Chromatography Forum

Hello all-

We are attempting to qualify some HPLCs from a wavelength range of 198-365 nm or so. Our problem is that the only standards we have are the NIST traceable holmium oxide standards. I'm told that these will cover the range from about 240nm to 365 nm. Does anyone know of a standard, or any other way, to qualify the instruments from the 198-240 range? Has anyone had this problem? This is for a pharmaceutical lab.

Thanks.

Given:
A. The lack of fine structure in UV spectra of organic compounds in solution,
B. The wide bandpass used in most HPLC systems to get adequate S/N, and
C. The fact that calibrators and samples are run on the same instrument and same day --

-- a high level of wavelength accuracy is not really required and a check at one wavelength in the mid-UV is generally sufficient. (i.e, there's no commonly available standard because nobody does it!)

It's not a great solution (pardon the pun)... but caffeine in water is often used as a wavelength accuracy check solution. There is an absorbance maximum at 205nm - I mention not ideal because it is quite a broad spectral peak.