ELSD detectors

[bunnahabhain]

Hello everybody

Our lab is about to buy an ELSD detector. We are fixed to Chromeleon 6.8 (best GLP features for HPLC software), so we are limited to Agilent (Varian) 1260 or Sedex devices, AFAICT.
Has anybodey experience how thes Agilent instruments (1260 or 1290) perform in comparison to the Sedex 80/85/90?
As for the Sedex: Is there a difference between 80 and 85 other than the data rate 40 vs. 100 Hz? I understand that the 95 is more sensitive due to the laser instead of LED light source.
Any practical experience (good or bad) are greatly appreciated.

Kind regards
Jörg

[entropiclabs]

I have experience with the Agilent 1260 ELSD (same as the Varian 380 ELSD). It is a great detector even for semi-volatiles, and utilizes a blue LED. The Agilent 1290 uses a blue laser, which they say improves sensitivity some 5-8x. The 1290 also allows you to cool the evaporation below ambient, down to 10C, allowing you analyze volatiles.

Both the 1260 and 1290 allow DMSO transparency, great for testing libraries. Also you can choose 10, 40 or up to 80Hz data acquisition rates for UHPLC.

The great thing about the 1260 and 1290 instruments is that you can also program gas-flow gradients. This helps when you are running a solvent gradient, as your compound will respond differently depending on the solvent composition. By programming gas-flow gradients, you can ensure the response of the detector remains linear despite the change in solvent composition.

I don't think you'll have much difference in performance between the Agilent and Sedex instruments. They are both great instruments, but I've only had experience with Agilent.

[bunnahabhain]

Thanks for sharing your experience. I think we'll go for Sedex, they are cheaper.

Jörg

[entropiclabs]

I'm sure you'll end up with a great instrument. Any chance you would be willing to share the price they quoted you? ... I'm very interested to know. Thanks.

[bunnahabhain]

One more question

We get the chance to buy a used Varian 380 from year 2008. Are ELSDs as robust as UV detectors in terms of longevity, or will they significantly drop in sensitivity or increase in noise over the years?

Entropiclabs: Let me know your e-mail and I'll tell you the price in private. If I were a manufacturer, I would not want my prices to show up in a public forum.

Jörg

[entropiclabs]

Hi Jorg,

Our Varian 380 ELSD is actually from 2008 as well. We bought it second hand a while back and haven't had any problems. We haven't needed to replace anything except the N2 filter every year. Since it is the same model as the Agilent and Polymer Labs series, parts are available.

The noise levels on the instrument when running pure water is between 0.2-0.4mV, which is within manufacturer specifications (<0.5mV). The light source is LED, which has never needed replacement. The heat sources on the nebulizer and evaporator tube still function just fine.

I guess the only things you should be worried about are the mass flow regulator and the photomultiplier (PMT). I assume if that needs replacement, you might as well buy a new unit. Anyone know the lifetime of the PMT on an ELSD?