ESA's CORONA Charged Aerosol Detector

[fuelquest]

Does anyone out there have experience with ESA's new charged aerosol detector? ESA launched it at Pittcon 2005, and they are marketing it as the best HPLC detection technology in over 2 decades. We just purchased one and I would like to get some feedback from the other "guinea pigs" out there.

[Broesen]

Hi.

I have just tried the CAD detector and I must admit that I was really disappointed about It. The peaks was broad and noisy. It cann't be used with gradient (the respons change by a factor of 8 during the gradient, ELSD change only by a factor of 2). The componds classes that could be detected was still the same as with our standard ELSD.The respons varied 50 % for differnt compound classes. So the conclusion was that our ELSD (SEDEX and Polymerlab) was far more a universal detector: The CAD detector is just another kind of ELS detector. I hope not that we have to wait two more decades to get the first real universal detector.

[gemm]

we just tested the CORONA detector and agree with Broesen. the gradient stability is poor and the results with this device are disappointing. we too are not going to change our ELSD.

fuelquest, maybe you can share your experience with us, once you have your CORONA detector installed.

[josebenjamin]

Dear Friends,

I have not used the detector, but I would like to offer the following thoughts. All new technologies have "teething" problems, and some never get to be mature, in other words, they die before long.

I always maintain a philosophy about new technologies that is as follows; do not try anything new until a year after the date of introduction. This way all the possible bugs and deficiencies can be detected and or corrected.

Good Luck,

josebenjamin

[Kostas Petritis]

Although you are partially correct, if everyone would wait a year before purchasing any new technology, all the new technologies wouldn't go far.

In addition, when you claim that you have "the best HPLC detection technology in over 2 decades" you should be ready either to backup to a certain extent your claims or suffer from users critisism.

[ravi]

we're thinking of evaluating the system in-house prior to possible purchase. Are there any things to look out for and to ask the tech?

thanks

[gemm]

evaluation is always a good idea. go ahead and do so.
imho the corona detector acts like a ELSD. to test the "universal signal response" (as promised by the manufacurer) of the corona detector, we tested it against a CLND (nitrogen detector). a mixture of test samples containing equal amount of nitrogen was measured after LC (gradient run). on the CLND, all signals appeared equal in size as expected. with the corona detector, we got different signal sizes, depending on the gradient (same as with ELSD).
well, it is not surprising that the CLND measures properly for what it is made for (additionally it it roughly twice as sensitive, as the corona detector). but for the corona detector, i do not see any benefit in comparison to the ELSD.
concerning the signal beeing proportional with the quantity of sample in the analyte, i am not as optimistic as the manufacturer of the corona CAD.

it would be very kind of you to post your impression of the corona CAD after the evaluation.

[Kostas Petritis]

we got different signal sizes, depending on the gradient (same as with ELSD).

Has anybody tried to add post-column an inverse gradient in order to keep the solvent composition (that goes to the ELSD) the same? It will affect of course a little bit the sensitivity but maybe the equimass response will be improved...

[Chris Pohl]

We had a limited opportunity to evaluate this detector last winter in the course of the development of our new Acclaim surfactant column. We found it to be approximately 5 times more sensitive than conventional ELSD. This relative sensitivity comparison was based on extensive experience with two commercially available ELSDs from two different vendors. Its advantage is significantly better signal near the detection limit as opposed to better signal well above the detection limit. In essence, the technique boosts the signal in the concentration regime where particle formation is problematic, giving significantly better linearity in the low concentration regime. So, it wouldn't surprise me to hear that working under conditions where the analyte concentration is well above the detection limit that the sensitivity benefit is minimal.

The new detector does, however, bring with it significantly higher sensitivity to trace components in the mobile phase (a natural consequence of its improved sensitivity for low concentration analytes), making it somewhat more challenging to get a flat baseline when doing gradient applications.