Calibration of the Wavelength Scale on Spectrophotometers by »The Indicator Method«

Abstract

This method was published by Parthasarathy & Sanghi (1958). They used the isobestic points of acid-base indicators to localize the specific wavelengths for these points on the photometer scale. A number of indicators were investigated and the isobestic points determined, but information concerning temperature coefficients and critical concentrations was not given. Bromophenol blue has been investigated, and the data necessary for its use to calibrate the wavelength scale are given below.