Rapid flow analysis with inductively coupled plasma atomic-emission spectroscopy using a micro-injection technique

Abstract

An introduction system for liquid micro-samples in inductively coupled plasma atomic-emission spectroscopy is described that allows the injection of 5–500-µl volumes into a rapidly flowing carrier reagent stream leading to the nebuliser. The effect on analyte signal was studied as a function of flow-rate, injection volume and sample concentration. It is shown that the carrier flow-rate determines the response time, sensitivity, precision and sample carry-over in the nebuliser. By the use of relatively rapid flow-rates of up to 7.5 ml min^–1, fast injection of 10-µl samples is achieved at an injection rate of 240 h^–1 with a relative standard deviation of 1.5% for a single-element analogue readout. Digital readout is used for multi-element determinations with similar or better precision. Detection limits of the order of 0.1 mg l^–1 are obtained for 10-µl injections, limited by the volume injected, with a proportionate decrease in detection limit for increasing volumes.