ANALYSIS OF HIGH-PURITY REAGENTS USING AUTOMATIC ONLINE COLUMN PRECONCENTRATION-SEPARATION AND ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

A fully automatic flow-injection on-line column preconcentration and s eparation procedure for electrothermal atomic absorption spectrometry is described for the determination of cadmium and lead in high-purity reagents. A microcolumn with 9 muL of solid sorbent, introduction of a ir prior to elution, and use of methanol as the eluent made it possibl e to elute the sorbed analyte quantitatively with only 80 muL of solve nt. The total eluate volume was transferred into the graphite tube whi ch was pre-heated to 80-degrees-C using a flow rate of 0.08 mL min-1 w hich allowed the solvent to evaporate in part during eluate introducti on. The efficiency of the total procedure was 0.63 and 0.65, and the e nrichment factor was 62 and 64 for cadmium and lead, respectively, com pared with the direct introduction of 30 muL of an aqueous solution. T he sample throughput was 13 h-1 for a sample loading time of 60 s and the detection limits (3 sigma) were 0.7 and 4.5 ng L-1 for cadmium and lead, respectively. The relative standard deviation of the entire pro cedure in the optimum working range was typically around 3% (n = 6). A number of high purity (suprapure) and analytical grade (pro analysi) reagents were analyzed, and spiking experiments resulted in recoveries of 97-104%.