Next generation microsampling towards sustainable forensic analysis: Volumetric DBS for cocaine and metabolites

This study introduces for the first time a reliable whole blood microsampling method for forensic analysis of cocaine and its metabolites using quantitative dried blood spot (qDBS) technology and UHPLC-MS analysis. This methodology offers accurate and less invasive sampling and aligns with the current trend towards sustainable and accessible analytical methods. Microsampling is subject-friendly, improves logistics, stability and efficiency, marking a shift towards modern forensic practices with wide-ranging application potential. The qDBS-UHPLC-MS method underwent comprehensive validation, confirming its linearity, sensitivity, precision, extraction efficiency and stability. UHPLC-MS achieved effective chromatographic separation and suitable sensitivity, with detection limits between 1.0 and 2.5 ng/mL, and quantitation limits from 2.5 to 7.5 ng/mL. Analytes showed over 85.1 % extraction yield and less than 7.5 % relative standard deviation in precision. Stability tests indicated superior analyte preservation in qDBS at room temperature versus refrigerated plasma, while minimal matrix effect highlighted the sample clean-up efficiency. Application to real samples yielded consistent quali-quantitative results between qDBS and plasma samples, confirming method suitability for forensic cocaine bioanalysis, thus addressing critical needs in drug testing and pharmaco-toxicological analysis.