Objective To establish a simple and rapid method for determination of trace chromium(Ⅵ) in drinking water. Methods In the weak acid solution containing n-butyl alchhol,trace chromium (Ⅵ) in the water connected with diphenylcarbazide and sodium dodecyl sulfate into purplish red ternary iron compound,which could be extracted by chloroform and quantified at wavelength of 550 nm. Results The detection limit was 0.001 mg/L,the RSDs were 1.1%-1.4% and the recovery rate was 96%-113%. Conclusion The method was rapid,simple and the sensitivity and accuracy will meet the requirement of standard test methods for drinking water.

Objective To develop a rapid determination method of nitrate-N in water.Methods In concentrated sulfuric acid,2-isopropyl-5-methyphenol reacts on nitrate and produces the nitro-compound which may turn into the yellow compound in the alkaline solution for the moleculars rearrange.The content of nitrate-N in water can be calculated according to the absorption value at the wave length of 415 nm.Results A good linear relation was found between the concentrations of nitrate-N and the absorption values in the range of 0-15.0 mg/L.The lowest determination concentration was 0.25 mg/L,the recovery rates were 96%-108% and RSD was 1.6%-4.0%.The results were consistent with those determined by UV spectrophotometry.Conclusion The method was simple,sensitive,rapid and accurate.

Objective To establish a method for determining VOCs in drinking water by headspace gas chromatography. Methods VOCs in the water were extracted by headspace technology, then analyzed with Rtx-WAX capillary column, in the same time, VOCs was determined with GC by controlling the temperature and the speed of nitrogen. The retention time of the peaks was used for qualitative analysis, external standard method was used for quantitative analysis. Results The linear ranges of dichloromethane, benzene, toluene, 1, 2-dichloroethane, ethylbenzene, p-xylene, m-xylene, o-xylene, isopropylbenzene, chlorobenzene, styrene were 6.2-311.2, 2.0-100.0, 1.6-81.5, 5.7-282.8, 1.9-93.4, 1.7～85.4, 1.7-87.2, 2.1-103.2, 1.5-76.3, 2.2-107.3 and 1.9-96.0 ?g/L respectively. The lowest determination limit were 0.5-5.9 ?g/L, the rate of recovery were 88.8%-109.6% and RSDs were 2.2%-5.9%. Conclusion This method is simple, rapid, sensitive and can efficiently separate and accurately determine 11 kinds of VOCs in drinking water.

Objective To establish a method to determine halogenated alkane hydrocarbon in drinking water with headspace gas chromatography. Methods Halogenated alkane hydrocarbon in the water were extracted by headspace technology, then analyzed with DB-5 capillary column, in the same time, they were determined with GC by controlling the temperature and the speed of nitrogen. The retention time of the peaks was used for qualitative analysis, while external standard method was used for quantitative analysis. Results The linear ranges for dichloromethane, trichloromethane, 1, 1, 1-trichloroethane, 1, 2-dichloroethane, carbon tetrachloride, trichloroethylene, bromodichloromomethane, 1, 1, 2-trichloroethane, dibromochloromethane, tetrachloroethylene, tribromomethane were 0.8-4 024.0, 0.007-33.5, 0.004-19.2, 1.4-6 821.0, 0.002-10.0, 0.005-25.6, 0.002-12.1, 0.1-717.8, 0.005-23.5, 0.002-8.1 and 0.02-87.7 ?g/L. The lowest determination limit were 0.01- 4.1 ?g/L, the rate of recovery were 89.7%-110.0% and RSDs were 2.8%-9.0%. Conclusion This method can efficiently separate and accurately determine 11 kinds of halogenated alkane hydrocarbon in drinking water. It is simple, rapid and sensitive.

Objective To establish a rapid determination method for sulfate in water. Methods In the weak acid solution, sulfate connected with barium chromate into sulfate barium and chromate. Surplus barium chromate precipitated when adding the mixture of CaCl2 and NH3?H2O. The chromate replaced by sulfate was detected at wave length of 420 nm. Results The RSDs were 1.8%-6.8% and the recovery rates were 98.9%-101.0%. Conclusion The method was rapid, simple and its sensitivity and accuracy can meet the requirement of standard examination methods for drinking water.

ve To explore the effectiveness of removal of arsenic from drinking water by polyferric sul-fate. Methods Per liter water sample containing arsenic ( Ⅲ ) was added and homogenized with 1 mg chlorine and then was treated with polyferric sulfate [?(Fe) = 9. 5% ] as a coagulant. Results The content of As3+ and iron were 0-0.024 mg/L and

This paper reports some histochemical,scanning and transmission electron mic-roscopical features of thymic nurse cell(TNC)of human fetuses.The results showedthat TNCs were all negative for ANAE,AcP,AlP,ATPase,5'-Nase and PAS.TNCcontained various numbers of lymphocytes.Some intracytoplasmic lymphocytes werepositive for ANAE,AcP,AlP and ATPase.Their ANAE positive percentage deter-mined were 26.8%.However,ANAE positive percentage of extracytoplasmic lym-phocytes of TNC were 51.3%.Our data demonstrated that there was significant dif-ference between these two ANAE positive percentages,P