General unknown screening procedure for the characterization of human drug metabolites in forensic toxicology: Applications and constraints

Abstract

LC coupled to single (LC-MS) and tandem (LC-MS/MS) mass spectrometry is recognized as the most powerful analytical tools for metabolic studies in drug discovery. In this article, we describe five cases illustrating the utility of screening xenobiotic metabolites in routine analysis of forensic samples using LC-MS/MS. Analyses were performed using a previously published LC-MS/MS general unknown screening (GUS) procedure developed using a hybrid linear IT-tandem mass spectrometer. In each of the cases presented, the presence of metabolites of xenobiotics was suspected after analyzing urine samples. In two cases, the parent drug was also detected and the metabolites were merely useful to confirm drug intake, but in three other cases, metabolite detection was of actual forensic interest. The presented results indicate that: (i) the GUS procedure developed is useful to detect a large variety of drug metabolites, which would have been hardly detected using targeted methods in the context of clinical or forensic toxicology; (ii) metabolite structure can generally be inferred from their "enhanced" product ion scan spectra; and (iii) structure confirmation can be achieved through in vitro metabolic experiments or through the analysis of urine samples from individuals taking the parent drug.

Rapid drug extraction from human whole blood using a modified QuEChERS extraction method

“…In general, protein precipitation (PP), liquid-liquid extraction (LLE) and solid phase extraction (SPE) are currently used as pretreatment techniques in toxicological analysis [1][2][3][4][5][6][7][8][9]. Although PP and LLE are simple methods, inadequate purification of samples may cause contamination to the instrument and problems with reliability of quantitative values.…”

Analyse toxicologique avec mesure par « masse exacte ». Caractérisation de métabolites urinaires par couplage UPLC/QTOF : apports et intérêts dans le cadre de la soumission chimique

“…Ainsi, trois pics supplémentaires importants ont été repérés correspondant pour l'un à une perte d'un groupement méthyle et pour les deux autres à la perte d'un groupement méthyle, plus l'ajout d'un oxygène dans la formule de l'alimé-mazine [32]. L'enrichissement de base de données de référence, par l'ajout de paramètres caractérisant quelques métabolites principaux de xénobiotiques a plusieurs intérêts majeurs [33]. Le premier, dans le cas d'une identification d'un principe actif à l'état de traces dans une matrice biologique, la possibilité de détecter simultanément un ou plusieurs métabolites permettra de confirmer sa présence, l'autre est de permettre un élargis-sement important de la fenêtre de détection d'un composé, cet aspect est déterminant dans le cadre de la caractérisation d'une soumission chimique où le toxicologue reçoit en première intention du sang et de l'urine.…”

Toxicology of Specific Substances

“…general unknown or systematic toxicological analysis (STA)) (Sauvage et al 2006(Sauvage et al , 2009Maurer 2007Maurer , 2009Peters et al 2009;Sturm et al 2010;Johnson and Botch 2011). An additional field for determination of sedative-hypnotics is the diagnosis of brain death, that is the exclusion of effective plasma concentrations of drugs that might mimic a flat-line electroencephalogram (EEG).…”