Chromatography Forum

Hi friends,

Recently our neighbouring research group bought Waters LC system with 2424 UV detector and 2489 ELSD, running Hexane:IPA 95:5 as mobile phase.

They have no experience about ELSD. What they found is: when no column attached, there are peaks in UV and ELSD signals. When column attahced, even as short as 3cm guard column, signal from ELSD gone. Only UV signals appeared.

They tried to change nebulizer temp, drift tube temp, pressure but no improvement.

Any suggestion? or reason about this? Thanks a lot

FYI, you've got the model numbers flipped - the 2489 is the UV detector, the 2424 is the ELSD.

https://www.waters.com/webassets/cms/su ... 1802rb.pdf

See page 152 of the pdf

I don't have experience with ELSD, but the listed possible causes for "no peaks detected" are that the sample is volatile at the detector conditions; the sample is being retained on the column; the detector output signal is not zeroed; no gain has been set; detector exhaust too strong; or drift tube temperature too high.

You might be below the detection limit of the ELSD. The band broadening on the column may bring the signal below the detection limit. Try a larger injection volume or concentration.