Determination of cocaine and methadone in urine samples by thin-film solid-phase microextraction and direct analysis in real time (DART) coupled with tandem mass spectrometry.

The use of thin-film solid-phase microextraction (SPME) as the sampling preparation step before direct analysis in real time (DART) was evaluated for the determination of two prohibited doping substances, cocaine and methadone, in urine samples. Results showed that thin-film SPME improves the detectability of these compounds: signal-to-blank ratios of 5 (cocaine) and 13 (methadone) were obtained in the analysis of 0.5 ng/ml in human urine. Thin-film SPME also provides efficient sample cleanup, avoiding contamination of the ion source by salt residues from the urine samples. Extraction time was established in 10 min, thus providing relatively short analysis time and high throughput when combined with a 96-well shaker and coupled with DART technique.