Ana Ballesteros-Gómez

Analytical methods for the determination of bisphenol A in food.

Food constitutes the primary route for human exposure to bisphenol A (BPA), one of the highest volume chemicals produced worldwide. The estrogenic properties of BPA, its wide dispersive use and the recent extensive literature describing low-dose BPA effects in animals, have raised concerns about its possible adverse effects on human health. A reliable health risk assessment of BPA relies basically on its unambiguous identification and accurate quantification in food, and the aim of the present review is to give an overview of the analytical methods reported so far for the determination of BPA in these matrices. Emphasis is placed on the main strategies developed for sample treatment, which usually consists of several laborious and time-consuming steps in order to achieve the required sensitivity and selectivity. Separation, identification and quantitation of BPA is today reliably made with mass spectrometric methods, namely liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS), and thus main attention is devoted to these techniques, but other methods using LC coupled to fluorescence or electrochemical detection, as well as immunochemical methods are also covered. Recent and expected future developments are discussed.

Supramolecular solvents in the extraction of organic compounds. A review

The increasing pressure to decrease organic solvent usage in laboratories is fostering the search for alternative solvents. The liquid-liquid phase separation of surfactants, induced by environmental conditions, viz. temperature, electrolytes, pH, etc., has been largely used in analytical extraction and concentration schemes. The surfactant-rich phase is a nano-structured liquid, recently named as supramolecular solvent, generated from the amphiphiles through a sequential self-assembly process occurring on two scales, molecular and nano. This review covers progress on both theoretical and practical aspects related to the use of supramolecular solvents in analytical extractions reported over the last decade. Advances allowing a better understanding of the mechanisms of solvent production and solvent structure are outlined. Emphasis is then placed on solvent composition and its consequences on extraction efficiency, concentration factors and suitability for solubilising analytes over a wide range of polarities. Recent developments in formats and strategies making supramolecular solvents compatible with chromatographic and electrophoretic techniques along with a variety of detection systems are discussed. Applications of supramolecular solvents to the extraction of organic compounds mainly in the biological, environmental and agrifood areas are critically reviewed and main future trends outlined.

Hemimicelles of Alkyl Carboxylates Chemisorbed onto Magnetic Nanoparticles: Study and Application to the Extraction of Carcinogenic Polycyclic Aromatic Hydrocarbons in Environmental Water Samples

In this work, magnetic nanoparticles (MNPs) coated with hemimicelles of alkyl (C(10)-C(18)) carboxylates, which have traditionally been used to prepare ferrofluids for technological applications, were used for the first time to extract organic contaminants from environmental water samples. The nanoparticles were coated by following a simple, rapid procedure (30 min at 85 degrees C) that uses commercially available magnetite of 20-30 nm mean particle diameter. The strong chemical bonding between the surfactant and magnetite relative to the electrostatic forces involved in conventional hemimicelle-based sorbents precludes leaching of the surfactant and facilitates its reuse and the obtainment of surfactant-free extracts. Tetradecanoate hemimicelles were used here to extract carcinogenic polycyclic aromatic hydrocarbons (CPAHs) prior to analysis by liquid chromatography (using a C(18) Supelcosil LC-PAH column and a gradient elution program with water and acetonitrile) and fluorescence detection. The procedure involved stirring filtered aqueous samples (350 mL) with 200 mg of tetradecanoate-coated MNPs for 15 min, isolating the sorbent with a Nd-Fe-B magnet and eluting the CPAHs with a mixture of acetonitrile and tetrahydrofuran. The extraction efficiency was not influenced by salt concentrations up to 1 M and pH values over the range 2.5-9. The preconcentration factor was 116. No cleanup of the extracts was needed, and the method proved matrix-independent. The limits of quantitation thus obtained, 0.2-0.5 ng L(-1), meet the stringent water quality requirements established by the recently amended European Water Framework Directive 2000/60/EC and also the U.S. EPA for the determination of CPAHs in surface and ground waters. The proposed method was successfully applied to the determination of these pollutants in surface and ground environmental water samples collected from various places in southern Spain. Recoveries from samples spiked with CPAHs at concentrations of 1-10 ng L(-1) ranged from 85 to 94% and relative standard deviations from 1 to 7%. CPAHs were only present in the sample from the Navallana reservoir, at concentrations over the range 0.42-0.96 ng L(-1).

Potential of supramolecular solvents for the extraction of contaminants in liquid foods

Amphiphile-based supramolecular solvents (ASSs), which are water immiscible liquids consisting of supramolecular aggregates in the nano- and micro-scale regimes dispersed in a continuous phase, were assessed for the extraction of trace contaminants in liquid foods. The ASS selected was made up of reversed micelles of decanoic dispersed in tetrahydrofuran (THF)-water and the contaminants used as a model were bisphenol A (BPA), ochratoxin A (OTA) and benzo(a)pyrene (BaPy). The influence of matrix components on the extractant solvent production, extraction recoveries and actual concentration factors was investigated by using commercial foods such as wine and wine-based products, beer, soft drinks and tea and coffee brews, and/or aqueous synthetic solutions containing specific food matrix components. The method involved the addition of decanoic acid (80mg) and THF (0.8-1.7mL) to the food sample (15mL), stirring of the mixture for 5min, centrifugation for 10min and analysis of 10-20microL of the extract by liquid chromatography coupled to fluorimetry for OTA and BaPy or to mass spectrometry for BPA. No clean-up of the crude extracts was required for any of the samples analysed. The quantification limits for the contaminants (14-31ngL(-1), 0.37-0.39ngL(-1) and 562-602ngL(-1) for OTA, BaPy and BPA, respectively) were far below their respective European legislative threshold limits. Recoveries for food samples were in the ranges 79-93%, 90-96% and 78-82% for OTA, BaPy and BPA, respectively, with relative standard deviations ranging from 1 to 7%, and actual concentrations factors between 65 and 141. The methods developed were applied to the determination of the target compounds in a variety of commercial foods. OTA was found in vinegar, must and beer samples, the concentrations ranging from 92 to 177ngL(-1), BaPy was quantified in samples of tea and coffee at concentrations between 1.5 and 16.6ngL(-1) whereas BPA was detected in two canned soft drinks and quantified in one of them (tea beverage) at a level of 2.3microgL(-1).

Dietary and sociodemographic determinants of bisphenol A urine concentrations in pregnant women and children

Bisphenol A (BPA) exposure during early life may have endocrine-disrupting effects, but the dietary and sociodemographic predictors of BPA exposure during pregnancy and childhood remain unclear. Our aim was to evaluate the correlations between, and sociodemographic and dietary predictors of, serial urinary BPA concentrations measured during pregnancy and childhood in a Spanish birth cohort study. BPA was measured in two spot urine samples collected from 479 women during the first and third trimester of pregnancy and in one urine sample from their 4-year old children (n=130). Average dietary intakes were reported in food frequency questionnaires during the first and third pregnancy trimester and at age 4years. Multivariate mixed models and linear regression models were used to estimate associations between sociodemographic and dietary factors and BPA concentrations. A small, but statistically significant correlation was found between serial maternal BPA concentrations measured during pregnancy (r=0.17). Pregnant women who were younger, less-educated, smoked, and who were exposed to second-hand tobacco smoke (SHS) had higher BPA concentrations than others. BPA concentrations were also higher in children exposed to SHS. High consumption of canned fish during pregnancy was associated with 21% [GM ratio=1.21; 95%CI 1.02, 1.44] and 25% [GM ratio=1.25; 95%CI 1.05, 1.49] higher urinary BPA concentrations in the first and third pregnancy trimester, respectively, compared to the lowest consumption group. This study suggests that canned fish may be a major source of BPA during pregnancy in Spain, a country of high canned fish consumption. Further evaluation of specific BPA exposure sources in the sociodemographic group of younger women who smoke, are exposed to SHS, and have a low educational level is needed. Studies identifying sources of exposure would benefit from repeat BPA measurements and questionnaires specifically focused on dietary and packaging sources.

Prenatal bisphenol a urine concentrations and early rapid growth and overweight risk in the offspring.

Background: Increasing experimental evidence suggests that prenatal bisphenol A (BPA) exposure induces offspring weight gain, but these effects remain largely unexplored in humans. We examined the effects of prenatal BPA exposure on postnatal growth and obesity. Methods: BPA concentrations were measured in two spot-urine samples collected in the 1st and 3rd trimesters of pregnancy from mothers in a Spanish birth cohort study (n = 402). We used the average of the two creatinine-adjusted BPA concentrations as the exposure variable. Rapid child growth was defined as a weight gain Z score >0.67 in the first 6 months of life. Age- and sex-specific Z scores for body mass index (BMI) were calculated at age 14 months and 4 years, based on the World Health Organization referent; overweight was defined as a BMI Z score greater than or equal to the 85th percentile. Age- and sex-specific waist circumference Z scores were calculated at age 14 months and 4 years using the analysis population mean. Results: Twenty-six percent of children were rapid growers; 25% were overweight at 14 months and 21% at 4 years. Geometric mean BPA concentrations were 2.6 &mgr;g/g creatinine (standard deviation = 2.3) in 1st trimester and 2.0 (2.3) in 3rd trimester samples (Pearson r = 0.13). At 4 years, BPA exposure was associated with increased waist circumference (&bgr; per log10 &mgr;g/g = 0.28 [95% confidence interval = 0.01 to 0.57]) and BMI (&bgr; = 0.28 [−0.06 to 0.63]). BPA was not associated with obesity-related outcomes at earlier ages. Conclusions: This study provides some evidence for an association between prenatal BPA exposure and obesity-related outcomes in childhood, although not in infancy. The large uncertainties in BPA exposure assessment require that findings be interpreted with caution.

Tetrahydrofuran-water extraction, in-line clean-up and selective liquid chromatography/tandem mass spectrometry for the quantitation of perfluorinated compounds in food at the low picogram per gram level

A new solvent extraction system was developed for extraction of PFCs from food. The extraction is carried out with 75:25 (v/v) tetrahydrofuran:water, a solvent mixture that provides an appropriate balance of hydrogen bonding, dispersion and dipole-dipole interactions to efficiently extract PFCs with chains containing 4-14 carbon atoms from foods. This mixture provided recoveries above 85% from foods including vegetables, fruits, fish, meat and bread; and above 75% from cheese. Clean-up with a weak anion exchange resin and Envi-carb SPE, which were coupled in line for simplicity, was found to minimize matrix effects (viz. enhancement or suppression of electrospray ionization). The target analytes (PFCs) were resolved on a perfluorooctyl phase column that proved effective in separating mass interferences for perfluorooctane sulfonate (PFOS) in fish and meat samples. The mass spectrometer was operated in the negative electrospray ionization mode and used to record two transitions per analyte and one per mass-labeled method internal standard. The target PFCs were quantified from solvent based calibration curves. The limits of detection (LODs) were as low as 1-5 pg analyte g(-1) food; by exception, those for C(4) and C(5) PFCs were somewhat higher (25-30 pg g(-1)) owing to their less favourable mass response. To the best of our knowledge these are among the best LODs for PFCs in foods reported to date. The analysis of a variety of foods revealed contamination with PFCs at levels from 4.5 to 75 pg g(-1) in 25% of samples (fish and packaged spinach). C(10)-C(14) PFCs were found in fish, which testifies to the need to control long-chain PFCs in this type of food. The proposed method is a useful tool for the development of a large-scale database for the presence of PFCs in foods.

Exposure to bisphenol A and phthalates during pregnancy and ultrasound measures of fetal growth in the INMA-Sabadell cohort.

Background: Prenatal exposure to bisphenol A (BPA) and phthalates may affect fetal growth; however, previous findings are inconsistent and based on few studies. Objectives: We assessed whether prenatal exposure to BPA and phthalates was associated with fetal growth in a Spanish birth cohort of 488 mother–child pairs. Methods: We measured BPA and eight phthalates [four di(2-ethylhexyl) phthalate metabolites (DEHPm), mono-benzyl phthalate (MBzP), and three low-molecular-weight phthalate metabolites (LMWPm)] in two spot-urine samples collected during the first and third trimester of pregnancy. We estimated growth curves for femur length (FL), head circumference (HC), abdominal circumference (AC), biparietal diameter (BPD), and estimated fetal weight (EFW) during pregnancy (weeks 12–20 and 20–34), and for birth weight, birth length, head circumference at birth, and placental weight. Results: Overall, results did not support associations of exposure to BPA or DEHPm during pregnancy with fetal growth parameters. Prenatal MBzP exposure was positively associated with FL at 20–34 weeks, resulting in an increase of 3.70% of the average FL (95% CI: 0.75, 6.63%) per doubling of MBzP concentration. MBzP was positively associated with birth weight among boys (48 g; 95% CI: 6, 90) but not in girls (–27 g; 95% CI: –79, 25) (interaction p-value = 0.04). The LMWPm mono-n-butyl phthalate (MnBP) was negatively associated with HC at 12–20 pregnancy weeks [–4.88% of HC average (95% CI: –8.36, –1.36%)]. Conclusions: This study, one of the first to combine repeat exposure biomarker measurements and multiple growth measures during pregnancy, finds little evidence of associations of BPA or phthalate exposures with fetal growth. Phthalate metabolites MBzP and MnBP were associated with some fetal growth parameters, but these findings require replication. Citation: Casas M, Valvi D, Ballesteros-Gomez A, Gascon M, Fernández MF, Garcia-Esteban R, Iñiguez C, Martínez D, Murcia M, Monfort N, Luque N, Rubio S, Ventura R, Sunyer J, Vrijheid M. 2016. Exposure to bisphenol A and phthalates during pregnancy and ultrasound measures of fetal growth in the INMA-Sabadell cohort. Environ Health Perspect 124:521–528; http://dx.doi.org/10.1289/ehp.1409190

Coacervative extraction of Ochratoxin A in wines prior to liquid chromatography/fluorescence determination

Coacervates made up of reverse micelles of decanoic acid were assessed as a new strategy for the simplification of wine sample treatment in the determination of Ochratoxin A (OTA). Simultaneous extraction/concentration of this contaminant was based on both hydrophobic and hydrogen bond OTA:coacervate interactions. Parameters affecting extraction efficiency and concentration factors were studied. Concentrations of decanoic acid and tetrahydrofuran (THF) were the most influential parameters, being 0.5% of acid and 5% of THF the selected ones. The procedure was very robust, so that the extractions were not influenced by the pH and the nature or concentration of matrix components. OTA recoveries from different types of wines (white, rosé and red) ranged between 85 and 100% and the actual concentration factors varied from 105 to 125 for sample volumes of 15 mL. The detection limits for OTA, after liquid chromatography/fluorimetry (LC/FL) analysis of the coacervate (20 microL), were 4.5 ng L(-1) in white and rosé wines and 15 ng L(-1) in red wines, values which were far below the threshold limit established for OTA by EU directives (2.0 microg L(-1)). No clean-up of the extracts was required for any of the samples analysed. The overall sample treatment took about 15-20 min and several samples could be simultaneously treated using conventional lab equipment. The precision of the method, expressed as relative standard deviation, was about 5%. The approach developed was successfully applied to the determination of OTA in different wine samples from the South of Spain. The concentrations found ranged between 0.015 and 0.091 microg L(-1).

Environment-Responsive Alkanol-Based Supramolecular Solvents: Characterization and Potential as Restricted Access Property and Mixed-Mode Extractants

Self-assembly, the process by which supramolecular solvents (SUPRAS) with an ordered structure are produced, provides unique opportunities to obtain tailored solvents with advanced functional features. In this work, environment-responsive (C(7)-C(14)) alkanol-based SUPRAS were synthesized and their potential for analytical extractions was assessed. The global composition of the solvent, the size of the coacervate droplets that form it, and the aqueous cavities of the inverted hexagonal arrangement of the alkanols can be tailored by controlling the environment [specifically, the tetrahydrofuran (THF):water ratio in the bulk solution] for alkanol self-assembly. Interestingly, supramolecular solvents are highly adaptive and the previous features can all be reversed by modifying the environment. The spontaneous self-assembly of these solvents followed predictable routes, and their composition and volume can be accurately predicted from equations derived in this work. The solvents were structurally elucidated by light and cryo-scanning electron microscopy. Extractive applications exploiting the molecular size-based restricted access properties of SUPRAS were developed and their ability to engage in mixed-mode mechanisms for solute solubilization was established. Thus, solutes of increasing molecular weight were extracted from food and environmental samples with recoveries dependent on vacuole size in the SUPRAS, while macromolecules such as proteins, carbohydrates, and humic acids were excluded. The ability of SUPRAS to establish hydrogen-bonding and dispersion interactions was exploited to extract carcinogenic chlorophenols (CCPs) from environmental waters, and a simple and fast method was developed with quantitation limits (e.g., 0.21-0.23 μg·L(-1)) low enough to comply with legislation (e.g., maximum permitted levels for pentachlorophenol are in the range 0.4-1 μg·L(-1)).