[Application of a new solid adsorbent tube for the determination of three kinds of epoxy eompounds in air].

Objective: To develop a new solid sorbent tube for simultaneously capturing ethylene oxide (EO) , propylene oxide (PO) and epichlorohydrin (ECH) in air, and establish a complete set of method. Methods: In June 2018, EO, PO and ECH in air were captured by the new solid sorbent tube filled with carbon aerogel adsorbent, desorbed with solution of 5% (V/V) methanol-methylene chloride, separated through capillary chromatographic column, and then analyzed by gas chromatography-flame ionization detector. Results: The linear ranges of EO, PO and ECH were 0.24-960.00, 0.60-2384.00 and 0.12-472.40 mg/L respectively, and the related coefficients were between 0.99995-0.99997. The relative standard deviations (RSD) within the group were 1.66%-4.09%, 1.36%-4.43%, and 1.99%-5.65%, respectively, and the RSD between the group were 2.69%-4.95%, 2.77%-5.30%, and 3.27%-6.67%, respectively. The average desorption efficiencies were 88.25%-94.50%, 98.17%-98.60%, and 97.79%-101.04%, respectively. The samples could be stored at 4 ℃ refrigerator for at least 27 days. Conclusion: The newly developed solid sorbent tube filled with carbon aerogel adsorbent and its complete set of gas chromatography method could be used for sampling and quantitative detection of EO, PO and ECH in workplace air.

[Simultaneous determination of four kinds methyl acrylate compounds in workplace air].

Objective: To develop a solvent desorption-gas chromatography method for simultaneous determination of methyl methacrylate (MMA) , ethyl methacrylate (EMA) , n-propyl methacrylate (PMA) and butyl methacrylate (BMA) in workplace air. Methods: MMA, EMA, PMA and BMA in workplace air were captured by charcoal tubes and desorbed with carbon disulfide, separated through capillary chromatographic column, and then analyzed by gas chromatography-flame ionization detector. Results: The linear ranges of MMA, EMA, PMA and BMA were 0-8 305.00 mg/L, 0-9 080.50 mg/L, 0-8 899.00 mg/L and 0-8 371.00 mg/L respectively, and the related coefficients were between 0.999 96-0.999 98. The relative standard deviations (RSD) within the group were 0.56%-1.71%, 0.45%-1.65%, 0.51%-1.49% and 0.45%-1.50% respectively, and the RSD between the group were 1.14%-2.79%, 0.79%-2.13%, 0.93%-2.30% and 1.09%-2.84% respectively. The average desorption efficiencies were 95.76%-99.58%, 97.82%-102.28%, 98.55%-102.28%and 98.70%-102.40% respectively. The minimum quantification concentrations were 0.12 mg/m(3), 0.10 mg/m(3), 0.07 mg/m(3) and 0.07 mg/m(3) respectively (3.00 L sample) . The samples could be stored at room temperature for at least 7 days. Conclusion: This method could be used for monitoring of MMA, EMA, PMA and BMA in workplace air.

[Determination of glycidyl methacrylate in the air of workplace captured adsorbent tube by gas chromatography].

Objective: To develop a new solid sorbent tube for capturing glycidyl methacrylate (GMA) in workplace air, and establish a complete set of method. Methods: GMA in workplace air was captured by the new solid sorbent tube filled with carbon aerogel adsorbent, desorbed with solution of 50% (V/V) dimethylformamide-carbon disulfide, separated through capillary chromatographic column, and then analyzed by gas chromatography-flame ionization detector. Results: The linear range of GMA was 0.38-604.80 mg/L, and the related coefficient was 0.999 82. The within-run and the between-run precision were 1.11%-2.80% and 2.53%-4.84% respectively. The average desorption efficiency was 93.20%-94.97%. The minimum quantification concentration and The minimum quantification concentration were 0.02 and 0.07 mg/m(3) respectively (3.00 L sample) . Samples could be stored for at least 8 days at room temperature. Conclusion: The newly developed solid sorbent tube and its complete set of gas chromatography method is simple, and has high sensitivity and precision, so it can be used for sampling and quantitative detection of GMA in workplace air.

[Determination of hippuric acid and methylhippuric acid in urine by high performance liquid chromatography after extracted with acetonitrile].

OBJECTIVE: To establish pretreatment conditions of hippuric acid (HA)and methyl-hippuric acid (MHA)in urine and HPLC conditions. METHODS: HA and MHA in urine were extracted with acetonitrile under acid condition and determinated by HPLC-DAD. The operating conditions by HPLC were C18 column (150 mm× 4.6 mm, 5 µm), methanol-0.2% acetic acid (contained 6.5 mmol/L potassium dihydrogen phosphate)(25∶75, V/V) as mobile phase,1 ml/min as flow rate and wavelength was at 254 nm. RESULTS: The standard curves for HA, 2-MHA and 3-MHA(4-MHA)showed good linearity between 9.91~2 974.20 µg/ml(r=0.999 98), 1.91~573.60 µg/ml (r=0.999 84)and 2.00~598.65 µg/ml (r=0.999 85), respectively. The mean recoveries were 96.38%~98.01%, 83.17%~94.05 %, 103.22%~104.45%, respectively. The within-run precision were 0.50%~1.20%, 0.51%~1.59%, 0.49%~0.95%, respectively, and the between-run precision were 1.70%~3.20%, 1.30%~2.67%, 0.86%~2.74%, respectively. The detection limit of HA, 2-MHA and 3-MHA(4-MHA)were 0.18 µg/ml, 0.46 µg/ml and 0.12 µg/ml, and the low determination concentrations of the method were 0.36 µg/ml, 0.92 µg/ml and 0.24 µg/ml(1 ml urine). The urine can be kept 15 days at 4 ℃ refrigerator without significantly loss. CONCLUSION: This method with simply pretreatment conforms to the relevant requirements of guide for establishing occupational health standards-part 5: determination methods of chemicals in biological materials. It can be used to detect HA and MHA in urine for occupational population exposure to toluene and xylene.

[Determination of volatile organic compounds in air by portable gas chromatography-mass spectroscopy].

Objective: To investigate the method of portable gas chromatography-mass spectroscopy (GC-MS) for the determination of common volatile organic compounds in air. Methods: The static volumetric method was used, with highly purified nitrogen gas as the diluents gas, to prepare the mixed standard gas of common volatile organic compounds with various mass concentrations. A portable GC-MS handheld probe was used for sampling and measurement, retention time and characteristic ion were used for qualitative analysis, and the full-scan mode was used for quantitative analysis. Results: The correlation coefficient of 12 volatile organic compounds determined by this method was higher than 0.999. The minimum detection mass concentration was 0.02~0.12 mg/m3, and the minimum quantitative mass concentration was 0.07~0.40 mg/m3. The relative standard deviation of precision was 4.10%~12.50%; the relative deviation of acetone, benzene, methylbenzene, and dimethylbenzene was-13.56% , 9.03% , -10.82% , and 8.67% , respectively. Conclusion: Portable GC-MS method can be used for the qualitative analysis and quantification of volatile organic compounds in occupational hazard factors and provide technical supports for identification of occupational hazard factors.

[Mebendazole-medicated-salt in the control of hookworm infection].

From 1984-1987, mass application of mebendazole-medicated salt was studied for the control of hookworm infection in 5 pilot areas (Wuming, Shanlin, Bobai, Guilin and Rongxian Counties) in Guangxi Zhuang Autonomous Region. The dosages of mebendazole (mixed with salt) administered were 15mg, 25mg, 30mg, 40mg, 50mg, 30mg, 70mg, 80mg, 100mg or 200mg per person per day for 15, 20 or 30 days. The results showed that 40mg/day for 15-20 days could result in stool egg negative conversion rates of 92.3 to 94.4%, while 50mg/day for 30 days resulted in 96.9 to 100%. Concurrently, the hookworm infection rate in pilot areas dropped by 57.9-71.7% in a short time; whereas the stool egg negative conversion rate of Ascaris lumbricoides was as high as 99.1% to 100% at the same dosage, when the dosage of 100mg/day for 30 days was given, the egg negative reversion rate for Trichuris trichiura was 97.6%. Promising result was also recorded concerning the tolerance of the medicated salt, as the side effects in the inhabitants were mild. In conclusion, the authors considered that the application of mebendazole-medicated salt was a simple and effective measure in controlling hookworm infection, especially in the light of solving the problem of incomplete mass detection and selected mass treatment. Furthermore, it is much more economic from the cost-effect point of view.