We have a Varex ELSD MK3, it is being used to determine Sucrose,fructose and glucose in aqueous samples at around 0.1%w/v. 10ul injections are from a 7125Rheodyne.
An 15cm x 3mmid. amino column is used with 75%ACN in water eluant and 0.5ml/min flow rate. Everything works OK but injection repeatability is poor, particularly the first 3-4 injections of the day. We have changed injection loops, syringes, nothing helps. The nebuliser and drift tube have been cleaned,carefully rebuilt with new O rings, to no avail.
After the 4-5th injection repeatability hovers around 5%CV
Has anyone experienced this sort of problem with ELSD detection, or any ideas on what is causing the variation. Incidentally we have never used ELSD quantitatively before!

Peak area variations of around 1-3% are quite commn with stray light detectors, because not the complete stream goes to the optical unit.
To improve precision, I recommend also to check a new nebulizer.

good luck

ELSD detector response greatly depends on the operational parameters, namely gas flow, temperature etc. I do not have experience with your type, but it looks like a slow stabilisation of the detector after switching on. Is there a trend for those first injections or are the variations random? Check also your gas supply - any fluctuations in its pressure (some cheap reduction valves can show significant hysteresis) will increase the CV.

We have Waters W2420 ELSD detector. We have just started with ELSD detection and faced with various problems, I suppose common for this detection technique. So, we are obtainig ghost peaks after the main one on different samples known to be pure and certified reagents. These peaks are irreproduceable and can be eliminated only by applying maximum (60 psi) nebulizing gas pressure, which causes decrease in sensitivity. Did anabody have experienced such a problem or have any useful idea about it. And I will be glad to know where can I find literature on ELSD detection. Thanks for any answer.