In forensic science, reconstructing the timing of events occurring during a criminal offense is of great importance. In some cases, the time when particular evidence was left on a crime scene is a critical matter. The ability to estimate the fingerprint age would raise the evidentiary value of fingerprints tremendously. For this purpose the most promising approach is the analysis of changes in the chemical compositions of fingerprint residues in the course of aging. The focus of our study is the identification of human specific compounds in fingerprint residues, characterized by a significant aging behavior that could analytically be used for the age determination of fingerprints in future. The first challenge is the sensitive detection of trace amounts of relevant human specific fingerprint compounds. Highly sensitive LC-MS methods were developed for the reliable structure identification of unsaturated triglycerides and their natural degradation products in order to proof the aging mechanism that takes place in fingerprint residues. Thus our results build the fundamental basis for further forensic method development and potential application in forensic investigation. Ozonolysis was found to be one of the major lipid degradation pathways in fingerprint residues in ambient air. High-resolution tandem mass spectrometry (HRMS) was carried out to identify the ozonolysis products (TG48:0-monoozonide) formed under exposure to the highly reactive ozone in atmospheric air. The obtained products were confirmed by matrix assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI). Despite several challenges and limitations in the age estimation of fingerprints, the identification of individual degradation products of specific unsaturated lipids in aged fingerprint samples represents a significant analytical progress, resulting in a strong increase in the validity of chemical analysis of fingerprints.

Abstract. GC-MS investigations were carried out to elucidate the aging behavior of unsaturated fatty acids in fingerprint residues and to identify their degradation products in aged samples. For this purpose, a new sample preparation technique for fingerprint residues was developed that allows producing N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) derivatives of the analyzed unsaturated fatty acids and their degradation products. MSTFA derivatization catalyzed by iodotrimethylsilane enables the reliable identification of aldehydes and oxoacids as characteristic MSTFA derivatives in GCMS. The obtained results elucidate the degradation pathway of unsaturated fatty acids. Our study of aged fingerprint residues reveals that decanal is the main degradation product of the observed unsaturated fatty acids. Furthermore, oxoacids with different chain lengths are detected as specific degradation products of the unsaturated fatty acids. The detection of the degradation products and their chain length is a simple and effective method to determine the double bond position in unsaturated compounds. We can show that the hexadecenoic and octadecenoic acids found in fingerprint residues are not the pervasive fatty acids Δ9-hexadecenoic (palmitoleic acid) and Δ9-octadecenoic (oleic acid) acid but Δ6-hexadecenoic acid (sapienic acid) and Δ8-octadecenoic acid. The present study focuses on the structure identification of human sebum-specific unsaturated fatty acids in fingerprint residues based on the identification of their degradation products. These results are discussed for further investigations and method developments for age determination of fingerprints, which is still a tremendous challenge because of several factors affecting the aging behavior of individual compounds in fingerprints.

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Synthetic cathinones comprise psychostimulants with desired effects like euphoria, increased vigilance, appetite suppression, and—mainly depending on certain structural features—entactogenic properties. 3,4‐EtPV (1‐(bicyclo[4.2.0]octa‐1,3,5‐trien‐3‐yl)‐2‐(pyrrolidin‐1‐yl)pentan‐1‐one) was first mentioned in an online drug forum in September 2021, where its imminent synthesis was announced. The goal was to produce a legal alternative to the phenylethylamines already banned by the German NpSG. In February and June 2022, two samples labeled with the name and molecular structure of 3,4‐EtPV were analyzed. The molecular structure of the obviously mislabeled compound was elucidated and comprehensively characterized within the ADEBAR project. The synthetic cathinone identified differed from the declared 3,4‐EtPV by a 3,4‐propylene bridge instead of a 3,4‐ethylene bridge and a piperidine ring instead of a pyrrolidine ring. The short name 3,4‐Pr‐PipVP (3,4‐propylene‐2‐(1‐piperidinyl)valerophenone) was suggested as a semisystematic name in collaboration with the European Monitoring Centre for Drugs and Drug Addiction. Herein, the results of the analyses are discussed and will enable forensic laboratories to update their databases quickly and identify 3,4‐Pr‐PipVP confidently. 3,4‐Pr‐PipVP is already scheduled under the German NpSG. This study highlights that there are ongoing efforts to deliberately circumvent generic definitions given, for example, in the German NpSG and that (unintentional?) mislabeling can be an issue. The end user purchasing substances online can never be sure that the material actually supplied will be the one ordered, and he might receive an illicit drug instead of an uncontrolled one. Furthermore, the purity is always unknown, creating health risks due to unexpected effects and potencies.