A drift correction procedure for ICP-AES systems

A method is reported for correction of long-term drift in ICP-AES measureme nts. The change in the intensity of thirty emission lines was monitored ove r eight hours without recalibration of the instrument. Drift values were fo und to give errors of up to 20% with respect to the first measurement. The suggested procedure utilises the drift pattern of an intrinsic plasma line, Ar 404.597 nm, and the results of a principal component analysis to remove the drift error. After correction, the drift values drop to less than +/- 2%.