On-line Solid Phase Extraction-high Performance Research Articles

Exposure assessment of polycyclic aromatic hydrocarbons in refined coal tar sealant applications.

Refined coal tar sealant (RCTS) emulsions are used to seal the surface of asphalt pavement. Nine of the 22 polycyclic aromatic hydrocarbons (PAHs) evaluated in this study are classified as known, probable, or possible human carcinogens. Exposure assessment research for RCTS workers has not been published previously. The overall objective of this study was to develop a representative occupational exposure assessment of PAH exposure for RCTS workers based on worksite surveys. The specific aims were to: 1) quantify full-shift airborne occupational exposures to PAHs among RCTS workers; 2) quantify workers' dermal exposures to PAHs; 3) quantify biomarkers of PAH exposure in workers' urine; 4) identify specific job titles associated with RCTS exposure; and 5) apply these results to a biological exposure index to assess risk of potential genotoxicity from occupational exposures. A total of twenty-one RCTS workers were recruited from three companies. Personal and area air samples were collected using a modification of NIOSH Method 5515. Dermal exposure was assessed by hand and neck wipes before and after shifts. Twenty-two PAHs were quantified via gas chromatography-mass spectrometry selected ion monitoring. Internal dose was estimated by quantifying select PAH metabolites in pre- and post-shift urine samples using on-line solid phase extraction-high performance liquid chromatography-tandem mass spectrometry. PAH levels in the worker breathing zones were highest for naphthalene, acenaphthene, and phenanthrene, with geometric means of 52.1, 11.4, and 9.8μg/m3, respectively. Hand wipe levels of phenanthrene, fluoranthene and pyrene were the highest among the 22 PAHs with geometric means of 7.9, 7.7, and 5.5μg/cm2, respectively. Urinary PAH biomarkers for naphthalene, fluorene, phenanthrene, and pyrene were detected in all workers and were higher for post-shift samples than those collected pre-shift. Urinary concentrations of the metabolite 1-hydroxypyrene were greater than the American Conference of Governmental Industrial Hygienists (ACGIH) Biological Exposure Index (BEI) for this metabolite in 89 percent of post-shift samples collected on the final day of the work week or field survey. Statistically significances were found between concentrations of fluorene, naphthalene, and phenanthrene in the breathing zone of workers and their corresponding urinary PAH biomarkers. Workers were placed in two work place exposure groups: applicators and non-applicators. Applicators had higher total PAH concentrations in personal breathing zone (PBZ) air samples than non-applicators and were more likely to have post-shift hand wipe concentrations significantly higher than pre-shift concentrations. Concentrations of post-shift urinary biomarkers were higher, albeit not significantly, for applicators than non-applicators. The exposure results from RCTS worker samples cannot be explained by proximal factors such as nearby restaurants or construction. Air and skin concentration levels were substantially higher for RCTS workers than previously published levels among asphalt workers for all PAHs. PAH profiles on skin wipes were more consistent with RCTS sealant product than air samples. Last day post-shift urinary concentrations of 1-hydroxypyrene greatly exceeded the ACGIH BEI benchmark of 2.5μg/L in 25 of 26 samples, which suggests occupational exposure and risk of genotoxicity. When pyrene and benzo[a]pyrene were both detected, concentration ratios from personal exposure samples were used to calculate the adjusted BEI. Concentrations of 1-hydroxypyrene exceeded the adjusted BEIs for air, hand wipes, and neck wipes in most cases. These results indicate the need to increase safety controls and exposure mitigation for RCTS workers.

Determination of Polybrominated Diphenyl Ethers and Hydroxylated Analogues in Serum Using High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry with Online Solid Phase Extraction

Online solid phase extraction-high performance liquid chromatography-inductively coupled plasma mass spectrometry (Online SPE-HPLC-ICP-MS) technique was developed for simultaneous determination of 6 kinds of polybrominated diphenyl ethers and 5 kinds of hydroxyl metabolites in serum. A serum sample (200 μL) was directly analyzed after protein precipitation and dilution. The target analytes were automatically enriched on a solid phase extraction column, and then separated and analyzed by liquid chromatography-inductively coupled plasma mass spectrometry with methanol/acetonitrile/water as mobile phase. The main parameters such as loading rate, elution time and elution solvent were optimized. As a result, Oasis HLB was selected as the SPE column, the loading solvent was pure water at a rate of 3.0 mL/min, the elution solvent was methanol-acetonitrile-water (54:26:20, V/V), the elution flow rate was 1.0 mL/min, and the liquid chromatography column was ZORBAX Eclipse Plus C18. The limits of quantification (LOQ) of the method were 0.14–0.74 ng/L, the recoveries were 61.8%–77.7%, and the relative standard deviations (RSDs) of the results were 3.7%–10.1% (n = 3). The established method was successfully applied to the analysis of 30 serum samples. A total of 4 kinds of polybrominated diphenyl ethers and 2 kinds of hydroxy polybrominated diphenyl ethers were detected, and their occurrence characteristics were consistent with previous reports. The results showed that this method could be applied to analyze actual samples in large quantities, which was of great practical value.

Per- and Polyfluoroalkyl Substances (PFAS) and Hormone Levels during the Menopausal Transition: Study of Women’s Health Across the Nation (SWAN)

Background: PFAS are endocrine disrupting chemicals that have been associated with an earlier age at menopause. However, information on their association with serum hormone concentrations is limited and inconsistent. We examined longitudinal associations between serum PFAS concentrations at baseline and serial serum concentrations of follicle stimulating hormone (FSH), estradiol (E2), testosterone (T) and sex hormone-binding globulin (SHBG) in the Study of Women’s Health Across the Nation (SWAN), a multi-racial/ethnic, community-based cohort of women transitioning through menopause. Methods: We assayed serum concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), 2-(N-ethyl-perfluorooctane sulfonamide) acetate (EtFOSAA), 2-(N-methyl-perfluorooctane sulfonamide) acetate (MeFOSAA), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA) in 1,398 women eligible for the SWAN Multi-Pollutant Study in 1999-2000 who were followed approximately annually to 2016. Serum PFAS concentrations were quantified by online solid phase extraction-high performance liquid chromatography-isotope dilution-tandem mass spectrometry. Hormone and PFAS concentrations were log-transformed. Linear mixed regression with random intercepts was used to analyze longitudinal associations, adjusting for menopausal status, smoking, parity, race/ethnicity, site and body mass index (BMI). Results: At baseline, women had a mean age of 49.5 years, a mean BMI of 28.0 and included white (50.5%), black (22.0%), Chinese (12.7%) and Japanese (14.8%) women. PFAS were not associated with E2. In adjusted models including BMI, FSH was positively associated with total PFOS (β=0.041, 95% CI=0.000, 0.0092), branched-PFOS, (β=0.044, 95% CI=0.006, 0.0083), and n-PFOA (β=0.055, 95% CI=0.008, 0.0103) but not with EtFOSAA, MeFOSAA, PFHxS, or PFNA. T and SHBG were negatively associated with PFOS, n-PFOA and EtFOSAA, but these associations were greatly attenuated and not significant after adjustment for BMI. Conclusions: The results of this prospective study suggest that PFAS, especially PFOS and its precursors (MeFOSAA and EtFOSAA), and PFOA are associated with higher FSH concentrations in women during the menopausal transition, consistent with findings that PFAS affects reproductive aging.

Per- and Polyfluoroalkyl Substances (PFAS) and Incident Diabetes in Midlife Women: Study of Women’s Health Across the Nation (SWAN)

Background: Diabetogenic effects of per- and polyfluoroalkyl substances (PFAS) have been suggested. However, evidence based on population-based prospective cohort studies is limited. We examined the association between serum PFAS concentrations and incident diabetes in the Study of Women’s Health Across the Nation (SWAN), a community-based population study of midlife women.Methods: We included 1,226 diabetes-free women aged 45-56 years at the baseline of the SWAN Multi-Pollutant Study in 1999-2000 who were followed up to 2016. Serum PFAS concentrations were quantified by online solid phase extraction-high performance liquid chromatography-isotope dilution-tandem mass spectrometry. We used k-means clustering and identified three overall PFAS concentration patterns as mixtures (low, medium, high). Cox proportional hazards models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs).Results: We identified 137 incident diabetes cases (median follow-up=16 years, incident rate=8.15 per 1000 person-years). After adjustment for age, race/ethnicity, site, education, income, body mass index, smoking status, alcohol, physical activity, menopausal status and hormone use, the HRs comparing the lowest with the highest tertiles were 1.56 (95% CI: 1.15-2.11) for n-perfluorooctanoate (n-PFOA) (p-for-trend=0.004); 1.56 (95% CI: 1.19-2.14) for perfluorohexane sulfonate (PFHxS) (p-for-trend=0.001); 1.43 (95% CI: 1.05-1.95) for branched-perfluorooctane sulfonate (branched-PFOS) (p-for-trend=0.02); and 1.61 (95% CI: 1.16-2.24) for 2-(N-methyl-perfluorooctane sulfonamide) acetate (MeFOSAA) (p-for-trend=0.003). The high overall PFAS concentration mixture pattern had a significantly higher HR of 1.44 (95% CI: 1.01-2.05) compared with the low mixture pattern.Conclusions: This prospective cohort study with up to 17 years of follow-up suggests that PFAS, especially PFOA, PFHxS, and PFOS and its precursor (MeFOSAA), individually or as mixtures, may increase diabetes risk in midlife women. Reduced exposure to PFAS may be an important preventative approach to lowering population-wide diabetes risk.

Associations ofPerfluoroalkyl Substances withIncident Natural Menopause: the Study of Women’s Health Across the Nation

Context: Previous epidemiologic studies of per- and polyfluoroalkyl substances (PFAS) and menopausal timing conducted in cross-sectional settings were limited by reverse causation because PFAS serum concentrations increase after menopause.Objectives: To investigate associations between PFAS serum concentrations and incident natural menopause.Design and Setting: A prospective cohort of midlife women, the Study of Women’s Health Across the Nation, from 1999 to 2017.Participants: 1120 multi-racial/ethnic premenopausal women (White, Black, Chinese and Japanese) aged 45-56 years in 1999-2000.Methods: Serum PFAS concentrations were measured using an online solid phase extraction-high performance liquid chromatography-isotope dilution-tandem mass spectrometry. The final menstrual period was determined during the annual follow-up visits. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).Results: Participants contributed 5466 person-years of follow-up, and 578 had incident natural menopause. Compared to the lowest tertile, women at the highest tertile of baseline serum concentrations had adjusted HR for natural menopause of 1.26 (95%CI: 1.02-1.57) for n-perfluorooctane sulfonic acid (n-PFOS) (Ptrend=0.03), 1.27 (95%CI: 1.01-1.59) for branched-PFOS (Ptrend=0.03), and 1.31 (95%CI: 1.04-1.65) for n-perfluorooctanoic acid (Ptrend=0.01). Women were classified into four clusters based on their overall PFAS concentrations as mixtures: low, low-medium, medium-high, and high. Compared to the low cluster, the high cluster had a HR of 1.63 (95% CI: 1.44-1.84), which is interpreted as 2.0 years earlier experience of natural menopause.Conclusion: This study suggests that select PFAS serum concentrations are associated with earlier natural menopause, a risk factor for adverse health outcomes in later life.

Analytical method development for α-amanitin and β-amanitin in plasma at ultra-trace level by online solid phase extraction-high performance liquid chromatography-triple quadrupole mass spectrometry and its application in poisoning events

α-Amanitin and β-amanitin are the main fatal mushroom toxins. The toxins metabolize rapidly in blood and are reported hard to be detected 24 h after poisoning. The main challenge is that of developing a highly sensitive method at sub-pg mL−1 level in blood to diagnose intoxication cause and to study the poisoning mechanism and blood toxicity kinetics. An analytical method for α-amanitin and β-amanitin at ultra-trace level was developed in this study by online solid phase extraction-high performance liquid chromatography-triple quadrupole mass spectrometry (online SPE-LC–MS/MS). Simple protein precipitation and liquid-liquid extraction were introduced to resolve the sample preparation problem of the online SPE-LC–MS/MS system with large-volume injection. A quick valve-switching technique with a quantitative loop as interface was used in the online system. This design can ensure the independence of flow path and pressure between the SPE and LC–MS/MS modules and can obtain the precise cleanup of the toxins. The limits of detection for α-amanitin and β-amanitin in plasma were both 0.02 ng mL-1. The linear ranges were 0.05–20 ng mL-1 with a correlation coefficient r >0.99. The average recoveries at three spiking levels were 82.9 %–92.2 % with the relative standard deviations (RSD) of 5.4 %–8.0 % for α-amanitin and 84.5 %–93.9 % with RSDs of 4.5 %–7.8 % for β-amanitin. The composition and concentration of the toxins in plasma from 18 patients in 5 mushroom poisoning events caused by aminitins were studied. The developed method has high positive confirmation ability and can identify toxins in plasma 40 h after poisoning.

Impact of enzymatic hydrolysis on the quantification of total urinary concentrations of chemical biomarkers

Human exposure to consumer and personal care products chemicals such as phenols, including parabens and other antimicrobial agents, can be assessed through biomonitoring by quantifying urinary concentrations of the parent chemical or its metabolites, often after hydrolysis of phase II conjugates. Developing suitable analytical methods for the concurrent quantification of multiple exposure biomarkers is challenging because optimal conditions for the hydrolysis of such conjugates (e.g., O-glucuronides, N-glucuronides, sulfates) may differ depending on the biomarker. We evaluated the effectiveness of seven commercial hydrolytic enzymes to simultaneously hydrolyze N-glucuronides (using the antibacterial triclocarban as example compound) and other conjugates (using select phenols and parabens as examples) by using on-line solid phase extraction–high performance liquid chromatography-isotope dilution-tandem mass spectrometry. Incubation (30 min, 55 °C) with a genetically engineered β-glucuronidase (IMCS, ≥15 units/μL urine) hydrolyzed N-glucuronide triclocarban, but did not fully hydrolyze the conjugates of phenols and parabens. By contrast, incubation (4 h, 37 °C) with solid β-glucuronidase (Helix pomatia, Type H-1, ≥30 units/μL urine) or liquid β-glucuronidase/arylsulfatase (Helix pomatia, 30 units/μL urine [i.e., 30 μL/100 μL urine]) in the presence of 100 μL methanol for 100 μL urine completely hydrolyzed N-glucuronide triclocarban and the conjugates of several phenols and parabens, without cleaving the ester bond of the parabens to form p-hydroxybenzoic acid. These results highlight the relevance of method validation procedures that include optimizing the hydrolysis of phase II urinary conjugates (e.g., enzyme type and amount used, reaction time, temperature) to quantify accurately and concurrently multiple exposure biomarkers for biomonitoring purposes.

Urinary triclosan concentrations and diminished ovarian reserve among women undergoing treatment in a fertility clinic

To investigate the association between urinary triclosan concentrations and antral follicle count (AFC), a well-accepted marker of ovarian reserve, among women from a fertility center. Prospective cohort study. Hospital fertility center. A total of 109 women. Urinary triclosan concentrations quantified by online solid phase extraction-high performance liquid chromatography-isotope dilution tandem mass spectrometry. AFC through transvaginal ultrasonography on the third day of an unstimulated menstrual cycle or on the third day of a progesterone withdrawal bleed. The geometric mean of the specific gravity-adjusted urinary triclosan concentrations for the 225 samples provided by the 109 women was 13.0μg/L (95% confidence interval [CI], 8.9, 19.1). Women had median (with interquartile range) AFC of 13 (8, 18). The specific gravity-adjusted urinary triclosan concentrations were inversely associated with AFC (-4%; 95% CI, -7%, -1%). Women with triclosan concentrations above the median had lower AFC compared with those whose triclosan concentrations were equal to or below the median, with an adjusted difference of -3.2 (95% CI, -3.9, -1.6) among those with a body mass index <25kg/m2 and -1.8 (95% CI, -3.2, -0.3) among those who were <35years old. Specific gravity-adjusted urinary triclosan concentrations were inversely associated with AFC in women seeking care at a fertility center. This association was modified by age and body mass index, with the younger and leaner women showing larger decreases in AFC.

Quantification of urinary mono-hydroxylated metabolites of polycyclic aromatic hydrocarbons by on-line solid phase extraction-high performance liquid chromatography-tandem mass spectrometry.

Human exposure to polycyclic aromatic hydrocarbons (PAHs) can be assessed through monitoring of urinary mono-hydroxylated PAHs (OH-PAHs). Gas chromatography (GC) has been widely used to separate OH-PAHs before quantification by mass spectrometry in biomonitoring studies. However, because GC requires derivatization, it can be time consuming. We developed an on-line solid phase extraction coupled to isotope dilution-high performance liquid chromatography-tandem mass spectrometry (on-line-SPE-HPLC-MS/MS) method for the quantification in urine of 1-OH-naphthalene, 2-OH-naphthalene, 2-OH-fluorene, 3-OH-fluorene, 1-OH-phenanthrene, the sum of 2-OH and 3-OH-phenanthrene, 4-OH-phenanthrene, and 1-OH-pyrene. The method, which employed a 96-well plate platform and on-line SPE, showed good sensitivity (i.e., limits of detection ranged from 0.007 to 0.09ng/mL) and used only 100μL of urine. Accuracy, calculated from the recovery percentage at three spiking levels, varied from 94 to 113%, depending on the analyte. The inter- and intra-day precision, calculated from 20 repeated measurements of two quality control materials, varied from 5.2 to 16.7%. Adequate method performance was also confirmed by acceptable recovery (83-102%) of two NIST standard reference materials (3672 and 3673). This high-throughput on-line-SPE-HPLC-MS/MS method can be applied in large-scale epidemiological studies. Graphical abstract Example LC-MS chromatogram of urinary mono-hydroxylated PAH metabolites.

An on-line solid phase extraction–liquid chromatography tandem mass spectrometry method for the determination of perfluoroalkyl substances in the Antarctic ice core samples

An on-line solid phase extraction–high performance liquid chromatography–tandem mass spectrometry method for the analysis of perfluoroalkyl substances (PFASs) in water samples was developed. The optimal analytical conditions were obtained through the optimization of the extraction efficiency of on-line solid phase extraction column, sample loading rate and loading volume, and the concentration of ammonium acetate in mobile phase. Under the optimal condition, the analytical method displayed good linearity (r2 > 0.99) for 12 PFASs (C5–C14 perfluoroalkyl carboxylic acids and C6/C8 perfluoroalkyl sulfonic acids) over a concentration range of 0.5–100 ng/L. The limits of quantitation for samples were between 0.025 ng/L and 0.5 ng/L and the relative standard deviations (RSD) of five consecutive analyses were less than 10% for 1 ng/L standard solution. Satisfactory results were obtained using this analytical method for the analysis of perfluoroalkyl substances in Antarctic ice core samples. The recoveries of all perfluoroalkyl substances were in a range of 73%–117% when the samples were spiked with standards at the concentrations of 2.5 ng/L and 25 ng/L.

Simultaneous Determination of Seven Metabolites of Polycyclic Aromatic Hydrocarbons in Human Urine by Online Solid Phase Extraction-High Performance Liquid Chromatography

Abstract A high performance liquid chromatographic method for simultaneous determination of seven metabolites of polycyclic aromatic hydrocarbons (PAHs), including 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2-hydroxyfluorene, 2-hydroxyphenanthrene, 4-hydroxyphenanthrene, 1-hydroxypyrene and 6-hydroxychrysene in human urine, was developed coupled with online solid phase extraction by use of a double ternary liquid chromatography system with a fluorescence detector. The target compounds were online concentrated on the Turboflow Cyclone solid phase extraction column, and then transferred by a six-way valve to the Hypersil Green PAH column for separation with acetonitrile and water as mobile phase at a flow rate of 1.0 mL min−1 and 35 °C. The analysis was completed in 20 min. Under the optimized chromatographic conditions, the method showed good linearity (r ≥ 0.999) in the range of 5−2000 ng L−1 or 50−20000 ng L−1 with the LODs of 0.5−15 ng L−1 and the recoveries of 80.7%−110.7%. The proposed method was successfully applied to the detection of metabolites of polycyclic aromatic hydrocarbons in urine from several smokers and non-smokers. The concentrations of 2-hydroxynaphthalene, 1-hydroxynaphthalene, 2-hydroxyfluorene, 2-hydroxyphenanthrene, 4-hydroxyphenanthrene and 6-hydroxychrysene in the smoker urine were much higher than those in non-smoker.

Application of On-line SPE-HPLC System in Pharmacokinetic Study of Highly Active Anti-cancer Compound TEB-415

Abstract An on-line solid phase extraction-high performance liquid chromatography (SPE-HPLC) system was developed for the plasma pharmacokinetic study of highly active anti-cancer compound TEB-415 in mouse. A C 18 column (Venusil MP, 100 mm × 4.6 mm, 5 μm) was used as the analytical column and a mixed solution of acetonitrile-5 mM monopotassium phosphate buffer (pH 3.5) at a flow rate of 1.0 mL min −1 as the mobile phase for the isocratic elution. The on-line solid phase extraction was carried out on an MF Ph-1 column (10 mm × 4 mm, 5 μm) with purified water as the washing solvent and 5 mM monopotassium phosphate buffer (pH 3.5) as the elution solvent. The detected wavelength was set at 262 nm. The pharmacokinetic parameters were calculated by WinNonlin 5.2 software. The linear range of TEB-415 was 100–20000 μg L −1 with a limit of qualification of 20 μg L −1 . The extraction recovery was 91.99%–99.14% and the RSD of intra- and inter-day precision was less than 3.5%. The accuracy of short-term stability, freeze-thaw stability and long-term stability were 91.5%–101.5%. After oral medication, the mean peak time ( T max ) of TEB-415 in mice was 5.29 h and the mean maximum concentration ( C max ) was 3403 μg L −1 . The area under the curve (AUC) of TEB-415 was 24600 μg L −1 h −1 . The mean half-life of drug in mice was 3.84 h, and the mean retention time (MRT) was 6.56 h. These parameters above suggest that TEB-415 has an appropriate rate of absorption and elimination for the mice. Meanwhile, it had preferable bioavailability.

Reliability of triclosan in repeated urine samples from Norwegian women

Background:Triclosan (TCS) is an antibacterial chemical that is used in personal care products and is measurable in urine. TCS has a short half-life, and body burden is mainly influenced by the individual’s use of TCS-containing products. Exposure to TCS has been associated with allergic disease in some studies, but knowledge about temporal variability of biomarkers of exposure to TCS is limited. A study of 6-10 year old US children found a reasonable degree of temporal reliability for TCS, but TCS reliability has not been examined among adults. Aims: To examine whether TCS concentrations in urine from gestational week 17 were consistent across later time points in pregnancy. Methods:Spot urine samples were collected in gestational weeks 17, 23, and 29 from 45 women in The Norwegian Mother and Child Cohort Study (MoBa). TCS was measured by online solid phase extraction-high performance liquid chromatography-isotope dilution tandem mass spectrometry. Spearman’s rank correlation coefficient (rs) and intraclass correlation coefficient (ICC) statistics were calculated. For concentrations below the assay’s limit of detection (2.3 µg/L) we used the instrumental reading values. The ICC was calculated using natural log transformed TCS values. Results: Overall, only 36% of the values (48/135) were detectable; 56% of the women had a least one detectable value, and 20 women had undetectable TCS concentrations in all three urine samples. The 95th percentile of TCS in the 135 urine specimens was 351 µg/g creatinine. The correlation for TCS concentrations between gestational weeks 17 and 23 was rs=0.69, and the correlation between weeks 17 and 29 was rs=0.49. For the three time points, the ICC was 0.49 (p&lt;0.001). Conclusions: The reliability of TCS in repeated urine samples from pregnant women was reasonable, suggesting a single urine sample may be adequate in representing TCS exposure during pregnancy.

Prenatal Exposure to Environmental Phenols: Concentrations in Amniotic Fluid and Variability in Urinary Concentrations during Pregnancy

Background: Maternal urinary biomarkers are often used to assess fetal exposure to phenols and their precursors. Their effectiveness as a measure of exposure in epidemiological studies depends on their variability during pregnancy and their ability to accurately predict fetal exposure.Objectives: We assessed the relationship between urinary and amniotic fluid concentrations of nine environmental phenols, and the reproducibility of urinary concentrations, among pregnant women.Methods: Seventy-one women referred for amniocentesis were included. Maternal urine was collected at the time of the amniocentesis appointment and on two subsequent occasions. Urine and amniotic fluid were analyzed for 2,4- and 2,5-dichlorophenols, bisphenol A, benzophenone-3, triclosan, and methyl-, ethyl-, propyl-, and butylparabens using online solid phase extraction–high performance liquid chromatography–isotope dilution tandem mass spectrometry.Results: Only benzophenone-3 and propylparaben were detectable in more than half of the amniotic fluid samples; for these phenols, concentrations in amniotic fluid and maternal urine collected on the same day were positively correlated (ρ = 0.53 and 0.32, respectively). Other phenols were detected infrequently in amniotic fluid (e.g., bisphenol A was detected in only two samples). The intraclass correlation coefficients (ICCs) of urinary concentrations in samples from individual women ranged from 0.48 and 0.62 for all phenols except bisphenol A (ICC = 0.11).Conclusion: Amniotic fluid detection frequencies for most phenols were low. The reproducibility of urine measures was poor for bisphenol A, but good for the other phenols. Although a single sample may provide a reasonable estimate of exposure for some phenols, collecting multiple urine samples during pregnancy is an option to reduce exposure measurement error in studies regarding the effects of phenol prenatal exposure on health.Citation: Philippat C, Wolff MS, Calafat AM, Ye X, Bausell R, Meadows M, Stone J, Slama R, Engel SM. 2013. Prenatal exposure to environmental phenols: concentrations in amniotic fluid and variability in urinary concentrations during pregnancy. Environ Health Perspect 121:1225–1231; http://dx.doi.org/10.1289/ehp.1206335

Environmental exposure to the plasticizer 1,2-cyclohexane dicarboxylic acid, diisononyl ester (DINCH) in US adults (2000—2012)

1,2-Cyclohexane dicarboxylic acid, diisononyl ester (DINCH) is a complex mixture of nine carbon branched-chain isomers. It has been used in Europe since 2002 as a plasticizer to replace phthalates such as di(2-ethylhexyl)phthalate (DEHP) and diisononyl phthalate (DINP). Urinary concentrations of the oxidative metabolites of DINCH, namely cyclohexane-1,2-dicarboxylic acid-monocarboxy isooctyl ester (MCOCH); cyclohexane-1,2-dicarboxylic acid-mono(oxo-isononyl) ester (MONCH); and cyclohexane-1,2-dicarboxylic acid-mono(hydroxy-isononyl) ester (MHNCH), can potentially be used as DINCH exposure biomarkers. The concentrations of MCOCH, MONCH and MHNCH were measured by online solid phase extraction-high performance liquid chromatography-tandem mass spectrometry in urine collected in 2000 (n=114), 2001 (n=57), 2007 (n=23), 2009 (n=118), 2011 (n=94) and 2012 (n=121) from convenience groups of anonymous U.S. adult volunteers with no known DINCH exposure. None of the DINCH metabolites were detected in samples collected in 2000 and 2001. Only one sample collected in 2007 had measureable concentrations of DINCH metabolites. The detection rate for all three metabolites increased from 2007 to 2012. The presence of oxidative metabolites of DINCH in urine suggests that these oxidative metabolites can be used as DINCH biomarkers for exposure assessment even at environmental exposure levels.

On-line solid phase extraction-high performance liquid chromatography–isotope dilution–tandem mass spectrometry approach to quantify N,N-diethyl-m-toluamide and oxidative metabolites in urine

Human exposure to N,N-diethyl-m-toluamide (DEET) occurs because of the widespread use of DEET as an active ingredient in insect repellents. However, information on the extent of such exposure is rather limited. Therefore, we developed a fast on-line solid phase extraction–high performance liquid chromatography–isotope dilution tandem mass spectrometry (HPLC-MS/MS) method to measure in urine the concentrations of DEET and two of its oxidative metabolites: N,N-diethyl-3-(hydroxymethyl)benzamide and 3-(diethylcarbamoyl)benzoic acid (DCBA). To the best of our knowledge, this is the first HPLC-MS/MS method for the simultaneous quantification of DEET and its select metabolites in human urine. After enzymatic hydrolysis of the conjugated species in 0.1mL of urine, the target analytes were retained and pre-concentrated on a monolithic column, separated from each other and from other urinary biomolecules on a reversed-phase analytical column, and detected by atmospheric pressure chemical ionization in positive ion mode. The limits of detection ranged from 0.1ngmL−1 to 1.0ngmL−1, depending on the analyte. Accuracy ranged between 90.4 and 104.9%, and precision ranged between 5.5 and 13.1% RSD, depending on the analyte and the concentration. We tested the usefulness of this method by analyzing 75 urine samples collected anonymously in the Southeastern United States in June 2012 from adults with no known exposure to DEET. Thirty eight samples (51%) tested positive for at least one of the analytes. We detected DCBA most frequently and at the highest concentrations. Our results suggest that this method can be used for the analysis of a large number of samples for epidemiological studies to assess human exposure to DEET.

Simultaneous online SPE–HPLC–MS/MS analysis of docetaxel, temsirolimus and sirolimus in whole blood and human plasma

Docetaxel and temsirolimus are some of the most used drugs in a wide range of solid tumors. In preclinical studies, mTOR inhibitors such as temsirolimus have demonstrated synergistic cytotoxic effects with taxanes providing the rationale for combination studies. These anticancer agents exhibit a narrow therapeutic concentration range and due to their high inter- and intra-individual pharmacokinetic variability, therapeutic dose monitoring by highly sensitive methods as LC-MS/MS are important for clinical research. Therefore, the aim of this study was to develop and validate a sensitive, fast and convenient method for the simultaneous identification and quantification of docetaxel, temsirolimus and its main metabolite, sirolimus, using paclitaxel, another anticancer drug, as the internal standard. These analytes were quantified by an integrated online solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) system. Separation was performed on a Zorbax eclipse XDB-C8 (150mm×4.6mm, 5μm) column. The mass spectrometer tandem quadruple detector was equipped with jet stream electrospray ionization, monitored in multiple reactions monitoring (MRM) and operated in positive mode. A combination of protein precipitation with methanol/zinc sulphate (70:30) (v/v) and online SPE using a Zorbax eclipse plus C8 (12.5mm×4.6mm, 5μm) cartridge was used to extract the compounds. This method allows the use of the same reagents, sample treatment and analytical technique independently of whether the samples are whole blood or plasma. The method has been successfully validated and applied to real samples. It is a suitable method for dose adjustment and for evaluating potential drug interactions during combined treatments.

Urinary Bisphenol A Concentrations and Implantation Failure among Women Undergoing in Vitro Fertilization

Background: Bisphenol A (BPA) is a synthetic chemical widely used in the production of polycarbonate plastic and epoxy resins found in numerous consumer products. In experimental animals, BPA increases embryo implantation failure and reduces litter size.Objective: We evaluated the association of urinary BPA concentrations with implantation failure among women undergoing in vitro fertilization (IVF).Methods: We used online solid phase extraction–high performance liquid chromatography–isotope dilution tandem mass spectrometry to measure urinary BPA concentrations in 137 women in a prospective cohort study among women undergoing IVF at the Massachusetts General Hospital Fertility Center in Boston, Massachusetts. We used logistic regression to evaluate the association of cycle-specific urinary BPA concentrations with implantation failure, accounting for correlation among multiple IVF cycles in the same woman using generalized estimating equations. Implantation failure was defined as a negative serum β-human chorionic gonadotropin test (β-hCG < 6 IU/L) 17 days after egg retrieval.Results: Among 137 women undergoing 180 IVF cycles, urinary BPA concentrations had a geometric mean (SD) of 1.53 (2.22) µg/L. Overall, 42% (n = 75) of the IVF cycles resulted in implantation failure. In adjusted models, there was an increased odds of implantation failure with higher quartiles of urinary BPA concentrations {odds ratio (OR) 1.02 [95% confidence interval (CI): 0.35, 2.95}, 1.60 (95% CI: 0.70, 3.78), and 2.11 (95% CI: 0.84, 5.31) for quartiles 2, 3, and 4, respectively, compared with the lowest quartile (p-trend = 0.06).Conclusion: There was a positive linear dose–response association between BPA urinary concentrations and implantation failure.

Polyfluoroalkyl Compounds in Texas Children from Birth through 12 Years of Age

Background: For > 50 years, polyfluoroalkyl compounds (PFCs) have been used worldwide, mainly as surfactants and emulsifiers, and human exposure to some PFCs is widespread.Objectives: Our goal was to report PFC serum concentrations from a convenience sample of Dallas, Texas, children from birth to < 13 years of age, and to examine age and sex differences in PFC concentrations.Methods: We analyzed 300 serum samples collected in 2009 for eight PFCs by online solid phase extraction–high performance liquid chromatography–isotope dilution–tandem mass spectrometry.Results: Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were detected in > 92% of participants; the other PFCs measured were detected less frequently. Overall median concentrations of PFOS (4.1 ng/mL) were higher than those for PFOA (2.85 ng/mL), PFNA (1.2 ng/mL), and PFHxS (1.2 ng/mL). For PFOS, PFOA, PFNA, and PFHxS, we found no significant differences (p < 0.05) by sex, significantly increasing concentrations for all four chemicals by age, and significantly positive correlations between all four compounds.Conclusions: We found no significant differences in the serum concentrations of PFOS, PFOA, PFNA, and PFHxS by sex, but increasing concentrations with age. Our results suggest that these 300 Texas children from birth through 12 years of age continued to be exposed to several PFCs in late 2009, years after changes in production of some PFCs in the United States.

Biomarkers of exposure to triclocarban in urine and serum

3,4,4′-Trichlorocarbanilide (triclocarban, TCC) is widely used as an antimicrobial agent in a variety of consumer and personal care products. TCC is considered a potential endocrine disruptor, but its potential toxic effects in humans are still largely unknown. Because of its widespread uses, the potential for human exposure to TCC is high. In order to identify adequate exposure biomarkers of TCC, we investigated the metabolic profile of TCC in adult female Sprague Dawley rats after administering TCC once (500 mg/kg body weight) by oral gavage. Urine was collected 0–24 h before dosing, and 0–24 h and 24–48 h after dosing. Serum was collected at necropsy 48 h after dosing. We identified several metabolites of TCC in urine and serum by on-line solid phase extraction-high performance liquid chromatography–mass spectrometry. We unambiguously identified two major oxidative metabolites of TCC, 3′-hydroxy-TCC and 2′-hydroxy-TCC, by comparing their chromatographic behavior and mass spectral fragmentation patterns with those of authentic standards. By contrast, compared to these oxidative metabolites, we detected very low levels of TCC in the urine or serum. Taken together these data suggest that in rats, oxidation of TCC is a major metabolic pathway. We also measured TCC and its oxidative metabolites in 50 urine and 16 serum samples collected from adults in the United States. The results suggest differences in the metabolic profile of TCC in rats and in humans; oxidation appears to be a minor metabolic pathway in humans. Total (free plus conjugated) TCC could serve as a potential biomarker for human exposure to TCC.