Chromatography Forum

We are looking to develop a method for checking the wavelength accuracy of an Agilent VWD using ChemStation Plus software, vB.02.03. The software allows a spectral scan to take place, but will not display the data - to do this, we would have to purchase an expensive macro from Agilent . We had thought of injecting caffeine at various wavelengths (eg +/- 10 nm of theorretical Amax, in 1 nm increments) and measuring the peak heights to determine Amax. This is a rather tedious way to check this. Does anyone know of a more user friendly technique? There is a holmium oxide check built into the software which covers higher wavelengths, but we need to verify the accuracy at < 300 nm.
Thanks in advance.

If You don't need validated method and curve print will be sufficient as document You can use "Intensity test" procedure.

You will scan full range first and then zoom into spectrum part of interest.
There are just some few problems:
1. To make comparison You have to scan water "spectra", the "baseline" is not a nice line.
2. You don't have numerical output- have to take notes from display (but it can be printed)
2 Absorbtion is not "peaks" but "waleys"

Thanks Rolandas, we'll try that.

Actually, the caffeine trick you describe is exactly how Dionex calibrates our new Variable-Wavelength Detector. We use a spreadsheet to calculate the maximum by fitting a parabola to the three points nearest maximum.

Mojo - you can set that up automatically: Method 1.M has wavelength 1, change wavelength, save as Method 2.M for wavelength 2, etc., and set up a sequence. Easy.