Chromatographic Methods for the Determination of Emerging Contaminants in Natural Water and Wastewater Samples: A Review.

This review is devoted to analytical methods published in the scientific literature in the last 10 years for the determination of emerging contaminants in aquatic media. The article is mainly focused on sample preparation and on instrumental techniques most used for the detection and quantification of the analytes of interest. The sample preparation techniques include classical liquid-liquid extraction and solid-phase extraction, but also recent microextraction techniques such as solid-phase microextraction, stir-bar sorptive extraction, dispersive liquid-liquid microextraction, ultrasound-assisted emulsification microextraction, or microextraction by packed sorbent. Most studies focus on minimizing the number of analysis steps and on the use of the lowest amount of solvents in the sample treatment step. Liquid chromatography and gas chromatography mainly coupled to tandem mass spectrometry are usually the employed analytical techniques. A large number of multiresidue methods are being developed for the determination of several families of these compounds with only one extraction step to minimize sample handling and treatment.

Liquid chromatography-electrochemical detection for the determination of ethoxyquin and its dimer in pear skin and salmon samples.

Ethoxyquin (EQ) is widely used as a synthetic antioxidant in animal feed, an antiscalding agent in apples and pears and as a color preservative in some spices. Since the presence of EQ in food products could cause negative health effects it is necessary to develop reliable analytical methods to evaluate the risk of human exposure. In this work, a sensitive, selective and accurate method based on solid-liquid extraction followed by clean-up with solid sorbent and liquid chromatography-electrochemical detection analysis with boron doped diamond electrode (LC-EC) for the determination of ethoxyquin and its dimer (EQDM) in pear skin and salmon samples, was developed. The method was validated according to the European Commission guidelines. The main variables of extraction were accurately optimized. The amounts of solid sorbents for clean-up procedure were optimized by using experimental design. A Box-Behnken design to obtain the optimum conditions was applied. For validation, a matrix-matched calibration was established and a recovery assay with spiked samples was carried out. The limits of detection (LODs) found were 0.05 and 0.1mgkg-1 for EQ and its dimer, respectively. The precision (as relative standard deviation, RSD) was lower than 15% with recoveries of compounds close to 100% in spiked samples.

Determination of bisphenols with estrogenic activity in plastic packaged baby food samples using solid-liquid extraction and clean-up with dispersive sorbents followed by gas chromatography tandem mass spectrometry analysis.

Bisphenols (BPs) are a family of chemicals with known endocrine disrupting activity. Bisphenol A (BPA) is the most representative prototype of this group of chemicals. Recently, the use of BPA, a prototype of endocrine disruptors, has been reduced and replaced with structural analogs due to its negative effects on both the environment and consumers. In this work, a new method is presented for the determination of seven BPs, with estrogenic activity in ready-to-eat plastic packaged baby foods. The procedure involves the isolation of the analytes using solid-liquid phase extraction with acetonitrile followed by a clean-up step with a mixture of dispersive-SPE sorbents (C18 and PSA) and magnesium sulphate, to reduce matrix effect from proteins, sugars and lipids. Extraction parameters were optimized using multivariate optimization methods. The compounds were detected and quantified by gas chromatography tandem mass spectrometry (GC-MS/MS). The limits of quantification were between 0.1 and 1.2ngg-1 for the studied analytes. The method was validated using matrix-matched calibration and recovery assays with spiked samples. Recovery rates were between 91% and 110% and % RSD was lower than 13% in all cases. The method has been successfully applied for the determination of these endocrine disrupting chemicals (EDCs) in samples of a novel type of food consumed by pre-schoolers. This is the first study to analyze EDCs in plastic packaged foods consumed by this target group.

Biomonitoring of 21 endocrine disrupting chemicals in human hair samples using ultra-high performance liquid chromatography-tandem mass spectrometry.

Rapid industrial growth has increased human exposure to a large variety of chemicals with adverse health effects. These industrial chemicals are usually present in the environment, foods, beverages, clothes and personal care products. Among these compounds, endocrine disrupting chemicals (EDCs) have raised concern over the last years. In the present work, the determination of 21 EDCs in human hair samples is proposed. An analytical method based on the digestion of the samples with a mixture of acetic acid/methanol (20:80, v/v) followed by a solid-liquid microextraction and analysis by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. The most influential parameters affecting the extraction method were optimized. The method was validated using matrix-matched calibration and recovery assays. Limits of detection ranged from 0.2 to 4 ng g-1, limits of quantification from 0.5 to 12 ng g-1, and inter- and intra-day variability was under 15% in all cases. Recovery rates for spiked samples ranged from 92.1 to 113.8%. The method was applied for the determination of the selected compounds in human hair. Samples were collected weekly from six randomly selected volunteers (three men and three women) over a three-month period. All the analyzed samples tested positive for at least one of the analyzed compounds.

Sorption, degradation and transport phenomena of alcohol ethoxysulfates in agricultural soils. Laboratory studies.

In the present work, laboratory studies were conducted in order to determine and model the sorption, degradation and transport processes of alcohol ethoxysulfates (AES), one of the most important groups of anionic surfactants. Adsorption/desorption isotherms were obtained for several structurally related AES ethoxymers (homologue AES-C12En with n = 0-10 ethoxymer units and homologue AES-C14En with n = 0-7 ethoxymer units) using a batch equilibrium method. Data were fitted to a linear and a Freundlich isotherm models. Additionally, experiments in continuous-flow soil columns were also carried out and the breakthrough curves observed for each compound were studied. Breakthrough curves were used to determine the fundamental parameters of the transport model (hydrodynamic dispersion coefficient, degradation rate constant and adsorption/desorption isotherm slope), that is the main phenomena that take place simultaneously when AES move through agricultural soil. When the results obtained for the AES ethoxymers are combined, they reveal a clear and consistent trend towards a sorption increase with the number of ethoxylated units and with the length of the alkyl chain that opens the possibility to estimate the values of the transport parameters for other structurally related ethoxymers.

Validated method for the determination of perfluorinated compounds in placental tissue samples based on a simple extraction procedure followed by ultra-high performance liquid chromatography-tandem mass spectrometry analysis.

Xenobiotic exposure during pregnancy is inevitable. Determination of perfluorinated compounds (PFCs), chemicals described as environmental contaminants by Public Health Authorities due to their persistence, bioaccumulation and toxicity, is a challenge. In the present work, a method based on a simplified sample treatment involving freeze-drying, solvent extraction and dispersive clean-up of the extracts using C18 sorbents followed by an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis was developed and validated for the determination of five perfluorinated carboxylic acids (C4-C8) and perfluorooctane sulfonate (PFOS) in placental tissue samples. The most influential parameters affecting the extraction method and clean-up were optimized using Design of Experiments (DOE). The method was validated using matrix-matched calibration. Found limits of detection (LODs) ranged from 0.03 to 2 ng g(-1) and limits of quantification (LOQs) from 0.08 to 6 ng g(-1), while inter- and intra-day variability was under 14% in all cases. Recovery rates for spiked samples ranged from 94% to 113%. The method was satisfactorily applied for the determination of compounds in human placental tissue samples collected at delivery from 25 randomly selected women.

Specific Antigens by Federal Entity in Patients at the Transplant Unit of Specialities Hospital, National Medical Center Twenty-First Century, Mexico.

BACKGROUND: The study of the kidney transplant involves understanding the immunologic basis, such as histocompatibility and the genetic basis of a population. In Mexico, the study of the genetic basis has led to a genetic map by federal entities. METHODS: We performed an HLA study with 1,276 kidney transplant patients (recipients and donors) in the Hospital of the National Medical Center Twenty-First Century, determining HLA class I (A, B, and Cw) and class II (DRß1 and DQß1) antigens with the use of SSOP-PCR. A descriptive analysis was conducted with measures of central tendency (mean, SD). RESULTS: Of 1,276 HLA patients studied, we obtained 2,552 results for each class by the composition of the 2 haplotypes, and for HLA-Cw we processed 796 patients, for a total of 1,592 antigens for this class. We found antigens specific to each federal entity, and it was found that the Federal District had the highest number of specific antigens (10) followed by Morelos (7), Querétaro and Mexico State (3 each), and Tamaulipas, Aguascalientes, Michoacán, Guerrero, Puebla, and Oaxaca (1 each). CONCLUSIONS: The genetic map allows us to know proportions of antigens in every state in the center and south of Mexico owing to the diversity and area of influence of the National Medical Center XXIst Century, as well as the wide number of patients. Furthermore, there are still preserved proportionally distinct genetic roots in every entity.

Analytical methods for the assessment of endocrine disrupting chemical exposure during human fetal and lactation stages: a review.

In the present work, a review of the analytical methods developed in the last 15 years for the determination of endocrine disrupting chemicals (EDCs) in human samples related with children, including placenta, cord blood, amniotic fluid, maternal blood, maternal urine and breast milk, is proposed. Children are highly vulnerable to toxic chemicals in the environment. Among these environmental contaminants to which children are at risk of exposure are EDCs -substances able to alter the normal hormone function of wildlife and humans-. The work focuses mainly on sample preparation and instrumental techniques used for the detection and quantification of the analytes. The sample preparation techniques include, not only liquid-liquid extraction (LLE) and solid-phase extraction (SPE), but also modern microextraction techniques such as extraction with molecular imprinted polymers (MIPs), stir-bar sorptive extraction (SBSE), hollow-fiber liquid-phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME), matrix solid phase dispersion (MSPD) or ultrasound-assisted extraction (UAE), which are becoming alternatives in the analysis of human samples. Most studies focus on minimizing the number of steps and using the lowest solvent amounts in the sample treatment. The usual instrumental techniques employed include liquid chromatography (LC), gas chromatography (GC) mainly coupled to tandem mass spectrometry. Multiresidue methods are being developed for the determination of several families of EDCs with one extraction step and limited sample preparation.

Improved sample treatment for the determination of fructooligosaccharides in milk related products by liquid chromatography with electrochemical and refractive index detection.

A simple and reliable method for the determination of the fructooligosaccharides (FOS) kestose (GF2), nystose (GF3), fructofuranosylnystose (GF4), in the presence of fructose, glucose and lactose in dairy products is proposed. The most relevant advantages of the proposed method are the simultaneous determination of the most common FOS in enriched products and a reduction of the time required for sample treatment since the method consists merely in addition of a precipitation solution for the removal of lipids and proteins. Furthermore, the method saves a substantial amount of reagents compared with other methods and sample manipulation is reduced. Two chromatographic separations are proposed. The first one is carried out on an amino phase column for liquid chromatography with refractive index detection (HPLC-RI) (concentration of analytes higher than 0.1 mg mL(-1)) and the second one on an anion-exchange Carbopac PA-1 column for high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) (concentration of FOS lower than 0.1 mg mL(-1)). The method was validated by recovery assays with spiked samples using matrix-matched calibration. The limits of quantification of the method ranged from 1.2 to 2.0 µg mL(-1) for HPAEC-PAD and from 140 to 200 µg mL(-1) for HPLC-RI, while inter- and intra-day variability was under 3.5% in all cases. The proposed method was applied to the determination of compounds in supplemented milk, infant formulas and milk related juices with good recoveries in all cases.

Determination of benzophenone-UV filters in human milk samples using ultrasound-assisted extraction and clean-up with dispersive sorbents followed by UHPLC-MS/MS analysis.

A new sample preparation method for the determination of five benzophenone UV-filters in human breast milk has been developed. The procedure involves the lyophilization of the sample, and its subsequent extraction by ultrasound sonication using acetonitrile. In order to reduce matrix effects produced by milk components that are coextracted, mainly proteins, sugars and lipids, a further clean-up step with a mixture of dispersive-SPE sorbents, C18 and PSA, was applied. Extraction parameters were optimized using experimental design, and the compounds were detected and quantified by ultrahigh performance liquid-chromatography tandem mass spectrometry (UHPLC-MS/MS) in positive ESI mode. Analytes were separated in 10 min. BP-d10 was used as internal standard. The limits of detection (LODs) were between 0.1 and 0.2 ng mL(-1), and the limits of quantification (LOQs) were between 0.3 and 0.6 ng mL(-1) for the target analytes. The inter- and intra-day variability was <12%. The method was validated using matrix-matched calibration and recovery assays with spiked samples. Recovery rates were between 90.9 and 109.5%. The method was successfully applied for the determination of these compounds in human milk samples collected from volunteers lactating mothers with no known occupational exposure to these compounds who live in the province of Granada (Spain). The analytical method developed here may be useful for the development of more in-depth studies on the prenatal exposure and biomonitoring of these commonly used UV-filters.

New method for the determination of parabens and bisphenol A in human milk samples using ultrasound-assisted extraction and clean-up with dispersive sorbents prior to UHPLC-MS/MS analysis.

A sensitive and accurate analytical method for the determination of methyl-, ethyl-, propyl- and butylparaben and bisphenol A in human milk samples has been developed and validated. The combination of ultrasound-assisted extraction (UAE) and a simplified and rapid clean-up technique that uses sorbent materials has been successfully applied for the preparation of samples prior to ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis. The analytes were extracted from freeze-dried human milk samples using acetonitrile and ultrasonic radiation (three 15-min cycles at 70% amplitude), and further cleaned-up with C18 sorbents. The most influential parameters affecting the UAE method and the clean-up steps were optimized using design of experiments. Negative electrospray ionization (ESI) in the selected reaction monitoring (SRM) mode was used for MS detection. The use of two reactions for each compound allowed simultaneous quantification and identification in one run. The analytes were separated in less than 10min. Deuterium-labeled ethylparaben-d5 (EPB-d5) and deuterium-labeled bisphenol A-d16 (BPA-d16) were used as surrogates. The limits of quantification ranged from 0.4 to 0.7ngmL(-1), while inter- and intra-day variability was under 11.1% in all cases. In the absence of certified reference materials, recovery assays with spiked samples using matrix-matched calibration were used to validate the method. Recovery rates ranged from 93.8% to 112.2%. The proposed method was satisfactorily applied for the determination of four selected parabens and bisphenol A in human milk samples obtained from nursing mothers living in the province of Granada (Spain).

Stir bar sorptive extraction: recent applications, limitations and future trends.

Stir bar sorptive extraction (SBSE) has generated growing interest due to its high effectiveness for the extraction of non-polar and medium-polarity compounds from liquid samples or liquid extracts. In particular, in recent years, a large amount of new analytical applications of SBSE has been proposed for the extraction of natural compounds, pollutants and other organic compounds in foods, biological samples, environmental matrices and pharmaceutical products. The present review summarizes and discusses the theory behind SBSE and the most recent developments concerning its effectiveness. In addition, the main results of recent analytical approaches and their applications, published in the last three years, are described. The advantages, limitations and disadvantages of SBSE are described and an overview of future trends and novel extraction sorbents and supports is given.

A multiresidue method for the determination of selected endocrine disrupting chemicals in human breast milk based on a simple extraction procedure.

In recent decades, in parallel to industrial development, a large amount of new chemicals have emerged that are able to produce disorders in human endocrine system. These groups of substances, so-called endocrine disrupting chemicals (EDCs), include many families of compounds, such as parabens, benzophenone-UV filters and bisphenols. Given the demonstrated biological activity of those compounds, it is necessary to develop new analytical procedures to evaluate the exposure with the final objective of establishing, in an accurate way, relationships between EDCs concentrations and the harmful health effects observed in population. In the present work, a method based on a simplified sample treatment involving steps of precipitation, evaporation and clean-up of the extracts with C18 followed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis for the determination of bisphenol A and its chlorinated derivatives (monochloro-, dichloro-, trichloro- and tetrachlorobisphenol A), parabens (methyl-, ethyl-, propyl- and butylparaben) and benzophenone-UV filters (benzophenone -1,-2, -3, -6, -8 and 4-hydroxybenzophenone) in human breast milk samples is proposed and validated. The limits of detections found ranged from 0.02 to 0.05 ng mL(-1). The method was validated using matrix-matched standard calibration followed by a recovery assay with spiked samples. Recovery rates ranged from 91% to 110% and the precision (evaluated as relative standard deviation) was lower than 15% for all compounds, being within the acceptable limits for the selected bioanalytical method validation guide. The method was satisfactorily applied for the determination of these compounds in human breast milk samples collected from 10 randomly selected women.

Gas chromatography and ultra high performance liquid chromatography tandem mass spectrometry methods for the determination of selected endocrine disrupting chemicals in human breast milk after stir-bar sorptive extraction.

In the present work, two specific, accurate and sensitive methods for the determination of endocrine disrupting chemicals (EDCs) in human breast milk are developed and validated. Bisphenol A and its main chlorinated derivatives, five benzophenone-UV filters and four parabens were selected as target analytes. The method involves a stir-bar sorptive extraction (SBSE) procedure followed by a solvent desorption prior to GC-MS/MS or UHPLC-MS/MS analysis. A derivatization step is also necessary when GC analysis is performed. The GC column used was a capillary HP-5MS with a run time of 26min. For UHPLC analysis, the stationary phase was a non-polar Acquity UPLC(®) BEH C18 column and the run time was 10min. In both cases, the analytes were detected and quantified using a triple quadrupole mass spectrometer (QqQ). Quality parameters such as linearity, accuracy (trueness and precision), sensitivity and selectivity were examined and yielded good results. The limits of quantification (LOQs) ranged from 0.3 to 5.0ngmL(-1) for GC and from 0.2 to 1.0ngmL(-1) for LC. The relative standard deviation (RSD) was lower than 15% and the recoveries ranged from 92 to 114% in all cases, being slightly unfavorable the results obtained with LC. The methods were satisfactorily applied for the determination of target compounds in human milk samples from 10 randomly selected women.

Disposable biosensor based on cathodic electrochemiluminescence of tris(2,2-bipyridine)ruthenium(II) for uric acid determination.

A new method for uric acid (UA) determination based on the quenching of the cathodic ECL of the tris(2,2-bipyridine)ruthenium(II)-uricase system is described. The biosensor is based on a double-layer design containing first tris(2,2-bipyridine)ruthenium(II) (Ru(bpy)3(2+)) electrochemically immobilized on graphite screen-printed cells and uricase in chitosan as a second layer. The uric acid biosensing is based on the ECL quenching produced by uric acid over the cathodic ECL caused by immobilized Ru(bpy)3(2+) in the presence of uricase. The use of a -1.1 V pulse for 1s with a dwelling time of 10s makes it possible to estimate the initial enzymatic rate, which is used as the analytical signal. The Stern-Volmer type calibration function shows a dynamic range from 1.0×10(-5) to 1.0×10(-3)M with a limit of detection of 3.1×10(-6)M and an accuracy of 13.6% (1.0×10(-4)M, n=5) as relative standard deviation. Satisfactory results were obtained for urine samples, creating an affordable alternative for uric acid determination.

Determination of benzophenones in human placental tissue samples by liquid chromatography-tandem mass spectrometry.

Benzophenones (BPs) are a family of compounds widely used to protect the skin and hair from UV irradiation. Despite human exposure to BPs through dermal application of products containing sunscreen agents and the increasing evidence that BPs are able to interfere with endocrine systems, few studies have examined the occurrence of BPs in humans. In this work, we propose a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to determine six BPs, namely, benzophenone-1 (BP-1), benzophenone-2 (BP-2), benzophenone-3 (BP-3), benzophenone-6 (BP-6), benzophenone-8 (BP-8) and 4-hydroxybenzophenone (4-OH-BP) in human placental tissue samples. The method involves an extraction step of the analytes from the samples using ethyl acetate, followed by a clean-up step using centrifugation prior to their quantification by LC-MS/MS using an atmospheric pressure chemical ionization (APCI) interface in the positive mode. Benzophenone-d(10) (BP-d(10)) was used as surrogate. Found detection limits (LOD) ranged from 0.07 to 0.3 ng g(-1) and quantification limits (LOQ) from 0.3 to 1.0 ng g(-1), while inter- and intra-day variability was under 5%. The method was validated using standard addition calibration and a recovery assay. Recovery rates for spiked samples ranged from 98 to 104%. This method was satisfactorily applied for the determination of BPs in 16 placental tissue samples collected from women who live in Granada (Spain).

Inhibidores enzimaticos de la angiotensina II. (2da parte). Uso clínicos: actualidad y futuro

Se hace una revisión sobre los fármacos inhibidores de la enzima de conversión de la angiotensinal. Se describen las clasificaciones y características farmacocinéticas de los mismos; así como sus mecanismos de acción, en particular: el efecto hemodinámico-hipotensor y el efecto sobre el riñón. Se actualiza el uso de dichos fármacos en la hipertensión arterial y la insuficiencia cardíaca congestiva, así como sus interacciones farmacológicas y reacciones adversas. Además, se señalan algunos aspectos actuales relacionados con el uso de los mismos.

Infacto agudo del miocardio. Estudio de un año.

Se estudiaron 338 pacientes ingresados por Infarto Agudo del Miocardio en el Hospital Clínico Quirúrgico Provincial de Sancti Spíritus durante el año 2002. De los 338 pacientes estudiados, 185 (54,7 po ciento) pertenecían al sexo masculino y 153 (45,3 por ciento) al femenino. Se apreció en ambos sexos un incremento del número de ingresos en los grupos de más edad, excepto para el grupo de 90 años y más, en el cual disminuyeron los ingresos en relación con los grupos precedentes. Se apreció en ambos sexos una mayor letalidad del Infarto Agudo del Miocardio en los grupos de edades extremas, presentando los mayores de 90 años las tasas más altas. Presentaron al menos un factor de riesgo 266 pacientes (78.7 por ciento), el más frecuente fue la edad de 60 años o más, presente en 266 pacientes (78.7 por ciento), le siguió el stress, (132 pacientes, 39 por ciento). Los pacientes con hiperlipidemia presentaron la letalidad más alta, 50 por ciento, precedido por los pacientes que consumían una dieta rica en colesterol, letalidad del 39.8 por ciento; la letalidad más baja, 16,6 por ciento, la presentaron los pacientes sin ningún factor de riesgo identificado. Los síntomas iniciales más frecuentes presentados por los pacientes fueron la sudoración y el dolor torácico, presentes en 325 (96.1 por ciento) y 322 (95.2 por ciento) pacientes respectivamente, les siguió en orden de frecuencia los síntomas gastrointestinales, 266 pacientes (78.6 por ciento), el resto de los síntomas afectó a menos del 50 por ciento de los pacientes. Se presentó una mayor frecuencia del infarto de cara anterior (57,1 por ciento), lo que se observó en ambos sexos. Las complicaciones cardiovasculares más frecuente fueron la taquicardia ventricular, en 127 pacientes (37,5 por ciento), y la insuficiencia cardíaca, en 121 pacientes (35,7 por ciento). Los resultados obtenidos se corresponden con lo observado en otros estudios. [AU]

Rotura de un aneurisma disecante de la arteria esplénica durante el posparto / Rupture of a dissecting splenic artery aneurysm in the postpartum

Se expone un caso de rotura espontánea de un aneurisma de la arteria esplénica durante el tercer día posparto. Los aneurismas son infrecuentes, asintomáticos, su existencia es desconocida en la mayoría de los casos y su primer signo de presentación es el shock hipovolémico, con consecuencias fatales. (AU)