Automated On-line Preconcentration System for Electrothermal Atomic Absorption Spectrometry for the Determination of Copper and Molybdenum in Sea-water

Abstract

A flow injection accessory for electrothermal atomic absorption spectrometry was developed. The performance of the on-line preconcentration system was tested by determining Cu and Mo in sea-water. Calibration graphs constructed from the preconcentration of standards in 0.2% HNO ₃ solution were used. On-line preconcentration is computer-controlled. A miniature Muromac A-1 resin column was inserted at the tip of the AS-60 autosampler arm. A modification of the AS-60 autosampler in the tubing line and circuit allowed either flow of the sample through the column or operation of the autosampler in the normal mode. Retention of the metal ions as complexes on the microcolumn was achieved by using Muromac A-1 as the chelating resin; 20% v/v HNO ₃ was then used for elution. With a 198.6 µl sample loop, the throughput is 14 samples h ^-1 . Detection limits are 0.009 µg l ^-1 for Cu (606.9 µl sample loop) and 0.06 µg l ^-1 for Mo (50 µl sample loop and repeated four times). The accuracy of the method was confirmed by the analysis of certified reference saline waters.