Accuracy and Linearity in UV Spectrophotometry with a Liquid Absorbance Standard

Abstract

Estimations of the uncertainty of eight significant values (λ = 235, 257, 313, 322, 323, 345, 346, and 350 nm) of apparent molar absorptivities in the UV region have been obtained for acidic potassium dichromate solutions at pH 2.21–2.25, recommended as Standard Reference Materials (SRMs). The uncertainties include all the usual sources of possible systematic error in a commercial microprocessor-controlled spectrophotometer. The comparison of these values with those provided by the National Bureau of Standards (U.S.A.) indicates that a precision of ±0.40% has been obtained throughout the absorptivity range. Likewise, the uncertainty in the linearity of experimental absorbances for the eight wavelengths has been estimated, and a table has been drawn up of the absorptivity values and their uncertainties at 10-nm increments over the wavelength range of 200 to 500 nm.