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Papers by pamela cabarcos

Analytical Methods

Membrane assisted solvent extraction (MASE) is an appealing environmental-friendly pre-treatment ... more Membrane assisted solvent extraction (MASE) is an appealing environmental-friendly pre-treatment for isolating trace targets. MASE applicability in the forensic laboratory is demonstrated by assessing synthetic cannabinoid receptor agonists in urine.

Analytical and Bioanalytical Chemistry, 2016

A simple sample pre-treatment method based on solid phase microextraction (SPME) and gas chromato... more A simple sample pre-treatment method based on solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) has been optimized and validated for the assessment of 15 residual solvents (2-propanol, 2-methylpentane, 3-methylpentane, acetone, ethyl acetate, benzene, hexane, methylcyclohexane, methylcyclopentane, m-xylene, propyl acetate, toluene, 1,2,4-trimethylbenzene, dichloromethane, and ethylbenzene) in seized illicit cocaine and heroin. DMSO and DMF as sample diluents were found to offer the best residual solvent transference to the head space for further adsorption onto the SPME fiber, and the developed method therefore showed high sensitivity and analytical recovery. Variables affecting SPME were fully evaluated by applying an experimental design approach. Best conditions were found when using an equilibration time of 5 min at 70 °C and headspace sampling of residual solvents at the same temperature for 15 min. Method validation, performed within the requirements of international guidelines, showed excellent sensitivity, as well as intra- and inter-day precision and accuracy. The proposed methodology was applied to 96 cocaine samples and 14 heroin samples seized in Galicia (northwestern Spain) within 2013 and 2014.

Microchemical Journal, 2016

A novel adsorbent, magnetic molecularly imprinted polymer (MMIP) based on magnetite nanoparticles... more A novel adsorbent, magnetic molecularly imprinted polymer (MMIP) based on magnetite nanoparticles surfacecovered with an MIP selective for cocaine (COC), was synthesised and used in batch micro-solid phase extraction (μ-SPE) for isolation of COC and metabolites (benzoylecgonine, BZE; cocaethylene, CE; and ecgonine methyl ester, EME) from plasma samples. High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used for performing analysis. Parameters such as sample pH, magnetic stirring speed, extraction temperature and time (loading stage), composition and volume of the eluting solution, and desorption time, were optimised. Under the most favourable conditions, the highest extraction yields were obtained by using 0.1 to 1.0 mL of plasma (pH adjusted at 8.5) plus 50 mg of MMIP, and magnetic stirring (20°C, 100 rpm) for 4 min. Elution was performed with 2 mL of a dichloromethane/2-propanol/ammonium hydroxide (75:20:5) mixture under ultrasound irradiation (325 W, 35 kHz) for 5 min. The limits of detection were between 0.013 and 0.36 ng L −1 , and the limits of quantification were from 0.043 to 1.2 ng L −1. The relative standard deviations of intra-and inter-day tests (three concentration levels tested) ranged from 1 to 9% and from 2 to 10%, respectively. Analytical recoveries were in the range of 91-102% when spiking drug-free plasma samples at three concentration levels. Accurate results were also obtained after analysing a BTMF 1/11-B control material.

Analytical and Bioanalytical Chemistry, 2015

Alcohol is the most popular legal drug used in our society today, and its consumption by pregnant... more Alcohol is the most popular legal drug used in our society today, and its consumption by pregnant women remains an important public health problem. Gestational alcohol consumption can result in a continuum of adverse fetal outcomes known as fetal alcohol spectrum disorder (FASD). Effective strategies are needed to prevent the increasing adoption of risky drinking behaviors. Because ethanol itself is only measurable for a few hours after ethanol intake in conventional matrices including blood, urine, and sweat, these matrices are only useful to detect recent ethanol exposure. Since approximately early 2000, the non-oxidative ethanol metabolites have received increasing attention because of their specificity and, in some cases, wide time window of detection in nonconventional matrices including hair and meconium. In the attempt to update analytical methods for the determination of non-oxidative markers of alcohol, the objective of this study is to review published studies that measure fatty-acid ethyl esters (FAEE), ethyl glucuronide (EtG), and phosphatidylethanol (PEth) in alternative biological matrices, focusing on the extraction and detection methods and full analytical conditions used.

Journal of neonatal-perinatal medicine, 2014

Alcohol consumption during pregnancy, even when moderate, implies a risk of impaired neurodevelop... more Alcohol consumption during pregnancy, even when moderate, implies a risk of impaired neurodevelopment, physical impairments and malformations. Its early identification is essential for establishing preventive measures to diminish disabilities among newborns. To determine the frequency of consumption of substance use in pregnant women, we have used the techniques of gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry to detect drugs and markers of chronic consumption of alcohol in meconium. We performed a prospective study during a period of 10 months among 110 infants in our hospital, assessing anthropometry, neuromuscular development and determination of toxic substances in urine and meconium. Furthermore, meconium analysis identified fatty acid ethyl esters (FAEEs) and ethyl glucuronide (Etg). We also conducted a survey regarding the obstetric history, toxic habits, and employment status of the mothers. According to early detection markers analy...

Forensic Toxicology, 2012

We have developed a gas chromatography-mass spectrometry (GC-MS) method for plasma for the determ... more We have developed a gas chromatography-mass spectrometry (GC-MS) method for plasma for the determination of new-generation antidepressants, including olanzapine (antipsychotic used in bipolar disorder), and antidepressant selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine and its metabolite norfluoxetine, paroxetine, sertraline, venlafaxine, and mirtazapine. Sample preparation was performed by liquid-liquid extraction with tert-butyl methyl ether. Fluoxetine, norfluoxetine, sertraline, and paroxetine required subsequent derivatization with 1-(heptafluorobutyryl) imidazole (HFBI). The GC separation lasts a total of 23.76 min. Qualitative and quantitative analysis were performed using an electron-impact ionization gas chromatograph interfaced to a mass-selective detector in selected-ion monitoring mode to increase the sensitivity of the method. Method validation was performed taking into account linearity, sensitivity, selectivity, accuracy, precision, and recovery, achieving good results for all the parameters studied. Calibration curves were prepared in the range of 0.005-2 lg/ml (according to the therapeutic and toxic concentrations of each individual compound), with all correlation coefficients R 2 [ 0.99. The limit of quantification was between 0.005 and 0.1 lg/ml, depending on the compound, whereas the limit of detection ranged from 0.0025 to 0.05 lg/ml. The method is fast and simple, allowing the identification and quantification of some of the most widely used antidepressants at therapeutic or toxic concentrations, and may be useful in routine clinical and forensic toxicology analysis.

Journal of Chromatography A, 2013

The possibility of assisting enzymatic hydrolysis (EH) procedures by sample disruption mechanisms... more The possibility of assisting enzymatic hydrolysis (EH) procedures by sample disruption mechanisms inherent to matrix solid phase dispersion (MSPD) has been explored in the current study. EH of hair specimens from poly-drug abusers was assisted by dispersing/blending the sample (0.05g) with alumina (2.25g) before loading the dissolved

Journal of Applied Toxicology, 2010

A rapid and sensitive method for the simultaneous determination of alfentanyl, sufentanyl and fen... more A rapid and sensitive method for the simultaneous determination of alfentanyl, sufentanyl and fentanyl (and its major metabolite norfentanyl) in urine was developed and validated. The method involved a liquid-liquid extraction in alkaline conditions, derivatization with pentafluoropropionic anhydride to improve the sensitivity for norfentanyl and subsequent analysis in GC/MS. The LODs are 0.08 ng ml-1 for all substances (0.04 ng ml-1 for alfentanyl). Intra-and inter-day precision coefficient of variation was always below 15%; mean relative error (accuracy) was always below 15%. The method was linear for all analytes, with quadratic regression of calibration curves always higher than 0.99. The method was applied to real samples of subjects who had received therapeutic doses of fentanyl, showing its suitability for the determination of low levels of these substances. The method was also applied to a subject whose death was attributed to fentanyl overdose.

Journal of Applied Toxicology, 2012

Many different biomarkers can be used to evaluate ethanol intake. Ethyl glucuronide (EtG) is a di... more Many different biomarkers can be used to evaluate ethanol intake. Ethyl glucuronide (EtG) is a direct phase II and minor metabolite of ethanol formed through the UDP-glucuronosyl transferase-catalyzed conjugation of ethanol with glucuronic acid. Its investigation is of interest in both clinical and forensic contexts because of the wide window of detection. A sensitive LC-MS/MS procedure has been developed and fully validated according to the guidelines of forensic toxicology for the analysis of EtG in hair. Sample preparation and chromatographic separation were thoroughly optimized. The analysis was performed in the multiple reaction monitoring mode using the transitions m/z 221 ! 203 (for the quantification) and 221 ! 85 or 75 (for the qualification) for EtG, and m/z 226 ! 208 (for quantification) and 226 ! 75 or 85 (for qualification) for EtG-D5, used as the internal standard. Analyses were carried out using an Inertsil ODS-3 column (100 Â 3 mm i.d., 3 mm particle size) and a mobile phase composed of formic acid and acetonitrile. Various SPE cartridges and solvents were tested in order to obtain the highest recoveries and cleanest extracts. The assay linearity of EtG was confirmed over the range from 20 to 2500 pg mg À1 , with a coefficient of determination (R 2) above 0.99. The lower limit of quantitation (LLOQ) was 20 pg mg À1 and the limit of detection was 10 pg mg À1. Intra-and inter-day assays were less than 15% except at the LLOQ (20%). The analytical method was applied to 72 post-mortem hair samples. EtG concentration in the hair ranged from 0 to 653 pg mg À1 hair.

Journal of Analytical Toxicology, 2009

In this study, the case of a newborn with symptoms of hyperexcitability was analyzed. After it wa... more In this study, the case of a newborn with symptoms of hyperexcitability was analyzed. After it was confirmed in the hospital that the mother had consumed drugs during pregnancy using an enzyme multiplied immunoassay technique, samples of the newborn's urine and meconium were sent to our laboratory to observe the evolution in the distribution of cocaine and opiates during the days following birth. For urine analysis, screening was done with an immunoassay technique, and the confirmation was done by gas chromatography-mass spectrometry (GC-MS) according to a published method. A GC-MS method for simultaneous analysis of cocaine, benzoylecgonine, codeine, morphine, and 6-acetylmorphine in meconium is described. GC-MS confirmation of urine and meconium results showed consumption of cocaine and codeine during pregnancy and also showed the levels of drugs gradually declined, totally disappearing by the third day.

Journal of Analytical Toxicology, 2010

The purpose of this study was to validate a high-performance liquid chromatography-photodiode-arr... more The purpose of this study was to validate a high-performance liquid chromatography-photodiode-array detetion method for the determination of six benzodiazepines in vitreous humor. The sample preparation was carried out using solid-phase extraction with Oasis HLB cartridges and 10% acetic acid/MeOH as elution solvent. The vitreous humor is less affected by postmortem changes and is a very useful sample when blood or urine specimens are not available. Linear curves for bromazepam, alprazolam, lorazepam, lormetazepam, diazepam, and tetrazepam were obtained within the range 0.03-3 µg/mL, with coefficients of correlation lower than 0.999. The limit of detection was 3 ng/mL, and the lower limit of quantification was 30 ng/mL for each benzodiazepine. Intraand interassay for precision and accuracy provided results less than 16.81% and 16.78%, respectively. Recoveries were higher than 68.51% in all cases. Finally, the method was applied to determine benzodiazepines in vitreous humor from intoxicated patients. Experimental Chemicals Materials and chemicals were obtained from the following suppliers: benzodiazepines from Cerilliant (Round Rock, TX); acetonitrile (HPLC grade), methanol (HPLC grade), acetic

Cocaína: manejo de …, 2009

Información del artículo Determinación de cocaína en muestras biológicas.

Analytical and Bioanalytical Chemistry, 2012

Ethanol is a legal and widely available substance. There are health and social consequences assoc... more Ethanol is a legal and widely available substance. There are health and social consequences associated with its abuse. One of the most important problems is related to alcohol consumption during pregnancy. In fact, prenatal ethanol exposure can be associated with fetal alcohol spectrum disorder (FASD), a term used to describe a wide range of potentially lifelong effects that include physical, mental, behavioral, and learning disabilities. Fatty acid ethyl esters (FAEEs), which are non-oxidative metabolites of ethanol, are currently used as biomarkers of direct ethanol consumption in different matrices, including hair, blood, skin surface, and meconium. Analysis of these compounds in meconium reveals exposure to alcohol during the second and third trimesters of pregnancy. An important finding for evaluation of gestational ethanol exposure is the fact that FAEEs do not cross the placenta. Because they accumulate in the fetal gut from approximately the 20th week of gestation until birth, this provides a wide window of detection of chronic exposure to alcohol. The sum of the concentrations of all the FAEEs, with a cutoff of 2 nmol g(-1) or 600 ng g(-1) meconium, has been recommended as evidence of maternal alcohol use. We introduce a novel technique to quantify ethyl myristate, ethyl palmitate, ethyl stearate, and their deuterated analogues (as internal standards, IS) in meconium using microwave-assisted extraction (MAE) coupled with gas chromatography-mass spectrometry (GC-MS). Limits of detection and quantification were 50 and 100 ng g(-1) for all analytes except ethyl stearate (LOD 100 ng g(-1) and LOQ 500 ng g(-1)). Calibration curves were linear from the LOQ to 5000 ng g(-1). The validated method was applied to the analysis of 81 meconium samples.

Analytical and Bioanalytical Chemistry, 2010

A simple and fast microwave-assisted-extraction (MAE) method has been evaluated as an alternative... more A simple and fast microwave-assisted-extraction (MAE) method has been evaluated as an alternative to solid-phase extraction (SPE) for the determination of six benzodiazepines widely prescribed in European countries (alprazolam, bromazepam, diazepam, lorazepam, lormetazepam and tetrazepam) in human plasma. For MAE optimization a Doehlert experimental design was used with extraction time, temperature and solvent volume as influential parameters. A desirability function was employed in addition to the simultaneous optimization of the MAE conditions. The analysis of variance showed that the solvent volume had a positive influence on the extraction of all the analytes tested, achieving a statistically significant effect. Also, the extraction time had a statistically significant effect on the extraction of four benzodiazepines. The selected MAE conditions-89°C, 13 min and 8 mL of chloroform/2propanol (4:1, v/v)-led to recoveries between 89.8±0.3 and 102.1±5.2% for benzodiazepines using a high performance liquid chromatography method coupled with diode-array detection. The comparison of MAE and SPE shows better results for MAE, with a lower number of steps in handling the sample and greater efficiency. The applicability of MAE was successfully tested in 27 plasma samples from benzodiazepine users.

Analytical and Bioanalytical Chemistry, 2016

A molecularly imprinted polymer (MIP) selective for cannabinoids [Δ 9-tetrahydrocannabinol (Δ9-TH... more A molecularly imprinted polymer (MIP) selective for cannabinoids [Δ 9-tetrahydrocannabinol (Δ9-THC), 11nor-9-carboxy-Δ 9-tetrahydrocannabinol (Δ9-THC-COOH), and 11-hydroxy-Δ 9-tetrahydrocannabinol (Δ9-THC-OH)] has been synthesized, fully characterized, and applied to the assessment of plasma and urine analysis of marijuana abuse by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Δ9-THC-COOH was used as a template molecule, whereas ethylene glycol dimethacrylate (EGDMA) was used as a functional monomer, divinylbenzene (DVB) as a cross-linker, and 2,2′-azobisisobutyronitrile (AIBN) as an initiator. The prepared MIP was found to be highly selective for cannabinoids typically found in blood and urine, and also for cannabinol (CBN) and cannabidiol (CBD). MIP beads (50 mg) were loaded inside a cone-shaped device made of a polypropylene (PP) membrane for microsolid-phase extraction (μ-SPE) in batch mode. Optimum retention of analytes (0.1 to 1.0 mL of plasma/urine) was achieved by fixing plasma/urine pH at 6.5 and assisting the procedure by mechanical shaking (150 rpm, 40°C, 12 min). Optimum elution conditions implied 2 mL of a 90:10 methanol/acetic acid and ultrasound extraction (35 kHz, 325 W) for 6 min. Good precision was assessed by intra-day and inter-day assays. In addition, the method was found to be accurate after intra-day and inter-day analytical recovery assays and after analyzing control serum and urine control samples. The limits of quantification were in the range of 0.36-0.49 ng L −1 (plasma analysis) and 0.47-0.57 ng L −1 (urine analysis). These values are low enough for confirmative conclusions regarding marijuana abuse through blood and urine analysis.

Analytical and Bioanalytical Chemistry, 2008

Analytical Methods

Membrane assisted solvent extraction (MASE) is an appealing environmental-friendly pre-treatment ... more Membrane assisted solvent extraction (MASE) is an appealing environmental-friendly pre-treatment for isolating trace targets. MASE applicability in the forensic laboratory is demonstrated by assessing synthetic cannabinoid receptor agonists in urine.

Analytical and Bioanalytical Chemistry, 2016

A simple sample pre-treatment method based on solid phase microextraction (SPME) and gas chromato... more A simple sample pre-treatment method based on solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) has been optimized and validated for the assessment of 15 residual solvents (2-propanol, 2-methylpentane, 3-methylpentane, acetone, ethyl acetate, benzene, hexane, methylcyclohexane, methylcyclopentane, m-xylene, propyl acetate, toluene, 1,2,4-trimethylbenzene, dichloromethane, and ethylbenzene) in seized illicit cocaine and heroin. DMSO and DMF as sample diluents were found to offer the best residual solvent transference to the head space for further adsorption onto the SPME fiber, and the developed method therefore showed high sensitivity and analytical recovery. Variables affecting SPME were fully evaluated by applying an experimental design approach. Best conditions were found when using an equilibration time of 5 min at 70 °C and headspace sampling of residual solvents at the same temperature for 15 min. Method validation, performed within the requirements of international guidelines, showed excellent sensitivity, as well as intra- and inter-day precision and accuracy. The proposed methodology was applied to 96 cocaine samples and 14 heroin samples seized in Galicia (northwestern Spain) within 2013 and 2014.

Microchemical Journal, 2016

A novel adsorbent, magnetic molecularly imprinted polymer (MMIP) based on magnetite nanoparticles... more A novel adsorbent, magnetic molecularly imprinted polymer (MMIP) based on magnetite nanoparticles surfacecovered with an MIP selective for cocaine (COC), was synthesised and used in batch micro-solid phase extraction (μ-SPE) for isolation of COC and metabolites (benzoylecgonine, BZE; cocaethylene, CE; and ecgonine methyl ester, EME) from plasma samples. High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used for performing analysis. Parameters such as sample pH, magnetic stirring speed, extraction temperature and time (loading stage), composition and volume of the eluting solution, and desorption time, were optimised. Under the most favourable conditions, the highest extraction yields were obtained by using 0.1 to 1.0 mL of plasma (pH adjusted at 8.5) plus 50 mg of MMIP, and magnetic stirring (20°C, 100 rpm) for 4 min. Elution was performed with 2 mL of a dichloromethane/2-propanol/ammonium hydroxide (75:20:5) mixture under ultrasound irradiation (325 W, 35 kHz) for 5 min. The limits of detection were between 0.013 and 0.36 ng L −1 , and the limits of quantification were from 0.043 to 1.2 ng L −1. The relative standard deviations of intra-and inter-day tests (three concentration levels tested) ranged from 1 to 9% and from 2 to 10%, respectively. Analytical recoveries were in the range of 91-102% when spiking drug-free plasma samples at three concentration levels. Accurate results were also obtained after analysing a BTMF 1/11-B control material.

Analytical and Bioanalytical Chemistry, 2015

Alcohol is the most popular legal drug used in our society today, and its consumption by pregnant... more Alcohol is the most popular legal drug used in our society today, and its consumption by pregnant women remains an important public health problem. Gestational alcohol consumption can result in a continuum of adverse fetal outcomes known as fetal alcohol spectrum disorder (FASD). Effective strategies are needed to prevent the increasing adoption of risky drinking behaviors. Because ethanol itself is only measurable for a few hours after ethanol intake in conventional matrices including blood, urine, and sweat, these matrices are only useful to detect recent ethanol exposure. Since approximately early 2000, the non-oxidative ethanol metabolites have received increasing attention because of their specificity and, in some cases, wide time window of detection in nonconventional matrices including hair and meconium. In the attempt to update analytical methods for the determination of non-oxidative markers of alcohol, the objective of this study is to review published studies that measure fatty-acid ethyl esters (FAEE), ethyl glucuronide (EtG), and phosphatidylethanol (PEth) in alternative biological matrices, focusing on the extraction and detection methods and full analytical conditions used.

Journal of neonatal-perinatal medicine, 2014

Alcohol consumption during pregnancy, even when moderate, implies a risk of impaired neurodevelop... more Alcohol consumption during pregnancy, even when moderate, implies a risk of impaired neurodevelopment, physical impairments and malformations. Its early identification is essential for establishing preventive measures to diminish disabilities among newborns. To determine the frequency of consumption of substance use in pregnant women, we have used the techniques of gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry to detect drugs and markers of chronic consumption of alcohol in meconium. We performed a prospective study during a period of 10 months among 110 infants in our hospital, assessing anthropometry, neuromuscular development and determination of toxic substances in urine and meconium. Furthermore, meconium analysis identified fatty acid ethyl esters (FAEEs) and ethyl glucuronide (Etg). We also conducted a survey regarding the obstetric history, toxic habits, and employment status of the mothers. According to early detection markers analy...

Forensic Toxicology, 2012

We have developed a gas chromatography-mass spectrometry (GC-MS) method for plasma for the determ... more We have developed a gas chromatography-mass spectrometry (GC-MS) method for plasma for the determination of new-generation antidepressants, including olanzapine (antipsychotic used in bipolar disorder), and antidepressant selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine and its metabolite norfluoxetine, paroxetine, sertraline, venlafaxine, and mirtazapine. Sample preparation was performed by liquid-liquid extraction with tert-butyl methyl ether. Fluoxetine, norfluoxetine, sertraline, and paroxetine required subsequent derivatization with 1-(heptafluorobutyryl) imidazole (HFBI). The GC separation lasts a total of 23.76 min. Qualitative and quantitative analysis were performed using an electron-impact ionization gas chromatograph interfaced to a mass-selective detector in selected-ion monitoring mode to increase the sensitivity of the method. Method validation was performed taking into account linearity, sensitivity, selectivity, accuracy, precision, and recovery, achieving good results for all the parameters studied. Calibration curves were prepared in the range of 0.005-2 lg/ml (according to the therapeutic and toxic concentrations of each individual compound), with all correlation coefficients R 2 [ 0.99. The limit of quantification was between 0.005 and 0.1 lg/ml, depending on the compound, whereas the limit of detection ranged from 0.0025 to 0.05 lg/ml. The method is fast and simple, allowing the identification and quantification of some of the most widely used antidepressants at therapeutic or toxic concentrations, and may be useful in routine clinical and forensic toxicology analysis.

Journal of Chromatography A, 2013

The possibility of assisting enzymatic hydrolysis (EH) procedures by sample disruption mechanisms... more The possibility of assisting enzymatic hydrolysis (EH) procedures by sample disruption mechanisms inherent to matrix solid phase dispersion (MSPD) has been explored in the current study. EH of hair specimens from poly-drug abusers was assisted by dispersing/blending the sample (0.05g) with alumina (2.25g) before loading the dissolved

Journal of Applied Toxicology, 2010

A rapid and sensitive method for the simultaneous determination of alfentanyl, sufentanyl and fen... more A rapid and sensitive method for the simultaneous determination of alfentanyl, sufentanyl and fentanyl (and its major metabolite norfentanyl) in urine was developed and validated. The method involved a liquid-liquid extraction in alkaline conditions, derivatization with pentafluoropropionic anhydride to improve the sensitivity for norfentanyl and subsequent analysis in GC/MS. The LODs are 0.08 ng ml-1 for all substances (0.04 ng ml-1 for alfentanyl). Intra-and inter-day precision coefficient of variation was always below 15%; mean relative error (accuracy) was always below 15%. The method was linear for all analytes, with quadratic regression of calibration curves always higher than 0.99. The method was applied to real samples of subjects who had received therapeutic doses of fentanyl, showing its suitability for the determination of low levels of these substances. The method was also applied to a subject whose death was attributed to fentanyl overdose.

Journal of Applied Toxicology, 2012

Many different biomarkers can be used to evaluate ethanol intake. Ethyl glucuronide (EtG) is a di... more Many different biomarkers can be used to evaluate ethanol intake. Ethyl glucuronide (EtG) is a direct phase II and minor metabolite of ethanol formed through the UDP-glucuronosyl transferase-catalyzed conjugation of ethanol with glucuronic acid. Its investigation is of interest in both clinical and forensic contexts because of the wide window of detection. A sensitive LC-MS/MS procedure has been developed and fully validated according to the guidelines of forensic toxicology for the analysis of EtG in hair. Sample preparation and chromatographic separation were thoroughly optimized. The analysis was performed in the multiple reaction monitoring mode using the transitions m/z 221 ! 203 (for the quantification) and 221 ! 85 or 75 (for the qualification) for EtG, and m/z 226 ! 208 (for quantification) and 226 ! 75 or 85 (for qualification) for EtG-D5, used as the internal standard. Analyses were carried out using an Inertsil ODS-3 column (100 Â 3 mm i.d., 3 mm particle size) and a mobile phase composed of formic acid and acetonitrile. Various SPE cartridges and solvents were tested in order to obtain the highest recoveries and cleanest extracts. The assay linearity of EtG was confirmed over the range from 20 to 2500 pg mg À1 , with a coefficient of determination (R 2) above 0.99. The lower limit of quantitation (LLOQ) was 20 pg mg À1 and the limit of detection was 10 pg mg À1. Intra-and inter-day assays were less than 15% except at the LLOQ (20%). The analytical method was applied to 72 post-mortem hair samples. EtG concentration in the hair ranged from 0 to 653 pg mg À1 hair.

Journal of Analytical Toxicology, 2009

In this study, the case of a newborn with symptoms of hyperexcitability was analyzed. After it wa... more In this study, the case of a newborn with symptoms of hyperexcitability was analyzed. After it was confirmed in the hospital that the mother had consumed drugs during pregnancy using an enzyme multiplied immunoassay technique, samples of the newborn's urine and meconium were sent to our laboratory to observe the evolution in the distribution of cocaine and opiates during the days following birth. For urine analysis, screening was done with an immunoassay technique, and the confirmation was done by gas chromatography-mass spectrometry (GC-MS) according to a published method. A GC-MS method for simultaneous analysis of cocaine, benzoylecgonine, codeine, morphine, and 6-acetylmorphine in meconium is described. GC-MS confirmation of urine and meconium results showed consumption of cocaine and codeine during pregnancy and also showed the levels of drugs gradually declined, totally disappearing by the third day.

Journal of Analytical Toxicology, 2010

The purpose of this study was to validate a high-performance liquid chromatography-photodiode-arr... more The purpose of this study was to validate a high-performance liquid chromatography-photodiode-array detetion method for the determination of six benzodiazepines in vitreous humor. The sample preparation was carried out using solid-phase extraction with Oasis HLB cartridges and 10% acetic acid/MeOH as elution solvent. The vitreous humor is less affected by postmortem changes and is a very useful sample when blood or urine specimens are not available. Linear curves for bromazepam, alprazolam, lorazepam, lormetazepam, diazepam, and tetrazepam were obtained within the range 0.03-3 µg/mL, with coefficients of correlation lower than 0.999. The limit of detection was 3 ng/mL, and the lower limit of quantification was 30 ng/mL for each benzodiazepine. Intraand interassay for precision and accuracy provided results less than 16.81% and 16.78%, respectively. Recoveries were higher than 68.51% in all cases. Finally, the method was applied to determine benzodiazepines in vitreous humor from intoxicated patients. Experimental Chemicals Materials and chemicals were obtained from the following suppliers: benzodiazepines from Cerilliant (Round Rock, TX); acetonitrile (HPLC grade), methanol (HPLC grade), acetic

Cocaína: manejo de …, 2009

Información del artículo Determinación de cocaína en muestras biológicas.

Analytical and Bioanalytical Chemistry, 2012

Ethanol is a legal and widely available substance. There are health and social consequences assoc... more Ethanol is a legal and widely available substance. There are health and social consequences associated with its abuse. One of the most important problems is related to alcohol consumption during pregnancy. In fact, prenatal ethanol exposure can be associated with fetal alcohol spectrum disorder (FASD), a term used to describe a wide range of potentially lifelong effects that include physical, mental, behavioral, and learning disabilities. Fatty acid ethyl esters (FAEEs), which are non-oxidative metabolites of ethanol, are currently used as biomarkers of direct ethanol consumption in different matrices, including hair, blood, skin surface, and meconium. Analysis of these compounds in meconium reveals exposure to alcohol during the second and third trimesters of pregnancy. An important finding for evaluation of gestational ethanol exposure is the fact that FAEEs do not cross the placenta. Because they accumulate in the fetal gut from approximately the 20th week of gestation until birth, this provides a wide window of detection of chronic exposure to alcohol. The sum of the concentrations of all the FAEEs, with a cutoff of 2 nmol g(-1) or 600 ng g(-1) meconium, has been recommended as evidence of maternal alcohol use. We introduce a novel technique to quantify ethyl myristate, ethyl palmitate, ethyl stearate, and their deuterated analogues (as internal standards, IS) in meconium using microwave-assisted extraction (MAE) coupled with gas chromatography-mass spectrometry (GC-MS). Limits of detection and quantification were 50 and 100 ng g(-1) for all analytes except ethyl stearate (LOD 100 ng g(-1) and LOQ 500 ng g(-1)). Calibration curves were linear from the LOQ to 5000 ng g(-1). The validated method was applied to the analysis of 81 meconium samples.

Analytical and Bioanalytical Chemistry, 2010

A simple and fast microwave-assisted-extraction (MAE) method has been evaluated as an alternative... more A simple and fast microwave-assisted-extraction (MAE) method has been evaluated as an alternative to solid-phase extraction (SPE) for the determination of six benzodiazepines widely prescribed in European countries (alprazolam, bromazepam, diazepam, lorazepam, lormetazepam and tetrazepam) in human plasma. For MAE optimization a Doehlert experimental design was used with extraction time, temperature and solvent volume as influential parameters. A desirability function was employed in addition to the simultaneous optimization of the MAE conditions. The analysis of variance showed that the solvent volume had a positive influence on the extraction of all the analytes tested, achieving a statistically significant effect. Also, the extraction time had a statistically significant effect on the extraction of four benzodiazepines. The selected MAE conditions-89°C, 13 min and 8 mL of chloroform/2propanol (4:1, v/v)-led to recoveries between 89.8±0.3 and 102.1±5.2% for benzodiazepines using a high performance liquid chromatography method coupled with diode-array detection. The comparison of MAE and SPE shows better results for MAE, with a lower number of steps in handling the sample and greater efficiency. The applicability of MAE was successfully tested in 27 plasma samples from benzodiazepine users.

Analytical and Bioanalytical Chemistry, 2016

A molecularly imprinted polymer (MIP) selective for cannabinoids [Δ 9-tetrahydrocannabinol (Δ9-TH... more A molecularly imprinted polymer (MIP) selective for cannabinoids [Δ 9-tetrahydrocannabinol (Δ9-THC), 11nor-9-carboxy-Δ 9-tetrahydrocannabinol (Δ9-THC-COOH), and 11-hydroxy-Δ 9-tetrahydrocannabinol (Δ9-THC-OH)] has been synthesized, fully characterized, and applied to the assessment of plasma and urine analysis of marijuana abuse by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Δ9-THC-COOH was used as a template molecule, whereas ethylene glycol dimethacrylate (EGDMA) was used as a functional monomer, divinylbenzene (DVB) as a cross-linker, and 2,2′-azobisisobutyronitrile (AIBN) as an initiator. The prepared MIP was found to be highly selective for cannabinoids typically found in blood and urine, and also for cannabinol (CBN) and cannabidiol (CBD). MIP beads (50 mg) were loaded inside a cone-shaped device made of a polypropylene (PP) membrane for microsolid-phase extraction (μ-SPE) in batch mode. Optimum retention of analytes (0.1 to 1.0 mL of plasma/urine) was achieved by fixing plasma/urine pH at 6.5 and assisting the procedure by mechanical shaking (150 rpm, 40°C, 12 min). Optimum elution conditions implied 2 mL of a 90:10 methanol/acetic acid and ultrasound extraction (35 kHz, 325 W) for 6 min. Good precision was assessed by intra-day and inter-day assays. In addition, the method was found to be accurate after intra-day and inter-day analytical recovery assays and after analyzing control serum and urine control samples. The limits of quantification were in the range of 0.36-0.49 ng L −1 (plasma analysis) and 0.47-0.57 ng L −1 (urine analysis). These values are low enough for confirmative conclusions regarding marijuana abuse through blood and urine analysis.

Analytical and Bioanalytical Chemistry, 2008