Junko Sajiki

Sensitive method for the determination of bisphenol-A in serum using two systems of high-performance liquid chromatography.

The aim of this study was to establish an easy and accurate method for the determination of bisphenol-A (BPA) in the body liquid such as serum and urine. Two high-performance liquid chromatography (HPLC) systems, HPLC with electrochemical detector (ED), and HPLC with mass spectrometry (MS) using electrospray ionization (ESI) interface were used for the assay in the serum samples prepared with solid-phase extraction method. Water or EtOH at a concentration below 50% was suitable for the extraction of BPA from serum. The limit of detection of BPA was 0.2 ng ml(-1) for the HPLC-ED method and 0.1 ng ml(-1) for HPLC-MS. There was a good correlation between the data obtained by the two HPLC systems. BPA concentrations in healthy human serum were low (0-1.6 ng ml(-1)). From various commercial fetal bovine serum and sheep plasma, however, significant amounts of BPA were detected. Since no BPA was detected from sheep plasma immediately after collection, the high amounts of BPA were considered to be caused by the handling of blood during the preparation of the products after blood collection. In vitro study showed that the amount of BPA leached from polycarbonate tube into sheep plasma were 40 times larger than those into water and the leached amount of BPA depended on the temperature (37 degrees C>20 degrees C>5 degrees C).

Leaching of bisphenol A (BPA) to seawater from polycarbonate plastic and its degradation by reactive oxygen species.

In this study, (1) change in the concentration of bisphenol A (BPA) leached from polycarbonate (PC) tube to control water (BPA free), seawater and river water at 20 and 37 degrees C as a function of time, (2) the fate of BPA caused by addition of H(2)O(2) and Fe(3+) to seawater containing BPA leached from PC tube were assessed. BPA leached from PC tube to all water samples increased with the ascendant of temperature and with the passage of time. The BPA leaching velocity in seawater was the fastest in three samples (11 ng/day for seawater, 4.8 ng/day for river water 0.8 ng/day for control water at 37 degrees C).BPA leaching velocity from PC tube was significantly high at pH 8 (50 mM Na(2)HPO(4)) and increased dose-dependently. There was no difference in the velocity of BPA among the 50 mM phosphate-buffers at pH 6.5, 7.0 and 7.5. BPA was leached three times higher by addition of Na(+) than K(+). However, the higher the K(+) concentration, the larger the BPA leached from PC tube. Na(+) mixed with PO(4)(-) was effective on BPA leaching from PC tube, but not with SO(4)(-) or Cl(-). The results suggested that BPA leaching from PC tube would be attributed to the concentration of bibasic phosphate such as Na(2)HPO(4) and K(2)HPO(4) in water samples. BPA was degraded in both control water and seawater in the presence of radical oxygen species, but the degradation rate was lower in seawater than in control water, suggesting that anti-oxidative system exists in seawater. Neo-synthesized substance in both control water and seawater in the presence of reactive oxygen species was identified as BPA-quinone by LC-MS.

Bisphenol A (BPA) and its source in foods in Japanese markets

The determination of bisphenol A (BPA) and/or bisphenol A diglycidyl ether (BADGE) in foods sold in Japanese markets and in water leached from six epoxy resin cans with similar diameters was carried out using high-performance liquid chromatography (HPLC) with electrochemical detection (LC/ECD), LC-mass spectrometric detection (LC/MS) and LC-tandem mass spectrometric detection (LC/MS/MS). BPA concentrations were 0–842 ng g−1 for 48 canned foods, 0–14 ng g−1 for 23 foods in plastic containers, and 0–1 ng g−1 for 16 foods in paper containers. No BADGE was detected in three canned foods. There was no difference in leaching concentrations of BPA into glycine buffers at pHs 8 and 11, and water. The amounts of BPA leached into water from six epoxy resin cans held at 121°C for 20 min were almost the same as the cans’ contents and were much higher than the amounts leached from cans held at or below 80°C for 60 min. The amount leached depended on the type of can, but not on the amount of BADGE leached from the cans. Considerably more BPA than BADGE leached to water from six cans. Two cans whose contents had high concentrations of BPA showed no BADGE leaching even at 121°C, suggesting the different kinds of epoxy resin can linings from others. The results imply that the main source of human exposure to BPA is food from cans with linings that contain high percentages of BPA as an additive or an unforeseen contaminant.

Concentrations of bisphenol A, bisphenol A diglycidyl ether, and their derivatives in canned foods in Japanese markets

Bisphenol A (BPA), bisphenol A diglycidyl ether (BADGE), and their derivatives in 38 canned foods sold in Japan were measured using high-performance liquid chromatography-mass spectrometry (LC-MS) and LC-tandem mass spectrometry (LC-MS/MS). BPA, BADGE, BADGE.2H 2O, BADGE.HCl.H2O, BADGE.HCl, and BADGE.2HCl were 0-235.4, 0-3.4, 0-247.2, 0.2-196.4, 0-3.0, and 0-25.7 ng/g, respectively, which did not exceed acceptable daily intake for BPA and specific migration limit for BADGEs. BADGE was degraded by 58, 100, 46, and 58% in water (pH 7), 0.01 N HCl (pH 2), 0.01 N NaCl (pH 6.8), and 0.01 N NaCl with acetic acid (pH 2.5), respectively, when it was allowed to stand at 120 degrees C for 30 min. The prominent derivatives formed were BADGE.2H 2O and BADGE.HCl.H2O, which was formed not only in BADGE with added HCl but also in that with NaCl. Acetic acid accelerated the formation of both BADGE.2H2O and BADGE.HCl.H2O in NaCl. No BPA was detected in any simulation samples started from BADGE. The results suggest that BPA and BADGE are independently leached into canned foods and that BADGE is easily changed to more stable compounds such as BADGE.2H2O and BADGE.HCl.H2O by sterilization.

Degradation of bisphenol-A (BPA) in the presence of reactive oxygen species and its acceleration by lipids and sodium chloride

In this study, (1) change in bisphenol-A (BPA) leached from polycarbonate (PC) tube to water samples at 37 degrees C, (2) effect of reactive oxygen species (ROS) produced by Fenton reaction on BPA recovery and thiobarbituric acid (TBA) value with or without generally existing environmental substances such as alcohol, lipids and NaCl, were investigated. Amounts of BPA leached from PC tube to water samples containing lipids possessing unsaturated fatty acid with high TBA values were significantly lower than the amount of BPA to water only, and addition of NaCl to lipid containing water further decreased BPA concentration. The result indicates that BPA could be degraded by lipoperoxides formed by auto-oxidation of lipid, and NaCl plays an important role in BPA degradation. In the presence of ROS, BPA recovery was the lowest in water and addition of EtOH increased in both BPA recovery and TBA value, suggesting that EtOH could play a role as scavenger of ROS on the oxidative BPA degradation. Furthermore, the higher the concentration of lipid and/or NaCl, the lower the BPA recovery and TBA value. Physiologically and environmentally important concentrations of NaCl could enhance oxidative degradation of BPA in the presence of ROS.

Determination of bisphenol A in blood using high-performance liquid chromatography-electrochemical detection with solid-phase extraction

A method for the determination of bisphenol A (BPA) in blood was investigated using high-performance liquid chromatography-electrochemical detection (HPLC-ED) with solid-phase extraction. When BPA at the concentrations of 25-100 ng/ml were added to whole blood, BPA recoveries were 26-48%. When BPA was added to water, plasma or hemolyzed red blood cells (H-RBC), BPA recoveries in water and plasma were almost similar (94%). However, the recovery in H-RBC was very low (36-46%). When BPA and plasma were added to H-RBC, the recovery was 70-85%. In authentic bovine metHb solution, BPA decreased depending on the metHb concentration, however, BPA recovery in the solution added with more than 17% plasma was higher than that in metHb only. These suggest that metHb influences the BPA recovery in whole blood. However, an accurate determination of BPA using HPLC was easily made possible by separating RBC from plasma.

Identification of eicosanoids in the red algae, Gracilaria asiatica, using high-performance liquid chromatography and electrospray ionization mass spectrometry.

Identification of eicosanoids which are metabolites of arachidonic acid in red algae Gracilaria asiatica, one of the popular seaweeds in Japan, was carried out using high-performance liquid chromatography (HPLC) interfaced with electrospray ionization mass spectrometry. Prostaglandin (PG) E2, 15-keto-PGE2, and 8-hydroxyeicosatetraenoic acid (HETE) were detected as major eicosanoids and PGA2, leukotriene B4 as minor ones in G. asiatica. 8- and 12-HETE had the same retention time in HPLC analysis, but using this analytical method, we were able to identify them.

Decomposition of bisphenol-A (BPA) by radical oxygen.

A change in bisphenol-A (BPA) concentration leached from polycarbonate (PC) tube to the phosphatidyl ethanolamine (PhE)-containing water was compared to water only. Time-dependent increase in BPA concentration was observed in both samples at 37 degrees C. The leaching velocity of BPA to water was three times faster than that to PhE-containing water and BPA concentration in water reached to 55.8 ng/ml 5 weeks later. When BPA was determined immediately after BPA addition of various concentration of PhE up to 2.5mg/ml to water, the BPA recoveries were over 93%. But, when incubated at 37 degrees C for a special time, BPA concentration in PhE-containing water in glass tube decreased time-dependently. In the presence of H2O2, time and Fe3+ dose-dependent decrease in the BPA concentration particularly, a drastic decrease above 0.44 mM Fe3+ was observed. These results suggest that BPA would be decomposed by radical oxygen including lipoperoxides. An addition of serum prevented BPA decrease from radical oxygen to a great extent but could not recover the BPA decrease. Thiobarbituric acid (TBA) value, a good parameter of lipid oxidation, decreased gradually in the mixture of H9O2 and Fe3+ in the presence of BPA, implying an inhibition of lipid oxidation due to BPA oxidation by radical oxygen.

Inhibition of seawater on bisphenol A (BPA) degradation by Fenton reagents.

To investigate bisphenol-A (BPA) degradation in seawater using Fenton reagents, changes in the BPA recovery and in the concentration of BPA metabolite, BPA-o-quinone in the three water samples; BPA free deionizad water (control water), 3% aq. NaCl and seawater as a function of time after BPA fortification in the presence of radical oxygen species (ROS) at 20 degrees C were investigated. The BPA recoveries were lower in both 3% aq. NaCl and seawater than in the control water. The BPA recovery in aq. NaOCl decreased as a function of NaOCl concentration, indicating that BPA could be degraded by the potent radical ion (OCl-) at the concentration of above 2 microM. A BPA metabolite, BPA-o-quinone was formed in all the water samples after addition of ROS which was produced by Fenton reaction (reaction of 0.11 M H2O2 and 0.44 mM FeCl3.6H2O). These results indicated that BPA degradation could occur by an addition of ROS and further accelerated by the formation of OCl- in salt containing water samples. BPA recovery was the highest in seawater immediately after addition of Fenton reagents and the amount of BPA-o-quinone was very low, which suggests that seawater possesses an inhibitory system on BPA degradation. There was a positive correlation (p<0.01) between the fortified iron concentration and turbidity in seawater. Turbidity might be originated from iron-binding substances. Degradation threshold of BPA was observed when Fenton reaction was employed in seawater fortified with high amount of BPA. The present study suggested that iron trapping caused an inhibition on BPA degradation by Fenton reagents.

Simple and accurate determination of bisphenol A in red blood cells prepared with basic glycine buffer using liquid chromatography-electrochemical detection.

For an accurate determination of bisphenol A (BPA) in red blood cells (RBC), the effect of pH on the concentration of BPA was investigated. Also, BPA recovery using ferric heme, methemoglobin (metHb) and hematin, were investigated to confirm whether BPA binds to ferric heme. BPA recovery in hemolysate was high at alkaline pH and was very low at acidic pH where oxyHb changed to metHb. BPA recovery decreased dose-dependently in metHb and hematin, but inorganic iron ions did not influence the recovery. These results suggested that BPA could be bound to ferric heme in RBC. The use of glycine-NaOH buffer (pH 11) as well as plasma had the highest recovery (97%). BPA was not detected in red blood cells of healthy adult volunteers (n=6). In sheep blood contaminated with BPA, BPA was detected in both plasma and RBC (10 times lower than in plasma), indicating that BPA could have migrated from plasma into RBC.