Spectrophotometric Determination of Trace Silica in Water After Enrichment on Polyurethane Foam and Complexation with Rhodamine B

[摘要] A highly sensitive spectrophotometric method has been developed for the rapid determination of nanogram amounts of silica in pure water. The method involves the formation of yellow molybdosilicate in nitric acid medium, its extraction on polyether based polyurethane foam, elution in acetone, formation of ion associate between molybdosilicate and Rhodamine B (RB) in nitric acid and finally measurement of absorbance at 596 nm. The detection limit was found to be 0.05 ng mL-1 Si. The method obeys Beer’s law over the concentration range 0.1 – 5 ng mL-1. The molar absorptivity was found to be 1.4043 x 106 L mol-1 cm-1. The proposed method was successfully applied for the determination of silica in highly purified water samples.

[学科分类] 分析化学

[关键词] Molybdosilicate; Polyurethane Foam; Ion associate; Rhodamine B