Size-exclusion flow extraction of bisphenol A in human urine for liquid chromatography–mass spectrometry

In vitro bioaccessibility of cyclodi-BADGE present in canned seafood: A new approach for the estimation of dietary exposure of the Spanish population

Human dietary exposure to chemical compounds is a priority issue for public health authorities since it constitutes a key step in risk assessment, and food packaging could be an important source of contamination. In this study, the bioaccessibility of cyclodi-BADGE was evaluated in canned seafood samples using a standardized protocol of in vitro gastrointestinal digestion and an analytical method based on liquid chromatography coupled to tandem mass spectrometry. The impact of enzymes, different gastric pHs, and food-covering liquids on the bioaccessibility of cyclodi-BADGE was studied. The results highlighted that cyclodi-BADGE was available to be absorbed at the intestinal level (90.9-112.3%), and its bioaccessibility increased substantially in fat food samples. Finally, the estimated dietary exposure to cyclodi-BADGE in the Spanish adult population reached values of 14.26 μg/kg bw/day for tuna in tomato, exceeding the tolerable daily intake (1.5 μg/kg bw/day) recommended for chemicals with high toxicological risk.

Colorimetric detection and bio-magnification of bisphenol A in fish organs and water sources using 3',6'-bis(diethylamino)-2- ((3,4,5trimethyl benzylidene) amino) spiro [isoindoline -1,9'-xanthen ]-3-one (BTSIXO)-Fe3+ ion conjugate

Current study is focusing mainly on the development of simple, novel, and cost-effective optical sensor to detect and quantify Bisphenol A (BPA) contamination. We designed a very selective and sensitive colorimetric sensor using synthesized 3', 6'- bis(diethylamino) -2- ((3,4,5 trimethyl benzylidene) amino)spiro [isoindoline-1,9'-xanthen] -3-one (BTSIXO) conjugated with Fe³⁺-ions via very simple eco- friendly synthetic protocol. The sensor has an excellent wide detection range for BPA from 0.1 to 150 ppm with LODs of 0.02 ppm. Finally, the applicability of the sensor was demonstrated in fish samples especially in the organs of Oreochromis mossambicus fingerlings and contaminated industrial water samples. The sensor was also applied for the quantification of BPA present drinking water stored in the plastic bottles. The developed sensor has shown a good agreement and accuracy when compared with ESI-Mass techniques.

Bisphenol A concentrations in human urine, human intakes across six continents, and annual trends of average intakes in adult and child populations worldwide: A thorough literature review

Bisphenol A (BPA) is an important industrial raw material that is widely applied in daily products. BPA is also an endocrine-disrupting chemical that may adversely affect humans. This review thoroughly collected data on BPA concentration in human urine and determined main influencing factors. The average BPA intake of humans across six continents or the average value worldwide was calculated based on a simple model. Results showed that the average BPA intake was ranked from high to low as follows: Oceania, Asia, Europe, and North America in the child population and Oceania, Europe, Asia, and North America in the adult population. The annual trend of the average BPA intake was similar between the adult and child populations. The BPA intake in the two populations evidently decreased from 2000 to 2008 and then slightly increased from 2008 to 2011. The BPA intake in the child population started to decrease again from 2011, whereas the corresponding intake in the adult population continued to increase. The distinct difference likely contributed to the wide prohibition of the use of BPA in food-related products for children in many countries since 2009; the bans effectively decreased the total BPA exposure in the child population.

Investigation on fragmentation pathways of bisphenols by using electrospray ionization Orbitrap mass spectrometry

RATIONALE

Bisphenols, such as bisphenol A (BPA) and bisphenol S (BPS), are widely used in industrial products, although they have been demonstrated to be environmental contaminants with toxicity. However, few studies on the mass spectrometric fragmentation pathway of these compounds have been reported using high-resolution mass spectrometry (HRMS).

METHODS

The MS/MS fragmentations of nine bisphenols, together with several corresponding isotope-labeled compounds, were studied by Orbitrap MS using electrospray ionization (ESI) in negative ion mode and higher energy collisional-dissociation (HCD). The [M - H](-) ions of the compounds formed by ESI were selected as the precursor ions for MS/MS. The accurate m/z values for product ions were acquired to deduce the elemental compositions and fragmentation pathways.

RESULTS

The elemental compositions of the ions were calculated from the accurate mass data. Common MS/MS product ions and characteristic neutral losses were summarized. Six bisphenols formed the common product ion at m/z 93 (C6 H5 O). The [M - H](-) ions of five bisphenols were found to lose a phenol group (C6 H5 OH). Four bisphenols formed the [M - H - CH4 ](-) ion. The proposed fragmentation pathways of representative compounds of BPA and BPS were verified from the analysis of isotope-labeled compounds.

CONCLUSIONS

The MS/MS fragmentation pathways of nine bisphenols were, for the first time, systematically investigated with HRMS. The obtained data could be valuable for the identification of a variety of bisphenols in environmental and biological samples.

[Pharmaceutical analysis of chemicals related with daily life products for safe and secure]

An association between exposure to trace hazardous chemicals such as endocrine disrupting chemicals and an increased incidence of human endocrine disease might be continued to study. The accurate and sensitive analytical methods for determination of various chemicals in human biospecimen such as urine, blood and breast milk have been studied by techniques including chromatography. In order to obtain the safe and secure life, the pharmaceutical analytical approaches might be applicable with the hopes of realizing scientific risk assessment of the chemicals derived from daily life products as regulatory sciences.

Simultaneous determination of multiple phthalate metabolites and bisphenol-A in human urine by liquid chromatography-tandem mass spectrometry

Phthalates and bisphenol A are environmental endocrine-disrupting chemicals used widely in common consumer products. There is increasing concern about human exposure to phthalates and bisphenol A due to the potential adverse effects related to the anti-androgenic activity of phthalates and estrogenic activity of bisphenol A. In assessing environmental exposure to phthalates and bisphenol A, it is essential to have a validated analytical method that can quantify trace concentrations of phthalate metabolites and bisphenol A in humans. In this study, we developed and validated an accurate, sensitive, and robust LC-MS/MS method to simultaneously quantify 5 phthalate monoester metabolites, including mono-methyl phthalate, mono-ethyl phthalate, mono-butyl phthalate, mono-benzyl phthalate, mono-2-ethylhexyl phthalate, and bisphenol A in human urine. In this method, the phthalate metabolites and bisphenol A, along with their isotope labeled internal standards, were extracted from 200 μl of human urine using automated off-line solid phase extraction. The analytes were quantitatively determined using LC-MS/MS operated in negative electrospray ionization multiple reaction-monitoring mode. The limit of quantification was 0.3 ng/ml for mono-methyl phthalate, mono-ethyl phthalate, mono-benzyl phthalate and bisphenol A, and 1 ng/ml for mono-butyl phthalate and mono-2-ethylhexyl phthalate. The precision and accuracy were well within the acceptable 15% range. This validated method has been used successfully in assessing exposure to phthalates and bisphenol A in humans.

Recent trends in biomonitoring of bisphenol A, 4-t-octylphenol, and 4-nonylphenol

Bisphenol A (BPA), 4-t-octylphenol (4-t-OP), and 4-nonylphenol (4-NP) are man-made alkylphenolic environmental contaminants possessing controversial endocrine disruption properties. Nowadays, an increased interest is raised for their accurate determination in biological media in order to estimate the exposure to these compounds and the associated health risk. The aim of this review is to present the available analytical methodologies for biomonitoring these three EDCs in human population. In non-occupational human exposure, they are detected in human matrices in trace level concentrations, commonly lower than 1ng/mL. The use of mass spectrometry based methods is particularly emphasized due to their well known superiority over sensitivity, selectivity and precision, even in difficult matrices, such as blood plasma and serum. Recent and most applicable sample preparation techniques are thoroughly presented. The benefits of solid phase extraction (SPE) and expected developments are demonstrated. Recent results from exposure assessment and epidemiologic studies for BPA, 4-t-OP and 4-NP are summarized and future trends are discussed.

Occurrence of bisphenol A in indoor dust from two locations in the eastern United States and implications for human exposures

Bisphenol A (BPA) is used in the production of polycarbonate plastics and epoxy resins, which are used in many consumer products. Sources of human exposures to BPA include packaged and canned food products, indoor air, and dust ingestion. Information on the relative contributions of the pathways to BPA exposures is limited. In this study, we measured concentrations BPA in indoor dust collected from two locations in the Eastern United States and evaluated the contribution of dust to total BPA exposures. BPA was found in 95% of the dust samples analyzed (n = 56) at concentrations ranging from <0.5 to 10,200 ng/g (mean 843; median 422). The median values for BPA intake by way of the ingestion of dust by adults and toddlers were calculated to be 0.35 and 5.63 ng/kg body weight/day. These estimated exposure doses of BPA through dust ingestion are of the same order of magnitude as the recently reported low concentrations that induced health effects in laboratory animal studies. The contribution of dust to total human BPA intake was estimated to be <1%, however, suggesting that dietary intake is the predominant source of exposures in humans.

Identification of chemicals and their metabolites from PHY906, a Chinese medicine formulation, in the plasma of a patient treated with irinotecan and PHY906 using liquid chromatography/tandem mass spectrometry (LC/MS/MS)

Traditional Chinese Medicine (TCM) is increasingly being used in combination with Western medicine. In general, TCM is comprised of multiple components in sharp contrast to Western medicine, where a single active chemical is used. Presently, there are no well-established standards for most of the chemical compounds of TCM and their respective metabolites. Moreover, there are no formal analytical methods for the identification of these chemicals, especially in trace amounts. The ability to measure the pharmacokinetic behaviors of chemicals and their metabolites from these herbal formulations are critical in understanding of the action of TCM. This paper describes the use of LC/MS/MS along with enzyme treatments and n-octanol/water partition coefficient, to investigate the chemical components of PHY906 and their metabolites in the plasma of a patient with metastatic colorectal cancer (mCRC) treated with irinotecan and PHY906. The chemicals from an aqueous extract of PHY906 and the plasma from a patient was prepared and separated on an Agilent ZORBAX-SB C(18) column, and eluted with acetonitrile/0.05% (v/v) formic acid. From the PHY906 aqueous extract, a total of 57 compounds and 27 metabolites were identified and tentatively assigned structures based on their identified mass spectrometry, enzyme digestion and n-octanol/water partition coefficient. In contrast, analysis of patient plasma identified only 33 chemicals and new metabolites. These findings demonstrated that LC/MS/MS was and effective and reliable method for studying the parent chemicals of the Chinese herbal medicine PHY906 and their metabolites in a patient with metastatic colorectal cancer.

Determination of endocrine-disrupting compounds in drinking waters by fast liquid chromatography-tandem mass spectrometry

Growing attention has been recently paid to safety of food and drinking water, making necessary the adoption of policies for water sources protection and the development of sensitive and rapid analytical methods to identify micropollutants. Endocrine-disrupting compounds (EDCs) have emerged as a major issue as they alter the functioning of the endocrine system. Since ingestion of EDCs via food is considered the major exposure route, there is a growing interest in understanding EDC fate during drinking water treatment and in monitoring potential contamination of surface waters and groundwaters. In this work, a fast liquid chromatography-electrospray ionization-tandem mass spectrometry method was developed for the determination of 4-n-nonylphenol (NP), bisphenol A (BPA), estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in drinking waters. In the literature analytical articles seldom provide details regarding fragmentation pathways. In this paper spectra of the five EDCs in negative ESI were interpreted with the support of accurate mass spectra acquired by a quadrupole time-of-flight instrument; fragmentation pathways were also proposed. The chromatographic separation of EDCs was optimized on a Pinnacle DB Biphenylic column with a water-acetonitrile gradient. Quantitative analysis was performed in multiple reaction monitoring (MRM) mode using bisphenol A-d(16) (BPA-d(16)) as internal standard; calibration curves showed good correlation coefficients (0.9989-0.9997). All figures of merit of the method were satisfactory; limits of detection were in the range 0.2-0.4 ng/ml. The method was applied to the determination of the analytes in waters sampled by polar organic chemical integrative samplers in a drinking water treatment plant. Rather low concentration of BPA, NP and E1 were measured in the inlet, while none of the considered EDCs was detected in the outlet.

Development of a fast liquid chromatography-tandem mass spectrometry method for the determination of endocrine-disrupting compounds in waters

A fast liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) method was developed to study five endocrine-disrupting compounds (4-n-nonylphenol, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol) in water. Different columns were tested; the chromatographic separation of the analytes was optimized on a Pinnacle DB biphenylic column with a water-acetonitrile gradient elution, which allowed the separation of the selected endocrine-disrupting compounds (EDCs) in less than 6 min. Quantitative analysis was performed in selected reaction monitoring (SRM) mode; two transitions were chosen for each compound, using the most abundant for quantitation. Calibration curves using bisphenol A-d (16) as internal standard were drawn, showing good correlation coefficients (0.9993-0.9998). All figures of merit of the method were satisfactory; limits of detection were in the low pg range for all analytes. The method was then applied to the determination of the analytes in real water samples: to this aim, polar organic chemical integrative samplers (POCIS) were deployed in the influent and in the effluent of a drinking water treatment plant in Liguria (Italy). The EDC level was rather low in the influent and negligible in the outlet, reflecting the expected function of the treatment plant.

Technological challenges of addressing new and more complex migrating products from novel food packaging materials

The risk assessment of migration products resulting from packaging material has and continues to pose a difficult challenge. In most jurisdictions, there are regulatory requirements for the approval or notification of food contact substances that will be used in packaging. These processes generally require risk assessment to ensure safety concerns are addressed. The science of assessing food contact materials was instrumental in the development of the concept of Threshold of Regulation and the Threshold of Toxicological Concern procedures. While the risk assessment process is in place, the technology of food packaging continues to evolve to include new initiatives, such as the inclusion of antimicrobial substances or enzyme systems to prevent spoilage, use of plastic packaging intended to remain on foods as they are being cooked, to the introduction of more rigid, stable and reusable materials, and active packaging to extend the shelf-life of food. Each new technology brings with it the potential for exposure to new and possibly novel substances as a result of migration, interaction with other chemical packaging components, or, in the case of plastics now used in direct cooking of products, degradation products formed during heating. Furthermore, the presence of trace levels of certain chemicals from packaging that were once accepted as being of low risk based on traditional toxicology studies are being challenged on the basis of reports of adverse effects, particularly with respect to endocrine disruption, alleged to occur at very low doses. A recent example is the case of bisphenol A. The way forward to assess new packaging technologies and reports of very low dose effects in non-standard studies of food contact substances is likely to remain controversial. However, the risk assessment paradigm is sufficiently robust and flexible to be adapted to meet these challenges. The use of the Threshold of Regulation and the Threshold of Toxicological Concern concepts may play a critical role in the risk assessment of new food packaging technologies in the future.

Sample clean-up with sol–gel enzyme and immunoaffinity columns for the determination of bisphenol A in human urine

The paper describes the development of a simple and highly selective analytical method for the determination of free and total bisphenol A in urine samples. Free bisphenol A levels can be determined after sample clean-up using sol-gel immunoaffinity columns containing anti-bisphenol A antibodies. In determining total bisphenol A levels, the sample pre-treatment procedure consists of sample preparation using an on-line combination of two sol-gel columns, an enzyme column containing glucuronidase and arylsulfatase, and an immunoaffinity column. Bisphenol A can then be quantified by high-performance liquid chromatography and fluorescence detection. The mean recovery was found to be 78% with a standard deviation of 3.4%, the LOD (S/N=3) was 0.2 ng/ml. The method was applied to determine free and total urinary BPA levels of healthy adults and dialysis patients.

Automated on-line column-switching HPLC-MS/MS method with peak focusing for the determination of nine environmental phenols in urine

We developed a method using isotope dilution on-line solid-phase extraction (SPE) coupled to high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for the determination in urine of nine environmental phenolic compounds: Bisphenol A; 4-tert-octylphenol; o-phenylphenol; 2,4-dichlorophenol; 2,5-dichlorophenol; 2,4,5-trichlorophenol; 2,4,6-trichlorophenol; benzophenone-3 (2-hydroxy-4-metoxybenzophenone); and triclosan (2,4,4'-trichloro-2'-hydroxyphenyl ether). A unique fully automated column-switching system, constructed using 1 autosampler, 2 HPLC pumps, and a 10-port switching valve, was designed to allow for concurrent SPE-HPLC operation with peak focusing. The phenols present in 100 microL of urine were retained and concentrated on a C18 reversed-phase size-exclusion SPE column. Then, the phenols were "back-eluted" from the SPE column and diluted through a mixing Tee before being separated from other urine matrix components using a pair of monolithic HPLC columns. The phenols were detected by negative ion-atmospheric pressure chemical ionization-MS/MS. The efficient preconcentration of the phenols by the SPE column, analyte peak focusing by the dilution, and minimal ion suppression in the LC/MS interface by the buffer-free mobile phases resulted in limits of detection as low as 0.1-0.4 ng/mL for most analytes. The method was validated on spiked pooled urine samples and on urine samples from 30 adults with no known occupational exposure to environmental phenols. The method can be used for quick and accurate analysis of large numbers of samples in epidemiologic studies for assessing the prevalence of human exposure to environmental phenols.

Automated on-line liquid chromatography–photodiode array–mass spectrometry method with dilution line for the determination of bisphenol A and 4-octylphenol in serum

A novel on-line liquid chromatography-photodiode array detection-mass spectrometry (LC-DAD-MS) system was established with restricted-access media (RAM) pre-column and dilution line combined with a column-switching valve. The serum samples were injected directly onto pre-column under diluted condition by dilution line. After elution of proteins in the serum, the analytes were backflushed onto an ODS analytical column using a six-port column-switching device. The influence of the composition of the mobile phase, for instance, organic modifer, ionic strength, pH, dilution times and the rotation time of the switching valve have been investigated using bisphenol A (BPA) and 4-octyphenol (4-OP) as analytes. The evaluations for peak responses and sensitivity were conducted by MS, and proteins were removed by RAM-column with DAD monitoring at 280 nm. The peak shape was improved by adding a dilution line, especially in the case of large volume injection (LVI), which increased the sensitivity of the analysis. The selective and sensitive quantification of BPA and 4-OP in serum sample could be finished within 25 min. The method had linearity in the range 0.1-500 ng/mL with a limit of quantification for BPA and 4-OP of 0.1 and 0.5 ng/mL, respectively. The recoveries were in the range of 80-101% with less than 9.0% RSDs. This on-line LC-MS method demonstrates potential application to evaluating the exposure and risk of BPA and 4-OP in human.

Development of stable isotope dilution quantification liquid chromatography-mass spectrometry method for estimation of exposure levels of bisphenol A, 4-tert-octylphenol, 4-nonylphenol, tetrabromobisphenol A, and pentachlorophenol in indoor air

The potential risks to human health and reproduction of phenolic xenoestrogens, such as bisphenol A (BPA), 4-tert-octylphenol (OP), 4-nonylphenol (NP), tetrabromobisphenol A (TBBPA), and pentachlorophenol (PCP), have not been fully elucidated. It is possible that healthy humans are exposed to phenolic xenoestrogens in their daily lives. It is also possible that the source of human exposure to trace amounts of phenolic xenoestrogens is indoor air. Therefore, we have established an accurate, sensitive, and selective method for determining BPA, OP, NP, TBBPA, and PCP in air samples by using stable isotope dilution techniques using 13C12-BPA, 4-(1-methyl) octylphenol-d5 (m-OP-d5), 13C12-TBBPA, 13C6-PCP, and liquid chromatography-mass spectrometry (LC-MS). Air sampling (71/min, 24 hours), using glass filters (GB-100R, 47 mm) and Empore SDB-XD filters (47 mm/0.5 mm, 3M, Tokyo, Japan) and subsequent extraction by washing were carried out. Then the extracted sample solution was subjected to LC-MS. The percentage recovery of these analytes ranged from 87.0% to 101.9% (SD 0.2% to 4.6%, n=3) with correction using the stable isotope dilution quantification method. The quantification limit (signal-to-noise ratio, S/N>10) in the air samples was 0.1 ng/m3. Our findings suggest that the LC-MS method can detect low levels of phenolic xenoestrogens in air samples and that these trace levels of analytes exist in indoor air.

Determination of bisphenol A in milk by solid phase extraction and liquid chromatography–mass spectrometry

A simple and reliable analytical method based on solid phase extraction (SPE) and liquid chromatography coupled with electrospray ionization mass spectrometry was developed for the determination of bisphenol A (BPA) in milk. The effects of the experimental parameters of the LC-ESI-MS system (mobile phase and additives, flow rate, temperature of the ionization source, cone voltage and capillary potential) on the obtained signal were assessed and the parameters were optimized to provide maximum sensitivity and detectability. In addition, the performance of three commercial SPE sorbents (C18, PS-DVB and hydroxylated PS-DVB) was evaluated using spiked water and milk, diluted with a mixture of water-methanol (8:1). By using C18 cartridges and BPA-d(16) as internal standard, the mean relative recoveries at three fortification levels ranged between 97 and 104% and the corresponding inter-day precision (RSD%) was below 6% for 50 and 500 ng/g and below 20% for 5 ng/g fortification levels. It is shown that the ion suppression during ESI, the losses from the sample preparation procedure and the inter-day instability of LC-ESI-MS were overcome by the use of the deuterated internal standard. The concentration of BPA found in commercial canned milk samples ranged from <1.7 to 15.2 ng/g.

Human exposure to bisphenol A

Bisphenol A (BPA), 2,2-bis(4-hydroxyphenyl)propane, is made by combining acetone and phenol. It has estrogenic activity and is acutely toxic to aquatic organisms. BPA is used mainly as a material for the production of epoxy resins and polycarbonate plastics. Due to an increase in products based on epoxy resins and polycarbonate plastics, human exposure to BPA has increased. The environment (aquatic environment, air and soil) can be one source of human BPA exposure, but the primary route of human exposure is foods. The daily human intake of BPA is <1 microg/kg body weight/day on the basis of several studies, and whether these doses can have an adverse endocrine disruptive effect on humans, especially fetuses, needs to be studied carefully.

Selective solid-phase extraction of bisphenol A using molecularly imprinted polymers and its application to biological and environmental samples

Molecularly imprinted polymers (MIPs) were prepared using bisphenol A (BPA) as a template by precipitation polymerization. The polymer that had the highest binding selectivity and ability was used as solid-phase extraction (SPE) sorbents for direct extraction of BPA from different biological and environmental samples (human serum, pig urine, tap water and shrimp). The extraction protocol was optimized and the optimum conditions were as follows: conditioning with 5 mL methanol-acetic acid (3:1), 5 mL methanol, 5 mL acetonitrile and 5 mL water, respectively, loading with 5 mL aqueous samples, washing with 1 mL acetonitrile, and eluting with 3 mL methanol. MIPs can selectively recognize, effectively trap and preconcentrate BPA over a concentration range of 2-20 microM. Recoveries ranged from 94.03 to 105.3%, with a relative standard deviation lower than 7.9%. Under the optimal condition, molecularly imprinted SPE recoveries of spiked human serum, pig urine, tap water and shrimp were 65.80, 82.32, 76.00 and 75.97%, respectively, when aqueous samples were applied directly. Compared with C18 SPE, a better baseline, better high-performance liquid chromatography separation efficiency and higher recoveries were achieved after molecularly imprinted SPE.

A study of the preparation and reactivity of potassium ferrate

In the context of water treatment, the ferrate ([FeO(4)](2-)) ion has long been known for its strong oxidizing power and for producing a coagulant from its reduced form (i.e. Fe(III)). However, it has not been studied extensively owing to difficulties with its preparation and its instability in water. This paper describes an improved procedure for preparing solid phase potassium ferrate of high purity (99%) and with a high yield (50-70%). The characteristics of solid potassium ferrate were investigated and from XRD spectra it was found that samples of the solid have a tetrahedral structure with a space group of D(2h) (Pnma) and a=7.705A, b=5.863A, and c=10.36A. The aqueous stability of potassium ferrate at various pH values and different concentrations was investigated. It was found that potassium ferrate solution had a maximum stability at pH 9-10 and that ferrate solution at low concentration (0.25 mM) was more stable than at high concentration (0.51 mM). The aqueous reaction of ferrate with bisphenol A (BPA), a known endocrine disrupter compound, was also investigated with a molar ratio of Fe(VI):BPA in the range of 1:1-5:1. The optimal pH for BPA degradation was 9.4, and at this pH and a Fe(VI):BPA molar ratio of 5:1, approximately 90% of the BPA was degraded after 60s.