In the toxicological field, the keratin matrix is of great interest because it allows to evaluate a possible past consumption of a substance, even after months, through the identification of active ingredients together with their products of endogenous biotransformation. THC is the psychoactive principle of Cannabis, one of the most popular substances of abuse since ancient times for its analgesic and sedative effects; THC has two main metabolites of phase I: 11-hydroxy-tetrahydrocannabinol (11-OH-THC) and 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH). The identification of a recent or previous consumption and/or exposure to substances of abuse is one of the main tasks of the forensic toxicologist. Therefore, the analysis of active ingredients and their metabolites in the keratin matrix plays a prominent role in the routine activity of the laboratory. The aim of this study was to develop two analytical methods that would lead to the identification of THC, 11-OH-THC and THCCOOH within the keratin matrix and subsequently evaluate their distribution in real hair samples from different users. Starting from samples positive for THC and/or THCCOOH, by means of two different analytical techniques in GC-MS/MS, we were able to evaluate the distribution of these analytes in 120 real samples. The use of a triple quadrupole GC-MS/MS system proved to be a prerequisite for achieving analytical sensitivities suitable for the identification of the two metabolites of interest. In order to evaluate THC and its two metabolites it was necessary, also based on the works in the literature analyzed, to use two different ionization sources: EI (electronic impact), a hard source was used to monitor THC and 11-OH-THC, while to evaluate the presence of THCCOOH NICI (negative chemical ionization) was preferred. Of the 120 samples analyzed, 20.8% were positive for all three molecules tested, 2.5% were positive only for THC, while in 21.6% of cases only the presence of THCCOOH was detected. It has been observed that 11-OH-THC is present in the samples only in those cases where the presence of the other two analytes has been confirmed at the same time. The future perspective is to try a procedure of sample preparation and derivatization that allows the monitoring of the three analytes by ionization with a single source. At the same time the two methods developed will be subject to complete validation, as required by the guidelines of the sector, so as to be able to use them during the routine investigations of the laboratory.
In ambito tossicologico, la matrice cheratinica è di grande interesse in quanto consente di valutare un possibile consumo pregresso di una sostanza, anche a distanza di mesi, attraverso l’identificazione dei principi attivi unitamente ai loro prodotti di biotrasformazione endogena. Il THC è il principio psicoattivo della Cannabis, una delle sostanze d’abuso più diffuse fin dall’antichità per i suoi effetti analgesici e sedativi; il THC presenta due metaboliti principali di fase I: 11- idrossi-tetraidrocannabinolo (11-OH-THC) e l’11-nor-9-carbossi-tetraidrocannabinolo (THC-COOH). L’identificazione di un consumo e/o di un’esposizione, recente ovvero pregressa, a sostanze dell’abuso è uno dei principali compiti del tossicologo forense. Pertanto, l’analisi dei principi attivi e dei loro metaboliti nella matrice cheratinica riveste un ruolo preminente dell’attività routinaria del laboratorio. L’obiettivo di questo studio è stato quello di sviluppare due metodi analitici che portassero all’identificazione di THC, 11-OH-THC e THCCOOH all’interno della matrice cheratinica e successivamente valutarne la distribuzione nei campioni reali di capelli provenienti da diverse utenze. Partendo da campioni positivi per THC e/o THCCOOH, mediante due differenti tecniche analitiche in GC-MS/MS, siamo riusciti a valutare la distribuzione di questi analiti su 120 campioni reali. L’utilizzo di un sistema GC-MS/MS a triplo quadrupolo è risultato un indispensabile requisito per il raggiungimento di sensibilità analitiche idonee all’identificazione dei due metaboliti di interesse. Per poter valutare il THC e i suoi due metaboliti è stato necessario, basandosi anche sui lavori in letteratura analizzati, utilizzare due sorgenti di ionizzazione differenti: EI (impatto elettronico), una sorgente hard è stata impiegata per monitorare il THC e l’11-OH-THC, mentre per valutare la presenza di THCCOOH si è preferita la NICI (ionizzazione chimica negativa). Dei 120 campioni analizzati il 20,8 % è risultato positivo a tutte e tre le molecole ricercate, il 2,5 % è risultato positivo solo al THC, mentre nel 21,6% dei casi si è rilevata la sola presenza del THCCOOH. Si è osservato come il 11-OH-THC è presente nei campioni solo nei casi in cui è stata confermata contestualmente la presenza degli altri due analiti oggetto di indagine. La prospettiva futura è quella di tentare una procedura di preparazione e di derivatizzazione del campione che consenta il monitoraggio dei tre analiti mediante la ionizzazione con un’unica sorgente. Contestualmente le due metodiche sviluppate saranno oggetto di completa validazione, secondo quanto previsto dalle linee guida di settore, di modo da poterne usufruire durante le indagini routinarie del laboratorio.
Valutazione della distribuzione del THC e dei suoi metaboliti, 11-OH-THC e THC-COOH, nel capello mediante GC-MS/MS
CARRÀ, FRANCESCA
2020/2021
Abstract
In the toxicological field, the keratin matrix is of great interest because it allows to evaluate a possible past consumption of a substance, even after months, through the identification of active ingredients together with their products of endogenous biotransformation. THC is the psychoactive principle of Cannabis, one of the most popular substances of abuse since ancient times for its analgesic and sedative effects; THC has two main metabolites of phase I: 11-hydroxy-tetrahydrocannabinol (11-OH-THC) and 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH). The identification of a recent or previous consumption and/or exposure to substances of abuse is one of the main tasks of the forensic toxicologist. Therefore, the analysis of active ingredients and their metabolites in the keratin matrix plays a prominent role in the routine activity of the laboratory. The aim of this study was to develop two analytical methods that would lead to the identification of THC, 11-OH-THC and THCCOOH within the keratin matrix and subsequently evaluate their distribution in real hair samples from different users. Starting from samples positive for THC and/or THCCOOH, by means of two different analytical techniques in GC-MS/MS, we were able to evaluate the distribution of these analytes in 120 real samples. The use of a triple quadrupole GC-MS/MS system proved to be a prerequisite for achieving analytical sensitivities suitable for the identification of the two metabolites of interest. In order to evaluate THC and its two metabolites it was necessary, also based on the works in the literature analyzed, to use two different ionization sources: EI (electronic impact), a hard source was used to monitor THC and 11-OH-THC, while to evaluate the presence of THCCOOH NICI (negative chemical ionization) was preferred. Of the 120 samples analyzed, 20.8% were positive for all three molecules tested, 2.5% were positive only for THC, while in 21.6% of cases only the presence of THCCOOH was detected. It has been observed that 11-OH-THC is present in the samples only in those cases where the presence of the other two analytes has been confirmed at the same time. The future perspective is to try a procedure of sample preparation and derivatization that allows the monitoring of the three analytes by ionization with a single source. At the same time the two methods developed will be subject to complete validation, as required by the guidelines of the sector, so as to be able to use them during the routine investigations of the laboratory.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
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https://hdl.handle.net/20.500.14239/13686