Evaluation of an axially and radially viewed inductively coupled plasma using an échelle spectrometer with wavelength modulation and second-derivative detection
A high-dispersion échelle spectrometer which incorporates wavelength modulation and second-derivative signal detection is used to view analyte emission from an inductively coupled plasma in both the axial (end-on) and radial (side-on) configurations. Movement of the plasma torch assembly between the viewing positions is computer controlled. Performance characteristics such as background intensity, repeatability, background equivalent concentration, limit of detection, dynamic range and interference effects are reported for 24 elements and in general, measurement in the end-on position produces an improvement in sensitivity. Using end-on measurement, the system is applied to the multi-element analysis of a certified reference water.