Study on the Solid Phase Extraction and Spectrophotometric Determination of Cobalt with 2-(2-Quinolylazo)-5-Diethylaminoaniline

摘要

A sensitive,selective and rapid method for the determination of cobalt based on the rapid reaction of cobalt(II)with QADEAA and the solid phase extraction of the Co(II)-QADEAA chelate with C_(18)membrane disks was developed.In the presence of pH = 5.5 buffer solution and cetyl trimethylammonium bromide(CTMAB)medium,QADEAA reacts with cobalt to form a violet complex with a molar ratio of 1:2(cobalt to QADEAA).This chelate was enriched by the solid phase extraction with C_(18)membrane disks.An enrichment factor of 50 was obtained by elution of the chelate from the disks with a minimal amount of isopentyl alcohol.In isopentyl alcohol medium,the molar absorptivity of the chelate is 1.43 x 10~5L mol~(-1)cm~(-1)at 625 nm.Beer's law is obeyed in the range of 0.01 ~ 0.6 mug mL~(-1)in the measured solution.The relative standard deviation for 11 replicate samples of 0.01 /mug mL~(-1)level is 1.18%.The detection limit reaches 0.02 ng L~(-1)in the original samples.This method was applied to the determination of cobalt in environmental samples with good results.