DIRECT INJECTION NEBULIZATION FOR INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY

An improved direct injection nebulizer (DIN) is used in a continuous-flow mode for inductively coupled plasma mass spectrometry (ICP/MS). Precision in cases where the signal is not limited by counting statistics is typically 0.5% relative standard deviation (RSD), an improvement by a factor of 4 over the precision obtained with conventional nebulizers. A rinse-out time of only 15 s is sufficient to reduce the analyte signal to 0.1% of its steady-state value, even for memory-prone elements such as Hg and I. Relative detection limits are similar to those obtained with conventional pneumatic nebulizers. Since the sample flow rate is only 120-mu-L min-1, the absolute detection limits are improved by up to an order of magnitude. The refractory oxide ion ratios (MO+/M+) are 3 times higher than with other nebulizers. Matrix effects caused by Na are comparable to those observed with other nebulizers.