Spectrophotometric determination of submicrogram amount of zinc with 5-(2 '-carbomethoxyphenyl)azo-8-quinolinol in the anionic micellar medium of sodium dodecylsulfate

Anionic micellar medium of sodium dodecylsulfate is utilized to solubilize the insoluble complex of zinc formed with 5-(2'-carbomethoxyphenyl)azo-8-qu inolinol in aqueous medium at pH 4.0-4.8. The dissolution of the complex re sults in an orange-red colour stable for 4 h and is proposed as a novel met hod for the determination of zinc at submicrogram level. The colour obeys B eer's law in the range 0-0.42 mu g of zinc per ml at 488 nm and has molar a bsorptivity and Sandell's sensitivity 4.14 x 10(4) dm(3) mol(-1) cm(-1) and 1.57 ng cm(2) respectively. The limit of determination and quantitation ar e 0.20 and 0.80 ppm in rock samples.