ASTM E158 – Standard Practice for Fundamental Calculations to Convert Intensities into Concentrations in Optical Emission Spectrochemical Analysis (Withdrawn 2004)

1.1 This practice covers fundamental forms of plots, used to convert measured intensities into concentrations in both photographic and direct reading analysis. It includes equations suitable for use with calculators or computers for such conversions, and methods for making background corrections and corrections for interferences from other elements.

1.2 A previous issue of this practice attempted to treat optical emission and X-ray fluorescence as one field, employing similar calculations to convert measured radiation intensities into concentrations. In fact, quite different procedures are used in the two fields. This practice confines itself to optical emission spectrochemical analysis. A separate practice will be devoted to calculations in X-ray fluorescence spectroscopy.

1.3 This practice is related to but should be distinguished from:

1.3.1 Practice E116, which describes procedures for converting either transmittance or optical density of lines on a photographic emulsion into intensities or relative intensities. This step is required in photographic analysis before the present practice can be applied.

1.3.2 Practice E305, which describes the procedures for fitting a curve to a group of plotted points, and for standardizing the equipment, in order to obtain optimum accuracy, guided by sound statistical practice.

1.3.3 Practice E876 discusses the statistical treatment commonly applied to spectrochemical data, such as calculating the standard deviation and the relative standard deviation.

1.4 This practice includes the following sections:

Section Referenced Documents 2 Terminology 3 Significance and Use 4 Fundamental Theory 5 Plotting Analytical Curves with a Constant Internal Standard 6 Plotting Analytical Curves with a Variable Internal Standard 7 Background Correction 8 Concentration Calculations 9 Corrections for Interferences from Other Elements 10

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.