An Extractive Spectrophotometric Determination of Tin as Sn(II)-6-Chloro-3-hydroxy-7-methyl-2-(4 -methoxyphenyl)-4-oxo-4H-1-benzopyran Complex into Dichloromethane

Tin(II) forms a yellow colored complex with 6-chloro-3-hydroxy-7-methyl-2-(4 -methoxyphenyl)-4-oxo-4H-1-benzopyran in hydrochloric acid medium. The complex is extractable into dichloromethane and shows maximum absorbance in the range 424-428 nm. The 1:2 (M: L) complex formed is found to be stable for more than 4 h in dichloromethane. Beer’s law is obeyed in the range 0.0 to 1.68 μg Sn(II) mL^-1 with an optimum range of determination as found from Ringbom plot is 0.23-1.51 μg mL^-1. The molar absorptivity and Sandell’s sensitivity of the complex are 6.29×10^4 L mol^-1 cm^-1 and 0.0019 μg Sn(II) cm^-2 at 426 nm, respectively. The method is free from interference of a large number of important anions/complexing agents and cations. The method is quite simple and has been satisfactorily applied to the analysis of tin in various samples including gun metal and tin can.