Synthesis, characterization, and application of a polymeric capillary fiber derived from methacrylic acid in the determination of cocaine in blood by FSI-MS

The development of probes/substrates that enable in-situ and in-natura biological analysis, capable of adsorbing analytes and enabling effective ionization, can be an alternative for detecting illicit drugs present in these matrices. Particularly, fiber spray ionization mass spectrometry (FSI-MS) shows promise because it enables straightforward and direct analyses without prior sample treatment or processing. In this study, a polymeric capillary fiber was developed and applied as a probe/substrate in FSI-MS experiments for the sampling and ionization of blood samples. The fiber was directly immersed in a solution of whole blood doped with cocaine (COC) and deuterated cocaine (COC-d3) to optimize the experimental conditions. The developed analytical approach was evaluated using whole blood samples taken from individuals suspected of drug abuse. Additionally, paper spray ionization mass spectrometry (PSI-MS) analyses were performed for comparison with the FSIMS technique. The FSI analysis in positive mode, FSI(+), was effective in detecting COC and its metabolites with high sensitivity and accurate mass measurements. Evaluation of the whole blood sample collected from a suspected user revealed higher sensitivity for COC detection by FSI than by PSI. The quantification of COC in whole blood by FSI(+) showed detection and quantification limits of 32.0 and 106.7 ng mL-1, respectively. In addition, linearity was observed, with a coefficient of determination above 0.99 and a relative standard deviation ranging from 0.47 % to 8.58 %.

Automated summary

This study developed a fiber spray ionization mass spectrometry (FSI-MS) method, which shows great potential in detecting illicit drugs. Compared with paper spray ionization mass spectrometry (PSI-MS), FSI-MS demonstrates higher sensitivity in COC detection.