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Approximately 99.1% of South Koreans have access to drinkable tap water from river basins. Due to such a high access rate, the South Korean government has been running, since 2013, a long-term program for monitoring the quality of tap water for drinking. Under this program, the maximum allowed concentrations of N-nitroso-di-n-methylamine (NDMA) and N-nitrosomethylethylamine (NMEA) are defined and applied. In this study, the data from this monitoring program were used to investigate the changes in six N-nitrosamine substances in the finished water of 33 drinking water treatment plants (DWTPs) in South Korea from 2013 to 2020, based on time and location. The effect of the applied water treatment steps on the appearance of N-nitrosamines was analyzed. The excess cancer risk (ECR) due to the oral intake of these substances was assessed. The results before the maximum allowed concentrations of NDMA and NMEA were defined showed that the oral intake ECR of these substances exceeded the carcinogenesis risk of one per one million people per year. After the maximum allowed concentrations of the substances were applied, the concentrations of the substances in the finished water of the DWTPs significantly dropped. The drinking water treated through sand filtration, and then with granular activated carbon, showed the highest efficiency in preventing the appearance of NDMA. Considering the potency of N-nitrosamines in tap water for drinking, the levels of these substances in the finished water of DWTPs in South Korea should be continuously monitored.

This study investigates the adverse effects and the associated underlying mechanism of bisphenol S (BPS) exposure on reproductive endocrine activity in adult zebrafish. Fish were exposed for 21 days to different BPS concentrations (0, 8, 40, and 200 µg/mL) determined via the lowest observed adverse effect level (LOAEL, i.e., < EC15 = 250 µg/mL) for zebrafish embryos. Exposure to 200 µg/mL BPS in female zebrafish in the absence of vitellogenic oocytes or the presence of degenerated oocytes in the ovary significantly decreased the biosynthesis of hepatic vitellogenin (VTG) mRNA, while hepatic VTG mRNA in male fish abundance was significantly elevated (P

Chemical accidents have frequently occurred in South Korea as a result of the huge amount of chemicals being used in various industries. Even though fire accidents accounted for 71.9% of chemical accidents during 2008–2018 in South Korea, most ecological research and investigation has focused on leakage accidents since most fire or explosion gases are diffused out and disappear into the atmosphere. In this study, the possibility of soil contamination by toluene combustion is proposed. A fire simulation batch test was performed and identified the combustion by-products such as methylbenzene, ethylbenzene, ethynylbenzene, benzaldehyde, 1-phenyl-1-propyne, naphthalene, 2-methylindene using gas chromatography coupled with mass spectrometry (GC–MS). Naphthyl-2-methyl-succinic acid, a metabolic intermediate of naphthalene metabolism derived from the combustion product of toluene, was also discovered in field soil and the secondary metabolites such as streptomycin 6-phosphate, 3-Nitroacrylate, oxaloacetate using LC–MS. Moreover, Streptomyces scabiei, participating in naphthalene metabolism, was also discovered in filed soil (contaminated soil) using 16s rRNA sequencing. As a result, bacterial stress responses in field soil (contaminated soil) affected by gas cloud were identified by discovering metabolites relating to bacterial self-defense action such as fatty biosynthesis. This study draws a conclusion that soil can be polluted enough to affect bacteria by gas cloud and soil bacteria and can encounter stress for a long term even though toluene and its combustion products had already decomposed in soil.

This study investigated the effects of accidental contamination of soils with phenol, toluene, nitric acid, and hydrogen fluoride (HF) by simulating chemical leakage in the soil with/without rain and characterizing the resulting metabolites and microbial. In the case of acid leakage, pH and cation exchange capacity were decreased, and the content of fluoride ion was increased in case of HF leakage. Using mass spectrometry-based metabolomics analysis, phytosphingosine was detected as a distinguishing metabolite in soils contaminated with phenol and HF in rain conditions. Microbial communities were identified by 16s rRNA metagenome sequencing. Sphingomonas was one of the dominant species in soils contaminated with phenol and HF. These results suggest that phytosphingosine and Sphingomonas might be used as biomarkers to evaluate the status of soils contaminated with phenol or HF. Under simulated rain conditions, the species alpha-diversity index of soil microbes and the physicochemical properties of the soil indicated values close to those of the uncontaminated soil. Rain played an important role in the recovery of microbial and metabolic profiles after chemical accidents. Metabolic profiling and microbial community analysis can serve as a diagnostic tool for ecotoxicological research at chemical accident sites.

Airborne pathogens causing infectious diseases are often highly transmittable between humans. Therefore, an airborne pathogen-monitoring system capable of on-site detection and identification would aid tremendously in preventing and controlling the early stages of pathogen spread. Here, we describe an integrated sampling/monitoring platform for on-site and real-time detection of airborne viruses. We used MS2 bacteriophage and avian influenza virus (AIV) H1N1 to evaluate bioaerosol sampling and detection performance of the platform. Our results show that, within 20 min, aerosolized viruses can be detected using the signal of near-infrared (NIR)-to-NIR nanoprobes. The pretreatment of the sampling pad improved the transfer efficiency of MS2 viruses to the detection zone, compared to an untreated pad. Our platform could detect concentrations as low as 104.294 50% egg infectious dose (EID50)/m3 AIVs collected from a cloacal swab sample (104.838 EID50/mL). These results indicate that our sampling/monitoring platform could be applied for the early detection of biological hazards in various fields.

Phthalate exposure has been reported to be more associated with obesity in children than in adults. The concentration of di(2-ethylhexyl)phthalate (DEHP) was high temporal variability in spot urine, so additional tools of assessing DEHP exposure were required. Therefore, we used relative metabolite ratios (RMRs) as well as concentrations, and RMRs did not need to be corrected to the creatinine concentration. We aimed to evaluate the levels of urinary DEHP metabolites and their RMRs in obese children in South Korea, and to investigate the potential of RMRs for assessing the risks for childhood obesity. We analyzed the four urinary DEHP metabolites (mono-2-ethylhexyl phthalate (MEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP)) in 240 children aged 5–16 years, using isotope dilution GC-MS/MS. The children were placed into three groups (“normal weight,” “overweight,” and “obese”) according to body mass index (BMI) percentiles. We statistically compared the concentrations and RMRs of DEHP metabolites among these groups. The obese group had lower MEHP levels, and higher secondary metabolite (MEHHP, MEOHP, and MECPP) levels, than the normal weight group. DEHP metabolite levels did not differ significantly between the normal weight and obese groups, whereas RMRA2 (as the ratio of the molar concentrations of MEOHP to MEHHP) was found to be negatively associated with BMI percentile (β= −0.236, p

The aim of this study was to optimize the dispersive liquid–liquid microextraction (DLLME) parameters for simultaneous analysis through DLLME-gas chromatography–mass spectrometry (GC–MS) of six iodo-trihalomethanes, four haloacetonitriles, and one halonitromethane, which are residual disinfection products found in drinking water. Eleven disinfection by-product (DBPs) remaining in aqueous samples were extracted and concentrated using a simple, rapid, and environmentally friendly DLLME method, and then analyzed simultaneously by GC–MS. The optimized DLLME parameters were a sample volume of 5 mL, 100 μL of dichloromethane as the extraction solvent, 1 mL of methanol as the dispersion solvent, an extraction time of 60 s, and 1.5 g of sodium chloride for the salting out effect. The enrichment factor values obtained using the established DLLME-GC–MS method were 19.8–141.5, and the limit of detection and limit of quantification were 0.22–1.19 μg/L and 0.75–3.98 μg/L, respectively. The calibration curves had correlation coefficients (r2) of 0.9958–0.9992 in the concentration range of 0.5–40 μg/L, and they exhibited good linearity in quantitative analysis. This new method could be useful for analyzing eleven DBPs that remain in drinking water.

The chemical structures of perfluorinated compounds(PFCs) have unique properties such as thermal and chemical stability that make them useful components in a wide variety of consumer and industrial products. Two of these PFCs, perfluorooctane sulfonate(PFOS) and perfluorooctanoic acid(PFOA), have received attention and were the most commonly detected. In this study it was analyzed the concentrations of 8 PFCs in samples were collected from drinking water treatment plants for 5 years(2012-2016). PFOS and PFOA were also high concentration and frequency. The mean concentrations of PFOA and PFOS were detected 0.0026-0.0069 μg/L and 0.0009-0.0024 μg/L in samples from drinking water treatment plants. These were relatively lower or similar compared to PFOS concentrations in Osaka(Japan). In general, these levels are below health-based values set by international authoritative bodies for drinking water. These results will be serve as the first monitoring data for PFCs in drinking water and be useful for characterizing the concentration distribution and management of PFCs in future studies.

1,2,5,6,9,10-hexabromocyclododecane (HBCD) is a brominated flame retardant that is used worldwide in expanded and extruded polystyrene foam and simultaneously emitted to the environment. HBCD can easily accumulate in animals and humans and cause neurotoxicity, thyroid hormone disruption, and reproductive disorders. Therefore, it is essential to monitor the HBCD concentrations in foods and estimate the human exposure through the diet. In this study a total of 521 food samples from eight food categories were sampled and analyzed for their HBCD content. Based on consumption data, the average dietary intake of the general Korean population and specific subgroups was calculated. The highest levels of HBCD were found in fish and shellfish (0.47 ng g(-1) ww), and this was attributed to natural exposure to the contaminated marine environments and the HBCD bioaccumulation. In addition, the use of expanded polystyrene buoys in aquaculture was also found to be a potential source of HBCD in bivalves. The high solubility of α-HBCD in water and the persistence of this diastereomer compared to β- and γ-HBCD in biological tissues, led to higher accumulation of α-HBCD in animal-based foods. In contrast, the diastereomeric selectivity and lower metabolic capacity in plants compared with animals led to the predominance of γ-HBCD in plant-based foods. The dietary intake of HBCD was estimated to be 0.82 ng kg(-1) bw d(-1) in the general population and 2.89 ng kg(-1) bw d(-1) in children up to 5 years of age. The high HBCD intake in children was found to be a result of their lower body weight and their high consumption of milk and homemade Korean baby foods that usually contain fish.

This study aimed to investigate the effect of mono-(2-ethylhexyl) phthalate (MEHP), one of the major phthalate metabolites that are widespread in aquatic environments, on reproductive dysfunction, particularly on endocrine activity in adult male and female zebrafish. For 21 days, the zebrafish were exposed to test concentrations of MEHP (0, 2, 10, and 50 μg/mL) that were determined based on the effective concentrations (ECx) for zebrafish embryos. Exposure to 50 μg/mL MEHP in female zebrafish significantly decreased the number of ovulated eggs as well as the hepatic VTG mRNA abundance when those of the control group. Meanwhile, in female zebrafish, the biosynthetic concentrations of 17β-estradiol (E2) and the metabolic ratio of androgen to estrogen were remarkably increased in all MEHP exposed group compared with those in the control group, along with the elevated levels of cortisol. However, no significant difference was observed between these parameters in male zebrafishes. Therefore, exposure to MEHP causes reproductive dysfunction in female zebrafishes and this phenomenon can be attributed to the alteration in endocrine activities. Moreover, the reproductive dysfunction in MEHP-exposed female zebrafishes may be closely associated with stress responses, such as elevated cortisol levels. To further understand the effect of MEHP on the reproductive activities of fish, follow-up studies are required to determine the interactions between endocrine activities and stress responses. Overall, this study provides a response biomarker for assessing reproductive toxicity of endocrine disruptors that can serve as a methodological approach for an alternative to chronic toxicity testing.

Rapid and sensitive on-site detection of avian influenza virus (AIV) is the key for achieving near real-time surveillance of AIV and reducing the risk of dissemination. However, unlike the laboratory-prepared transparent buffer solutions containing a single type of influenza virus, distinction between real- and false- positive outputs and detection of low concentrations of AIV in stool specimens or cloacal swabs are difficult. Here, we developed a rapid and background-free lateral flow immunoassay (LFA) platform that utilizes near-infrared (NIR)-to-NIR upconversion nanoparticles (UCNPs) to yield a sensor that detects AIV nucleoproteins (NPs) from clinical samples within 20 min. Ca2+ as a heterogeneous dopant ion in the shell enhanced the NIR-to-NIR upconversion photoluminescence (PL) emission without inducing significant changes in the morphology of the UCNPs. In a mixture of opaque stool samples and gold nanoparticles (GNPs), which are components of commercial AIV LFA, the background signal of the stool samples masked the absorption peak of GNPs. However, UCNPs dispersed in the stool samples still show strong emission centered at 800 nm when excited at 980 nm, which enables the NIR-to-NIR upconversion nanoparticle-based lateral flow immunoassay (NNLFA) platform to detect 10-times lower viral load than a commercial GNP-based AIV LFA. The detection limit of NNLFA for LPAI H5N2 and HPAI H5N6 viruses was 102 and 103.5 EID50/mL, respectively. Moreover, the viruses were successfully detected within dark brown-colored samples using the NNLFA but not the commercial AIV LFA. Therefore, the rapid and background-free NNLFA platform can be used for sensitive on-site detection of AIV.

This study was aimed to examine the association the blood/urinary concentration of toxic metal (Hg, Pb, and Cd) with children’s dietary patterns. This cross-sectional study included 1026 school children aged 8–17 years. Dietary patterns were defined using factor loading scores for 108 foods from a Semi-Quantitative Food Frequency Questionnaire. A high blood Hg level was found in boys with a high score in the ‘fish’ pattern (p = 0.02), and in girls with a high score in ‘fruit’ pattern (p = 0.04). The concentration of Pb was related to the ‘imprudent’ pattern in high school boys (p = 0.02). The effect of the ‘vegetable’ pattern on high excretion of urinary Cd was observed in low grade elementary (p = 0.04) and middle school students (p

Trihalomethanes (THMs) are chemicals regulated by Environmental Protection Agency's first drinking water regulation issued after the passage of the Safe Drinking Water Act. Among THMs, iodotrihalomethanes (I-THMs) are produced by treating water containing iodides ion with chlorine or ozone. I-THMs are more carcinogenic and biotoxic than chlorinated or brominated THMs. The purpose of this study was to analyze of I-THMs in drinking water using the liquid-liquid extraction (LLE) method with various extraction solvents. The calibration curves ranged from 0.01 to 20 ng/mL and the correlation coefficient showed a good linearity of 0.99 or more. The method detection limit ranged from 0.01 to 0.10 ng/mL. The accuracy of the LLE method ranged from 99.43 to 112.40%, and its precision ranged from 1.10 to 10.36%. Good recoveries (71.35-118.60%) were obtained for spiked drinking water samples, demonstrating that the LLE method is suitable for the analysis of drinking water samples. Dichloroiodomethane, bromochloroiodomethane, and dibromoiodomethane were identified in drinking water collected from 70 places of water purification plants in Korea. The samples were classified by disinfection systems, regions, seasons, and water sources. The concentration of I-THMs in pre-/postchlorination facilities owing to excess chlorine usage was higher than in ozonization/postchlorination facilities. Moreover, the concentrations of I-THMs were high in the coastal region, because of the large amount of halide ions from the sea. There was no seasonal difference; however, the concentration of I-THMs in pre-/postchlorination facilities increased in spring and summer. The concentration of I-THMs in water sources was high in samples from the Geum River and the Yeongsan and Sumjin River. The concentration and detection frequency of I-THMs in Han River and Nakdong River were high in the coastal region, because of numerous pre-/postchlorination facilities and the abundance of halide ions from the ocean.

Pyrrolizidine alkaloids (PAs) are naturally occurring plant toxins associated with serious hepatic disease in humans and animals. In this study, rapid and sensitive analytical method was developed for the determination of 9 toxic PAs in popularly high lipid foodstuffs by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). PAs in lipid foodstuff were effectively purified by freezing lipid precipitation (FLP) and strong cation exchange (SCX)-solid-phase extraction (SPE). Especially, FLP could easily remove the large amounts of triacylglycerols in the lipid sample extract and effectively combine with SPE cleanup. During the FLP procedure, over 77% of the lipids in the foodstuff extracts were rapidly eliminated without any significant loss of the PAs with over 81% recovery. The elimination efficiency of lipids by FLP was tested with LC-atmospheric chemical ionization (APCI)-MS. For further purification, SCX-SPE cartridge could successfully purify PAs from the remaining interfering substances by the variation pH with 5% NH4OH in methanol. For precise quantification and confirmation of PAs in complicate sample matrices, appropriate transition ions in LC-MS/MS-multiple-ion reaction monitoring (MRM) mode were selected on the basis of MS/MS fragmentation pathways of PAs. The established analytical method was validated in terms of the linearity, limits of detection (LOD), and quantification (LOQ), precision, and accuracy. The method was deemed satisfactory by inter- and intra-day validation and exhibited both high accuracy and precision (relative standard deviation

Tryptophan (Trp) is an essential amino acid that plays an important role in protein synthesis and is a precursor of various substances related to diverse biological functions. An imbalance in Trp metabolites is associated with inflammatory diseases. The accurate and precise measurement of these compounds in biological specimens would provide meaningful information for understanding the biochemical states of various metabolic syndrome-related diseases, such as hyperlipidemia, hypertension, diabetes, and obesity. In this study, we developed a rapid, accurate, and sensitive liquid chromatography-tandem mass spectrometry-based method for the simultaneous targeted analysis of Trp and its related metabolites of the kynurenine (Kyn), serotonin, and tryptamine pathways in urine. The application of the developed method was tested using urine samples after protein precipitation. The detection limits of Trp and its metabolites were in the range of 0.01 to 0.1 μg/mL. The method was successfully validated and applied to urine samples from controls and patients with metabolic syndrome. Our results revealed high concentrations of Kyn, kynurenic acid, xanthurenic acid, and quinolinic acid as well as a high Kyn-to-Trp ratio (KTR) in patients with metabolic syndromes. The levels of urine Kyn and KTR were significantly increased in patients under 60 years old. The profiling of urinary Trp metabolites could be a useful indicator for age-related diseases including metabolic syndrome. ᅟ.

This study assessed the level of 24 polybrominated diphenyl ethers (PBDEs) in Korean foods following a Progressive Total Diet Study (TDS). The experiments comprised 96 types of dietetically representative foods, all were either cooked or edible raw. PBDEs were widely encountered in foodstuffs with the highest concentration in plant oils, fishes and shellfishes. Of all congeners tested for, BDE-47 was the most predominant and encountered in almost all food items except meats. The presence of nona-BDEs at significant levels indicated that Korean environments are still contaminated by deca-BDE. The daily dietary intake of PBDEs was estimated to be 63 ng d(-1). The highest PBDEs intake was observed in the 19-39 year old group and gradually decreased as age increased. Our study suggests that the TDS approach using foods in the table-ready form should be used for a better estimation of dietary exposure to PBDEs.

Alkoxyalcohols are used as solvents or preservatives in various consumer products such as wet wipes. The metabolites of alkoxyalcohols are known to be chronically toxic and carcinogenic to animals. Thus, an analytical method is needed to monitor alkoxyalcohols in wet wipes. The aim of this study was to develop a simultaneous analytical method for 14 alkoxyalcohols using headspace gas chromatography coupled with mass spectrometry to analyze the wet wipes. This method was developed by comparing with various headspace extraction parameters. The linear calibration curves were obtained for the method (r 2 > 0.995). The limit of detection of alkoxyalcohols ranged from 2 to 200 ng mL �1 . The precision of the determinative method was less than 18.20% coefficient of variation both intra and inter days. The accuracy of the method ranged from 82.86% to 119.83%. (2-Methoxymethylethoxy)propanol, 2-phenoxyethanol, and 1-phenoxy-2-propanol were mainly detected in wet wipes.

Phthalates are used in industry products, household items, and medical tools as plasticizers. Human exposure to phthalates has raised concern about its toxicity. In the present study, optimization was conducted for the simultaneous analysis of eight kinds of phthalate metabolites using gas chromatography-mass spectrometry (GC-MS): MEP, MiBP, MnBP, MBzP, MiNP, MEHP, MEOHP, and MEHHP. In order to minimize the matrix effect and to do quantitative analysis, isotope dilution and LLE-GC-MS methods were performed. Urine samples were enzymatically hydrolyzed, extracted with a mixture of n-hexane and ethyl ether (8:2; v:v), and subsequently derivatized with trimethylsilylation. All eight kinds of analytes showed clear resolution and high reproducibility in GC-MS results. The method detection limit ranged from 0.05 ng/mL to 0.2 ng/mL. Calibration curves were found to be linear from 0.2 to 100 ng/mL with -(2)>0.992. The relative standard deviation of the intraday precision using water and urine ranged from 2.1% to 16.3%. The analysis was performed with urine samples that were collected from adults residing in the Republic of Korea. The analyzed concentration results were compared according to gender and region. As a result, DEHP metabolites showed the highest detected concentration (75.92 μg/g creatinine, 100%), and MiNP, a metabolite of DiNP, showed the lowest detected concentration (0.42 μg/g creatinine, 22.5%). On average, female urine (200.76 μg/g creatinine) had a higher detected concentration of ∑8 phthalate metabolites than male urine. Samples from rural regions (211.96 μg/g creatinine) had higher levels than samples from urban regions.

In this study, total mercury and methyl mercury in whole blood of Korean was analyzed so as to investigate the correlation between total mercury (T-Hg) and methyl mercury (Me-Hg). 4000 whole blood samples were divided in four groups, according to T-Hg concentration in percentile: group I (p25-p50), group II (p50-p75), group III (p75-p95) and group IV (p95-p100). 100 samples were randomly selected from the each group, and Me-Hg concentration was measured. T-Hg concentration in whole blood was analyzed using a Direct Mercury Analyzer-80 and obtained limit of detection (LOD) was 0.2 µgL �1 . Me-Hg concentration was analyzed with ethylate derivatization using headspace-gas chromatography-mass spectrometry, and obtained LOD of methyl mercury was 0.5 µgL �1 . The geometric means of T-Hg and Me-Hg were 6.35 µgL �1 and 4.44 µgL �1 , respectively, and 71.91% of T-Hg was presented as Me-Hg.

Di(2-ethylhexyl) phthalate (DEHP) is one of the common phthalate plasticizers used primarily in soft polyvinyl chloride, which is a plastic polymer that makes up the total weight of goods from 1% up to 40% in many consumer products. The aims of this study were to examine the urinary DEHP metabolites in South Korean children and to investigate the correlation between mother and child DEHP urine excretion. Three kinds of urinary DEHP metabolites: mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (5-OH-MEHP) and mono(2-ethyl-5-oxohexyl) phthalate (5-oxo-MEHP), were analyzed. The total of 954 samples (nChildren=392, nMothers=265, nAadults=297), including 258 mother and child pairs, were analyzed using isotope dilution gas chromatography–mass spectrometry. Many studies present higher concentration of DEHP metabolites detected from adults in reproductive age than adults in other ages. Therefore, adults who are age-matched to mothers were evaluated to serve as a standard of comparison against mothers. All statistical analysis was made by adjusting detected volume concentrations (μg/L) with respect to creatinine concentrations (mg/dL) since urinary DEHP metabolites were studied using human reference. The difference in median levels of sum of urinary DEHP metabolites was only significant when children were analyzed in relation to region (p-value≤0.005). Among the three DEHP metabolites, only MEHP of children was significantly correlated to that of paired mothers (p-value≤0.01). The present paper defines the relative metabolic rate (RMR) of DEHP metabolism for the first time in study on phthalates. Children had faster RMR than mothers and adults, specifically in the first step of DEHP metabolism (RMR1: MEHP hydroxylation to 5-OH-MEHP), and RMR1 of children between 1 and 24 months was the fastest. The above results may be used to study and assess human health risk from DEHP exposures, especially among mothers and children in Korea. Keywords: DEHP metabolites, Human exposure, Children, Biomonitoring

We investigated the effects of different grilling tools, temperatures, and tea marinades on the formation of benzo[a]pyrene in grilled pork belly as well as the antioxidant capacities of tea marinades. The least amount of benzo[a]pyrene was detected in modified charcoal-grilled pork belly (1.28μg/kg). The highest risk factors for the formation of benzo[a]pyrene are direct contact with flames and fat excess on the heating source. A modified charcoal grill can be used as an alternative grilling tool to meet consumer needs for safety and taste. The marination of pork bellies with tea increased radical-scavenging activity and prevented lipid oxidation in proportion to the concentration of tea infusion and marinating time. The yerba mate tea marinade significantly increased the radical-scavenging activity and prevented benzo[a]pyrene formation more than the green tea marinade. Tea marinade can be applied to seasoning or sauce as pretreatment to preserve the quality of meat and to decrease benzo[a]pyrene formation during cooking.

Department of Environmental Health, Korea University, Seoul 136-701, KoreaReceived October 15, 2011, Accepted September 4, 2012Headspace (HS) and headspace solid-phase microextraction (HS-SPME) were studied for extracting volatileorganic compounds (VOCs) from whole blood, with chemical and instrumental variables being optimized formaximum sensitivity: incubation at 60 °C, equilibration for 30 min, pH 11, and 2 mL injection volume. Bothtechniques provided accurate analyses, with detection limits of 0.05-0.1 ng mL

Objective We assessed the associations of percentage fractions of urinary di(2-ethylhexyl) phthalate (DEHP) metabolites with obesity and insulin resistance in Korean girls. Methods In total, 137 girls, aged 6 to 13 years (65 overweight cases and 72 controls), were recruited. Anthropometric indices and the homeostatic model assessment of insulin resistance (HOMA-IR) index were determined. Four major urinary DEHP metabolites were analyzed in spot urine samples by gas chromatography-tandem mass spectrometry, including mono(2-ethylhexyl) phthalate, mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono(2-ethyl-5-carboxypentyl) phthalate. Results There were no significant differences in the urinary concentrations of the DEHP metabolites between the overweight and control groups. The percentage fraction of MEHHP (MEHHP%) among all DEHP metabolites was significantly higher in the overweight prepubertal girls than in the controls (P = 0.035). MEHHP% was positively associated with the body mass index percentile, waist circumference, body fat percentage, and HOMA-IR index in the prepubertal girls. After adjusting for covariates, the prepubertal girls in a higher MEHHP% quartile were found to have a higher odds ratio for central obesity than those in a lower quartile (odds ratios: 5.05 for quartile 3; 7.30 for quartile 4). The relative rate of MEHHP oxidation to MEOHP was negatively associated with the body mass index percentile and waist circumference in the prepubertal girls. However, no such association was observed in the pubertal girls. Conclusions MEHHP% was positively associated with obesity and insulin resistance in prepubertal girls. Further studies are necessary to elucidate the causal links between altered phthalate metabolism and increased susceptibility to insulin resistance in children.

Perfluorinated compounds have characteristics of resistance to heat, acidic, basic conditions and also resist water, oil, grease, pollutant. Futhermore they are used by various industrial material, nowadays, they produced in large scale for indutrial and commercial areas. However, they also resist metabolizing and degrading in environmental system (plant, animal, even human body). Moreover, in animal`s bodies, PFCs can be accumulated in organ (eg; liver) and lead to liver cell necrosis even oncogenesis. Perfluorinated compounds are newly registered as new persistent organic pollutants (POPs) on Stockholm convention in 2009. Therefore necessity for analytical methodology for determination of PFCs in various environmental samples is even more increased. This study discussed sample preparation and instrumental conditions for the analysis of PFCs in environmental and biota samples.

The bioequivalence of two cyclosporine A (CyA) 100 mg soft capsules (Chong Kun Dang's as the test drug; Korea Novartis' Sandimmun as the reference drug) was assessed in healthy male Korean volunteers after oral administration of 200 mg CyA according to a randomized crossover design. The whole blood samples were analyzed for the determination of parent CyA in the blood by using a validated HPLC/diode array detector method. The mean values for reference and test products were and , respectively. The mean values were for the reference product, and for the test product. was for the reference and for the test product. The differences of , and were -3.35, -13.28 and +10.63%, respectively. The point estimates and 90% confidence intervals for and were 0.981 (0.9171 to 1.0514) and 0.876 (0.8229 to 0.9336), respectively. Based on the pharmacokinetic and statistical data, we conclude that these two products are bioequivalent and can be considered interchangeable in the medical practice.

A sensitive and simple method of determining the plasma levofloxacin (LFX, CAS 100986-85-4) concentrations in human volunteers by liquid-liquid extraction were developed and validated by using a high-performance liquid chromatography/diode array detector. The method was also applied to pharmacokinetic study of LFX. LFX was orally administered to 8 healthy male Korean volunteers at single lowest dose of 200 mg, compared to the published reports in which more than 500 mg of LFX was orally administered. LFX in human plasma was determined. The detection limit of LFX was . value was . } and were and , respectively. The terminal half-life was . Our pharmacokinetic parameters were very consistent with that previously reported, showing good correlation between LFX doses and AUC (). This method can be useful for the pharmacokinetics and bioequivalence study with relatively low dose for reducing the main side effects of LFX.

An analytical method has been developed for measuring chlorostyrenes in fish tissue sample. Extraction of chlorostyrenes from fish tissue was carried out by ultrasonication using acetone/n-hexane (5:2, v/v) mixture. Most of the lipids in the extract were eliminated by freezing-lipid filtration, prior to solid-phase extraction (SPE) cleanup. During freezing-lipid filtration, about 90% of the lipids extracted from the fish samples were easily removed without any significant losses of chlorostyrenes. For purification, SPE using Florisil was used for the rapid and effective cleanup. Quantification was performed using gas chromatography-mass spectrometry in the selected ion monitoring mode. Spiking experiments were carried out to determine the recovery, precision, and limits of detection (LODs) of the method. The overall recovery was above 80% in the spiked fish tissue sample at 10 and 100 ng/g levels, respectively. The detection limits for chlorostyrenes were ranged from 0.05 to 0.1 ng/g. This developed method is demonstrated to give efficient recoveries and LODs for detecting chlorostyrenes spiked into fish tissue with high lipid content.

3-Monochloro-1,2-propanediol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) are not only produced in the manufacturing process of foodstuffs such as hydrolyzed vegetable proteins and soy sauce but are also formed by heat processing in the presence of fat and low water activity. 3-MCPD exists both in free and ester forms, and the ester form has been also detected in various foods. Free 3-MCPD and 1,3-DCP are classified as Group 2B by the International Agency for Research on Cancer. Although there is no data confirming the toxicity of either compound in humans, their toxicity was evidenced in animal experimentation or in vitro. Although few studies have been conducted, free 3-MCPD has been shown to have neurotoxicity, reproductive toxicity, and carcinogenicity. In contrast, 1,3-DCP only has mutagenic activity. The purpose of this study was to analyze 3-MCPD and 1,3-DCP in various foods using gas chromatography -mass spectrometry. 3-MCPD and 1,3-DCP were analyzed using phenyl boronic acid derivatization and the liquid–liquid extraction method, respectively. The analytical method for 3-MCPD and 1,3-DCP was validated in terms of linearity, limit of detection (LOD), limit of quantitation, accuracy and precision. Consequently, the LODs of 3-MCPD and 1,3-DCP in various matrices were identified to be in the ranges of 4.18~10.56 ng/g and 1.06~3.15 ng/g, respectively.

A simple and specific method for determination of methyltestosterone (MT) has been established by a gas chromatography/mass selective detector and applied in plasma of healthy male volunteers received a single oral dose of 50 mg MT for bioavailability test. This method involves using liquid-liquid extraction of the sample with diethyl ether and derivatization with MSTFA. MT showed good resolution in this condition. The detection limit of quantitation was 5 ng/ml. A good linearity (r>0.996) was obtained at the range of 5-250 ng/ml of MT. Intra-day precision and accuracy were 2.76-12.56% and 0.39-8.01 %, and inter-day precision and accuracy were 2.29-17.69% and 0.42-7.99%, respectively. The established method was applied on bioavailability test of MT in human volunteers. The value of to last was and that of was determined to be . The values of and were and , respectively. The mean elimination half-life was . This analytical method is suitable and useful for the pharmacokinetics and bioequivalence studies of MT.

The objective of this study was to develop an assay for mequitazine (MQZ) for the study of the bioavailability of the drug in human subjects. Using one mL of human plasma, the pH of the sample was adjusted and MQZ in the aqueous phase extracted with hexane; the organic layer was then evaporated to dryness, reconstituted and an aliquot introduced to a gas chromatograph/mass spectrometer (GC/MS) system with ion-trap detector. Inter- and intra-day precision of the assay were less than 15.1 and 17.7%, respectively; Inter- and intra-day accuracy were less than 8.91 and 18.6 %, respectively. The limit of quantification for the current assay was set at 1 ng/mL. To determine whether the current assay is applicable in a pharmacokinetic study for MQZ in human, oral formulation containing 10 mg MQZ was administered to healthy male subjects and blood samples collected. The current assay was able to quantify MQZ levels in most of the samples. The maximum concentration (Cmax) was 8.5 ng/mL, which was obtained at 10.1 h, with mean half-life of approximately 45.5 h. Under the current sampling protocol, the ratio of AUCt--last to AUCt--infinity was 93.4%, indicating that the blood collection time of 216 h is reasonable for MQZ. Therefore, these observations indicate that an assay for MQZ in human plasma is developed by using GC/MS with ion-trap detector and validated for the study of pharmacokinetics of single oral dose of 10 mg MQZ, and that the current study design for the bioavailability study is adequate for the drug.

A convenient and simple method for the analysis of 1,4-dioxane in water was developed by liquid–liquid extraction combined with gas chromatography/mass spectrometry and applied to the water samples in Korea. Evaluation of the liquid–liquid extraction method was demonstrated by comparing with two extraction methods, which were solid-phase extraction and purge and trap method. They were referred to the standard methods for the examination of water in Japan and U.S. EPA methods. Liquid–liquid extraction was conducted by using methylene chloride and sodium chloride. This method was combined with gas chromatography/mass spectrometry. Recoveries showed in the range from 86 to 102% with relative standard deviation of 3.0 to 5.2%. The correlation coefficient of the linear regression curve was above 0.99 and method detection limit of 1,4-dioxane was 0.2 ng mL −1 for 20 mL of water sample. The precision and accuracy were obtained within error rate of 9%. 1,4-Dioxane was detected in the treated water and raw water near Nakdong River from 0 to 240.0 ng mL −1 . It has surveyed constantly with the national problem in Korea. The developed method may be suitable to analyze and observe 1,4-dioxane regularly.

A sensitive and solvent-free procedure for the determination of hydroxy metabolites of polychlorinated biphenyls (PCBs) in urine samples was studied using solid-phase microextraction (SPME) followed by on-fiber silylation and gas chromatography/mass spectrometry (GC/MS) determination. The analytical procedure involved headspace adsorption with coated fiber and headspace derivatization with bis(trimethylsilyl)-trifluoroacetamide (BSTFA) in a sample vial. Experimental SPME parameters such as selection of coating material, addition of salt, extraction time and temperature of adsorption were optimized. The optimum extraction conditions for hydroxy-PCBs were obtained with a polydimethylsiloxane/divinylbenzene (PDMS/DVB) coated fiber at 90 °C for 60 min in urine, added 10% sodium chloride. Derivatization of the hydroxy-PCBs with BSTFA was performed on the SPME fiber at 60 °C for 10 min. The calibration curves for derivatized forms showed good linearity in the range of 0.01–10 ng mL−1 and method detection limits proved to be 0.01–0.1 ng mL−1 in 2 mL of urine.

A sensitive derivatization and extraction method is proposed for the determination of hydroxy-PCBs in urine. Phenolic hydroxyl groups of PCBs were allowed to react with five different reagents such as iodomethane, iodoethane, iodopropane, BSTFA and MTBSTFA. Propylated products at 100 °C for 30 min showed the best sensitivity with mass selective detector. Extraction recoveries and relative standard deviations of hydroxy-PCBs by SPE using C2 column were in the range of 78.0–112.3% and 2.5–9.6%, respectively. Instrumental detection limits for derivatized hydroxy-PCBs were in the range of 1–2 pg and were 10–1000 times more sensitive than those of non-derivatized hydroxy-PCBs. The correlation coefficients of the linear regression curves exceed 0.99, and the intra- and inter-day precisions were evaluated by RSDs within 10% at the concentrations of 0.4 and 4.0 ng/mL.

Bioanalysis and Biotransformation Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, KoreaReceived June 15, 2004A gas chromatography/mass spectrometric assay method was developed for the determination of persistentorganochlorine pollutants (POPs) in hair. For the exact extraction study was used hair of rat exposed withPOPs. Sonication of the hair matrix with 3 M HCl solution in methylene chloride of the extraction methodsstudied was the most efficient and rapid sample prepar ation method. After sonication of rat hair was achievedclean up with a solid phase extraction procedure using silica gel-florisil. Elution was performed with 8 mL ofmethylene chloride. The eluate was concentrated to approximately 100 µL and analyzed by gaschromatography-mass spectrometry (GC-MS). Detection limits of POPs were in the concentration range of0.6-1.2 ng/g in rat hair. Aldrin, dieldrin, p,p-DDT and mi rex were dosed rat for 4 weeks at concentration of 0.01mg/L in drinking water and detected in rat hair at concentration of 2.8, 11.3, 7.9 and 15.6 ng/g, respectively.Aldrin and p,p-DDT were metabolized to dieldrin and p,p-DDE, which were detected in concentration of 9.7and 2.9 ng/g in rat hair, respectively. The developed method may be valuable to be used to analyze POPs inhuman hair.Key Words : Persistent organochlorine pollutants, Hair, Sonication, Gas chromatography/mass spectrometryIntroductionThe chlorinated pesticides named as persistent organicpollutants (POPs) bioaccumulate in the food chain due totheir lipophilicity and persistence, and they have become amajor issue of research in order to investigate theirubiquitous environmental occurrence, biochemical and toxiceffects, human exposure and health risk assessment.

An analytical method the determination of benzo(a)pyrene (BaP) and its hydroxylated metabolites, 1hydroxybenzo(a)pyrene (1-OHBaP), 3-hydroxybenzo(a)pyrene (3-OHBaP), benzo(a)pyrene-4,5-dihydrodiol (4,5-diolBaP) and benzo(a)pyrene-7,8-dihydrodiol (7,8-diolBaP), in rat urine and plasma has been developed by HPLC/FLD and GC/MS. The derivatization with alkyl iodide was employed to improve the resolution and the detection of two mono hydroxylated metabolites, 1-OHBaP and 3-OHBaP, in LC and GC. BaP and its four metabolites in spiked urine were successfully separated by gradient elution on reverse phase ODS C 18 column (4.6 mm I.D., 100 mm length, particle size 5 μm) using a binary mixture of MeOH/H2O (85/15, v/v) as mobile phase after ethylation at 90 o C for 10 min. The extraction recoveries of BaP and its metabolites in spiked samples with liquid-liquid extraction, which was better than solid phase extraction, were in the range of 90.3101.6% in n-hexane for urine and 95.7-106.3% in acetone for plasma, respectively. The calibration curves has shown good linearity with the correlation coefficients (R 2 ) varying from 0.992 to 1.000 for urine and from 0.996 to 1.000 for plasma, respectively. The detection limits of all analytes were obtained in the range of 0.010.1 ng/mL for urine and 0.1-0.4 ng/mL for plasma, respectively. The metabolites of BaP were excreted as mono hydroxy and dihydrodiol forms after intraperitoneal injection of 20 mg/kg of BaP to rats. The total amounts of BaP and four metabolites excreted in dosed rat urine were 3.79 ng over the 0-96 hr period from adminstration and the excretional recovery was less than 0.065% of the injection amounts of BaP. The proposed method was successfully applied to the determination of BaP and its hydroxylated metabolites in rat urine and plasma for the pharmacokinetic studies.

The profiling analysis of biogenic amines, including catecholamines and serotonin, and their metabolites in mouse brain tissue provides an important key to understanding their roles in the body and the possibility of simple and accurate diagnosis of neural diseases. A novel approach in the analysis of biogenic amines and their acidic metabolites in brain tissue using gas chromatography-tandem mass spectrometry (GC-MS/MS) is presented. Biogenic amines and their acidic metabolites in brain tissue were effectively separated using a mixed-cation-exchange solid-phase extraction (MCX-SPE) cartridge with a variation in the composition of the SPE elution solvents. A selective derivatization with hexamethyldisilazane (HMDS) and N-methyl-bis-heptafluorobutyramide (MBHFBA) was used to increase the detection sensitivity and to prevent the formation of any side-products. The identification and quantification of the target analytes were performed by gas chromatography triple quadrupole mass spectrometry (GC-MS/MS) using multiple ion reaction monitoring (MRM) mode. The overall recovery yields of the biogenic amines and their metabolites were above 87.5% at 10ng/g and 92.4% at 100ng/g of spiking concentration range. The isotopic-labeled internal standards were used for the precise quantification of bioamines and their metabolites. The calibration curves for the biogenic amines and their metabolites obtained through GC-MS/MS were linear (r(2)>0.995) over the concentration range of 1 (2 or 3)-200ng/mL. The present method was reproducible (relative standard deviation range 0.6-9.3%) and accurate (range 85.4-107.9%), with LLOQs of 0.71-3.69ng/mL. The developed method was successfully applied to the determination and quantification of bioamines and their metabolites in rat brain tissue samples.

Bisphenol-A (BPA) possesses estrogenic properties both in vitro and in vivo as an endocrine disrupting chemical. Humans experience a long-term and cumulative exposure to BPA. BPA was detectable in 97.3% of 1904 urine specimens from Korean adults. We investigated urinary estrogen concentrations in subjects with low and high BPA concentrations and its possible association with estrogen metabolism. Urine samples were collected from a high BPA concentration group (BPA-H; n=100, 11.05 ± 20.47 μg/g creatinine) and a low BPA concentration group (BPA-L; n=100, 0.70 ± 0.22 μg/g creatinine) from Korea Biomonitoring Program of Hazardous Materials Survey 2009-2010. Urinary estrogens were enzymatically hydrolyzed, extracted, and then derivatized for quantitative analysis by gas chromatography-mass spectrometry. Estrogen levels were higher in the BPA-H group than in the BPA-L group. Concentrations of estrone, 17β-estradiol, and their hydroxylated metabolites in both men and women were significantly higher in the BPA-H group than in the BPA-L group (p0.04). Furthermore, in the BPA-H group, estrogen metabolism to 4-hydroxy-estrone and 4-hydroxy-17β-estradiol was more active than that to 2-hydroxy-estrone and 2-hydroxy-17β-estradiol. Although single measurement and/or single spot urine samples limit the measurement of long-term exposure to BPA, we found significant differences of estrogen metabolism in the BPA-H and the BPA-L groups. The increase of hydroxyestrogens, especially 4-hydroxyestrogens, can be an important factor resulting negative effects of prolonged exposure to BPA.

Mercury (Hg) is a nonessential and toxic metal that is widely distributed in the environment. This study was performed to estimate the representative blood Hg level, to determine the contributing factors to Hg exposure, and to analyze the association of blood Hg with metabolic syndrome in Korean adults. Mercury exposure is assessed by total Hg concentration in blood. A total of 2,114 healthy adults who have not been exposed to Hg occupationally were sampled by the multistaged, sex-, and age-stratified probability method. Information was collected regarding the subjects’ demographic characteristics, lifestyles, and past medical history. The participants then underwent physical examination and blood sampling. The geometric mean concentration of Hg in whole blood was 3.90 μg/L, which was significantly influenced by sex, age, smoking, alcoholic consumption, residence area, and seafood intake after adjustment for confounders. Significant increases in body mass index, waist circumference, diastolic blood pressure, total cholesterol, and triglyceride were observed according to the blood Hg levels after adjustment for covariates. Also, Hg exposure was significantly associated with metabolic syndrome and their components such as obesity and increased fasting glucose. The blood Hg level in Korean adults is higher than that in USA and other Western countries, while it is similar to or lower than that in other Asian countries. The blood Hg level is influenced by sociodemographic factors and individual lifestyles including dietary habits. Furthermore, blood Hg is associated with metabolic syndrome, in which Hg exposure may play a role as a possible risk factor for cardiovascular diseases.

Persistent organochlorine pesticides (OCPs) are well known to accumulate in environment and to instigate disruptions in endocrine system. In the present study, 18 kinds of OCPs were bio-monitored from 1904 adult serums. Analysis was performed with headspace gas chromatography (HS-GC) which has the advantage to require small volume of serum (1mL) without complex pretreatment and (13)C isotope labeled internal standard mix was used for quantitation. As a result, eleven out of 18 OCPs, including hexachlorobenzene (HCB) and dichlorodiphenyltrichloroethane metabolites (DDTs) were detected. HCB was the most frequently detected OCP (8.0%) with an average concentration of 1.74ngg(-1) lipid (2.10ngg(-1) lipid-99.80ngg(-1) lipid). p,p'-Dichlorodiphenyldichloroethylene (p,p'-DDE) had the highest average concentration of 21.65ngg(-1) lipid (12.80ngg(-1) lipid-2270ngg(-1) lipid) and was detected from 7.5% of serum samples. The average concentration of ∑DDT metabolites was 32.04ngg(-1) lipid (6.61ngg(-1) lipid-2800ngg(-1) lipid) with detection frequency of 9.0%. Results interpreted with respect to age groups showed increase in ∑OCPs and ∑DDTs concentrations as age increases, except for the 20. Results interpreted with respect to gender, in general, illustrated higher detected concentration of OCPs in male serums than in female serums; however, the result trend was reversed in age group of the sixties. The above results will be applicable to health impact assessment of Koreans in relation to environmental contaminations.

An analytical method for the determination of organochlorine pesticides (OCPs) in sediment samples involves ultrasonic extraction, solid-phase extraction (SPE), gas-chromatography (GC)/electron-capture detection (ECD), and GC/mass spectrometry (MS). OCPs were extracted from sediment samples by ultrasonication in mixtures of n-hexane and acetone. Several SPE sorbents [Florisil, silica gel, C18, Oasis HLB, and graphitized carbon black (GCB)] were evaluated as means of preliminary purification. GCB SPE cartridges successfully removed major contaminants such as non-polar hydrocarbons when eluted with an acetone-acetonitrile mixture. After purification, the extract was preferentially screened using GC/ECD and confirmed and quantified using GC/MS. The percentage recovery of samples spiked with 10 or 100ng/g OCP ranged from 73.9% to 106.0% with a relative standard deviation of 0.4-5.7%. Detection limits ranged from 0.002 to 0.005ng/g for GC/ECD and from 0.03 to 0.50ng/g for GC/MS detection. The linear dynamic range extended from 0.2 to 20ng/g, with a correlation coefficient (R(2)) greater than 0.995. The method was validated using a standard reference material (SRM 1941b) and spiked sediment samples. Real sediment samples collected from a river near a Korean industrial area exhibited low levels of several OCPs when analyzed using this method.

The simultaneous analysis of diuretic agents by reversed-phase liquid chromatography with a diode-array detector (DAD) was performed by using a gradient elution with acetonitrile and phosphate buffer on a Hypersil-ODS column. For the spiked urine the extraction recovery of solid-phase extraction (SPE) using Sep-Pak C18 cartridge was compared with that of liquid-liquid extraction (LLE) with diethyl ether at various pH. The standard calibration curves were linear from 0.20-20.0 micrograms/mL for all diuretic agents except amiloride, 1.0-20.0 micrograms/mL, and the detection limit was about 0.2 micrograms/mL for 3 mL of urine, except that of amiloride, which was 1.0 micrograms/mL. The confirmation analysis was performed by gas chromatography/mass spectrometry (GC/MS) following methylation. The characteristic mass fragment ions obtained by electron-impact (EI) ionization (70 eV) provided identification of each diuretic agent.

This study examines a novel sample preparation method for the determination of 11 hydroxy metabolites of polychlorinated biphenyls (PCBs) in plasma and organ tissues, followed by gas chromatography with mass spectrometric detection (GC/MS). The clean-up method was optimized to eliminate the interference matter by using a silica column and 10 mL of n-hexane/dichloromethane (4:6, v/v) as an eluent. Solid-phase and solvent extraction procedures were used for the plasma and tissues samples, respectively. Compared to C(18) and C(8) solid-phase, C(2) showed higher extraction efficiency with n-hexane as the eluent for plasma. The hydroxy-PCB extraction recoveries achieved with this combined extraction and clean-up procedure from plasma ranged from 87 to 117%, while those from tissues ranged from 82 to 111%. The linear detector responses for propyl derivatives of hydroxy-PCBs were obtained with the coefficients of determination varying from 0.992 to 0.998 in the concentration range of 0.1-20 ng mL(-1). The method detection limits ranged from 0.1 to 0.5 ng mL(-1) in 1 mL of plasma and from 0.1 to 0.5 ng g(-1) in 1g of tissues. This procedure was successfully applied to the study of 3-OH-2,3',4,4',5-PeCB in rat plasma and liver samples after intraperitoneal injection (20 mg/kg) of 2,3',4,4',5-PeCB.

The use of stable, isotopically labeled compounds in controlled exposure experiments at environmentally relevant levels allows for the distinguishing of urinary metabolites associated with known exposure from background levels generally present in the urine. Exposures of volunteers to (13)C-benzene for 2 h at 40+/-10 p.p.b. were conducted after obtaining informed consent, and urinary phenol, catechol, hydroquinone and trans,trans- muconic acid were measured. Each isotopically labeled urinary metabolite was determined in the presence of significantly higher concentrations of the unlabeled metabolite. Following exposure, free and acid hydrolyzed phenol, acid hydrolyzed catechol and hydroquinone, and free trans,trans-muconic acid were determined by GC/MS. The percentage of trans,trans-muconic acid excreted was higher than reported following exposure at occupational levels. The use of isotopically labeled compounds has the potential to investigate the metabolism of common environmental contaminants for validation of toxicokinetic models and improve risk extrapolation from high concentration occupational exposures and animal studies to environmentally relevant pollutant levels.

A new technique is proposed for the determination of bisphenol A in environmental water. The sample preparation consists of a single-step extraction of bisphenol A from a water sample with methylene chloride and the cyanomethyl derivatization of bisphenol A. 2,2'-Biphenol is used as an internal standard. Bisphenol A and biphenol can be quantitatively converted to their corresponding cyanomethyl ethers, which are then measured by gas chromatography with nitrogen-phosphorus detection. Peak shape and quantification of bisphenol A are excellent, with linear calibration curves over a range of 0.1-100 ng/ml. The detection limit is 0.1 ng/ml in water samples. The average recovery and RSD at a concentration of 5 ng/ml are 89.3 and 4.5%, respectively. The procedure is applicable to the quantification of bisphenol A in tap water, raw water and stream water.

The pharmacokinetics and metabolism of synthetic 2-hydroxymesocarb and 4-methyl-2-hydroxymesocarb analyzed by HPLC-DAD and thermospray LC-MS were studied in rats. Multistep liquid-liquid extraction (LLE) was used with diethyl ether at pH 7.0. The major metabolites of 2-hydroxymesocarb in both urine and plasma of the rat were the p-hydroxylated derivative of the phenylcarbamoyl group of the parent drug. The metabolites of 4-methyl-2-hydroxymesocarb in urine of rats may be the oxidized forms at the phenylcarbamoyl group of the parent drug. Absorption (ka) and elimination (ke) rate constants in plasma of 2-hydroxy-mesocarb were 0.0300 and 0.00485 min−1, respectively; those of 4-methyl-2-hydroxy-mesocarb were 0.0546 and 0.00797 min−1, respectively. The half-lives (t 1 3 ) of 2-hydroxymesocarb and 4-methyl-2-hydroxymesocarb in plasma were 144 and 86 min, respectively.