A computer program to process data from a direct current plasma emission spectrometer

Abstract

This program processes data from a Spectraspan IIB spectrometer retrofitted with a Spectrajet III plasma excitation source (Spectrametrics, Inc ., Andover, MA). The spectrometer is operated manually and can determine only one element at a time. Accordingly, the program treats data for each element individually. Two of the spectrometer's performance characteristics tend to change gradually during normal operation: average blank count and analytical sensitivity. The program compensates for these variations. For the program to process data from the spectrometer, a reagent blank and a high standard (in this order) should be aspirated first; then the high standard and blank (in this order) should be run again after every six or fewer samples . The program, moreover, causes all data to be converted to logarithmic form before being used in computation. This makes possible the calculation of statistically valid confidence limits about predicted analyte concentrations. The program consists of a main section, DCPEOES, and three external sub-routines: BASELINE, SENSITIV, and XLNSQFT. BASELINE compensates for any change in the average blank count, and SENSITIV corrects for any variation in analytical sensitivity. XLNSQFT governs all correlation and prediction functions and has two interchangeable versions: one for first-order; the other for second-order, correlation.