Amino acid profiling from fingerprints, a novel methodology using UPLC-MS†
Fingermark evidence is extensively used in criminal investigations. Hence, there have been many investigations into the chemical compounds present in fingerprint deposits. In this technical note we describe the analysis of non-derivatised amino acid profiles obtained from fingerprints. We used UPLC with an amide stationary phase and subsequent detection using a triple quadrupole MS/MS and TOF-MS detector. The linearity (R2) was satisfactory for both MS detectors (>0.98 for all amino acids in the case of the triple quadrupole MS/MS and >0.96 in the case of the TOF-MS). Although the triple quadrupole had a higher sensitivity for most amino acids, both mass spectrometers were able to retrieve the amino acid profiles of fingerprints from 19 donors. Between these profiles, only minor differences were observed between the separate analyses on the different mass analyzers, mainly in L-proline, L-lysine and L-phenylalanine abundances. Surprisingly, the mean RSD in amino acid profiles from duplicate fingerprints turned out to be lower for the TOF-MS (18.6% ± 6.6% vs. 13.2% ± 3.8%), as did the mean RSD of the intraday reproducibility (8.22% ± 1.94% vs. 9.54% ± 3.07%).