compounds were successfully detected when TiO2 was used as the matrix in positive mode, although, generally, the overall ion signals were lower than the previously studied CFP. TiO2 provided quality mass spectrometry (MS) images of endogenous and exogenous latent fingerprint compounds. The subsequent addition of traditional matrices on top of the TiO2 powder was ineffective for universal detection of latent fingerprint compounds. Forensic TiO2 development powder works as an efficient single-step development and matrix technique for MALDI-MSI analysis of latent fingerprints in positive mode and does not require a high-resolution mass spectrometer for analysis.

Determining Fingerprint Age with Mass Spectrometry Imaging via Ozonolysis of Triacylglycerols.

Despite the common use of fingerprints as a trusted means of identification, no method currently exists to reliably establish the time since deposition of latent fingerprints. A reproducible method of establishing latent fingerprint age would allow forensic personnel to determine if a latent fingerprint was relevant to a crime. This work investigates the ambient aging of triacylglycerols (TGs) and other lipids in latent fingerprint residue utilizing matrix-assisted laser desorption/ionization mass spectrometry imaging. Unsaturated TGs were found to undergo ambient ozonolysis resulting in a decrease over time. At the same time, two series of compounds related to the degradation of unsaturated TGs due to ambient ozonolysis emerged with time and were detectable within a single day of aging. Tracking the degradation of unsaturated TGs over time proved to be relatively reproducible in multiple individuals and is suggested as a means of establishing latent fingerprint age.

Carbon-Based Fingerprint Powder as a One-Step Development and Matrix Application for High-Resolution Mass Spectrometry Imaging of Latent Fingerprints.

Carbon-based materials are often used as matrices for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and its imaging (MALDI-MSI). However, researchers have refrained from using carbon-based fingerprint powder (CFP) as a matrix due to high background and contamination. In this work, the compatibility of CFP is reevaluated with MALDI-MSI using a high-resolution mass spectrometer (HRMS) and compared to traditional organic matrices. Relevant fingerprint compounds were easily distinguished from carbon cluster peaks when using HRMS. For fair comparison, half of a fingerprint was dusted with CFP while the other half was dusted with traditional organic matrices. All compounds studied had comparable, or higher, signal-to-noise (S/N) ratios when CFP was used as the matrix. Additionally, chemical image qualities closely followed the trend of S/N ratios. CFP proved to be an effective one-step development and matrix application technique for MALDI-MSI of latent fingerprints, when carbon cluster peaks are well separated by a HRMS.

Preconcentration of DNA using magnetic ionic liquids that are compatible with real-time PCR for rapid nucleic acid quantification.

Nucleic acid extraction and purification represents a major bottleneck in DNA analysis. Traditional methods for DNA purification often require reagents that may inhibit quantitative polymerase chain reaction (qPCR) if not sufficiently removed from the sample. Approaches that employ magnetic beads may exhibit lower extraction efficiencies due to sedimentation and aggregation. In this study, four hydrophobic magnetic ionic liquids (MILs) were investigated as DNA extraction solvents with the goal of improving DNA enrichment factors and compatibility with downstream bioanalytical techniques. By designing custom qPCR buffers, we directly incorporated DNA-enriched MILs including trihexyl(tetradecyl)phosphonium tris(hexafluoroacetylaceto)nickelate(II) ([P6,6,6,14+][Ni(hfacac)3-]), [P6,6,6,14+] tris(hexafluoroacetylaceto)colbaltate(II) ([Co(hfacac)3-]), [P6,6,6,14+] tris(hexafluoroacetylaceto)manganate(II) ([Mn(hfacac)3-]), or [P6,6,6,14+] tetrakis(hexafluoroacetylaceto)dysprosate(III) ([Dy(hfacac)4-]) into reaction systems, thereby circumventing the need for time-consuming DNA recovery steps. Incorporating MILs into the reaction buffer did not significantly impact the amplification efficiency of the reaction (91.1%). High enrichment factors were achieved using the [P6,6,6,14+][Ni(hfacac)3-] MIL for the extraction of single-stranded and double-stranded DNA with extraction times as short as 2 min. When compared to a commercial magnetic bead-based platform, the [P6,6,6,14+][Ni(hfacac)3-] MIL was capable of producing higher enrichment factors for single-stranded DNA and similar enrichment factors for double-stranded DNA. The MIL-based method was applied for the extraction and direct qPCR amplification of mutation prone-KRAS oncogene fragment in plasma samples. Graphical abstract Magnetic ionic liquid solvents are shown to preconcentrate sufficient KRAS DNA template from an aqueous solution in as short as 2 min without using chaotropic salts or toxic organic solvents. By using custom-designed qPCR buffers, DNA can be directly amplified and quantified from four MILs examined in this study.

Revealing Individual Lifestyles through Mass Spectrometry Imaging of Chemical Compounds in Fingerprints.

Fingerprints, specifically the ridge details within the print, have long been used in forensic investigations for individual identification. Beyond the ridge detail, fingerprints contain useful chemical information. The study of fingerprint chemical information has become of interest, especially with mass spectrometry imaging technologies. Mass spectrometry imaging visualizes the spatial relationship of each compound detected, allowing ridge detail and chemical information in a single analysis. In this work, a range of exogenous fingerprint compounds that may reveal a personal lifestyle were studied using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Studied chemical compounds include various brands of bug sprays and sunscreens, as well as food oils, alcohols, and citrus fruits. Brand differentiation and source determination were possible based on the active ingredients or exclusive compounds left in fingerprints. Tandem mass spectrometry was performed for the key compounds, so that these compounds could be confidently identified in a single multiplex mass spectrometry imaging data acquisition.

Chemical Imaging of Cyanoacrylate-Fumed Fingerprints by Matrix-assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

For new techniques to be incorporated into forensic science, they must be compatible with current practices. Here, cyanoacrylate fuming, a common development technique for latent fingerprints, is studied for its compatibility with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for chemical imaging of latent fingerprints. Half of a fingerprint was fumed while the other half was not; then, the changes in chemical composition and signal intensity were compared with MALDI-MS imaging. No evidence was found that fingerprint compounds are chemically altered by fuming or their signal intensities affected. The only exceptions were significant signal loss for quaternary ammonium compounds from hygiene products and moderate signal loss for tertiary amine compounds. This result is in striking contrast with the previous attempts by others, which is attributed to the difference in instrumentation.

Cellular and Subcellular Level Localization of Maize Lipids and Metabolites Using High-Spatial Resolution MALDI Mass Spectrometry Imaging.

Recent technological advances have pushed the achievable spatial resolution for mass spectrometry imaging (MSI) to cellular and subcellular levels. Direct visualization of maize tissues by this tool has provided key insights into the localization of metabolites and lipids. This chapter outlines methodology for sample preparation, data acquisition, and data analysis of maize tissue sections using high-spatial resolution matrix-assisted laser desorption ionization (MALDI)-MSI, as well as the incorporation of a multi-resolution optical system, which allows for simple inter-conversion between different resolution setups (5, 10, and 50 µm imaging).

Detection of phenazepam in impaired driving.

Phenazepam is a potent 1,4-benzodiazepine that has gained notoriety among recreational drug users. First synthesized in Ukraine in the 1970s, it is one of the most commonly prescribed benzodiazepines in Russia and other commonwealth of independent state nations, where it is used therapeutically as a prescription drug. Reports of abuse are widespread and several European countries have taken steps to control its use. However, in the USA, phenazepam is not approved for use by the Food and Drug Administration, nor scheduled under the Federal Controlled Substances Act. Phenazepam is widely available on the Internet, and recreational drug users report a potency 10-fold greater than that of nordiazepam. We report a case of a 24-year-old male driver who was apprehended for impaired driving following a two-vehicle crash. The subject exhibited slurred speech and profound psychomotor impairment. Toxicology testing revealed phenazepam at a concentration of 76 ng/mL in blood, with no other drugs detected. This case report not only demonstrates the potential for adverse traffic safety consequences following the misuse of phenazepam, but also highlights the importance of analytical factors such as immunoassay cutoff concentration, cross-reactivity and comprehensive screening using chromatographic-based techniques for impaired driving investigations.