Studies of speciation and new separation-concentration methods for ultra trace elements in natural water

点击翻译按钮获取中文摘要

A highly sensitive, rapid and facile method of fluorophotometry is described for the determination of phosphate using the ion pair formation of molybdophosphate with Rhodamine 6G. This ion pair is collected on the membrane filter made of cellulose nitrate when the sample solution is adjusted to 0.35 mol dm^<-3> in sulfuric acid, 1.9 mmol dm^<-3> in ammonium molybdate and 3.1 mumol dm-3 in Rhodamine 6G, and it is filtered through the membrane filter under suction. The membrane filter together with the ion pair is dissolved into Methyl Cellosolve. The fluorescence intensity of this solution is measured at 555 nm with the excitation at 535 nm. The calibration curve of phosphate is linear from 5 to 100 ng of phosphate(n=12). Although arsenic(V) causes positive error, no ions, including silicate, commonly existing in natural water interfere with the determination of phosphate. The proposed method was applied to the determination of phoshate-phosphorus in water samples and satisfactory resul … More ts were obtained.Accumulation voltammetry of copper(II) at a chemically modified carbon paste electrode(CMCPE) containing 2-(Salicylideneamino)thiophenol was studied. Copper(II) was accumulated as the complex on the electrode based on the chemical reaction without the applied potential. The reduction peak of the complex was observed. The calibration curve of copper(II) was linear over the range of 10^<-9>-10^<-7> M. The proposed method was applicable to the determination of copper(II) in standard reference materials prepared by the National Institute for Environmental Studies, and the results were acceptable.In order to clarify the relation ship between functional groups and copper(II) binding sites in humic acids, pH and conductimetric titration curves of humic acids were compared with those of the model compounds (EDTA, phenylalanine, citric acid and hydroxyhydRoquinone). Moreover, the kinds of functional groups in humic acids were identified by the data obtained from element analysis and FT-IR spectra. Furthermore, effect of ionic strength on the copper(II) complexing abilities of humic acid was investigated. Less