Performance characteristics of an ultrasonic nebulizer coupled to a 40.68 MHz inductively coupled plasma atomic emission spectrometer

Abstract

Analytical performance characteristics [limits of detection (LODs), memory effects, long and short-time reproducibility, effect of high salt content and accuracy] of an air-cooled ultrasonic nebulizer coupled to a 40.68 MHz r.f. inductively coupled plasma (ICP) were evaluated. Approximately 10-fold enhancements in the LODs, only slightly affected by ICP power, were observed with a simultaneous, sequential polychromator. Limits of detection were somewhat better than those quoted in the literature for 27 MHz r.f. ICP generators. The present configuration allowed the determination of trace elements at the µg dm^–3 and sub-µg dm^–3 concentration level in pristine and waste waters. The use of a Trassy–Mermet sheath gas assembly and a 3 mm injector tube allowed the direct analysis of saline solutions containing trace elements at the µg dm^–3 level using matrix-matched calibration protocols. With this configuration, memory effects were minimum and the long- and short-term variations could be compensated for with the use of internal references. As a result relative standard deviations are improved and the need for frequent system readjustment and recalibration was eliminated. A comparison of the data for standard reference and spiked materials indicated that the accuracy was satisfactory.