BETA-CORRECTION SPECTROPHOTOMETRIC DETERMINATION OF CALCIUM WITH CALCON-CARBOXYLIC ACID

Calcium has been determined by beta-correction spectrophotometry with calcon-carboxylic acid (CCA). This reaction Is sensitive and selective in the presence of both ascorbic acid and triethylamine used to mask other metal ions. The beta-correction method can eliminate completely the effect of excess of CCA in its Ca(II) coloured solution to give ou t the real absorbance of chelate produced, improving sensitivity, prec ision and accuracy. The Beer's law is obeyed over the range till 2.0 m g l(-1) Ca at 460 nm and the true molar absorptivity of Ca-CCA chelate equals to 1.0x10(4) l mol(-1) cm(-1). The detection limit of calcium is 0.04 mg l(-1) and the results show that the relative standard devia tion was less than 2.9% with the recovery between 90.3 and 108%.