Improved performance in the analysis of drinking waters and wastewaters by U.S. EPA Method 200.8 with an SC-FAST System
U.S. EPA Method 200.8 contains a lengthy, detailed description of procedures, both required and recommended. A summary of the experiments that must be performed to establish the performance of the instrument, along with a 10-step daily analysis procedure, can be found in Table 1 (Page 2).
A PerkinElmer® ELAN® 9000 ICP-MS was used for the analysis of natural and certified water samples described in this work. Sample introduction was accomplished with an Elemental Scientific, Inc. sampler changer SC-FAST sample introduction system. Instrumental conditions for the ICP-MS and SC-FAST, as well as experimental parameters used throughout this work, are presented in Tables 2 and 3 (Pages 3 and 4).
The SC-FAST is a sample introduction system consisting of an autosampler, diaphragm vacuum pump, 6-port switching valve, merging stream manifold, high-efficiency PFA-ST nebulizer, and a Peltier-cooled cyclonic spray chamber. The system is shown schematically in Figure 1 (Page 2). The contents of the sample loop, which is large enough to provide a steady state signal, are injected into an acid carrier stream that merges with the internal standard solution. The length of tubing connecting the output of the switching valve with the nebulizer is short so that the time between injection and measurement is minimized. The instrument response as a function of time for back-to-back sample injections is illustrated schematically in Figure 2 (Page 2).