Microemulsion medium-spectrophotometric determination of micro tin with dibromo-p-methyl carboxyazo

The color reaction of the reagent dibromo-p-methyl carboxyzo(DBpMCA) with Sn(Ⅳ) in the presence of CTMAB microemulsiom was studied,and a new spectrophotometric method for the determination of micro tin has been established.Results show that the new color reagent reacts with Sn(Ⅳ)to form a stable purple-red complex(mole ratio 1∶3)in the presence of NH3·H2ONH4Cl buffer solution at pH10.4.The maximum absorption wavelength and apparent molar absorptivity are 544 nm and 1.04×105 L·mol-1·cm-1 respectively.Beer′s law is obeyed in the range of 0.02-12 μg in 10 mL experimental liquor.The detection limit is 6×10-4 μg/ mL.The method has been applied to the direct determination of tin in fly ash with the recovery of 99.4%-101.6% and the relative standard deviation of 0.59%-1.06%.