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- Quantification of Δ9-THC, 11-OH-THC and THCCOOH by SPE and GC-MS-MS in whole blood samples for forensic purposesPublication . Castro, André Lobo; Tarelho, Sónia; Quintas, Maria José; Costa, Pedro; Melo, Paula; Castañera, Antonio; Dias, MárioIntroduction: Cannabis sativa represents the most frequently abused illicit drug around the world. Its abuse represents a major issue in terms of public health, not only due to its physical and psychological effects in terms of individual behaviour, but also due to consequences in terms of impairment, mainly as to driving capabilities is concerned. Detection and accurate quantification at low levels, namely for 9-THC and 11-OH-THC, seems crucial, in terms of response of a forensic toxicology laboratory to answer to legal requirements. The aim of this work considers the analytical validation for detection and quantification of 9-THC, 11-OH-THC and THCCOOH in whole blood samples, in vivo and post-mortem, for forensic purposes. Material and methods: The method included an SPE procedure with HLB OASIS® (WATERS) cartridges, derivatization with BSTFA:TMCS 99:1 (SUPELCO) and an hyphenated instrumental technique based in a GC-450 gas chromatograph coupled to a MS-300 triple quadrupole mass detector (BRUKER). Results: The procedure included a chromatographic run, with full separation of the three compounds, and the MS-MS detection was characterized by two product-ions (289 m/z ; 305 m/z), obtained from the parent-ion 371 m/z. The ion 289 was used for quantification. The respective tri-deuterated substances were used as internal standards. The validation included several parameters, as specificity/selectivity (with 0% of False Positives and False Negatives), LOD and LOQ (1 ng/mL to all compounds), linearity (1 – 100 ng/mL to all compounds), extraction recovery, carryover, inter and intra-day run precision (both under 15%), among others. Discussion: The developed method has shown to be fit to purpose, with good results in terms of increased sensibility and detection limits, due to an optimal response from the analytical equipment, based on tandem MS technology. The LOD and LOQ are compatible with reference values for positive real samples, namely applied to traffic roadside testing. This method has been applied to the laboratory routine, representing an effective improvement in terms of the lab response to legal requirements.
- Quantification of GHB by SPE and GC-MS-MS in whole blood samples for forensic purposesPublication . Castro, André Lobo; Dias, Mário; Reis, Flávio; Teixeira, HelenaIntroduction: Gamma-Hydroxybutyrate (sodium hydroxybutyrate; sodium oxybutyrate; GHB) is known to be an endogenous, naturally occurring, short-chained fatty acid found in mammalian tissues, with wide distribution and action in several brain areas (hipothalamus, basal ganglia). Although it was first synthesised in 1960, it soon was noticed that it is no more than an endogenous compound. With more than 30 years of clinical use, both in Europe and the U.S.A, its illicit use includes recreational use, muscle building effects in bodybuilders and drug-facilitated sexual abuse. Used as a club drug, alone or mixed with other substances, it´s symptoms mimetize MDMA, ketamine and ehtanol. On the ohter hand, it is also used for drug-facilitated sexual abuse (DFSA) purposes. Aim: In this work, the authors developed and validated an analytical procedure for GHB detection in whole blood (in vivo and post-mortem), for forensic purposes. Material and Methods: The analytical method was developed preparing the samples by a SPE procedure with MCX OASIS® cartridges, followed by derivatization with BSTFA-TMCS (99:1) and instrumental analysis developed by GC-MS-MS in a Triple Quadrupole apparatus (BRUKER). Results and Discussion: The described method shows good fitness for purpose for whole blood samples. The obtained LOD and LOQ were 200 ng/mL, for 100 uL of sample. This increase in sensitivity was obtained due to an optimized SPE procedure and an instrumental technique state-of-the-art. The work range started at 200 ng/mL, far below the suggested cut-off for whole blood samples (5-10 mg/L). These results will allow the possibility to distinguish post-mortem production, endogenous values and external consumption, whenever this diagnosis should be determined, being applicable to forensic purposes.