DETECTION AND SPECTROPHOTOMETRIC DETERMINATION OF EDTA WITH COBALT(II) AND PHOSPHOMOLYBDIC ACID IN URINE AND DETERGENTS

A simple, rapid, sensitive and selective method for the microgram dete ction and spectrophotometric determination of EDTA in water, human uri ne and detergents, based on its reaction with Co(II) and phosphomolybd ic acid at pH 0.5-2.0 is reported. Absorbance is measured against Co(I I)-phosphomolybdic acid reference solution at 750 nm. The effect of ti me, temperature, pH and Co(II) or phosphomolybdic acid concentration i s studied, and optimum operating conditions are established. Beer's la w is applicable in the concentration range 0.3-1.9 mu g ml(-1) of 10(- 5)M EDTA. Its detection limit is 0.14 mu g in the solution phase and 0 .03 mu g in the resin phase. The relative standard deviation is +/-0.1 3 mu g. Ag(I), Zn(II), Cu(II), Ni(II), Pb(II), Cd(II), Ca(II), Mg(II), Fe(III), Cr(III), U(VI), chloride, nitrite, phosphate. oxalate, berat e and amino acids do not interfere. (C) 1998 Elsevier Science B.V. All rights reserved.