Occurrence, temporal trends, and half-lives of perfluoroalkyl acids (PFAAs) in occupational workers in China.

Paired serum and urine samples were collected from workers in a fluorochemical plant from 2008 to 2012 (n = 302) to investigate the level, temporal trends, and half-lives of PFAAs in workers of a fluorochemical plant. High levels of perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), and perfluorooctanesulfonate (PFOS) were detected in serum with median concentrations of 764, 427, and 1725 ng mL-1, respectively. The half-lives of PFAAs in workers were estimated by daily clearance rates and annual decline rates of PFAAs in serum by a first-order model. The geometric mean and median value for PFHxS, PFOA, and PFOS were 14.7 and 11.7, 4.1 and 4.0, 32.6 and 21.6 years, respectively, by the daily clearance rates, and they were 3.6, 1.7, and 1.9 years estimated by annual decline rates. The half-lives estimated by the limited clearance route information could be considered as the upper limits for PFAAs, however, the huge difference between two estimated approaches indicated that there were other important elimination pathways of PFAAs other than renal clearance in human. The half-lives estimated by annual decline rates in the present study were the shortest values ever reported, and the intrinsic half-lives might even shorter due to the high levels of ongoing exposure to PFAAs.

Deoxynivalenol (DON) sulfonates as major DON metabolites in rats: from identification to biomarker method development, validation and application.

Deoxynivalenol (DON) is a trichothecene mycotoxin regularly occurring in cereals. Rats are often used to study toxicokinetics of DON and related compounds, yet only about 30 % of the administered dose is typically recovered. Recently, it was reported that DON is partly metabolised to previously undetected DON- and deepoxy-DON (DOM) sulfonate in rats and tentative structures were proposed. The present work describes the production and characterisation of DON-, DOM- and DON-3-glucoside (D3G) sulfonates of three different series; the development and validation of liquid chromatography tandem mass spectrometry (LC-MS/MS)-based methods for determination of DON, DOM, D3G and their sulfonates in rat faeces and urine; and application of the methods to samples from a DON and D3G feeding trial with rats. In addition to previously produced DON sulfonates (DONS) 1, 2 and 3, D3G sulfonates 1, 2 and 3; and DOM sulfonates (DOMS) 2 and 3 were synthesised, purified and characterised. The developed methods showed apparent recoveries of all investigated compounds between 68 and 151 % in faeces and between 48 and 113 % in urine. The recovery of DON, D3G and their metabolites from faeces and urine of rats (n = 6) administered in a single dose of 2.0 mg/kg b.w. DON or the equimolar amount of D3G was 75 ± 9 % for the DON group and 68 ± 8 % for the D3G group. DON-, DOM- and D3G sulfonates excreted in faeces accounted for 48 and 47 % of the total amount of administered DON and D3G. Urinary excretion of sulfonates was <1 %. In both treatment groups, DONS 2 was the major metabolite 0-24 h after treatment, whereas DOMS 2 was predominant thereafter. The developed methods can also be used for investigation of DON (conjugate) sulfonate formation in other animal species.

Perfluorinated compounds in serum and urine samples from children aged 5-13 years in South Korea.

Serum and urine samples from 120 children aged 5-13 years from Dae-gu, Korea, were analyzed for 16 perfluorinated compounds (PFCs). The total PFC concentrations in the serum were 4.26-29.70 ng/mL, and perfluorohexanesulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS, which was dominant overall, at 6.58 ng/mL), and perfluoroundecanoic acid (PFUndA) were detected in all serum samples. The total PFC concentrations in the urine ranged from below the detection limit to 14.9 ng/mL, and perfluoropentanoic acid (PFPeA) was predominant. The PFOS (p < 0.005) concentration was higher in the serum of children than that of Korean adults aged 20-29. Some of the PFC concentrations in the serum correlated negatively with body mass index and tended to increase with the duration of breastfeeding. However, there were no gender-specific differences in the PFC concentrations and no correlations between PFC concentrations in serum and urine.

The selective determination of sulfates, sulfonates, and phosphates in urine by capillary electrophoresis/mass spectrometry.

Metabolite identification and metabolite profiling are of major importance in the pharmaceutical and clinical context. However, anions of biological relevance such as sulfates, sulfonates, and phosphates are rarely included in common techniques for metabolite studies. In this protocol, we demonstrate a unique method to selectively determine these anions. The method comprises a capillary electrophoresis separation using an acidic background electrolyte (pH ≤ 2) and anodic detection by mass spectrometry via negative electrospray ionization. In this way, only anions of strong acids like sulfates are determined. The selectivity for sulfur-containing species is proved based on the specific isotopic ratios. In conjunction with the accurate mass from the time-of-flight mass spectrometer, the presented method is well suited for clinical and pharmaceutical applications to identify possible metabolites and to quantify known metabolites.

Exceptionally high serum concentrations of perfluorohexanesulfonate in a Canadian family are linked to home carpet treatment applications.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are normally the dominant perfluoroalkyl substances (PFASs) in human serum, but here a Canadian family of seven was identified with particularly high exposure to perfluorohexanesulfonate (PFHxS). Disproportionately high serum PFHxS concentrations (range 27.5-423 ng/mL) and moderately high PFOS (range 15.2-108 ng/mL) and PFOA (range 2.40-9.23 ng/mL) concentrations were detected in the family members, with all three chemicals being highest in the youngest children. We therefore sought to identify the source(s) and pathway(s) of this unusual exposure, and to study the excretion of PFASs for this family. Serum, urine, and stool were sampled from family members, carpet, dust, and air were sampled in the home, and a questionnaire was administered. Over 15 years, the family's household carpets were treated 8 times with Scotchgard formulations. Elevated concentrations of PFHxS were detected in household dust (2780 ng/g dust) and in family room carpet (2880 ng/g carpet), and the primary mode of excretion for the major PFASs was through urine. The high PFHxS and moderately high PFOS concentrations in serum and household samples are consistent with the known PFAS content of certain Scotchgard formulations, and exposure was likely through dust ingestion and/or inhalation.

Comparative pharmacokinetics of perfluorohexanesulfonate (PFHxS) in rats, mice, and monkeys.

Perfluorohexanesulfonate (PFHxS) has been found in biological samples from wildlife and humans. The human geometric mean serum PFHxS elimination half-life has been estimated to be 2665days. A series of studies was undertaken to establish pharmacokinetic parameters for PFHxS in rats, mice, and monkeys after single administration with pharmacokinetic parameters determined by WinNonlin(®) software. Rats and mice appeared to be more effective at eliminating PFHxS than monkeys. With the exception of female rats, which had serum PFHxS elimination half-life of approximately 2 days, the serum elimination half-lives in the rodent species and monkeys approximated 1month and 4months, respectively, when followed over extended time periods (10-24weeks). Collectively, these studies provide valuable insight for human health risk assessment regarding the potential for accumulation of PFHxS in humans.

The metabolism of methazolamide - identification of metabolites in guinea pig urine.

The in vivo metabolism of methazolamide, a carbonic anhydrase inhibitor, was studied using guinea pigs as the animals. (14)C-Labeled methazolamide was synthesized. Eighty percent of intraperitoneally injected radioactivity was recovered from urine and feces within 24 hours. HPLC analysis on a C(18) column detected 2 radioactive metabolites (Peaks A and B). The Peaks A and B were isolated from the urine of the animals dosed with non-radioactive methazolamide.They were purified on the C(18) column. Their chemical structure was revealed by UV-absorbance spect a and LC/MS, and confirmed by comparing it with that of chemically synthesized compound. They were a glucuronide, (2-acetylimino-3-methyl-Δ(4)-1,3,4-thiadiazol-5-yl)-1-thio-ß-D-glucopyranosiduronic acid, and a sulfonic acid, N-[3-methyl-5-sulfo-1,3,4-thiadiazol-2(3H)-ylidene]acetamide.

Determination of the herbicide benfuresate by its photo-induced chemiluminescence using flow multicommutation methodology.

The present paper deals with an analytical strategy based on coupling photo-induced chemiluminescence in a multicommutation continuous-flow methodology for the determination of the herbicide benfuresate. The solenoid valve inserted as small segments of the analyte solution was sequentially alternated with segments of the NaOH solution for adjusting the medium for the photodegradation. Both flow rates (sample and medium) were adjusted to required time for photodegradation, 90 s; and then, the resulting solution was also sequentially inserted as segments alternated with segments of the oxidizing solution system, hexacyanoferrate (III) in alkaline medium. The calibration range from 1 microg L(-1) to 95 mg L(-1), resulted in a linear behaviour over the range 1 microg L(-1) to 4 mg L(-1) and fitting the linear equation: I=4555.7x+284.2, correlation coefficient 0.9999. The limit of detection was 0.1 microg L(-1) (n=5, criteria 3 sigma) and the sample throughput was 22 h(-1). The consumption of solutions was very small; per peak were 0.66 mL, 0.16 mL and 0. 32 mL sample, medium and oxidant, respectively. Inter- and intra-day reproducibility resulted in a R.S.D. of 3.9% and 3.4%, respectively. After testing the influence of a large series of potential interferents the method is applied to water samples obtained from different places, human urine and to one formulation.

Identification of a rare sulfonic acid metabolite of andrographolide in rats.

Andrographolide is widely used in clinic as an anti-inflammatory and antibiotic drug. In this paper, the metabolites of andrographolide in rats after single oral doses of 120 mg/kg were investigated. The structures of the metabolites were elucidated by high-resolution mass spectra, NMR spectroscopy including 1H NMR, 13C NMR, and two-dimensional NMR, through comparison to a synthetic standard. The main metabolite of andrographolide in rats was 14-deoxy-12(R)-sulfo andrographolide. In the proposed mechanism, the beta-carbon of alpha, beta-unsaturated carbonyl was attacked by sulfonic acid, to form the sulfonate compound. This was a rare metabolic reaction. It may be the main metabolic pathway of andrographolide in rats. The polarity of the sulfonate metabolite increased greatly and could be easily eliminated from body.

Metabolism and disposition of luminol in the rat.

1. The metabolism and disposition of Luminol (LMN, 3-aminophthalhydrazide), a widely used forensic and laboratory reagent that chemiluminesses upon oxidation, was determined as part of its overall toxicological characterization. 2. Radiolabelled LMN was well absorbed, metabolized and excreted following p.o. administration of a range of doses. About 90% of the total dose was recovered within 24 h of administration in urine in the form of two metabolites identified as LMN N8-glucuronide and LMN N8-sulphamic acid. 3-Aminophthalic acid, the oxidative product of LMN in the light-emitting reaction, was apparently not formed in vivo. 3. Metabolism and disposition of an i.v. administered dose was similar to that following gavage. Little or no LMN-derived radioactivity was present in tissue within 12 h post-dosing. Excretion of radioactivity in bile following i.v. injection was minimal (approximately 8% of the total dose in 6 h) and consisted of the same urinary-excreted glucuronide and sulphate conjugates. 4. LMN was not absorbed dermally in rat, potentially a major route of exposure to human. If the fate of LMN is similar between species, this compound should have little potential for either dermal absorption, bioaccumulation in tissues following other routes of exposure or chronic toxicity in humans.

Human urinary excretion of sulfamate and glucuronide conjugates of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MelQx).

The contribution of Phase II conjugation reactions to human disposition of 2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MelQx) was investigated by analysis of urine for MelQx and its sulfamate and glucuronide metabolites. Subjects consumed pan-fried fish, beef, or bacon and collected 0-12 and 12-24-h postconsumption urine samples. MelQx content of the samples was determined both with and without acid treatment that quantitatively hydrolyzes the Phase II conjugates. The amount of unconjugated MelQx in the urine of seven subjects ranged between 2 and 36 ng in the first 12-h sample and was undetectable in the second. Hydrolysis increased the MelQx content 3-13-fold in the urine of six subjects, while the urine of one subject showed no significant change. Unconjugated MelQx excreted in urine was found to range between 0.5 and 4.7% of the ingested dose. In acid-treated urine the amount of MelQx was found to range between 1 and 14% of the ingested dose. A method for isolating the acid-labile conjugates in urine was developed, which included the following steps: acetone/methanol precipitation; solid-phase extraction; ion exchange fractionation, normal phase aminopropyl fractionation, and reverse phase high pressure liquid chromatography separation of the metabolites. Acidic hydrolysis of the fractions obtained in the last step, followed by gas chromatography-mass spectrometry analysis of the MelQx produced, was used to confirm the presence of the sulfamate and the glucuronide metabolites in human urine. The results provide evidence that glucuronidation and amine sulfamation are significant pathways of detoxification of MelQx in humans. In addition, the increased amount of MelQx released after acid hydrolysis facilitates the quantitative analysis of urinary MelQx.

Metabolism of tetramethrin isomers in rat. I. Identification of a sulphonic acid type of conjugate and reduced metabolites.

1. Urinary and faecal metabolites in rat treated with 14C-labelled (1RS, trans)-tetramethrin [3,4,5,6-tetrahydrophthalimidomethyl (1RS, trans)-chrysanthemate] were identified using chromatographic techniques and spectroanalyses (nmr and ms). 2. 3-Hydroxy-cyclohexane-1,2-dicarboximide was found to be a major and unique urinary metabolite, reduced at the 1,2-double bond of the 3,4,5,6-tetrahydrophthalimide moiety. 3. The major faecal metabolites were sulphonic acid conjugates, having a sulphonic acid group incorporated into the double bond of the 3,4,5,6-tetrahydrophthalimide moiety. 4. On the basis of the metabolites identified here, the major biotransformation reactions of trans-tetramethrin in rats are: (1) cleavage of the ester linkage; (2) cleavage of the imide linkage; (3) hydroxylation of the cyclohexene or cyclohexane ring of the 3,4,5,6-tetrahydrophthalimide moiety; (4) oxidation at the methyl group of the isobutenyl moiety; (5) reduction at the 1,2-double bond of the 3,4,5,6-tetrahydrophthalimide moiety; and (6) incorporation of a sulphonic acid group into the 1,2-double bond of the 3,4,5,6-tetrahydrophthalimide moiety.

Gas chromatographic assay for the new antitumor agent sulfamic acid diester (NSC 329680) and its stability in buffer, blood and plasma.

A sensitive gas chromatographic assay with electron-capture detection has been developed for sulfamic acid diester (sulfamic acid 1,7-heptanediyl ester, NSC 329680) based on its conversion to 1,7-diiodoheptane in the presence of excess sodium iodide. The assay is linear up to 1 microgram/ml sulfamic acid diester and has a lower limit of detection of 25 ng/ml from 0.5 ml plasma. The coefficient of variation of the assay is 6.4% at 1 microgram/ml and 8.0% at 100 ng/ml. Sulfamic acid diester is relatively stable in 0.9% sodium chloride and 0.1 M sodium phosphate buffers, pH 7.0-9.0, with half-lives greater than 38 h. The major breakdown product of sulfamic acid diester is sulfamic acid 1,7-heptane-monoyl ester. When added to whole blood sulfamic acid diester shows concentration-dependent breakdown. At 50 and 100 micrograms/ml sulfamic acid diester, the half-time in whole blood is 6.9 h and 65% of the drug is sequestered by the blood cells. At 10 micrograms/ml sulfamic acid diester in blood, there is no detectable breakdown of the drug over 24 h and all of the drug is sequestered by the blood cells. Protein binding of sulfamic acid diester in human plasma is 82% at 10 micrograms/ml and 68% at 100 micrograms/ml.

Metabolic studies with the nonnutritive sweetener cycloheptylsulfamate.

The nonnutritive sweetener cycloheptylsulfamate was administered orally to rabbits and rats. The urine of each species was separately collected for 3 days and examined for the metabolites cycloheptylamine, cycloheptanone, and cycloheptanol and for cycloheptylsulfamate. A previously tested GLC method was adapted for the determination of the metabolites. Cycloheptylsulfamate was assayed by hydrolysis and subsequent measurement of the absorbance of the product formed (lambdamax=489 nm) by the liberated amine with p-benzoquinone. The conversions to the metabolites were 0.276, 0.390, and 0.170%, respectively, in rabbits and 0.064, 0.022, and 0.017%, respectively, in rats.

Pharmacokinetics of sulbenicillin, a new broad-spectrum semisynthetic penicillin.

In a pharmacolinetic study on a new semisynthetic penicillin, alpha-sulfobenzylpenicillin, sulbenicillin, serum level, serum half-life, apparent distribution volume, renal clearance, urinary excretion, and metabolism were determined after a 4-gm intravenous dose and compared to that of carbenicillin in 5 patients with normal renal function. In the case of sulbenicillin, the mean serum concentration at 1 hr was 157 plus or minus 25 mug/ml, the mean serum half-life was 70 plus or minus 10 min, the renal clearance was 95 plus or minus 25 ml/min, and the total urinary recovery after 24 hr was about 80% of the dose. The only metabolite detected in the urine was the penicilloic acid derivative, in an amount usually less than 5% of the dose. Serum values, serum half-live, renal clearances, and excretion pattern did not differ significantly from that of carbenicillin. In 8 patients with decreased renal function (creatinine clearance less than 50 ml/min) there was an inverse correlation between creatinine clearance and serum half-life.