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41The use of vitreous humor and pericardial fluid as alternative matrices to blood and plasma in the field of 42 forensic toxicology is described to quantitate low levels of Salvinorin A using ethion as internal standard. 43The method was optimized and fully validated using international accepted guidelines. The developed 44 methodology utilizes a solid phase extraction procedure coupled to gas chromatography mass 45 spectrometry operated in the selected ion monitoring mode. The method was linear in the range of 5.0 to 46 100 ng/mL with determination coefficients higher than 0.99 in 100 µL of vitreous humor and in 250 µL 47 of each matrix pericardial fluid, whole blood and plasma. The limits of detection and quantitation were 48 experimentally determined as 5.0 ng/mL, intra-day precision, intermediate precision and accuracy were in 49 conformity with the criteria normally accepted in bioanalytical method validation. The sample cleanup 50 step presented mean efficiencies between 80 and 106% in the different biological specimens analysed. 51According to the low volumes of samples used, and the low limits achieved using a single quadrupole 52 mass spectrometer, which is available in most laboratories, we can conclude that the validated 53 methodology is sensitive and simple and is suitable for the application in forensic toxicology laboratories 54for the routine analysis of Salvinorin A in both conventional and unconventional biological samples. 55 56

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This paper presents a method for the determination of xylazine in whole blood using solid-phase extraction and gas chromatography-mass spectrometry. This technique required only 0.5 mL of sample, and protriptyline was used as internal standard (IS). Limits of detection and quantitation (LOQ) were 2 and 10 ng/mL, respectively. The method was found to be linear between the LOQ and 3.50 microg/mL, with correlation coefficients higher than 0.9922. Precision (intra- and interday) and accuracy were in conformity with the criteria normally accepted in bioanalytical method validation. The analyte was stable in the matrix for at least 18 h at room temperature and for at least three freeze/thaw cycles. Mean recovery, calculated at three concentration levels, was 87%. To the best of our knowledge, this is the first time that solid-phase extraction is used as sample preparation technique for the determination of this compound in biological media. Because of its simplicity and speed when compared to other extraction techniques, the herein described method can be successfully applied in the diagnosis of intoxications by xylazine.

Cocaine is still one of the most abused drugs worldwide and, as such, it is often screened for in driving-under-the-influence or workplace drug - testing scenarios. A large number of samples have usually to be processed in those situations, and this requires fast and simple extraction procedures for the detection and quantification of the drugs. The present work describes an ultrafast and fully validated procedure for the simultaneous detection and quantification of cocaine and its two main metabolites, ecgonine methyl ester and benzoylecgonine, in urine using microextraction by packed sorbent and GC-MS. A small sample volume (200 μL) was used, and a fast extraction procedure together with a microwave-assisted derivatization (800 W, 2 min) allowed the quantification of all analytes in a range of 25 to 1000 ng/mL (r > 0.99). Inter-day precision revealed coefficients of variation (CVs) lower than 10% for all analytes at the tested concentration levels, with an accuracy within a ±7% interval, with the exception of EME's lowest calibrator (±17%). Intra-day CVs were lower than 15% at the studied concentration levels, with a mean relative error within a ±13% interval. Recoveries ranged from 14.5 to 37.2% (EME), 67.0 to 83.3% (cocaine), and 24.6 to 43.5% (BEG), allowing the limits of detection and quantification to be set at 25 ng/mL for all compounds. Graphical Abstract Schematized analysis of cocaine and metabolites in urine by MEPS- GC/MS.