COMPARATIVE-STUDY OF BARIUM SALTS OF 2,5-DIHALO-3,6-DIHYDROXY-P-BENZOQUINONE AS REAGENTS FOR THE SPECTROPHOTOMETRIC DETERMINATION OF SULFATE

The spectrophotometric determination of sulphate employing barium salts of fluoranilic, bromanilic or iodanilic acid was studied. The synthesis of fluoranilic and iodanilic acids and the preparation of the barium salts of the haloanilic acids as reagents are described. Suitable reaction conditions for linear calibration were established. The molar absorptivities for the reaction products of the Ba haloanilates with sulphate were between 1.87 X 10(4) and 2.78 X 10(4) l mol-1 cm-1 at their absorption maxima. The relative standard deviation at 5-mu-g of sulphate was < 2%.