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Significance and Use
4.2 These practices should be used to determine whether a spectral bandwidth specified in a method can be realized with a given spectrophotometer and thus whether the instrument is suitable for use in this application. If accurate absorbance measurements are to be made on compounds with sharp absorption bands (natural half band widths of less than 15 nm) the spectral bandwidth of the spectrometer used should be better than 1/8th of the natural half band width of the compound’s absorption.
4.3 These practices allow the user of a spectrophotometer to estimate the actual spectral bandwidth of the instrument under a given set of conditions and to compare the result to the spectral bandwidth calculated from data given in the manufacturer's literature or indicated by the instrument.
1.2 These practices are applicable to all modern spectrophotometer designs utilizing computer control and data handling. This includes conventional optical designs, where the sample is irradiated by monochromatic light, and ‘reverse’ optic designs coupled to photodiode arrays, where the light is separated by a polychromator after passing through the sample. For spectrophotometers that utilize servo-operated slits and maintain a constant period and a constant signal-to-noise ratio as the wavelength is automatically scanned, and/or utilize fixed slits and maintain a constant servo loop gain by automatically varying gain or dynode voltage, refer to the procedure described in Annex A1. This procedure is identical to that described in earlier versions of this practice.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
E131 Terminology Relating to Molecular Spectroscopy
E275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers
ICS Number Code 17.180.30 (Optical measuring instruments)
UNSPSC Code 41115406(Spectrophotometers)
ASTM E958-13, Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers, ASTM International, West Conshohocken, PA, 2013, www.astm.orgBack to Top