4 research outputs found
紫外分光光度法测定控释尿素的透膜扩散速率
No full text使用控释氮肥能提高其利用率，减轻环境污染。（包膜型）控释尿素是近几年发展较快的控释氮肥之一。控释尿素透膜扩散速率是其控释性能的一个重要指标。研究表明，使用对二甲氨基苯甲醛为显色剂，在酸性水溶液介质中显色络合物的最大紫外吸收峰在λ=426m处，尿素浓度在7．5～210μg·mL^-1范围内，其浓度与吸光度呈线性关系。据此，建立了在此紫外波段测定水溶液中尿素的含量来实现控释尿素透膜扩散速率的测定方法，其回收率为96．1％～103．9％
连续测量水中挥发性有机物的膜进样单光子电离质谱仪的研制及其应用
No full textA single photon ionization time of flight mass spectrometer with membrane inlet has been described and applied for on-line measuring volatile organic compounds (VOCs) in water. Automatic sampling, enrichment and measurement of VOCs were achieved by using a polyolimethyl siloxane (PDMS) membrane with a thickness of 50 mu m, a peristaltic pump and electric switch valve. There is almost no memory effect in the membrane inlet system. Single photon ionization processes were accomplished with photons of 10.6 eV emitted from a commercial low pressure discharge krypton lamp, and almost no free fragment was found in mass spectrum. Thus, it can be used for chemical compounds identification according to their molecular weight. The response times for benzene, toluene, xylene and chlorobenzene were all shorter than 100 s. The detection limit of benzene is 3 x 10(-9) (volume fraction), and an excellent linear response was observed in the range of 10 x 10(-9) (V/V) to 1 x 10(-6) (WV). The instrument was tested to analyze VOCs in the sewerage from a chemical plant, and more than twenty compounds of VOCs with concentration in 10 x 10(-9) (V/V) level were observed in 200 s. The results indicate that the single photon time-of-flight mass spectrometer with membrane inlet has a great application potential for on-line analyzing VOCs in water
连续测量水中挥发性有机物的膜进样单光子电离质谱仪的研制及其应用
No full textA single photon ionization time of flight mass spectrometer with membrane inlet has been described and applied for on-line measuring volatile organic compounds (VOCs) in water. Automatic sampling, enrichment and measurement of VOCs were achieved by using a polyolimethyl siloxane (PDMS) membrane with a thickness of 50 mu m, a peristaltic pump and electric switch valve. There is almost no memory effect in the membrane inlet system. Single photon ionization processes were accomplished with photons of 10.6 eV emitted from a commercial low pressure discharge krypton lamp, and almost no free fragment was found in mass spectrum. Thus, it can be used for chemical compounds identification according to their molecular weight. The response times for benzene, toluene, xylene and chlorobenzene were all shorter than 100 s. The detection limit of benzene is 3 x 10(-9) (volume fraction), and an excellent linear response was observed in the range of 10 x 10(-9) (V/V) to 1 x 10(-6) (WV). The instrument was tested to analyze VOCs in the sewerage from a chemical plant, and more than twenty compounds of VOCs with concentration in 10 x 10(-9) (V/V) level were observed in 200 s. The results indicate that the single photon time-of-flight mass spectrometer with membrane inlet has a great application potential for on-line analyzing VOCs in water
