Ddiymium has been used as a wavelength reference for many years as a glass filter. We now offer a quartz cell filled and permanently sealed with didymium perchlorate solution that will evaluate more effectively the optical performance of your instrument. Didymium offers sharp, stable peaks over the range of 290 to 870nm. Didymium perchlorate is used to assure that the wavelength scale of your instrument is within the manufacturers tolerances to the actual wavelength being measured. The use of the filled quartz cell assures that the optical configuration for your quality control is exactly the same as for a normal analysis.

Didymium presents a wide range of crisply resolvable peaks which are easily used to correlate the wavelength indicator on your spectrophotometer to the known Didymium peaks. The first procedure should be to scan the cell over the useable range to assure that all of the peaks can be resolved. Alter the slit width and scan rate to produce a useable spectra. Check each peak to assure that the reading on your spectrophotometer is within the manufacturer's tolerances for the wavelength of your spectrophotometer. If not, get a service technician to check and, if necessary, adjust your instrument. Didymium is measured against an air blank.

Periodically check the spectra, at a minimum in the area where you are doing your analysis. The periodic use of your Didymium cell will build a log of your instrument's wavelength accuracy for use with certification and troubleshooting should the correlation change over time.

Compare the wavelength peaks from your instrument with the expected values on the certificate supplied with the reference set. If the readings are within the expected range for your instrument then your wavelength scale is correct. If not, consult your service techincian and have the instrument evaluated

Each time that the analysis is repeated you can compare the new results with the previous results to check for any variance. If your instrument needs service because of a change in resolution, the historical data will greatly assist the service technician.