ONLINE MICROCOLUMN PRECONCENTRATION WITH DESOLVATION AND DETERMINATION OF TRACE-ELEMENTS BY FLOW-INJECTION INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

A desolvation device was connected to a microcolumn (40 mm x 3.0 mm i.d.) in which 8-hydroxyquinoline-5-sulphonic acid was immobilized on the substrate of active carbon-silica gel. The analyte and 1.0 M sodium acetate-acetic acid buffer solution (pH 5.6) were mixed and pumped through the microcolumn. The analyte was then preconcentrated and eluted from the column with 2.0 M hydrochloric acid. The efficiency of desolvation, improvement in sensitivity and signal stability over the temperature range 70-120-degrees-C were studied in detail. It was found that aluminium, copper, cadmium, iron and manganese could be separated from various co-existing elements with a sample volume of 1.2 ml and a carrier flow-rate of 1.2 ml min-1. The desolvation efficiency at a desolvation temperature of 120-degrees-C was 73%. The column could be used more than 100 times. The detection limits for the above metal ions were 0.34-5.1 ng ml-1 and the relative standard deviations (n = 6) were 2.6-4.3%. The reliability of the method was confirmed for the analysis of human serum, and the results were in good agreement with those given by graphite furnace atomic absorption spectrometry.