Spectrophotometric determination of sulphate in ethanol fuel using dibromosulphonazo III [Determina??o espectrofotométrica de sulfato em álcool etílico combustível empregando dibromosulfonazo III]

摘要

A sensitive spectrophotometric method was developed for sulphate determination in automotive ethanol fuel. The method based on the reaction of the analyte with barium-dibromosulphonazo(III) complex lead to a decrease in the magnitude of the absorbance signals monitored at 649 nm. No sample pretreatment is required and the proposed method allows sulphate determination in the 0.45 - 6.50 mg L~(-1) range with R.S.D. < 2% and limit of detection of 0.14 mg L~(-1). The method has been successfully applied for sulphate determination in automotive ethanol fuel and the results agreed with the reference chromatographic method.