THE DETERMINATION OF LEAD IN INDUSTRIAL SAMPLES BY SPECTROPHOTOMETRY WITH 2-(2-SULFOPHENYLAZO)-7-(2,6-DIBROMO-4-METHYPHENYLAZO)- 1,8-DIHYDROXYNAPHTHALENE- 3,6-DISULFONIC ACID

Abstract

ABSTRACT An excellent method for spectrophotometric determination of trace lead in industrial samples has been developed. The method is based on the reaction of lead(II) with new reagent 2-(2-sulfophenylazo)-7-(2,6-dibromo-4-methyphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid(SDBM). Under optimal conditions, SDBM reacts with lead(II) to give a 1 : 2 blue complex in a phosphoric acid media, which has an maximum peak at 630 nm; 0–20 µg of lead(II) obeyed Beer's law in 25 mL solution. The color reaction is instantaneous and the absorbance stable for 24 h; its the apparent molar absorption coefficient, Sandell's sensitivity, the limit of detection and the limit of quantification were found to be 1.07 × 105 L mol−1 cm−1, 1.94 ng cm−2, 3.12 ng mL−1 and 10.0 ng mL−1 respectively. Effect of foreign ions have been examined in detail. The experiment indicated that most of metal ions studied can be tolerated in considerable amounts, especially transition metal ions such as Ag(I), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Al(III), Cr(III) and Hg(II). Therefore, the proposed method is simple, high sensitive and selective, it has been applied to determine trace lead in real samples with satisfactory results.