Use of solid-phase microextraction for the analysis of bisphenol A and bisphenol A diglycidyl ether in food simulants

A new method has been developed to simultaneously analyse bisphenol A (BPA) and bisphenol A diglycidyl ether (BADGE) in aqueous based food simulants. The method consists on direct immersion solid-phase microextraction (SPME) of the analytes from the liquid matrix and subsequent chromatographic analysis by gas chromatography-mass spectrometry. Using the proposed method, a whole analysis (including chromatographic step) can be completed in less than 40 min, with minimum sample handling. The SPME method shows good analytical performance for simultaneous BPA and BADGE analysis, except for BADGE determination in the aqueous alcohol (simulant C) solution. Detection limits ranging from 0.1 to 2.0 ng/g for BPA and from 13 to 15 ng/g from BADGE were obtained, with a linear range from the low-ng/g to several-microg/g range for BPA and from 0.1 microg/g to 40 microg/g for BADGE. A possible optimisation method has been also developed and introduced.     

Improved detectability with a polymer-based trapping device in rapid HPLC analysis for ultra-low levels of bisphenol A (BPA) in environmental samples.

A new high-performance liquid chromatography (HPLC) method has been developed to detect ultra-low concentrations of bisphenol-A (BPA) (below 1 ng/L (ppt)) using column switching electrochemical detection (ECD). The results were superior to those obtained from manual pretreatment procedure with membrane stationary phase. BPA is inherently ubiquitous in the environment, including tools and solvents used for its analysis; to obtain meaningful results, therefore, the concentration of the overall BPA contamination must be below the detection limit for BPA using the analytical system. Therefore, purified water for preparing the standard BPA solution must be filtered with a hydrophobic membrane to suppress BPA background levels of contamination. In addition, we investigated methods for effectively preserving environmental water containing BPA. The addition of a small amount of ethylenediaminetetraacetic acid (EDTA) provided good recovery even after overnight storage. By employing these precautionary measures and procedures to reduce BPA contamination from the analytical procedure, we could accurately determine l(-10) ppt of BPA in environmental water samples using a column switching HPLC system.     

Trace determination of bisphenol A and phytoestrogens in infant formula powders by gas chromatography-mass spectrometry

This investigation describes a reliable and sensitive method for simultaneously determining bisphenol A (BPA) and two major phytoestrogens, daidzein and genistein, in powdered milks and infant formulas by gas chromatography-mass spectrometric analysis after trimethylsilylation. To reduce the matrix interference associated with the constituents of the formulas, the dissolved formula solutions were firstly ultra-centrifuged and the analytes in the supernatant were then extracted using a C18 solid-phase extraction column. The accuracy and precision of the method were determined and the technique was successfully employed to measure trace concentrations of BPA, daidzein and genistein in powdered formulas. The results show that BPA, daidzein and genistein were detected in all the testing samples (n = 6) at concentrations from 45 to 113 ng/g (except one infant formula), 20 to 2050 ng/g and 21 to 6510 ng/g, respectively. The highest concentrations of daidzein and genistein (i.e., 2050 and 6510 ng/g) were detected in a soy-based powdered infant formula. The quantitation limits were 1.0 ng/g for BPA, and 10 ng/g for daidzein and genistein using 0.5 g powdered milk samples.     

Importance of control of enzymatic degradation for determination of bisphenol A from fruits and vegetables

The purpose of this study was to develop an analytical method for determination of bisphenol A (BPA) from fruits and vegetables. The present method developed for extraction of BPA from samples was based on solid-phase extraction (SPE) method and solvent extraction. Recovery results in the samples spiked with a 10 ng/ml BPA [no detection (<1 ng/g) to 77%] were lower than those in the samples with a 50 ng/ml BPA (26-96%). The fact that the low recovery results were caused by BPA degradation by enzymes is found. These problems were proved by the pH (pH ≤3) and the heating treatment (at ≥80 °C for 5 min). However, because the heating treatment at temperatures of ≥80 °C for 5 min is more difficult and time-consuming method than the pH control, we suggest that the pH control is useful to prevent BPA degradation. Good recovery results (82-101%) were obtained from all fruit and vegetable samples after pH treatment (pH ≤3). Effective elimination of impurities and a good detection limit (1 ng/g) were obtained with a method involving two SPE cartridges (OASIS HLB and Sep-Pak Florisil cartridge).     

Determination of bisphenol A and 4-nonylphenol in human milk using alkaline digestion and cleanup by solid-phase extraction.

A highly sensitive and selective method based on alkaline digestion for the simultaneous determination of bisphenol A (BPA) and 4-nonylphenol (NP) was developed. The method consists of digestion of the matrix with ethanolic KOH, extraction with diethyl ether under a mild alkaline condition, cleaning with successive aminopropyl (NH2) cartridges and derivatization followed by a GC-MS analysis. The assay accuracies, expressed as recoveries, were 82 - 113% for BPA and 89 - 97% for NP. The limits of detection of BPA and NP were 0.09 ng/g and 0.50 ng/g, respectively. The procedure will be reliable for the trace analysis of BPA and NP in human milk, since alkaline digestion can diminish their documented association with protein.     

Quantification of the xenoestrogens 4-tert.-octylphenol and bisphenol A in water and in fish tissue based on microwave assisted extraction, solid-phase extraction and liquid chromatography-mass spectrometry

Extraction methods were developed for quantification of the xenoestrogens 4-tert.-octylphenol (tOP) and bisphenol A (BPA) in water and in liver and muscle tissue from the rainbow trout (Oncorhynchus mykiss). The extraction of tOP and BPA from tissue samples was carried out using microwave-assisted solvent extraction (MASE) followed by solid-phase extraction (SPE). Water samples were extracted using only SPE. For the quantification of tOP and BPA, liquid chromatography mass spectrometry (LC-MS) equipped with an atmospheric pressure chemical ionisation interface (APCI) was applied. The combined methods for tissue extraction allow the use of small sample amounts of liver or muscle (typically 1 g), low volumes of solvent (20 ml), and short extraction times (25 min). Limits of quantification of tOP in tissue samples were found to be approximately 10 ng/g in muscle and 50 ng/g in liver (both based on 1 g of fresh tissue). The corresponding values for BPA were approximately 50 ng/g in both muscle and liver tissue. In water, the limit of quantification for tOP and BPA was approximately 0.1 microg/l (based on 100 ml sample size).     

NMR Characterization of Substituted Aromatic Poly (Ether Sulofone)s

Abstract

The synthesis of a variety of substituted bisphenol A polysulfones, including nitro, amino, aminomethyl, ethyl, and methyl derivatives, is described. Nuclear magnetic resonance (NMR) (both proton and carbon, and several 2-D experiments) data confirm conclusions on the substitution site based on arguments on inductive effects in the phenyl rings. The proton ortho to the oxygen in the bisphenol A (BPA) residue is replaced in electrophilic substitution reactions. The degree of substitution was also calculated from the NMR results. The ethyl and methyl derivatives were expected, from the starting reactants, to each have a BPA ring substituted. The NMR data showed that, on the average, this is true. The nitro derivative also has substitution in every BPA ring, while the amino and aminomethyl derivatives have only intermittent BPA rings substituted. Measured degrees of substitution (DS) varied from 0.11 to 2.25.     

Quantification of free and total bisphenol A and bisphenol B in human urine by dispersive liquid-liquid microextraction (DLLME) and heart-cutting multidimensional gas chromatography-mass spectrometry (MD-GC/MS)

A novel method combining dispersive liquid-liquid microextraction (DLLME) and heart-cutting multidimensional gas chromatography coupled to mass spectrometry was developed for the determination of free and total bisphenol A (BPA) and bisphenol B (BPB) in human urine samples. The DLLME procedure combines extraction, derivatization and concentration of the analytes into one step. Several important variables influencing the extraction efficiency and selectivity such as nature and volume of extractive and dispersive solvents as well as the amount of acetylating reagent were investigated. The temperature and time to hydrolyze BPA and BPB conjugates with a β-glucuronidase and sulfatase enzyme preparation were also studied. Under the optimized conditions good efficiency extraction (71-93%) and acceptable total DLLME yields (56-77%) were obtained for both analytes. Matrix-matched calibration curves were linear with correlation coefficients higher than 0.996 in the range level 0.1-5 μg/l, and the relative standard deviations (%RSD) were lower than 20% (n = 6). The limits of detection were 0.03 and 0.05 μg/l for BPA and BPB, respectively. The applicability of the proposed method for determining urinary free and total BPA and BPB was assessed by analyzing the human urine of a group of 20 volunteers. Free BPA was detected in 45% of the sample whereas total BPA was detected in 85% of the samples at concentrations ranging between 0.39 and 4.99 μg/l. BPB was detected in conjugated form in two samples.     

QbD-driven development and validation of HPLC method for determination of Bisphenol A and Bis-sulphone in environmental samples

ABSTRACT

A large number of hazardous chemicals have entered the environment due to the rapid growth of urbanisation and industrial development and are exerting harmful effects on wildlife as well as on human health. Plastic materials are one of the most leading causes for this contamination which are widely used in daily activities of human beings, i.e. disposal purpose, food packaging, bottles, containers, cups, grocery bags, etc. These materials contain Bisphenol A (BPA) and Bis-sulphone (BIS) which have been recognised as potential endocrine disruptors. In the present study, a selective and reliable high-performance liquid chromatography (HPLC) based method was developed with the mobile phase of 10 mM ammonium acetate buffer-acetonitrile (58:42 v/v, pH: 5) using quality by design (QbD) approach and the method was validated for the simultaneous assessment of BPA and BIS. The method was observed with a good linearity range of 50–500 ng/mL with an r² value of 0.998 and 0.999 for BPA and BIS, respectively. The developed and validated method was applied for the estimation of endocrine-disrupting chemicals in sewage water and soil samples. The results showed a considerable amount of BPA and BIS in the samples. This preliminary data explored the presence of BPA and BIS in these environmental samples that give the primary awareness of the effluence of BPA and BIS in the environment.     

Measurement of bisphenol A and bisphenol B levels in human blood sera from healthy and endometriotic women

A sensitive HPLC method with fluorescence detection was developed for the determination of bisphenol A (BPA) and bisphenol B (BPB) in human blood serum. The detection limits of the method were 0.18 and 0.20 ng/mL for BPA and BPB, respectively. A single‐step liquid–liquid extraction was used for the pre‐treatment of serum samples. The recoveries of BPA and BPB spiked to sera were 85.6 and 87.7%, respectively. The analyses of sera from both healthy and endometriotic women emphasized the absence of bisphenols in all the control cases (11 women), whereas BPA was found in 30 sera (51.7%) and BPB was found in 16 sera (27.6%) in the group of 58 patients with endometriosis; in nine of such sera BPA and BPB were present simultaneously. Only relatively to the sera quantitated, BPA concentrations ranged from 0.79 to 7.12 ng/mL (mean concentration 2.91 ± 1.74 ng/mL), whereas BPB concentrations ranged from 0.88 to 11.94 ng/mL (mean concentration 5.15 ± 4.16 ng/mL). Therefore, the presence of at least one of the two bisphenols was verified in a percentage as high as 63.8% in the sera from endometriotic women, suggesting the existence of a relationship between endometriosis and BPA and/or BPB exposure. Indeed, it is well known that bisphenols can work as xenoestrogens, owing to their structural similarity to natural and synthetic estrogens (e.g. estradiol and dietilstilbestrol). However, further studies are necessary to confirm this hypothesis and to assess the actual dose at which exposures to bisphenols are able to increase the sensitivity of the endometriotic cells to estradiol. Copyright © 2009 John Wiley & Sons, Ltd.     

Simultaneous determination of endocrine-disrupting phenols and steroid estrogens in sediment by gas chromatography-mass spectrometry

A simple and effective method has been developed to simultaneously determine endocrine-disrupting phenolic xenoestrogens and steroid estrogens in sediment by using ultra-sonicated extraction in combination with silica gel fractionation, derivatization with pentafluropropionic anhydride, and gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode (SIM). Satisfactory recoveries have been obtained for phenolic xenoestrogens and steroid estrogens. The method enables the determination of targets at concentrations of lower nanogram-per-gram in sediments. The method has been successfully applied to the sediments collected from Pearl River Estuary (PRE), South China Sea, China. Nonylphenol and bisphenol-A (BPA) were detected in the range from 204.2 to 664.5 ng/g and 0.6 to 4.0 ng/g, respectively. None of the estrogens were found in the sediment samples.     

高效液相色谱法测定大鼠组织中双酚A和4-壬基酚浓度

建立了大鼠组织中双酚A和4-壬基酚的提取和含量测定方法。大鼠组织样品经甲醇-乙酸铵缓冲液匀浆、 正己烷-乙醚混合溶剂提取、氮气吹干后用流动相溶解,以乙腈-0.01 mol/L乙酸铵缓冲液(pH 4.5)(体积比为75∶25)为流动相,经C18色谱柱分离,在激发波长227 nm、发射波长313 nm下进行荧光检测。大鼠心、脑、肝和肾脏组织样品中,双酚A的检出限为3.2~4.6 ng/g,4-壬基酚的检出限为11.8~15.6 ng/g;日内检测精密度为0.89%~4.50%,日间检测精密度为3.10%~12     

Determination of Platinum-Group Elements (PGE) from catalytic converters in soil by means of docimasy and INAA

The nickelsulfide fire assay (docimasy) for the enrichment of platinum-group elements (PGEs) has been modified for the use with small samples and combined with instrumental neutron-activation analysis (INAA). This procedure has been applied to the determination of PGEs exhausted from catalytic converters and deposited in soil near the Wiesbadener Kreuz (highway A3, Frankfurt-Köln). Our results show a considerable enhancement of the Pt (up to 330 ng/g), Pd (6.6 ng/g) and Rh (7.5 ng/g) contents close to the highway.     

Determination of Platinum-Group Elements (PGE) from catalytic converters in soil by means of docimasy and INAA

The nickelsulfide fire assay (docimasy) for the enrichment of platinum-group elements (PGEs) has been modified for the use with small samples and combined with instrumental neutron-activation analysis (INAA). This procedure has been applied to the determination of PGEs exhausted from catalytic converters and deposited in soil near the Wiesbadener Kreuz (highway A3, Frankfurt-Köln). Our results show a considerable enhancement of the Pt (up to 330 ng/g), Pd (6.6 ng/g) and Rh (7.5 ng/g) contents close to the highway.     

Evaluation of the VIDAS staph enterotoxin II (SET 2) immunoassay method for the detection of staphylococcal enterotoxins in selected foods: collaborative study

A multilaboratory study was conducted to determine the limit of detection (LOD) of Staphylococcal enterotoxins (SET) in 5 foods. Cooked chicken, ham, potato salad, pasteurized liquid whole milk, and canned mushrooms were each spiked with a different enterotoxin (A, B, C1, D, or E), and tested at 0.25 and 0.5 ng/g SET levels to determine the LOD of the assay for those foods in a collaborative study. Unspiked controls were also included. A total of 19 laboratories representing government and industry participated. In this study, 1674 test portions were analyzed, of which 1638 were used in the statistical analysis. Of the 1638 test portions used in the statistical analysis, 1104 were spiked test portions, of which 1073 were positive by the VIDAS Staph enterotoxin II (SET 2) method. The detection rates at the 0.25 ng/mL level were cooked chicken, 98.2%; ham, 99.0%; potato salad, 99.1%; liquid whole milk, 85.2%; and canned mushrooms, 100%. The detection rates at the 0.5 ng/mL level were cooked chicken, 97.4%; ham, 98.1%; potato salad, 100%; liquid whole milk, 99.0%; and canned mushrooms, 100%. The data indicate that the SET 2 method is capable of detecting SET at 0.25 ng/g in cooked chicken, ham, potato salad, and canned mushrooms and at 0.5 ng/g in pasteurized liquid whole milk.     

A New Method for the HPLC Analysis of Pt(II) in Urine

Abstract

An analytical method has been developed to measure Pt(II) in urine via derivatization and UV or HPLC analysis. A measured quantity of urine is heated briefly with diethyl ammonium diethyl-dithiocarbamate, and the resulting Pt(Et₂NCS₂)₂ is extracted into a measured volume of chloroform. Concentrations of Pt(II) are determined by UV absorption at 346 nm or by reverse phase HPLC analysis. The detection limit for Pt(II) as its dithiocarbamate is ～ 1 ng by HPLC; the concentration limit for HPLC analysis by direct extraction was ～ 25 ng/ml. Chromatographic response was linearly related to Pt(II) concentration over the range 100-4, 000 ng/ml; dilution of more concentrated samples has extended this range to at least 30, 000 ng/ml. This method has been applied to the analysis of Pt(II) in the urine of patients who have received cis-dichlorodiamniineplatinum(II) (CDDP) chemotherapy.     

Spectrophotometric determination of nickel in biological samples using 1-azobenzene-3-(3-hydroxyl-2-pyridyl)-triazene

A new sensitive and selective chromogenic reagent, 1-azobenzene-3-(3-hydroxyl-2-pyridyl)-triazene (ABHPT), was synthesized. It has been found that ABHPT reacts with nickel(II) in a borax buffer solution (pH 10.0) to form 2: 1 red complexes with the maximum absorption at 530 nm. The apparent molar absorptivity of the complex is 2.6 × 10⁵ L/(mol cm). Most metal ions can be tolerated in considerable amounts, whereby only zinc and mercury may interfere with the determination of nickel(II). Nevertheless, this can be easily eliminated by prior separation with sulfhydryl dextran gel. A new method for the spectrophotometric determination of trace nickel(II) was developed. Beer’s law is obeyed for 0–15 μg of nickel(II) in 25 mL of solution. The limit of quantification, limit of detection, and relative standard deviation are 0.74 ng/mL, 0.25 ng/mL, and 1.0%, respectively. The method has been applied to the determination of trace nickel(II) in biological samples with satisfactory results. The text was submitted by the authors in English.     

Simultaneous quantification of bisphenol A and its glucuronide metabolite (BPA-G) in plasma and urine: applicability to toxicokinetic investigations

Bisphenol A (BPA) is a widely used plasticizer that can contaminate food and the wider environment and lead to human exposure. In humans, it is mainly metabolized to bisphenol A-glucuronide (BPA-G) and eliminated in the urine. As BPA causes adverse physiological effects at low doses, it is necessary to document the toxicokinetics of both molecules for risk assessment. Because BPA-G is not available as an analytical standard, it is usually quantified after the assay of BPA, following an enzymatic hydrolysis with β-glucuronidase. With this approach, two separate assays are required for BPA and BPA-G quantification, which can lead to critical pitfalls in terms of accuracy and analysis time. To overcome this problem, we have developed a new method for the isolation and purification of BPA-G from urine by flash chromatography. Large amounts of BPA-G (1 g) were isolated and characterized by mass spectrometry and NMR. This BPA-G is suitable for an use as analytical standard and enabled us to develop a novel method for the simultaneous quantification of BPA and BPA-G in biological matrices by UPLC/MS/MS. It has also been used for in vivo toxicokinetic studies in sheep. The method of quantification was validated according FDA guidelines and used to monitor the time course of plasma and urine concentrations of BPA or BPA-G following their administration. The simultaneous quantification of BPA and BPA-G was compared to the commonly used method for urine and plasma samples. For plasma samples, the results obtained with the direct assay of BPA-G were similar to those obtained by quantification after enzymatic hydrolysis. With urine samples, the simultaneous quantification appeared to be more suitable than the hydrolysis method for the BPA-G determination.     

Copper Oxide Nanoparticles with Graphitic Carbon Nitride for Ultrasensitive Photoelectrochemical Aptasensor of Bisphenol A

In this work, g‐C₃N₄, CuO and g‐C₃N₄/CuO?X (where × can be 3, 6, or 9) were synthesized through hydrothermal and calcination methods and used to fabricate photoelectrochemical (PEC) aptasensor for detection of bisphenol A (BPA). CuO nanoparticles covered with g‐C₃N₄ were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The aptasensor based on g‐C₃N₄/CuO‐6 possessed high PEC activity due to its good conductivity and low electron recombination rate. PEC experiments demonstrate that the aptasensor based on g‐C₃N₄/CuO‐6 exhibits a broad linear range towards BPA from 0.02–10 ng L^?1 and 50–1200 ng L^?1 and reveals superior stability, selectivity and repeatability. Thus, g‐C₃N₄/CuO‐6 composite is a promising material for the determination of BPA in PEC field and has commercially viable.     

Simultaneous determination of tetrabromobisphenol A, tetrachlorobisphenol A, bisphenol A and other halogenated analogues in sediment and sludge by high performance liquid chromatography-electrospray tandem mass spectrometry

A high performance liquid chromatography-electrospray (negative) ionization-tandem mass spectrometry (HPLC-ESI(-)-MS-MS) based method has been developed for simultaneous determination of bisphenol A (BPA), tetrachlorobisphenol A (TCBPA), and tetrabromobisphenol A (TBBPA), as well as lower brominated BPA analogues in sediment and sludge samples. Samples were extracted with MTBE, target compounds were partitioned by aqueous solution of sodium hydroxide. The solution was subsequently acidified, and the enrichment and desalting were performed via solid phase extraction (SPE). After cleanup the target compounds were determined by HPLC-ESI(-)-MS-MS. The method limits of quantification (MLOQs) from sediment and sludge for BPA, monobromo-bisphenol A (mono-BBPA), dibromo-bisphenol A (di-BBPA), tribromo-bisphenol A (tri-BBPA), TBBPA and TCBPA were 0.15, 0.02, 0.02, 0.04, 0.05, and 0.03 ng/g (dry weight), respectively. Mean recovery of the analytes from spiked samples ranged from 70 to 105%, and the relative standard deviation ranged from 4.9 to 13.1%. The method was successfully applied to sediment and sludge samples analysis.