Psychoactive plants have played a significant role in Andean cultures for millennia. Whilst there is evidence of the importance of psychoactive plants in the Andean archaeological record, none of these are direct proof that these culturally significant plants were used by ancient Andean populations. This project utilised liquid chromatography tandem mass spectrometry (LC-MS/MS) to investigate the use of psychoactive plants in individuals from cemetery sites in Chile and Peru by analysing hair specimens for a variety of psychoactive compounds. Hair specimens from 46 individuals buried at cemetery sites in the Azapa Valley (northern Chile) belonging to the Cabuza culture (c AD 300 ¿ 1000) indicated around half of these people ingested coca, as evidenced by the detection of BZE in hair specimens. Two individuals from this population tested positive for bufotenine, the main alkaloid in Anadenanthera snuff. There is a specific material culture associated with snuffing. These findings confirm Anadenanthera was consumed in the Azapa Valley. The 11 individuals from Peru came from the necropolis at Puruchuco-Huaquerones in the Rímac valley near Lima. These individuals belonged to the Ichma culture, but would have been under Inca imperial control during the Late Horizon. Although only a small sample, two-thirds tested positive for BZE, suggestive that access to coca was widespread. This project presents a synthesis of the archaeological evidence for the use of various psychoactive plants in Andes. Also presented is the first report of the detection of bufotenine in ancient hair samples and additional data contributing to the understanding of the use of coca in the Andes. / Arts and Humanities Research Council (AHRC). Andy Jagger and Francis Raymond Hudson funds at the University of Bradford

No / Nanoscale reversed-phase liquid chromatography (LC) combined with electrospray ionization-tandem mass spectrometry (ESI-MS/MS) has been used as a method for the direct identification of multiple cytochrome P450 (P450) isoforms found in male and female rat liver. In this targeted proteomic approach, rat liver microsomes were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by in-gel tryptic digestion of the proteins present in the 48- to 62-kDa bands. The resultant peptides were extracted and analyzed by LC-ESI-MS/MS. P450 identifications were made by searching the MS/MS data against a rat protein database containing 21,576 entries including 47 P450s using Sequest software (Thermo Electron, Hemel Hempstead, UK). Twenty-four P450 isoforms from the subfamilies 1A, 2A, 2B, 2C, 2D, 2E, 3A, 4A, 4F, CYP17, and CYP19 were positively identified in rat liver.

No / Surfactants are commonly used as cleansing agents and yet there are concerns they may also have a role in skin irritation. Presently, the lack of suitable methods for quantitative and qualitative analysis of surfactant deposition on skin has hindered the in-depth investigation of such effects. Here, we report the application of reverse phase liquid chromatography electrospray ionisation mass spectrometry (LC/ESI-MS/MS) assays for two surfactants commonly used in consumer products, namely sodium lauryl ether sulphate (SLES) and laurylamidopropyl betaine (LAPB), to a baseline study aiming to assess deposition levels on human skin. The linearity of the assays was established at 3-20 ng, with coefficient of variation below 5%. Detection limits were 100 pg for LAPB and 1 ng for SLES; quantitation limits were 500 pg for LAPB and 2.5 ng for SLES. The baseline study was conducted using a panel of 40 healthy volunteers. Skin extract samples were taken in triplicate from forearms, using ethanol. SLES was detected on most volunteers, with 75% of them having SLES deposits in the range of 100-600 ng/cm2. LAPB was detected on the skin of all volunteers with 85% of them having deposit levels within the concentration range of 1-100 ng/cm2. These results demonstrate the extent to which commonly used surfactants remain on the skin during the day. The analytical methods reported here can be applied to the investigation of surfactants in relation to general skin condition and the development and optimisation of new consumer wash products. / EPSRC

No / Surfactants are commonly used as cleansing agents and yet there are concerns that they may also have a role in skin irritation. The lack of suitable methods for the quantitative and qualitative analysis of surfactant deposition on skin has hindered the in-depth investigation of such effects. Here, we report the application of reversed-phase liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) assays for two surfactants commonly used in consumer products, namely sodium lauryl ether sulfate (SLES) and laurylamidopropyl betaine (LAPB), to a baseline study aiming to assess deposition levels on human skin. The linearity of the assays was established at 3-20 ng, with coefficient of variation below 5%. The detection limits were 100 pg for LAPB and 1 ng for SLES; quantitation limits were 500 pg for LAPB and 2.5 ng for SLES. The baseline study was conducted using a panel of 40 healthy volunteers. Skin extract samples were taken in triplicate from forearms, using ethanol. SLES was detected on most volunteers, with 75% of them having SLES deposits in the range of 100-600 ng/cm(2). LAPB was detected on the skin of all volunteers with 85% of them having deposit levels within the concentration range of 1-100 ng/cm(2). These results demonstrate the extent to which commonly used surfactants remain on the skin during the day. The analytical methods reported here can be applied to the investigation of surfactants in relation to general skin condition and to the development and optimisation of new consumer wash products. / EPSRC-DTA award / School Life Sciences

Nordihydroguaiaretic acid (NDGA), is a naturally-occurring lignan isolated from the creosote bush (Larrea tridentata). The aqueous extract of this shrub, commonly referred to as Chaparral tea, was listed in the American pharmacopeia as an ethnobotanical used to treat tuberculosis, arthritis and cancer. Other documented traditional applications of creosote bush extract include treatment for infertility, rheumatism, arthritis, diabetes, gallbladder and kidney stones, pain and inflammation among many others. In spite of the numerous pharmacological properties, NDGA use has been associated with toxicities including hepatotoxicity in humans. Previous studies in our group showed that oxidative cyclization of NDGA (a di-catechol) at physiological pH forms a dibenzocyclooctadiene that may have therapeutic benefits whilst oxidation to ortho-quinone likely mediates toxicological properties. In order to investigate the structural features responsible for pharmacological and toxicological properties, a series of NDGA analogues were designed, synthesized and characterized for the purpose of studying their oxidative metabolism. Literature procedures were modified to successfully prepare seven lignan analogues via multi-step synthesis. In our effort to understand the mechanisms of NDGA intramolecular cyclization, the prepared analogues were incubated under previously established conditions where NDGA autoxidized to yield the dibenzocyclooctadiene derivative. We also evaluated the stability of the analogues under the conditions of this study. Furthermore, we evaluated bioactivation potential of the prepared analogues with a goal of eliminating reactive metabolite liability through rational structural modification. We incubated NDGA and its analogues in rat liver microsomes (RLM) in the presence of glutathione as a nucleophilic trapping agent. Standards for comparison were generated by performing glutathione trapping experiments with chemical and enzyme oxidation systems. The potential of the dibenzocyclooctadiene lignan 2 derived from NDGA under physiological conditions to contribute to toxicological properties via reactive metabolite formation was also evaluated. Glutathione conjugates were detected by electrospray ionization-mass spectrometry (ESI-MS) scanning for neutral loss (NL) 129 Da or 307 Da in positive ion mode or precursor ion (PI) scanning for 272 Da in negative ion mode and further characterized by liquid chromatography–tandem mass spectrometry (LC–MS/MS) or in a single LC-MS run using multiple reactions monitoring (MRM) as a survey scan to trigger acquisition of enhanced product ion (EPI) data. We determined that NDGA autoxidation at pH 7.4 is dependent on substituents and/or substitution pattern on the two aromatic rings. In particular, spontaneous intramolecular cyclization to a dibenzocyclooctadiene required a di-catechol lignan, raising the possibility that o-Q formation may not be necessary for cyclization to occur. Cyclization was significantly inhibited in the presence of excess GSH which supports the involvement of free radicals as opposed to o-Q in the intramolecular cyclization process. The mono-catechol analogues A1 and A4 underwent oxidation to o-Q but no evidence of cyclization was found implying that electrophilic substitution cannot account for NDGA cyclization. The phenol-type analogues were oxidatively more stable in comparison with the catechol-type analogues at pH 7.4. The results demonstrate that electrophilic substitution makes no contribution to the intramolecular cyclization process and that a radical mediated process accurately describes the situation for NDGA. Oxidative metabolism and bioactivation studies on NDGA and its analogues revealed that reactive metabolites formation is dependent on substitution and/or substitution pattern of the aromatic rings. Cytochrome P450-mediated oxidation of NDGA and its catechol-type analogues yielded electrophilic intermediates which reacted with GSH. The GSH mono-conjugates were identified as ring adducts derived from o-Q although the position at which the GSH binds to the aromatic rings could not be determined. We also found that NL 129 or 307 scanning in positive ionization mode has potential diagnostic utility in distinguishing between aromatic and benzylic GSH conjugates although further studies may be required for validation. We found no evidence of p-QM either directly or via isomerization of o-Q intermediates suggesting that o-Q is the major reactive toxicophore responsible for reactive metabolite mediated toxicities associated with NDGA use. In addition, we demonstrated that the NDGA-derived dibenzycyclooctadiene lignan (cNDGA 2) undergoes P450-mediated oxidation to a reactive metabolite which might have toxicological implications. There was no evidence of P450-mediated oxidation to reactive metabolites for the phenol-type NDGA analogues. It is concluded that structural modification efforts should focus on phenol-type analogues to potentially enhance the safety profile of NDGA.

Eicosapentaenoic acid (EPA) is a polyunsaturated fatty acid (PUFA) with neuroprotective and cardioprotective properties. It is thought that some of the actions of EPA may be attributed to its elongated metabolite, the PUFA docosapentaenoic acid (DPA). Docosahexaenoic acid (DHA) and arachidonic acid (AA) are bioactive PUFA ubiquitously expressed in neural tissues. EPA and AA can be converted by cyclooxygenase (COX) to prostanoids and by lipoxygenase (LOX) to hydroxy fatty acids. PUFA can also be converted to ethanolamides in the brain. These mediators are involved in physiological and pathological processes in many bodily systems. The purpose of this study was to examine the production of eicosanoids, hydroxy fatty acids and fatty acid ethanolamides in young and aged rat brain following EPA or DPA enriched diets. The effects of specific PUFA on human platelet eicosanoid production were also investigated as these mediators play a role in adhesion and aggregation. Liquid chromatography coupled to tandem mass spectrometry (LC/ESI-MS/MS) assays were developed and used to measure lipid mediators in rat brain and human platelets. Ageing in rat brain was accompanied with several changes in the prostanoid and hydroxy fatty acid profiles. Supplementing the diet with EPA or DPA at a daily dose of 200 mg/kg for 8 weeks prevented these changes and decreased levels of PGE2. DPA changed the profile of hydroxy fatty acids synthesised in the brain tissue of young animals. This study has shown that levels of eicosapentaenoylethanolamide (EPA-EA) increase in the brain as a result of ageing and that this is accompanied by an increase in levels of anandamide. Feeding aged animals EPA or DPA further increased the levels of EPA-EA but prevented any change in the level of anandamide. Niacin is used to treat hypercholesterolaemia although it is associated with an unpleasant PGD2 mediated skin flush. This exploratory study has shown that human platelets treated with niacin did not show any changes in their prostanoid and hydroxy fatty acid profiles. Platelets treated with EPA showed increased production of TXB3 and 12-HEPE. Niacin augmented the effects of EPA on human platelet mediator synthesis. Overall, this study has demonstrated that EPA can change brain and platelet lipid mediator synthesis and has provided evidence that could explain some of the neuroprotective and cardioprotective actions of this PUFA.

Les troubles reliés à la dépression, l’épuisement professionnel et l’anxiété sont de plus en plus répandus dans notre société moderne. La consommation croissante d’antidépresseurs dans les différents pays du monde est responsable de la récente détection de résidus à l’état de traces dans les rejets urbains municipaux. Ainsi, ces substances dites « émergentes » qui possèdent une activité pharmacologique destinée à la régulation de certains neurotransmetteurs dans le cerveau suscitent maintenant de nombreuses inquiétudes de la part de la communauté scientifique. L’objectif principal de ce projet de doctorat a été de mieux comprendre le devenir de plusieurs classes d’antidépresseurs présents dans diverses matrices environnementales (i.e. eaux de surfaces, eaux usées, boues de traitement, tissus biologiques) en développant de nouvelles méthodes analytiques fiables capables de les détecter, quantifier et confirmer par chromatographie liquide à haute performance couplée à la spectrométrie de masse en tandem (LC-QqQMS, LC-QqToFMS). Une première étude complétée à la station d’épuration de la ville de Montréal a permis de confirmer la présence de six antidépresseurs et quatre métabolites N-desmethyl dans les affluents (2 - 330 ng L-1). Pour ce traitement primaire (physico-chimique), de faibles taux d’enlèvement (≤ 15%) ont été obtenus. Des concentrations d’antidépresseurs atteignant près de 100 ng L-1 ont également été détectées dans le fleuve St-Laurent à 0.5 km du point de rejet de la station d’épuration. Une seconde étude menée à la même station a permis l’extraction sélective d’antidépresseurs dans trois tissus (i.e. foie, cerveau et filet) de truites mouchetées juvéniles exposées à différentes concentrations d’effluent dilué traité et non-traité à l’ozone. Un certain potentiel de bioaccumulation dans les tissus (0.08-10 ng g-1) a été observé pour les spécimens exposés à l’effluent non-traité (20% v/v) avec distribution majoritaire dans le foie et le cerveau. Une intéressante corrélation a été établie entre les concentrations de trois antidépresseurs dans le cerveau et l’activité d’un biomarqueur d’exposition (i.e. pompe N/K ATPase impliquée dans la régulation de la sérotonine) mesurée à partir de synaptosomes de truites exposées aux effluents. Une investigation de l’efficacité de plusieurs stations d’épuration canadiennes opérant différents types de traitements a permis de constater que les traitements secondaires (biologiques) étaient plus performants que ceux primaires (physico-chimiques) pour enlever les antidépresseurs (taux moyen d’enlèvement : 30%). Les teneurs les plus élevées dans les boues traitées (biosolides) ont été obtenues avec le citalopram (1033 ng g-1), la venlafaxine (833 ng g-1) et l’amitriptyline (78 ng g-1). Des coefficients de sorption expérimentaux (Kd) calculés pour chacun des antidépresseurs ont permis d’estimer une grande sorption des composés sertraline, desméthylsertraline, paroxetine et fluoxetine sur les solides (log Kd > 4). Finalement, un excellent taux d’enlèvement moyen de 88% a été obtenu après ozonation (5 mg L-1) d’un effluent primaire. Toutefois, la caractérisation de nouveaux sous-produits N-oxyde (venlafaxine, desmethylvenlafaxine) par spectrométrie de masse à haute résolution (LC-QqToFMS) dans l’effluent traité à l’ozone a mis en lumière la possibilité de formation de multiples composés polaires de toxicité inconnue. / Mood disorders such as depression, burn-out and anxiety have increased in our modern society. Increasing amounts of antidepressant prescriptions around the world are now suspected to be the main cause of the recent detection of traces of antidepressant residues within urban wastewaters. These so-called “emerging” substances that possess pharmacological activity towards neurotransmitter regulation in the brain have raised serious concerns from the scientific community. The initial goal of the study was to better understand the fate of various classes of antidepressants present in different environmental matrices (e.g. surface waters, wastewaters, treatment sludge, and biological tissues) by developing novel reliable analytical methods that can detect, quantify and confirm antidepressants using high performance liquid chromatography coupled to tandem-mass spectrometry (LC-QqQMS,LC- QqToFMS). A preliminary study completed at the Montreal sewage treatment plant (STP) confirmed the presence of six antidepressants and four N-desmethyl metabolites in raw sewage (2 – 330 ng L-1). For this primary treatment (physico-chemical), low removal rates (≤ 15%) were obtained. Concentrations of antidepressant close to 100 ng L-1 were also detected directly in the St. Lawrence River at 0.5 km of the effluent outfall. A second study conducted at the same STP allowed the selective extraction of antidepressants in three biological tissues (e.g. liver, brain, and filet) dissected from juvenile brook trouts previously exposed to diluted untreated and treated effluents with ozone. Bioaccumulation of antidepressants was readily observed in fish tissues (0.08-10 ng g-1) for the specimens exposed to untreated effluent (20% v/v), with major distribution in liver and brain. During experiments, a significant correlation was established between the concentrations of three antidepressant detected in brain tissues and the activity of a selected biomarker of exposition (e.g. an N/K ATPase pump involved in the serotonin regulation) measured within dissected synaptosomes from trout exposed to effluents. Investigation of estimated treatment removal efficiencies from various Canadian STPs operating different disinfection modes showed that secondary treatments (biological) were more efficient than primary (physico- chemical) to remove antidepressants (mean removal rates : 30%). The highest amounts detected in treated sludge (biosolids) were obtained respectively with citalopram (1033 ng g-1), venlafaxine (833 ng g-1), and amitriptyline (78 ng g-1). Experimental calculated sorption coefficients (Kd) of each antidepressant predicted fairly good sorption capacities for sertraline, desmethylsertraline, paroxetine, and fluoxetine to solid matters (log Kd > 4). Finally, an excellent mean removal rate of 88% was obtained after ozonation (5 mg L-1) of a primary effluent. However, the characterization of new N-oxide side-products (venlafaxine, desmethylvenlafaxine) in ozonized effluent by high-resolution mass spectrometry (LC-QqToFMS) highlighted the possibility of formation of multiple polar compounds with unknown toxicity.

Contrairement aux méthodes de polymérisation par voie humide, la « plasma-polymérisation » de précurseurs siliconés (typiquement l'hexaméthyldisiloxane) fournit des couches minces peu solubles, considérées comme riches en chaines courtes et ramifiées, structures cycliques et réticulées, à mi-chemin entre un poly(diméthylsiloxane) (PDMS) et une silice. Ces caractéristiques confèrent des propriétés barrières, électriques ou mécaniques uniques aux substrats traités mais sont autant de difficultés pour leur analyse par spectrométrie de masse. La caractérisation fine d'un plasma polymère serait pourtant d'autant plus utile qu'elle permettrait – indirectement – de proposer ou de valider des mécanismes d'activation et d'oligomérisation du précurseur en phases plasma et solide, connaissance essentielle s'il en est pour la maîtrise des caractéristiques d'un dépôt. Cependant, l'interprétation de données MS/MS en vue de relier un comportement dissociatif à des caractéristiques structurales nécessite l'établissement préalable de règles de fragmentation à partir de modèles pertinents. En l'absence d'étalons plasma-polymère de structure contrôlée, il s'agit donc d'explorer différents modèles potentiels afin d'établir des relations structure/fragmentation pour comprendre les données MS/MS obtenues pour des échantillons réels. Ces études contribueront d'ailleurs à enrichir la littérature sur la fragmentation de polymères siliconés, très réduite en comparaison de polymères à chaine carbonée.A partir des données obtenues depuis les parties solubles de plasma-polymères, les comportements MS/MS d'un ensemble de polymères de référence dument choisis ont été explorés et explicités. / This thesis work aimed at describing the molecular and structural composition of silicon-based plasma-polymers (ppHMDSO) by mass spectrometry. Deposited under a micro-discharge regime at atmospheric pressure, these plasma-polymers exhibit a very low solubility in common solvents, assigned to their highly cross-linked structures, and are hence not easily amenable to ionization. Moreover, structural information cannot be readily deduced from fragmentation data obtained from species extractable from the studied thin films due to the lack of appropriate rules to understand dissociation of the observed gas-phase ions. This research work has thus consisted of developing an analytical strategy to address both of these challenging issues.Owing to the very limited number of articles dealing with tandem mass spectrometry of silicon-containing oligomers, mechanistic investigations were performed on the collision-induced decomposition of selected polymer standards holding different end-groups, expected to be relevant to characterize oligomers suspected to be present in the soluble part of the ppHMDSO samples. Focusing on ammonium adducts, fragmentation routes have first been established for symmetric poly(dimethylsiloxane) (PDMS) polymers holding trimethylsilyl, hydride, or methoxy terminations. POSS molecules were also investigated to understand the influence of cross-linked structures on PDMS adduct dissociation. Some discrepancies between MS/MS spectra of the standards and of the analytes were evidenced, assigned to random branching which could not be modeled by any commercially available compounds.

A venlafaxina (VEN), em razão de sua eficácia e brandos efeitos adversos, tem sido um dos antidepressivos mais prescritos no tratamento da depressão e ansiedade. Neste trabalho, um método analítico empregando as técnicas MISPE miniaturizada e cromatografia líquida acoplada à espectrometria de massas em Tandem, foi utilizado para a determinação de VEN e seus principais metabólitos em amostras de plasma para fins de monitorização terapêutica. A fase MIP foi sintetizada via polimerização radicalar por precipitação, fazendo uso de VEN (molécula molde), ácido metacrílico (monômero funcional), etileno glicol dimetacrilato, (reagente reticulante) e 2,2 azobisisobutironitrila (iniciador radicalar) em tolueno (solvente). Para controle utilizou-se o polímero não impresso (NIP), sintetizado por procedimento análogo ao do MIP, porém sem o uso da molécula molde. A caracterização química e estrutural dos polímeros foi realizada por espectroscopia no infravermelho com transformada de fourier e microscopia eletrônica de varredura. A otimização das variáveis de MISPE miniaturizada favoreceu a detectabilidade analítica e diminuiu o efeito de memória. As extrações realizadas com MIP apresentaram taxa de recuperação de 84% para VEN e de 2-28% para os antidepressivos (clorpromazina, fluoxetina, clomipramina, imipramina e sertralina). O polímero não impresso apresentou baixa recuperação para a VEN (taxa de recuperação: 49%) e para os demais antidepressivos (taxas de recuperação menores que 40%). Estes experimentos comprovam a seletividade da fase MIP desenvolvida. O método padronizado apresentou linearidade na faixa de 3 a 700 ng mL-1 para VEN, 5 a 700 ng mL-1 para O-desmetilvenlafaxina (ODV) e de 3 a 500 ng mL-1 para N-desmetilvenlafaxina (NDV), precisão com coeficientes de variação menores que 15% e exatidão com valores de erro padrão relativo na faixa de -11,8 a 16,01 %. As concentrações correspondentes aos limites inferiores de quantificação para VEN (3 ng mL-1) e ODV ( 5 ng mL-1) foram inferiores aos intervalos terapêuticos preconizados. O método desenvolvido, quando comparado a aos métodos da literatura para determinação de VEN e metabolitos, apresentou maior seletividade, menor consumo de amostra e de solventes orgânicos e permitiu a reutilização da fase extratora. Segundo os parâmetros de validação analítica avaliados e amostras de pacientes em terapia com VEN analisadas, o método proposto é adequado para determinação de VEN, ODV e NDV em amostras de plasma para fins de monitorização terapêutica. / Venlafaxine elicits a small number of adverse effects, so it is one of the most frequently prescribed drugs to treat major depression, generalized anxiety, and social anxiety disorders in adults. In this study, venlafaxine (VEN), O-desmethylvenlafaxine (ODV), and N-desmethylvenlafaxine (NDV) were pre-concentrated with the aid of miniaturized SPE based on MIPs as extraction phase. MIPs are synthetic polymers with cavities specifically designed to hold a target molecule or structurally similar compounds. The molecularly imprinted polymers were prepared by addition of VEN, metacrylic acid (MAA, monomer), ethylene glycol dimethacrylate (EGDMA, cross-linker), and 2,2-azobisisobutyronitrile (AIBN, initiator) to toluene (solvent). The non-imprinted polymer (NIP), used for comparison, was also synthesized by following exactly the same procedure, but excluding the template VEN from the formulation. The polymer was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). Optimization of the MIP phase extraction variables favored miniaturized analytical detectability and reduced the memory effect. The extractions performed with the synthesized MIP showed recovery rate of 84% for VEN and 2-28% for other antidepressants (chlorpromazine, fluoxetine, clomipramine, imipramine, and sertraline). The non-imprinted polymer provided low recovery of VEN (recovery rate: 49%) and other antidepressants (recovery rates lower than 40%). These experiments demonstrated the selectivity of the developed MIP phase. The standardized method was linear in the range of 300 - 700 ng mL-1 for VEN, 5-700 ng mL-1 for ODV, and 3 to 500 ng mL-1 for NDV. Precision had coefficients of variation smaller than 15%; the accuracy standard error values ranged from -11.8 to 16.01%. Compared with literature methods, the developed method was more selective for determination of VEN and metabolites, required lower consumption of sample and organic solvents, and enabled reuse of the extraction phase. According to the assessed analytical validation parameters and to the analysis of samples obtained from patients undergoing therapy with VEN, the proposed method is suitable to determine VEN, NDV, and ODV in plasma samples for therapeutic drug monitoring.

Pregnenolona (PREG) e 17-alfa-hidroxipregnenolona (17OHPREG) são dois esteroides produzidos pela glândula adrenal e precursores de vários hormônios esteroidais. A dosagem desses compostos tem aplicações clínicas, como o diagnóstico de doenças relacionadas aos corticoesteroides e mineralocorticóides e especialmente na avaliação da atividade da enzima 3-β-hidroxidesidrogenase que é decisiva no diagnóstico de um dos tipos de hiperplasia da glândula adrenal que causa defeitos severos na síntese de esteroides. Métodos cromatográficos associados à espectrometria de massas superaram a especificidade reduzida dos imunoensaios e tem sido crescentemente utilizados na quantificação de esteroides. Os últimos anos tem sido marcados pela hegemonia da cromatografia líquida acoplada à espectrometria de massas em tandem (LC-MS/MS) em grande parte devido à velocidade e possibilidade da análise direta de vários analitos. Porém, no caso específico dos esteroides de tipo 3-hidroxi-5-eno, que apresentam baixa afinidade protônica e, portanto, baixa eficiência de ionização, são necessárias muitas etapas para a conversão em derivados mais detectáveis. Embora desfavorecida em relação ao LC-MS/MS nos últimos anos, a cromatografia gasosa acoplada à espectrometria de massas (CG-MS) apresenta várias características favoráveis para a análise de esteroides como a eficiência cromatográfica ainda insuperável. Adicionalmente, a incorporação da espectrometria de massas em tandem ao CG (CG-MS/MS) torna a técnica tão seletiva quanto LC-MS/MS. No presente trabalho, foi desenvolvido um novo método que permite a extração e derivatização simultâneas da PREG e 17OHPREG de amostras de soro tornando o método de preparo da amostra tão simples quanto os descritos para LC-MS/MS. O método de detecção desenvolvido baseado em ionização química no modo negativo obteve a sensibilidade necessária para o diagnóstico da deficiência da enzima 3-beta-hidroxidesidrogenase utilizando apenas 250 &#181:L de amostra. / Pregnenolone (PREG) and 17α-hydroxypregnenolone (17OHPREG) are two steroid precursors produced by the adrenal gland. The quantification of these compounds is essential for the evaluation of 3-β-hidroxidesidrogenase enzyme activity, which promotes the conversion of PREG in 17OHPREG. The 3-&#946:-hidroxidesidrogenase deficiency is a rare but severe type of adrenal hyperplasia that causes serious defects in steroid synthesis. Chromatographic methods coupled to mass spectrometry overcame immunoassays limitations such as reduced specificity, and have been widely used for steroids quantification. Recent years have been marked by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) hegemony due to the speed and possibility to analyze directly several analytes. However, in the case of type 3-hydroxy-5-ene steroids, which have low affinity for protons and, therefore, low ionization efficiency, many steps are required for conversion to detectable products. Notwithstanding, gas chromatography coupled to mass spectrometry (GC-MS) has some favorable features for steroid analysis such as unbeatable chromatographic efficiency. In addition, the incorporation of tandem mass spectrometry (GC-MS/MS) makes it as selective as LC-MS/MS. In this study, a new method for simultaneous extraction and derivatization of PREG and 17OHPREG from serum was developed. This procedure makes sample preparation for GC-MS/MS as simples as those described for LC-MS/MS. The detection method based on negative mode chemical ionization achieved the sensitivity required for the diagnosis of 3-β-hidroxidesidrogenase defficiency using only 250 µL of sample.