Detector calibration :?:

[sudhis]

As per our SOP and in general as per pharmacopias we perform detector calibration and wavelngth accuracy in the range from 260nm to 280nm and we concluding results and passing the tests at this range only. But even we are operating the same detector at some times down to 200nm and high at 360nm . So is not necessary to confirm the entire Uv range we are calibrating or is it ok only specified range from 260nm to 280nm .if so why only that range.

[DR]

Caffeine has local max & min absorbances between 240 & 280. You can use those for a 2 point accuracy check. If you want a 4² point check, you can prepare K-permangenate solutions in 3 different concentrations and check each of 4 wavelengths, calculate the absorbtivities etc. etc. (Shimadzu method). I have not yet encountered any lab that is interested in checking every wavelength in the range used. I guess the holmium oxide standard based tests available in many PDAs (and some UV/Vis units) would be as close as you could conveniently get to being that thorough. I guess the theory is that if the detector is close at at least 2 points, it should be OK throughout the range covered by the grating and its associated components.