SEQUENTIAL LIQUID-LIQUID-EXTRACTION GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRIC (GFAAS) AND SPECTROPHOTOMETRIC DETERMINATION OF ZIRCONIUM(IV) WITH CALIXARENE HYDROXAMIC ACID

A new calixarene hydroxamic acid, 25,26,27,28-tetrahydroxy-5,11,17,23- tetrakis (N-p-chlorophenyl) calix[il]arene hydroxamic acid (CPCHA) is synthesized and used for the extraction and graphite furnace atomic ab sorption determination of zirconium(IV). The extract is also determine d spectrophotometrically as CPCHA-SCN complex having maximum absorbanc e at 447 nm with molar absorptivity 9.4 x 10(3) l mol(-1) cm(-1). The Beer's law obeys in the range of 1.0-9.5 ppm of zirconium. The graphit e atomic absorption (GFAAS) increases the sensitivity by about 50 fold s. The method is applied to the trace determination of zirconium(IV) i n standard samples. (C) 1998 Elsevier Science B.V. All rights reserved .