Simultaneous multielement determination in microliter samples by rapid-scanning spectrometry coupled to a microwave-induced plasma

A modified electrothermal atomizer is coupled to a helium microwave-induced plasma (m.i.p.) for atomic emission spectrometry. For preliminary evaluation, this arrangement was coupled to a monochromator to quantify single elements in microliter samples. Detection limits range from 3 to 25 pg for Cd, Fe, Pb, Mn and Au and linear dynamic ranges are 2–4 orders of magnitude. The monochromator, fitted with a rapid scanning galvanometer mirror, is also used as a multielement detector. A spectral window of ca. 40 nm is rapidly scanned (10 Hz) across the exit slit and five elements from one solution are determined in rapid sequence. In the multielement mode, the detection limits are in the range 50–250 pg, as might be expected, owing to the decreased duty cycle. However, there is a significant improvement when compared to an earlier report from this laboratory. By narrowing the spectral coverage and taking data more rapidly this drawback is minimized.