Determination method for p-Phenylazoaniline and 2-methyl-4-(2-tolylazo)aniline in workplace air by high-performance liquid chromatography.

OBJECTIVES: The purpose of this research was to develop a method for the simultaneous determination of p-Phenylazoaniline (also called 4-aminoazobenzene, AAB) and 2-methyl-4-(2-tolylazo)aniline (also called o-aminoazotoluene, AAT) in workplace air for risk assessment. METHODS: The characteristics of the proposed method, such as recovery, limit of quantitation, reproducibility and storage stability of the samples were examined. RESULTS: An air sampling cassette containing two sulfuric acid-treated glass fiber filters was chosen as the sampler. The AAB and AAT were extracted from the sampler filters by methanol and then analyzed by a high-performance liquid chromatograph equipped with a photo-diode array detector. The overall recoveries from spiked samplers were 77-98 and 85-98% for AAB and AAT, respectively. The recovery after 5 days of storage in a refrigerator exceeded 96%. The overall limits of quantitation were 5.00 and 2.50 µg/sample for AAB and AAT, respectively. The relative standard deviations, which represent the overall reproducibility defined as precision, were 0.6-1.8 and 0.5-2.2% for AAB and AAT, respectively. CONCLUSIONS: The proposed method enables 4-h personal exposure monitoring of AAB and AAT at concentrations of 21 to 2,000 µg/m3 for AAB and 10 to 2,000 µg/m3 for AAT, respectively. The proposed method is useful for estimating worker exposure to AAB and AAT.

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.

OBJECTIVES: The purpose of this study was to develop an analytical method for the simultaneous determination of inorganic arsenic [As(III) and As(V)] and monomethylarsonic acid (MMA) in urine by gas chromatography-mass spectrometry (GC-MS) for the biological monitoring of exposure to inorganic arsenic. METHODS: Arsenic compounds (after reduction of arsenic to the trivalent state) were derivatized with 2,3-dimercapto-1-propanol and then analyzed using a GC-MS. The proposed method was validated according to the US Food and Drug Administration guidelines. The accuracy of the proposed method was confirmed by analyzing Standard Reference Material (SRM) 2669 (National Institute of Standards and Technology). RESULTS: Calibration curves showed linearity in the range 1-100 µg/l for each of the arsenic species, with correlation coefficients of >0.999. For each of the arsenic species, the limits of detection and quantification were 0.2 µg/l and 1 µg/l, respectively. The recoveries were 96-100%, 99-102% and 99-112% for As(III), As(V) and MMA, respectively. Intraday accuracy and precision were 82.7-99.8% and 0.9-7.4%, respectively. Interday accuracy and precision were 81.3-100.0% and 0.8-9.9%, respectively. The analytical values of SRM 2669 obtained by the proposed method were sufficiently accurate. CONCLUSIONS: The proposed method overcame the disadvantages of high-performance liquid chromatography with inductively coupled plasma mass spectrometry. It was a robust, selective and cost-effective method suitable for routine analyses and could be useful for the biological monitoring of occupational exposure to inorganic arsenic.

Determination method for mono- and diethanolamine in workplace air by high-performance liquid chromatography.

OBJECTIVES: The purpose of this research was to develop a simultaneous determination method for monoethanol-amine (MEA) and diethanolamine (DEA) in workplace air for risk assessment. METHODS: The characteristics of the proposed method, such as recovery, quantitation limit, reproducibility and storage stability of the samples, were examined. RESULTS: An air sampling cassette containing two sulfuric acid-treated glass fiber filters was chosen as the sampler. The MEA and DEA were extracted from the sampler filters, derivatized with 9-fluorenylmethyloxycarbonyl chloride and then analyzed by a high-performance liquid Chromatograph equipped with a fluorescence detector or photo-diode array detector. The overall recoveries from spiked samplers were 86-99 and 88-99% for MEA and DEA, respectively. The recovery after 5 days of storage in a refrigerator exceeded 95%. The overall limits of quantitation were 0.750 and 0.100 jug/sample for MEA and DEA, respectively. The relative standard deviations, which represent the overall reproducibility defined as precision, were 0.3-1.6 and 0.4-5.7% for MEA and DEA, respectively. CONCLUSIONS: The proposed method enables 4-h personal exposure monitoring of MEA and DEA at concentrations equaling 1/3,000-2 times the threshold limit value-time-weighted average (TLV-TWA: 3 ppmfor MEA, 1 mg/m(3) for DEA) adopted by the American Conference of Governmental Industrial Hygienists and also by the Japan Society for Occupational Health. The method is useful for estimating worker exposure to MEA and DEA.

Determination method for xylidines in workplace air.

OBJECTIVES: The purpose of this research was to develop a determination method for xylidines (XLDs) in workplace air for risk assessment. METHODS: The characteristics of the proposed method, such as recovery, detection limit, reproducibility, and storage stability of the samples were examined. RESULTS: An air sampler cassette containing two sulfuric acid-treated glass fiber filters was chosen as the sampler. The XLDs were extracted from the sampler filters, derivatized with heptafluorobutyric anhydride, and then analyzed by a gas chromatograph equipped with a mass spectrometer. The average recoveries of XLDs from the spiked sampler were 83-101% for personal exposure monitoring. The recovery after 5 days of storage in a refrigerator exceeded 90%. The overall limit of quantitation (LOQ) was 0.600 g/sample. The relative standard deviation, which represents the overall reproducibility defined as precision, was 0.8-10.3%. CONCLUSIONS: The proposed method enables 4-hour personal exposure monitoring of XLDs at concentrations equaling 0.001-2 times the threshold limit value-time-weighted average (TLV-TWA: 0.5 ppm) adopted by the American Conference of Governmental Industrial Hygienists, and is useful for estimating worker exposure to XLDs.

Determination method for nitromethane in workplace air.

OBJECTIVES: The purpose of this research was to develop a determination method for nitromethane (NM) in workplace air for risk assessment. METHODS: A suitable sampler and appropriate desorption condition were selected by a recovery test in which a spiked sampler was used. The characteristics of the proposed method, such as recovery, detection limit, and reproducibility, and the storage stability of the sample were examined. RESULTS: A sampling tube containing bead-shaped activated carbon was chosen as the sampler. NM in the sampler was desorbed with acetone and analyzed by a gas chromatograph equipped with a flame ionization detector. The recoveries of NM from the spiked sampler were 81-97% and 80-98% for personal exposure monitoring and working environment measurement, respectively. On the first day of storage in a refrigerator, the recovery from the spiked samplers exceeded 90%; however, it decreased dramatically with increasing storage time. In particular, the decrease was more remarkable for the smaller spiked amounts. The overall LOQ was 2 microg/sample. The relative standard deviation, which represents the overall reproducibility, was 1.1-4.0%. CONCLUSIONS: The proposed method enables 4-hour personal exposure monitoring of NM at concentrations equaling 0.001-2 times the threshold limit value-time-weighted average (TLV-TWA: 20 ppm) proposed by the American Conference of Governmental Industrial Hygienists, as well as 10-minute working environment measurement at concentrations equaling 0.02-2 times TLV-TWA. Thus, the proposed method will be useful for estimating worker exposure to NM.