EVALUATION OF CONTROLLED-PORE GLASS IMMOBILIZED IMINODIACETATE AS A REAGENT FOR AUTOMATED ONLINE MATRIX SEPARATION FOR INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

A new iminodiacetate chelating reagent, immobilized onto a controlled- pore glass support, was evaluated as a substrate for on-line matrix se paration for ICP-MS. An automated FI manifold was constructed, incorpo rating a glass mini-column of the iminodiacetate reagent, One compromi se set of optimum conditions was obtained for a range of analytes, usi ng the variables of matrix separation flow rate, buffer pH and concent ration and eluent acid concentration, With a sample volume of 3 ml and an elution volume of 0.3 ml, a preconcentration factor of 10 was obta ined in addition to matrix separation, The range of elements found to be retained by the column included transition metal cations, uranium a nd lead, These could be quantitatively eluted using nitric acid (0.5 m ol dm(-3)). Calibrations prepared from both pure water and artificial sea-water matrices were found to be comparable in terms of sensitivity , illustrating that the presence of a saline matrix did not affect the separation process, Both calibration sets showed good linearity with least squares regression coefficients between 0.996 and 0.999 for the analytes measured, The method gave acceptable reproducibility with pre cisions (s(r)) at the 5 ng ml(-1) level of < 5%, for 5 replicates. Rec overies between 62 and 113% were obtained for all the elements analyse d except Mn, which gave a very low recovery (<35%), under the compromi se conditions used, The chelating material was found to have a capacit y of approximately 0.1 mmol g(-1) for a range of elements. The procedu re was validated by accurate analysis of the National Research Council of Canada, CRMs SLEW-1 (Estuarine Water) and CASS-2 (Coastal Sea-Wate r).