FLOW-INJECTION SPECTROPHOTOMETRIC DETERMINATION OF CALCIUM USING MUREXIDE AS A COLOR AGENT

FI spectrophotometric determination of calcium using murexide has been developed. The problem of the color of the dye fading and/or its comp lex in an alkaline medium in the batch method can be overcome by takin g advantage of FIA. A calcium solution is injected into an ethylenedia mine-ethylenediamine hydrochloride buffer (1 M, pH 11) which also serv es as a masking agent, and is then merged with the aqueous murexide (0 .005%, w/v) and continuously monitored. Simple FIA manifolds, includin g an LED colorimeter detector hooked up to a PC-based data acquisition and evaluation system an described. Optimization of FIA systems has b een made. The proposed procedures have been validated by using referen ce materials and comparing the results with the standard methods, and then applied to ores and drug samples. (C) 1998 Elsevier Science B.V. All rights reserved.