Salting out assisted liquid-liquid extraction for liquid chromatography tandem-mass spectrometry determination of amphetamine-like stimulants in meconium

In the last decade there has been a dramatic increase in the availability and abuse of synthetic cathinones – new amphetamine-like stimulants. Even though their abuse during pregnancy could have serious adverse effects on the fetus, cathinones are not readily included in neonatal toxicological screenings. Meconium (first neonatal stool) is the specimen of choice to reveal long term drug exposure, however as it is a highly complex matrix, the sample preparation is a critical step before the instrumental analysis. The aim of this work was to develop a suitable meconium sample extraction technique using the advantages of salting-out assisted liquid-liquid extraction (SALLE) and using only MS-friendly organic ammonium salts. We further developed and validated liquid chromatography tandem-mass spectrometry method for the determination of ‘traditional’ stimulants (methamphetamine, amphetamine, MDMA) and cathinones (mephedrone, methylenedioxypyrovalerone (MDPV), α-pyrrolidinopentiophenone (α-PVP), methylone, butylone, flephedrone, and naphyrone). Matrix-matched calibration was prepared in the concentration range 10–2000 ng/g. The limits of quantification were determined as 10 ng/g, recoveries ranged from 48.2% to 94.3% and the matrix effect was between 60.2% and 101.4%. Accuracy (86.1–114.5%) and precision (4.9–14.9%) were determined and all validation criteria were met for all analytes except for naphyrone. Finally, our analytical method was tested on a set of real meconium samples, which were found positive for amphetamine, methamphetamine and methylone, thus demonstrating the validity of the method.