6- By CAP, how are spectrophotometer wavelength and absorbance accuracy checked?
6- By CAP, how are spectrophotometer wavelength and absorbance accuracy checked?
Wavelength selection validation: use substance with sharp absorbance peaks at known wavelengths (substance with sharp peak at 360 should show such on spectrophotometer). Most accurate way is with deuterium lamp, which has strong emission lines at well-defined wavelengths. Most commonly used is holmium oxide glass filter, which has sharp absorbance peaks at several points.