title: Simultaneous determination of silicate and phosphate in environmental waters using pre-column derivatization ion-pair liquid chromatography.
abstract: A highly sensitive HPLC method for the simultaneous determination of soluble silicate and phosphate in environmental waters was developed, using ion-pair liquid chromatography preceded by the formation of their yellow alpha-heteropolymolybdates. The moderate-pH mobile phase enabled to use a highly efficient reversed-phase silica column. The pre-column coloring reactions at moderate-pH were reproducible for both silicate and phosphate in all quantification ranges with R.S.D.s less than 2% and 5%, respectively. The linear calibration lines between concentrations (mg-SiO(2)/L and mg-PO(4)/L) and peak area intensities were obtained for silicate and phosphate both with acceptable determination coefficients (r(2)) of 0.9999. The limits of determination for both analytes were 0.007 mg-SiO(2)/L and 0.003 mg-PO(4)/L, which were calculated theoretically using 10sigma/slope. The four-digit dynamic ranges were obtained for 0.007-10mg-SiO(2)/L and 0.003-20mg-PO(4)/L. The developed method was applied for the analysis of tap water, river water, coastal seawater, well water, hot-spring water, commercial mineral water, and laboratory water. The results were very reasonable and acceptable from the environmental viewpoints, which were well correlated with those confirmed by the molybdenum-blue spectrophotometry.
authors: Department of Analytical Chemistry, Faculty of Engineering, Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan. yokyuk@ynu.ac.jp
authors: Yukio
authors: Y
authors: Yokoyama
authors: Takenobu
authors: T
authors: Danno
authors: Mizuki
authors: M
authors: Haginoya
authors: Yukari
authors: Y
authors: Yaso
authors: Hisakuni
authors: H
authors: Sato
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods* / Q000592:standards; D004785:Environmental Pollutants; D005618:Fresh Water / Q000737:chemistry; D010710:Phosphates / Q000032:analysis*; D012623:Seawater / Q000737:chemistry; D017640:Silicates / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D004785:Environmental Pollutants; D010710:Phosphates; D017640:Silicates; D014874:Water Pollutants, Chemical