The Beckman DU 640 spectrophotometer that we use has a built in performance
validation procedure that measures wavelength accuracy, wavelength
repeatability, resolution, baseline flatness, noise, and stability. Each of
these tests is performed automatically, requiring no user interaction with the
instrument. If instrument performance meets/passes each of these test criteria
then we then examine the following standard reference materials.
We use a NIST traceable Holmium Oxide standard (SRM 2034) for measuring the
wavelength accuracy of UV/VIS spectrophotometers over a range of 240-650 nM.
The standard (4% Holmium Oxide) is contained in a sealed quartz cuvette in 10 %
perchloric acid as supplied by NIST. The wavelengths for 14 measured peak
absorbance values (or the wavelengths for the minimum transmittance values when
measuring Transmittance) were compared to expected wavelengths of minimum
transmittance for 14 bands with an expected tolerance of 0.1 nm. The 14 bands
of minimum transmittance are published standard results given for multiple slit
widths.
Crystalline Potassium Dichromate Ultraviolet Absorbance Standard (SRM935a as
described in the certificate of analysis) is used as a reference standard for
verification of accuracy and linearity of absorbance over the range of 235-350
nm. The standards and blanks are prepared essentially as specified in National
Bureau of Standards publication 260-54 (section 5; Measurment of the Apparent
Specific Absorbances of SRM935). Preparation and analysis of the Potassium
Dichromate standards was completed by Albert Tse in our lab.
Hope this helps
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