Spectrophotometric microdetermination of tin: use of a sensitiser and Kalman filtering to improve the sensitivity and selectivity

Abstract

A spectrophotometric method for the microdetermination of tin with o-nitrophenyl fluorone(O-NPF), using a sensitiser and Kalman filtering is described. The use of N-[1-(1'-chloro-2'-hydroxylpropyl)polyoxyethenyl-2-hydroxylpropyl]-N-hexadecyl-N,N-dimethylammonium chloride (PHDAC), synthesised in this laboratory, improved the sensitivity of the colour reaction. In the absence of PHDAC the absorption spectrum of tin-o-NPF solution was essentially the same as that of the reagent blank; however, strong bathochromic and hyperchromic effects occurred when PHDAC was added and the tin-o-NPF complex had a maximum absorption at 515 nm with a molar absorptivity of 1.85 × 10⁵ l cm^-1 mol^-1. Kalman filtering was used as a “chemometrics filter,” filtering out the interferences from relatively large amounts of molybdenum and tungsten. The method was applied to the determination of tin in metallurgical samples with satisfactory results.