ABSTRACT
Hygrine and cuscohygrine, two coca leaf alkaloids, have been previously proposed as markers to differentiate legal and illegal cocaine consumption. This is a very common problem in some countries of South America, where the consumption of coca leaves has a long tradition. Analytical methods focusing on the assessment of coca leaf alkaloids, such as cuscohygrine, hygrine, tropacocaine and t-cinnamoylcocaine, in oral fluid are virtually non-existent in forensic toxicology laboratories worldwide due to their lack of application. However, the problem of differentiating legal and illegal cocaine use in criminal justice, DUID (drug-impaired driving) and WDT (workplace drug testing) programs is growing. Therefore, researchers are obliged to develop methods to measure coca leaf alkaloids (cuscohygrine, hygrine and t-cinnamoylcocaine) in biological matrices for further validation for routine analyses in forensic toxicology laboratories. This work aims to optimize a previously published separation method by protein precipitation in oral fluid by using solid-phase extraction (SPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) operating in multiple reaction monitoring (MRM) mode. The use of SPE allowed the matrix effect and the background to be reduced in the chromatograms due to the obtained cleaner extracts. Consequently, improved detection and quantification limits were reached. Findings showed that the detection windows for coca leaf alkaloids were longer than three hours in real oral fluid samples from volunteers who drank a cup of coca tea. These detection windows are quite higher than those previously obtained when using the method based on separation by protein precipitation.
Subject(s)
Alkaloids , Coca , Cocaine , Humans , Coca/chemistry , Chromatography, Liquid , Tandem Mass Spectrometry , Cocaine/analysis , Plant Leaves/chemistry , Tea , Solid Phase ExtractionABSTRACT
Actualmente el fluido oral (FO) es aceptado como una matriz biológica alternativa para detectar drogas en toxicología clínica y forense. En países como Argentina donde el uso de hojas de coca (mascar hojas de coca o beber té de coca) es legal son necesarios procedimientos adecuados para logar una clara diferenciación entre los individuos que usan las hojas de coca de manera legal de aquéllos que usan cocaína en forma ilegal. Poca es la información que hay en la literatura sobre el perfil de los alcaloides de la hoja de coca en FO de personas que mascan hojas de coca o toman té de coca y hasta el presente trabajo no se hallaron datos sobre el perfil en FO de la higrina (HIG) y cuscohigrina (CUS). De este estudio preliminar participaron dos voluntarios. Los resultados mostraron que la CUS e HIG siguieron siendo positivas después que la cocaína (COC) y benzoilecgonina (BE) cayeron por debajo de los valores cut- off propuestos por las guías internacionales para FO en casos de screening (15 a 20 ng/ mL) y de confirmación (8 a 10 ng/mL) en el caso del mascador de coca. En el participante que tomó una taza de té de coca, en el último punto examinado (1 h) resultó ser positivo para la COC y BE y también para la CUS e HIG. El FO podría ser una muestra útil para confirmar el uso legal de la hoja de coca, aun cuando futuros estudios son necesarios para corroborar estos primeros datos.
Nowadays oral fluid (OF) is accepted as an alternative biological sample for detecting drugs in clinical and forensic toxicology. In countries like Argentina, where the use of coca leaves (coca leaves chewing and coca tea drinking) is legal, adequate procedures are required to allow a clear differentiation between people who use coca leaves (legal practice) and those who use cocaine (illicit practice). There is scarce literature regarding coca leaf alkaloids profile in OF from people who chew coca leaves and drink coca tea. Until now, coca leaf alkaloids profile of hygrine (HYG) and cuscohygrine (CUS) in OF were not described in the literature. The current preliminary study was performed with two healthy volunteers. In this research CUS and HYG have been found to be positive (detectable) even when cocaine (COC) and benzoylecgonine (BE) are dropped below the cut-off values proposed by international guidelines for screening (15 to 20 ng/mL), and confirmation (8 to 10 ng/mL) in OF. In addition, CUS and HYG were also found to be positive at the same time of the last detection of COC and BE after coca tea consumption. The OF would be a useful sample to confirm the legal use of coca leaf, even when more researches are therefore needed.
Subject(s)
Humans , Substance Abuse Detection/methods , Cocaine/analogs & derivativesABSTRACT
An analytical approach providing an insight into speciation of iodine in water insoluble fraction of edible seaweed (Nori) was developed. The seaweed, harvested in the Galician coast (Northwestern Spain), contained 67.7±1.3 µg g(-1) iodine of which 25% was water soluble and could be identifies as iodide. Extraction conditions of water insoluble residue using urea, NaOH, SDS and Triton X-100 were investigated. The protein pellets obtained in optimized conditions (after precipitation of urea extracts with acetone), were digested with trypsin and protease XIV. Size exclusion chromatography-ICP-MS of both enzymatic digests demonstrated the occurrence of iodoaminoacids putatively present in proteins. Intact proteins could be separated by gel electrophoresis after an additional extraction of the protein extract with phenol. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) with laser ablation ICP-MS detection of (127)I indicated the presence of iodine in protein bands corresponding to molecular masses of 110 kDa, 40 kDa, 27 kDa, 20 kDa and 10 kDa. 2D IEF-SDS PAGE with laser ablation ICP-MS (127)I imaging allowed the detection of 5 iodine containing protein spots in the alkaline pI range.
Subject(s)
Iodine/analysis , Plant Proteins/chemistry , Porphyra , Acetone/chemistry , Electrophoresis, Polyacrylamide Gel , Lasers , Mass Spectrometry/methods , Octoxynol/chemistry , Peptide Hydrolases/chemistry , Phenol/chemistry , Seaweed , Sodium Dodecyl Sulfate/chemistry , Sodium Hydroxide/chemistry , Solvents/chemistry , Trypsin/chemistry , Urea/chemistry , Water/chemistryABSTRACT
Objetivo: Desarrollar un polímero de impronta molecular para la determinación de metilmercurio en muestras de alimentos de origen marino. Material y métodos: Se sintetizó un polímero de impronta molecular (MIP) que emplea fenobarbital como ligando no vinilado para unirse al metilmercurio. Se utilizó la técnica de polimerización por precipitación. El MIP sintetizado fue empleado para funcionalizar nanopartículas magnéticas con el fin de mejorar el proceso de extracción del metilmercurio de las muestras. Resultados: El MIP con fenobarbital fue aplicado para la determinación de la concentración de metilmercurio en dos materiales de referencia de concentración certificada para el análisis de muestras de alimentos marinos (BCR-463, tejido de atún, y TORT-2, hepatopáncreas de langosta). Los valores de concentración experimentales obtenidos fueron de 3,04±0,16 μg/g y 0,152±0,013 μg/g respectivamente, coincidiendo con los valores certificados de forma estadísticamente significativa (test t, 95% confianza). Conclusiones: Se ha sintetizado un MIP para la determinación de la concentración de metilmercurio a bajas concentraciones en muestras de alimentos de origen marino (AU)
Objective: The development of a molecularly imprinted polymer support for methylmercury determination in fish and seafood samples. Materials and methods: A molecularly imprinted polymer was synthesized using the precipitation technique and phenobarbital as a non-vinylated ligand for binding methylmercury. The synthesized MIP was used for the functionalization of magnetic nanoparticles in order to improve the process of methylmercury extraction from the samples. Results: The MIP prepared with phenobarbital was applied to the determination of methylmercury concentration in two certified reference materials used for fish and seafood samples analysis (BCR-463, tuna fish, and TORT-2, lobster hepatopancreas). The experimental values (3.04±0.16 μg/g and 0.152±0.013 μg/g respectively) and the certified values showed no statistically significant difference (t test, 95% confidence level). Conclusions: We have synthesized a MIP for determining methylmercury in fish and seafood samples at low concentrations (AU)
Subject(s)
Methylmercury Compounds/analysis , Polymers/analysis , Polymers/pharmacology , Food Analysis/methods , Phenobarbital , Molecular Imprinting/instrumentation , Molecular Imprinting/methods , Tuna/microbiology , Food/standards , Food , Molecular Imprinting/organization & administration , Molecular Imprinting/standards , Molecular Imprinting/trendsABSTRACT
A simple transformation that uses the half-range and central value has been used as a data pre-treatment procedure for principal component analysis (PCA) and pattern recognition techniques. The results obtained have been compared with the results from classical normalisation of data (mean normalisation, maximum normalisation and range normalisation), autoscaling and the minimum-maximum transformation. Three data sets were used in the study. The first was formed by determining 17 elements in 53 tea samples (901 pieces of data). The second and third data sets arose from two long-term drift studies performed to examine instrumental stability at standard and robust conditions. The instruments used were an inductively coupled plasma atomic emission spectrometer and an inductively coupled plasma mass spectrometer. Each drift diagnosis experiment consisted of replicate determinations of a test solution containing 15 analytes at 10 mg l-1 over 8 h without recalibration. Twenty-nine emission lines were determined 99 times, thus, each data set was formed by 2881 pieces of data. Data pre-treatment was applied to the three data sets prior to the use of principal component analysis, cluster analysis, linear discrimination analysis and soft independent modelling of class analogy. The study revealed that the half-range and central value transformation resulted in a better classification of the tea samples than that achieved using the classical normalisation. The loadings in the PCA for the long-term stability study, under both standard and robust conditions, were found to be similar to the drift trends only when the minimum-maximum transformation and the mean or maximum normalizations were used as data pre-treatments.
Subject(s)
Models, Theoretical , Pattern Recognition, Automated , Tea/chemistry , HumansABSTRACT
Experimental designs were used for the optimisation of acid-leaching procedures assisted by ultrasonic energy for the extraction of Ca, Cu, Fe, Mg, Mn and Zn from human hair samples. A Plackett-Burman 2(7) x 3/32 design for seven factors ([HNO3], [HCl], [H2O2], acid/oxidant solution volume, exposure time to ultrasounds, temperature of the ultrasonic bath and hair particle size) was used in order to choose the variables affecting the acid-leaching process. The variables [HNO3], [HCl] and temperature of the ultrasonic bath were found to be the most important parameters for the acid-leaching procedure, and these variables were optimised by a response surface design (central composite design 2(3) + star) which involved 16 experiments. Optimum values in the 3.7-4.2 M range were found for [HNO3], while optimum values between 3.0 and 3.5 M were found for [HCl]. The optimum temperature of the ultrasonic bath was between 80 and 90 degrees C. An acid digestion induced by microwave energy (details given) was used to obtain the total metal concentration and also for comparative purposes. Ca, Cu, Fe, Mg and Zn were measured by flame atomic absorption spectrometry (FAAS) using a conventional air/acetylene flame, while Mn was determined by electrothermal atomic absorption spectrometry (ETAAS) under optimised conditions. Two different reference materials, IAEA-085 International Atomic Energy Agency, Monaco) and NIES No. 13 (National Institute for Environmental Studies, Japan), with certified metal contents for some of the elements investigated, were used in order to verify the accuracy of the methods.
Subject(s)
Hair/chemistry , Trace Elements/analysis , Calcium/analysis , Copper/analysis , Humans , Hydrogen-Ion Concentration , Iron/analysis , Magnesium/analysis , Manganese/analysis , Microwaves , Spectrophotometry, Atomic/methods , Ultrasonics , Zinc/analysisABSTRACT
Fifteen metallic species, silver (Ag), aluminum (Al), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), lead (Pb), strontium (Sr) and zinc (Zn), were determined in 46 cocaine samples confiscated by the Spanish police in Galicia (northwest Spain). Classification of these cocaine samples according to their geographic origin (Colombia and Venezuela) was achieved by the application of pattern recognition techniques to the metallic content data. Cocaine samples, around 0.5 g, were directly dissolved in 2 mL of 35.0% (v/v) HNO3, diluted to 10 mL with ultrapure water. The metals were quantified by means of electrothermal atomic absorption spectrometry (Ag, Al, Cd, Cr, Cu, Mn, Ni, Pb and Sr), flame atomic absorption spectrometry (Ca, Fe, Mg and Zn), and flame atomic emission spectrometry (K and Na). Results show that two geographic origins can be established through the presence of trace and major elements.
Subject(s)
Cocaine/classification , Drug Contamination , Illicit Drugs/chemistry , Metals/analysis , Substance Abuse Detection/methods , Cocaine/chemistry , Humans , Spectrophotometry, Atomic/methods , TemperatureABSTRACT
Methods for the direct determination of Ni in sea water samples by ETAAS were developed using Zeeman effect background correction system (ZEBC) and a multi-injection technique. A mass of palladium nitrate of 2.5 mug (for an injection volume of 100 mul) was used as chemical modifier. The optimum pyrolysis and atomization temperatures were 1700 and 2100 degrees C, respectively. The characteristic mass (m(0)) and characteristic concentration (C(0)), precision and accuracy were studied for different injection volumes (20, 100 and 200 mul). For an injection volume of 100 mul (five 20 mul aliquot) of sample the accuracy analysis of different certified materials (saline and non saline water) was agreeable. The total time of the proposed procedure is 6 min. A m(0) and C(0) of 34.5 pg and 0.3 mug l(-1), respectively were obtained for this injection volume (100 mul). Finally, interferences from major and minor components of sea water was studied.
ABSTRACT
Methods for the determination of aluminium and manganese in human scalp hair samples by electrothermal atomic absorption spectrometry using the slurry sampling technique were developed. Palladium and magnesium nitrate were used as chemical modifiers. Hair samples were pulverized using a zirconia vibrational mill ball, and were prepared as aqueous slurries. Determinations can be performed in the linear ranges of 1.9-150 mug l(-1) Al(3+) and 0.03-10.0 mug l(-1) Mn(2+). Limits of detection of 0.9 mg kg(-1) and 27.6 mug kg(-1) were obtained for aluminium and manganese, respectively. The analytical recoveries were between 99.6 and 101.8% for aluminium and in the 98.3-101.3% range for manganese. The repeatability of the methods (n=11), slurry preparation procedure and ETAAS measurement, was 16.0 and 7.9% for aluminium and manganese, respectively. The methods were finally applied to the aluminium and manganese determination in 25 scalp hair samples from healthy adults. The levels for aluminium were between 8.21 and 74.08 mg kg(-1), while concentrations between 0.03 and 1.20 mg kg(-1) were found for manganese.
ABSTRACT
Methods for the direct determination of silver and manganese in cocaine and heroin by electrothermal atomic absorption spectrometry using palladium as chemical modifier have been developed. Cocaine samples, 0.5 g, were dissolved in 2 ml of 35.0% (m/v), HNO(3) diluting to 10 ml with ultrapure water. A comparative study of palladium, magnesium nitrate, palladium-magnesium nitrate and nitric acid used as chemical modifiers was carried out, and it was found that palladium alone is adequate to stabilize silver and manganese at charring temperatures of 1000 and 1300 degrees C respectively. A study was made on the insertion of a cooling step before the atomization step, and this approach was not advantageous. Limits of detection of 2.3 and 6.9 microg kg(-1) were obtained for silver and manganese respectively. The analytical recovery oscillated between 95.9 and 103.6% for silver and between 99.7 and 103.0% for manganese. Finally, a study of some interferences and a study of the precision and analytical recovery of the amount of sample were also carried out.
ABSTRACT
A method for the determination of lead in human hair slurries by electrothermal atomic absorption spectrometry was optimized. Particle size reduction was achieved with a vibrational mill ball equipped with zirconia cups, 20 min being sufficient grinding time to achieve an adequate particle diameter (<1 mum). The use of different thickening agents, namely glycerol, Triton X-100 and Viscalex HV30, was studied and glycerol was found to be the best. The use of Pd and Mg(NO(3))(2) at optimum concentrations of 20 and 25 mg l(-1) respectively was found to be satisfactory for stabilizing lead at 1100 degrees C. A limit of detection of 0.21 mg kg(-1) was obtained. The limit of detection can be reduced to 0.05 mg kg(-1) without loss of analytical performance by increasing four-fold the amount of hair sample. Accuracy was studied by analysis of a CRM 397 human hair reference material with a certified lead content of 33.0 +/- 1.2 mg Pb kg(-1). The standard addition method was used for the determination of lead in hair samples from healthy people, the levels being between 2.3 and 35.5 mg kg(-1).
ABSTRACT
A comparative study of different chemical modifiers for the direct determination of arsenic in real and in synthetic sea water samples of high (72.8 per thousand ) and low (34.2 per thousand ) salinity was carried out. The use of lanthanum chloride and magnesium nitrate (LOD=3.0 microg l(-1)) offers good recoveries for low salinities, while for high salinities an enhancement higher than 200% was obtained, rendering this method unsuitable for sea water samples. The use of silver nitrate (LOD=2.0 microg l(-1)) produces unfavourable analytical recoveries, around 150 and 300% for synthetic sea water of low and high salinity. Zirconium oxychloride (LOD=1.8 microg l(-1)) and palladium nitrate alone or combined with magnesium nitrate and reducing agents (LOD=1.1-1.3 microg l(-1)) produce analytical recoveries close to 100% for all arsenic concentration tried over all salinities; thus, a single calibration curve using aqueous standard solutions may be applied to the analysis of sea water samples over all salinities. Finally, the addition of reducing agents and magnesium nitrate to palladium does not improve the sensitivity.
ABSTRACT
Methods for the direct determination of silver in sea water samples by ETA-AAS using different chemical modifiers were studied. The effect of salinity was studied using synthetic sea water of high (72.8 per thousand) and low (34.2 per thousand) salinity, and the results were compared with aqueous standard solutions. The charring temperatures achieved were 800 and 900 degrees C for magnesium nitrate and ammonium dihydrogen phosphate respectively, being 1100 degrees C for palladium nitrate and their mixtures. The best sensitivity obtained in the peak-height measurement mode was achieved by using reduced palladium (limit of detection (LOD) between 0.5 and 1.1 mug l(-1) for an injection volume of 20 mu1) with analytical recoveries close to 100% for synthetic and real sea water samples. The use of ammonium dihydrogen phosphate (LOD of 1.3 mug l(-1) for an injection volume of 20 mu1) produced good recoveries for low salinity; at high salinity an increase of around 25% was obtained, the method being unsuitable for sea water analysis. Finally, an interference study of the major components of sea water was carried out and applied to the analysis of surface sea water from the Galicia coast.
ABSTRACT
A method for the determination of total chromium in cocaine and heroin by flameless atomic absorption spectrometry is presented. Cocaine samples were dissolved in 2 ml of HNO(3) 35.0% (v/v) and diluted to 10 ml with ultrapure water; heroin samples were dissolved in ultrapure water, adding 0.4 ml of HNO(3) 35.0% (v/v) to dissolve inert species, and also diluted to 10 ml. Mg(NO(3))(2) and HNO(3), as chemical modifiers, were compared in terms of sensitivity, precision and accuracy, a lower detection limit being obtained for the use of Mg(NO(3))(2), 5.77 mug kg(-1) (7.23 mukg(-1) for HNO(3)). Within-batch precision was found to be 6.19% and 1.48% for drug solution spiked with 0 and 10 mug l(-1) of Cr(3+), respectively, when using Mg(NO(3))(2), and 7.45 and 1.19% for the same respective concentration levels when using HNO(3). Similar results on analytical recovery were obtained for both Mg(NO(3))(2) and HNO(3). Mg(NO(3))(2) was selected as the more adequate of the two chemical modifiers. A study of the introduction of a cooling-down step of 50 degrees C was carried out and compared in terms of sensitivity to the programme without a cooling-down step, but no advantage was observed. Studies on the variation in precision and analytical recovery with the amount of sample, and interferent effects of different species on chromium determination were developed. Finally, chromium concentrations obtained in cocaine samples varied between 0.02 and 0.14 mg kg(-1), the levels in the heroin samples being in the 0.05-0.59 mg kg(-1) range.
