The impact of lipid degradation on fingerprint quality on fired firearm cartridges

The recovery of identifiable fingerprints from fired cartridge cases is challenging. Therefore, the characterization of chemical modifications and their effects on fingerprint integrity post-firing is essential. In this study, the primary fingerprint lipids, including myristic acid, pentadecanoic acid, palmitoleic acid, palmitic acid, stearic acid, squalene, and cholesterol in fired and unfired cartridges, were extracted with acetonitrile, followed by derivatization using N,O-Bis(trimethylsilyl)trifluoroacetamide with 1% trimethylchlorosilane (BSTFA/1%TMCS). Squalane was used as the internal standard, and all quantifications were performed using gas chromatography coupled with mass spectrometry using a triple-quadrupole mass filter. All lipids identified in the unfired cartridges were also detected in the fired cartridges, and statistical analysis using Student's t-test and F tests was performed with a 95% confidence level. The concentration of lipids in the unfired cartridges was found to be similar to that detected in the fired cartridges, except for squalene, the recovery of which was 28% lower in the fired cartridges.

Analysis of Diglycolic Acid After Mass Poisoning by Diethylene Glycol

In December 2019, unusual cases of acute renal failure with neurological changes were observed in the State of Minas Gerais, Brazil. Criminal investigations indicated cases of intoxication after consumption of beers contaminated with diethylene glycol (DEG). The elimination of DEG by the body is fast, but its metabolite, diglycolic acid (DA), may persist for a long time. To assess the level of intoxicated victims who consumed the contaminated beers, qualitative and quantitative methods were developed to determine DA in biological matrices by gas chromatography coupled to a mass spectrometer (GC-MS) and gas chromatography coupled to a mass spectrometer with triple-quadrupole mass filter (GC-MS/MS), respectively. The validated qualitative method presents good selectivity and limit of detection of 1 µg/mL (whole blood, urine, vitreous humor and cerebrospinal fluid) and 5 µg/g (liver and kidney). A quantitative method for whole blood presented satisfactory performance to determine DA. Twelve victims presented positive results for DA in whole blood, with concentrations ranging from 2 to 108 µg/mL. The toxicology laboratory of the Institute of Forensic Medicine of Minas Gerais was the first governmental agency to identify DA in whole blood, vitreous humor, cerebrospinal fluid, kidney and urine in victims affected by this contaminant. The results of this study legally supported the prohibition to the continued consumption of the beer and avoided further intoxications. Our results showed, for real cases of human intoxication, that it can still be detected in alternative matrices, even when non-detectable in blood, demonstrating the importance of collecting different kinds of samples for a proper investigation.