To check the resolution power of a spectrophotometer, the ratio of the peak maximum at λmax (269 nm) to the absorbance of the minimum at λmin (266 nm) is calculated. This gives a measure of the spectral bandwidth of the instrument.

Determination of the resolution is carried out against the 667-UV9 hexane blank reference filter, which is supplied with every filter set. Measurement is the same for all bandwidths. The wavelength range between 265 nm and 270 nm is scanned and the peak maxima and minima are determined. Then the peak/trough ratio is calculated and compared to the reference values.

The ratio of the absorbance value at 269 nm to the absorbance value at 266 nm should not be less than the one calculated from the values given in the certificate. Contact the manufacturer of your instrument if the ratio is considerably lower (e.g. 15%). Please note, however, that the result also depends on your specific measuring conditions; consequently when using particularly small slit widths the integration time should be sufficiently long.