Norihiro Sakui

Mercury speciation and analysis in drinking water by stir bar sorptive extraction with in situ propyl derivatization and thermal desorption-gas chromatography-mass spectrometry.

A method for mercury analysis and speciation in drinking water was developed, which involved stir bar sorptive extraction (SBSE) with in situ propyl derivatization and thermal desorption (TD)-GC-MS. Ten millilitre of tap water or bottled water was used. After a stir bar, pH adjustment agent and derivatization reagent were added, SBSE was performed. Then, the stir bar was subjected to TD-GC-MS. The detection limits were 0.01 ng mL(-1) (ethylmercury; EtHg), 0.02 ng mL(-1) (methylmercury; MeHg), and 0.2 ng mL(-1) (Hg(II) and diethylmercury (DiEtHg)). The method showed good linearity and correlation coefficients. The average recoveries of mercury species (n=5) in water samples spiked with 0.5, 2.0, and 6.0 ng mL(-1) mercury species were 93.1-131.1% (RSD<11.5%), 90.1-106.4% (RSD<7.8%), and 94.2-109.6% (RSD<8.8%), respectively. The method enables the precise determination of standards and can be applied to the determination of mercury species in water samples.

Hollow-fiber-supported liquid phase microextraction with in situ derivatization and gas chromatography–mass spectrometry for determination of chlorophenols in human urine samples

A simple and highly sensitive method that involves hollow-fiber-supported liquid phase microextraction (HF-LPME) with in situ derivatization and gas chromatography-mass spectrometry (GC-MS) was developed for the determination of chlorophenols (CPs) such as 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TrCP), 2,3,4,6-tetrachlorophenol (TeCP) and pentachlorophenol (PCP) in human urine samples. Human urine samples were enzymatically de-conjugated with beta-glucuronidase and sulfatase. After de-conjugation, HF-LPME with in situ derivatization was performed. After extraction, 2 microl of extract was carefully withdrawn into a syringe and injected into the GC-MS system. The limits of detection (S/N=3) and quantification (S/N>10) of CPs in the human urine samples are 0.1-0.2 ng ml(-1) and 0.5-1 ng ml(-1), respectively. The calibration curve for CPs is linear with a correlation coefficient of >0.99 in the range of 0.5-500 ng ml(-1) for DCP and TrCP, and of 1-500 ng ml(-1) for TeCP and PCP, respectively. The average recoveries of CPs (n=6) in human urine samples are 81.0-104.0% (R.S.D.: 1.9-6.6%) with correction using added surrogate standards. When the proposed method was applied to human urine samples, CPs were detected at sub-ng ml(-1) level.

Highly sensitive and selective analysis of widely targeted metabolomics using gas chromatography/triple-quadrupole mass spectrometry

In metabolomics studies, gas chromatography coupled with time-of-flight or quadrupole mass spectrometry has frequently been used for the non-targeted analysis of hydrophilic metabolites. However, because the analytical platform employs the deconvolution method to extract single-metabolite information from co-eluted peaks and background noise, the extracted peak is artificial product depending on the mathematical parameters and is not completely compatible with the pure component obtained by analyzing a standard compound. Moreover, it has insufficient ability for quantitative metabolomics. Therefore, highly sensitive and selective methods capable of pure peak extraction without any complicated mathematical techniques are needed. For this purpose, we have developed a novel analytical method using gas chromatography coupled with triple-quadrupole mass spectrometry (GC-QqQ/MS). We developed a selected reaction monitoring (SRM) method to analyze the trimethylsilyl derivatives of 110 metabolites, using electron ionization. This methodology enables us to utilize two complementary techniques-non-targeted and widely targeted metabolomics in the same sample preparation protocol, which would facilitate the formulation or verification of novel hypotheses in biological sciences. The GC-QqQ/MS analysis can accurately identify a metabolite using multichannel SRM transitions and intensity ratios in the analysis of living organisms. In addition, our methodology offers a wide dynamic range, high sensitivity, and highly reproducible metabolite profiles, which will contribute to the biomarker discoveries and quality evaluations in biology, medicine, and food sciences.

Determination of dimethyl sulfoxide and dimethyl sulfone in urine by gas chromatography-mass spectrometry after preparation using 2,2-dimethoxypropane.

A method for routinely determination of dimethyl sulfoxide (DMSO) and dimethyl sulfone (DMSO(2)) in human urine was developed using gas chromatography-mass spectrometry. The urine sample was treated with 2,2-dimethoxypropane (DMP) and hydrochloric acid for efficient removal of water, which causes degradation of the vacuum level in mass spectrometer and shortens the life-time of the column. Experimental DMP reaction parameters, such as hydrochloric acid concentration, DMP-urine ratio, reaction temperature and reaction time, were optimized for urine. Hexadeuterated DMSO was used as an internal standard. The recoveries of DMSO and DMSO(2) from urine were 97-104 and 98-116%, respectively. The calibration curves showed linearity in the range of 0.15-54.45 mg/L for DMSO and 0.19-50.10 mg/L for DMSO(2). The limits of detection of DMSO and DMSO(2) were 0.04 and 0.06 mg/L, respectively. The relative standard deviations of intra-day and inter-day were 0.2-3.4% for DMSO and 0.4-2.4% for DMSO(2). The proposed method may be useful for the biological monitoring of workers exposed to DMSO in their occupational environment.

Development of an Analytical Method for the Determination of Arsenic in Urine by Gas Chromatography-mass Spectrometry for Biological Monitoring of Exposure to Inorganic Arsenic

Development of an Analytical Method for the Determination of Arsenic in Urine by Gas Chromatography‐mass Spectrometry for Biological Monitoring of Exposure to Inorganic Arsenic: Akito TAKEUCHI, et al. Osaka Occupational Health Service Center, Japan Industrial Safety and Health Association—

A Method for Routine Analysis of Urinary 4,4′-methylenebis (2-chloroaniline) by Gas Chromatography-Electron Capture Detection

A Method for Routine Analysis of Urinary 4,4‘‐methylenebis (2‐chloroaniline) by Gas Chroma‐tography‐Electron Capture Detection: Akito TAKEU‐CHI, et al. Osaka Occupational Health Service Center, Japan Industrial Safety and Health Association—

Determination Method for Xylidines in Workplace Air

Determination Method for Xylidines in Workplace Air: Akito Takeuchi, et al. Osaka Occupational Health Service Center, Japan Industrial Safety and Health Association—