Direct Injection High Efficiency Nebulization in Inductively Coupled Plasma Mass Spectrometry under Cool and Normal Plasma Conditions

The direct injection high efficiency nebulizer (DIHEN) was investigated for application to inductively coupled plasma mass spectrometry (ICPMS) with a cool plasma. Elements are organized into three categories based on their performance in the cool and normal plasma. Sensitivity, precision, and detection limits are presented for elements (39K, 40Ca, and 56Fe) that suffer from mass spectral interferences (38ArH+, 40Ar+, and 40Ar16O+) derived from the plasma gas. Figures of merit are also reported for a group of elements that are suitable for analysis using either the cool or normal plasma condition. In a departure from previous published accounts, however, a group of elements is investigated that is suitable for analysis in the cool plasma only by measurement of the metal oxide ion because the sensitivity and precision of the atomic ion are inferior to those obtained for the metal oxide ion. The sensitivity and precision obtained for these molecular species are comparable to those obtained for the atomic ions of elements that are suitable for analysis using the cool plasma. Calibration curves for the metal oxide signal as a function of the metal concentration in the cool plasma are linear over six orders of magnitude, covering the concentration range from 1 ppt to 1 ppm. Nerve tonic tablets that contain Na, Mg, K, Ca, and Fe in unspecified amounts were analyzed under cool plasma conditions.