Determination of diphenylmethane diisocyanate in workplace air by HPLC with impregnated filter membrane / 中华劳动卫生职业病杂志

Objective@#To develop a method for determining diphenylmethane diisocyanate in workplace air by HPLC with impregnated filter membrane.@*Methods@#MDI in workplace air reacted with 1- (2-pyridyl) piperazine on impregnated filter membrane to form MDI-urea derivatives, after elution and filtration, it was detected by HPLC-UV.@*Results@#Limit of detection was 0.003 8 μg/ml and limit of quantification was 0.013 μg/ml. Good linearity was obtained in the range of 0.013~2.000 μg/ml (r=0.999 7) . The precision was 3.10%~8.03% (n=6) , while the recovery was 96.3%~101.9%. Asorption capacity of the membrane was 40.8 μg MDI, and could be stored for 14 days in the light-proof environment of 2~8 ℃.@*Conclusion@#The method optimized testing steps for MDI's standard curve, and provided good guidance for determination of MDI in workplace air with impregnated fiter membrane.

Determination of epichlorohydrin in workplace air by gas chromatograph-electron capture detector / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To develop a method for determining epichlorohydrin in the workplace air by gas chromatograph-electron capture detector (GC-ECD).</p><p><b>METHODS</b>Epichlorohydrin in the workplace air was collected by activated charcoal tubes, desorbed using acetone, and analyzed by GC-ECD.</p><p><b>RESULTS</b>A good linearity was obtained in the range of 1.0-50 µg/mL (r=0.999 7). The detection limit was 0.012 µg/ml, while the recovery rate was 88.1% and relative standard deviation ranged from 1.11% to 3.57%. The samples could be stored for seven days at room temperature.</p><p><b>CONCLUSION</b>This method effectively eliminates the interferences of alkanes on determination of epichlorohydrin and improves the sensitivity by 1 to 2 orders of magnitude, which can solve the problem of detection limit above standard in GBZ/T 160.58-2004.</p>

Determination of 24 metal elements and their compounds in air of workplace by ICP-AES / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To establish a method for determination of the levels of 24 metal elements and their compounds in the air of workplace by inductively coupled plasma-atomic emission spectroscopy (ICP- AES).</p><p><b>METHODS</b>Sampling filters were digested by microwave, and diluted to 25 ml. Twenty-four elements (Mg, Ni, K, Mo, Zn, Ca, Ba, Pb, Mn, Cd, Cr, Co, Cu, Sr, Bi, Tl, Sn, Li, Sb, Zr, In, V, Y, and Be) were simultaneously measured by ICP-AES.</p><p><b>RESULTS</b>The detection limits for 24 elements were 0.001∼0.029 mg/L; liner correlation coefficient r values were all equal to or above 0.9994; the relative standard derivations were less than 5%; the recovery rates were 91.2%∼103.9%; the degradation rates in 7 days were less than 9.7%.</p><p><b>CONCLUSION</b>ICP-AES technique is a simple, rapid, accurate, and reliable method, which can be used to measure 24 metal elements and their compounds in the air of workplace.</p>

COMPARISON BETWEEN CRUDE FIBER AND DIETARY FIBER CONTENTS IN FOODS / 营养学报

Contents of crude fiber and neutral detergent fiber in 34 common foods have been determined and compared. In all foods, crude fiber content is lower than neutral detergent fiber. The percentage of crude fiber to neutral detergent fiber ranges from 13.04% to 65.63%. It is higher in vegetables, medium in legumes and fruits, and lower in cereals. In some categories of food, there is a good correlation between crude fiber content and neutral detergent fiber content. For fresh vegetables and fruits, the regression equation is Y = 0.4230+ 1.2425x and Y = 0.0456 + 4.6161x for cereals. It is proposed that the neutral detergent fiber content may be estimated at crude fiber content.

DIETARY FIBER CONTENTS AND ITS COMPONENTS IN FOODS / 营养学报

Dietary fiber contents in 34 common foods perchased in Beijing markets have been determined with detergent method, including neutral detergent fiber, acid detergent fiber, cellulose, hemicellulose and lignin. On dry basis, the dietary fiber contents of vegetables varied with kinds of food: the dietary fiber contents were higher in tender stems, leaves, stalks and flowers; lower in starchy tubers and roots; medium in non-starchy tubers and roots. The propotions of dietary fiber components were different in various categories of foods. Cellulose was the major component in vegetables and legumes, but in most cereals, hemicellulose content was higher than cellulose. All foods had the lowest lignin content with the exception of garlic bolt.