Search

Due to their antimicrobial properties, parabens are a family of synthetic chemical compounds widely used as preservative additives in food and cosmetics. For this reason, humans are highly exposed to them. These substances are capable of altering the proper functioning of the endocrine system and are classified as endocrine disrupting chemicals (EDCs). Traditionally, urine has been the typical matrix studied as an excretion route. However, faeces contain valuable information. In the present study, the presence of methyl-, ethyl-, isopropyl-, propyl-, isobutyl-, butyl- and phenylparaben in stool samples from children has been evaluated. A new analytical method has been optimised and validated. The method is based on the use of ultrasound-assisted extraction followed by clean-up of the extracts by dispersive solid phase extraction dSPE). Parabens were analysed by ultrahigh performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The matrix effect was evaluated and a significant effect was observed for all analytes. Therefore, calibration and validation were performed by addition of different concentrations of analytes to faecal blanks. The coefficient of determination (%R

Ultraviolet filters (UV-filters) are specific chemicals that absorb and reflect UVA and UVB radiation from the sun. They are regularly used in sunscreens and in other personal care products (PCPs), and in products like plastics, adhesives, toys, or furniture finishes. This work develops and validates a new method to determine concentrations of UV-filters (BP-1, BP-2, BP-3, BP-6, BP-8, 4-OH-BP, THB, AVB) in human nail samples. Nails are easily available and are considered to be suitable indicators of cumulative and continued exposure to harmful chemicals. The treatment of nail samples includes microwave assisted digestion/extraction (MAE) in a methanolic solution of o-phosphoric acid (0.05 mol L−1) followed by analyte determination using ultra-high performance liquid chromatography–mass spectrometry (UHPLC–MS/MS) in multiple reaction monitoring mode. The analytes were separated in less than 10 min. The digestion procedure was optimized using multivariate techniques. Matrix-matched calibration with a pig hoof matrix was used for validating the method. A study of accuracy with spiked blank samples was also conducted. The calculated detection limits varied between 0.2 and 1.5 ng g−1, and quantification limits between 1.0 and 5.0 ng g−1. The trueness of the method was an estimation of the recovery, which was between 90.2% and 112.2%; with an estimated precision (relative standard deviation, % RSD) lower than 12.3% for all UV-filters. Nail samples were obtained from 22 volunteers (male and female). The results showed that BP-1 and BP-3 mainly bioaccumulate in human nails.

Increasing concerns have been raised over recent decades about human exposure to Endocrine Disrupting Chemicals (EDCs), especially about their possible effects on embryo, foetus, newborn, and child. Parabens (PBs) and ultraviolet filters (UV-filters) are prevalent EDCs widely used as additives in cosmetics and personal care products (PCPs). The objective of this study was to determine the presence of four PBs and ten UV-filters in placental tissue samples using a novel analytical method based on ultrasound-assisted extraction (UAE) and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS). Multivariate optimization strategies were used to accurately optimize extraction and clean-up parameters. Limits of quantification ranged from 0.15 to 0.5 μg kg−1, and inter-day variability (evaluated as relative standard deviation) ranged from 3.6% to 14%. The method was validated using matrix-matched standard calibration followed by a recovery assay with spiked samples. Recovery percents ranged from 94.5% to 112%. The method was satisfactorily applied for the determination of the target compounds in human placental tissue samples collected at delivery from 15 randomly selected women. This new analytical procedure can provide information on foetal exposure to compounds, which has been little studied.

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.

A new sensitive, selective and accurate method to determine 17 quinolone and 14 β-lactam antibiotic residues in raw cow milk samples has been validated. The method is based on the extraction of the antibiotics by ultrasound-assisted extraction (UAE) followed by a clean-up step using a dispersive solid-phase extraction (d-SPE) sorbent. Experimental designs have been used for extraction and clean-up optimization. The extraction solvent selected was a mixture of acetonitrile/methanol/McIlvaine buffer solution (60:25:15; v/v/v) at pH 6. A volume of 15 mL of this extraction solvent was added to freeze-dried milk samples and the mixtures were sonicated during 20 min at 70% amplitude. The extracts were further cleaned-up with PSA (primary-secondary amine) sorbent and analysed by UHPLC-ESI(+)-MS/MS. Cincophen and piperacillin were used as surrogates for quinolones and β-lactams, respectively. The method was validated according to European Directive 2002/657/EC and FDA guideline. Recovery rates ranged from 96.0% to 104.5%. The limits of quantification of the method ranged from 0.3 to 2.0 ng g−1, while inter- and intra-day variability was under 7.1% in all cases. The method was applied to the determination of selected antibiotics in 28 raw cow milk samples. A percentage of 28% of the samples were positive in any of the studied antibiotics, however, only 11% were considered non-compliant with the current European Union legislation (Commission Regulation 37/2010).

Rapid industrialization has resulted in a progressive increase in human exposure to hazardous chemicals. The present work develops and validates a new method to determinate 18 endocrine disrupting chemicals (EDCs) in human nail samples. In contrast to other common biological samples, nail sampling is non-invasive and since they take several months to grow out, they are well suited for measuring and reflecting the cumulative exposure to harmful substances in the long term. A digestion of samples with a 0.04 M solution of sodium hydroxide is carried out followed by ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS), working in multiple-reaction-monitoring (MRM) mode. The compounds were separated in 8 min. Multivariate optimization strategies were used for the optimization of the parameters that affects the digestion procedure. The validation was developed using a matrix-matched calibration and a recovery assay with spiked samples. The limits of detection and quantification ranged from 0.3 to 1.2 ng g−1 and from 1 to 5 ng g−1, respectively. Recovery rates for spiked samples were between 88% and 113% and the relative standard deviation (% RSD) was lower than 12.7% for all studied EDCs. The method was applied for the analysis of these compounds in human nail samples from volunteers. All samples tested positive for several of the analyzed EDCs.

An ultrahigh performance liquid chromatography-tandem mass spectrometry method for the identification and quantification of neurotransmitters, metabolites and precursors at different stages in zebrafish life was developed. Betaine, glutamine, glutamic acid, γ-aminobutyric acid, phosphocholine, glycerophosphocholine, cytidine 5'-diphosphocholine, choline, acetylcholine, dopamine, norepinephrine, serotonin, tyrosine, epinephrine, tryptophan, 5-hydroxyindolacetic acid and agmatine were selected as analytes. The method consisted of a simple deproteinization of samples using methanol and formic acid, subsequent injection onto the chromatographic equipment and quantification with a triple quadrupole mass spectrometer detector using an electrospray ionization interface in positive mode. Limits of detection ranged from 0.02 to 11ngmL(-1) and limits of quantification from 0.1 to 38ngmL(-1), depending on the analyte. The method was validated according to US Food and Drugs Administration (FDA) guideline for bioanalytical assays. Precision, expressed as relative standard deviation (%RSD), was lower than 15% in all cases, and the determination coefficient (R(2)) was equal or higher than 99.0% with a residual deviation for each calibration point lower than ±25%. Mean recoveries were between 85% and 115%. The method was applied to determine of these compounds in zebrafish from early stages of development to adulthood and showed the time-course of neurotransmitters and others neurocompounds through the life cycle. The possibility of measuring up to 17 compounds related with the main neurotransmitter systems in a simple analytical method will complement and reinforce the use of zebrafish in multiple applications in the field of neurosciences. The proposed method will facilitate future studies related with brain development.

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.

Seventeen quinolone antibiotics were determined in cows’ milk. A method of high sensitivity, selectivity and accuracy was developed. Accuracy (trueness and precision), linearity, sensitivity, selectivity, decision limit and detection capability were established following the recommendations of the Commission Decision 2002/657/EC and the Food and Drug Administration (FDA) guideline. The use of polar stir-bar sorptive extraction (SBSE) prior to UHPLC-MS/MS analysis is proposed. The variables that affect SBSE were optimised using multivariate optimisation strategies. The ionic strength, the extraction time and the sample volume were studied. pH and stir-bar coating (polydimethylsiloxane, PDMS, and polyethyleneglycol modified silicone, PEG) were studied. PEG showed the best extraction yield at pH 6. For validation, a matrix-matched calibration and a recovery assay were carried out. Limits of quantification from 0.5 μg kg−1 for nalidixic acid, flumequine and piromidic acid, to 4.0 μg kg−1 for sarafloxacin were calculated. The precision (%, RSD) was lower than 15% for all antibiotics. Recoveries in fortified samples were between 88 and 114%.

In recent decades, in parallel to industrial development, a large amount of new chemicals have emerged that are able to produce disorders in the human endocrine system. These groups of substances, so-called endocrine disrupting chemicals (EDCs), include many families of compounds, such as parabens, benzophenones 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 EDC concentrations and the harmful health effects observed in the population. In the present study, a method based on a sample treatment by matrix solid phase dispersion (MSPD) for the extraction of four parabens (methyl-, ethyl-, propyl- and butylparaben), five bisphenols (bisphenol A and monochloro-, dichloro-, trichloro- and tetrachlorobisphenol A) and benzophenone-3 in human placental tissue samples, followed by ultra high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) analysis is proposed. The extraction parameters were accurately optimized using multivariate optimization strategies. Ethylparaben ring- 13 C 6 , benzophenone-d 10 and bisphenol A-d 16 were used as surrogates. The found limits of quantification (LOQ) ranged from 0.2 to 0.4 ng g − 1 and the precision, evaluated as relative standard deviation, ranged from 6.1% to 14.8%. The method was validated using matrix-matched standard calibration followed by a recovery assay with spiked samples. Recovery rates from 96% to 105% were obtained. The method was satisfactorily applied for the determination of target compounds in human placenta samples from 10 randomly selected women.

A new analytical method coupling a (off-line) solid-phase microextraction with an on-line capillary electrophoresis (CE) sample enrichment technique was developed for the analysis of ketoprofen, naproxen and clofibric acid from water samples, which are known as contaminants of emerging concern in aquatic environments. New solid-phase microextraction fibers based on physical coupling of chromatographic supports onto epoxy glue coated needle were studied for the off-line preconcentration of these micropollutants. Identification and quantification of such acidic drugs were done by capillary zone electrophoresis (CZE) using ultraviolet diode array detection (DAD). Further enhancement of concentration sensitivity detection was achieved by on-line CE “acetonitrile stacking” preconcentration technique. Among the eight chromatographic supports investigated, Porapak Q sorbent showed higher extraction and preconcentration capacities. The screening of parameters that influence the microextraction process was carried out using a two-level fractional factorial. Optimization of the most relevant parameters was then done through a surface response three-factor Box-Behnken design. The limits of detection and limits of quantification for the three drugs ranged between 0.96 and 1.27 µg∙L−1 and 2.91 and 3.86 µg∙L−1, respectively. Recovery yields of approximately 95 to 104% were measured. The developed method is simple, precise, accurate, and allows quantification of residues of these micropollutants in Genil River water samples using inexpensive fibers., The Council of Scientific and Humanistic Development (abbreviated as CONDES in Spanish). The University Sector Planning Office (abbreviated as OPSU in Spanish) and the Research Division of the Engineering Faculty.

Irrigation with reclaimed water and soil amendment with sewage sludge are becoming common practices in arid and semiarid areas. When wastewater treatments do not efficiently remove all the contaminants, these contaminants can later end up in agricultural soils. These contaminated soils are a potential source of surface and groundwater pollution by leaching and runoff. In the present work, we assessed the behavior of alcohol sulfates (AS) in agricultural soil. For the experimental work, a tract of soil was irrigated with linear alcohol sulfates with 12–18 hydrocarbon chain and subsequently tested for AS concentration from November 2014 to July 2015. The highest concentrations of AS were found at the top layer of soil (29.80 to 6.23 mg kg−1). The adsorption rate and the amount of surfactant adsorbed increased as the length of the hydrocarbon chain increases. AS homologues can leach up to 60 cm. A mathematical model was applied to predict the environmental behavior of AS in the agricultural soils studied. Disappearance rate constant (k) values for AS homologues were between −5.10·10−3 and −1.68·10−2 h−1, and average half-life values were between 37 and 135 h. Coefficients of determination (R 2) between 92.4 and 99.1% showed that the proposed model satisfactorily describes the experimental results. The present study provides a conceptual framework and essential parameters for predicting and understanding the environmental behavior of AS in agricultural soils.

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.

Background: A new method for the determination of four perfluoroalkyl carboxylic acids (from C5 to C8) and perfluorooctane sulfonate in human milk samples using stir-bar sorptive extraction-ultra-HPLC–MS/MS has been accurately optimized and validated. Methodology: Polydimethylsiloxane and polyethyleneglycol modified silicone materials were evaluated. Discussion: Overall, polyethyleneglycol led to a better sensitivity. After optimizing experimental variables, the method was validated reaching detection limits in the range of 0.05–0.20 ng ml-1; recovery rates from 81 to 105% and relative standard deviations fewer than 13% in all cases. The method was applied to milk samples from five randomly selected women. All samples were positive for at least one of the target compounds with concentrations ranging between 0.8 and 6.6 ng ml-1, being the most abundant perfluorooctane sulfonate.