Experience with Charged aerosol detectors?

Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.

10 posts Page 1 of 1
Hi everyone

We are thinking about extending our range of available detectors with a Charged aerosol detector. The advertisment looks promising (as always), but I'd like to know if there is hands-on experience with this type of detecor here in the forum.
I'd like to replace our ELSD (which does not pass PQ due to high baseline noise) but want to know if the response is really "universal" as described. Or are there still analytes that cannot be detected?

Kind regards
Jörg
Hi Jörg.
I've had some experience with CAD recently and although I have not been using for more than a few applications they seem to be quite universal in detection. It is a good compliment to UV.

However, there are of course cons to this detection type.
- Since the patent is still limiting the market to a monopoly there is not that much information to receive when you get stuck with a specific application which the manufacturers lack knowledge about.

- Lacking knowledge is a key word in my opinion. It is really noticable how new and small this area is. Sometimes when the service technicians (or even the instrument specialists) visit us to answer questions regarding issues with the CAD the cannot answer us. If we're lucky someone else in some other country might have an answer.

- We've also noticed how their new models seems to perform worse for our applications and they are planning to bring the old models out of service.
The newer models seem to be needing higher purity solvents than the old Ultra model to perform at the same level, which is annoying. I at least would expect the new model to be outperforming the old models.

- Another key Word, and this is a BIG one, is individuals. Each unit we've had has been performing differently than the other. Some are good with acetonitril gradients and some with methanol gradients. Another mystery which we have not received an answer for.

I hope this helps you Jörg. I would like to point out that we are working with difficult analytes and a very narrow application window, so what we've seen might not show up for you. But you should probably ask for a demo of the instruments using your analytes/applications.
Hi Jörg,

I have some experience with the CAD's, the old ones as well as the new ones.
The actual models, Corona Veo and Veo RS, have some totally new technical features built in, such as improved nebulization technology (now similar to MS ESI source)which is considerably more consistent, improved aerosol dry-out technology. The pressurized waste bottle has been eliminated. A lot of internal redesign has been done.
THe Veo's are definitly more sensitive than CAD/Ultra, which amongst others requires high-quality solvents. UHPLC-grade or even LC/MS-grade. Otherwise you'll observe a higher background signal.

If you want to share your company address, I'll be able to send you more details.

Regards,
Hi LCwatcherGE

We have arranged a product demonstration with Thermo in July. I'd be interested in your experience so I can ask some discomfortable questions :)
Please contact me at joerg.johannes@laus.de
Kind regards
Jörg
There are not many good CAD users out there and they sometimes get flooded (liquid flow gets into the CAD with gas off) by the user which requires disassembling and cleaning.
It can see nanogram/picogram level so high purity solvents are critical to achieve sensitivity, afterall its called a "poor mans Mass Spec"
I would ask for technical power point slides and app support to assist your method. What problems are you experiencing?

If you have a standard fused silica nebulizer tip, it can be replaced with a stainless steel tip which has better resistance to Acetonitrile. I have seen high ACN usage corrode the fused silica tip, which resulting in poor nebulizer plume which equals poor sensitivity.
By the way In Spanish, Veo means eye ( It sees everything)
Hi My Corona Ultra has a flow ratio low problem, anyone has an idea how to fix it? Not the waste bottle problem. Anyone know a good service provider to fix this problem? Thanks!
yuanpengz@yahoo.com wrote:
Hi My Corona Ultra has a flow ratio low problem, anyone has an idea how to fix it? Not the waste bottle problem. Anyone know a good service provider to fix this problem? Thanks!

Check your connections with soapy water. You have a leak somewhere (I assume that you have a correct nitrogen (or air) pressure/flow set up.
Vlad Orlovsky
HELIX Chromatography
My opinions might be bias, but I have about 1000 examples to support them. Check our website for new science and applications
www.helixchrom.com
BostonFSE wrote:
There are not many good CAD users out there and they sometimes get flooded (liquid flow gets into the CAD with gas off) by the user which requires disassembling and cleaning.
It can see nanogram/picogram level so high purity solvents are critical to achieve sensitivity, afterall its called a "poor mans Mass Spec"
I would ask for technical power point slides and app support to assist your method. What problems are you experiencing?

If you have a standard fused silica nebulizer tip, it can be replaced with a stainless steel tip which has better resistance to Acetonitrile. I have seen high ACN usage corrode the fused silica tip, which resulting in poor nebulizer plume which equals poor sensitivity.
By the way In Spanish, Veo means eye ( It sees everything)



I flooded my CADs few times when running overnight. Never disassembled it. When you flood CAD it star showing Error 80. I just left the unit on with no mobile phase flow and higher flow of the gas (we use air)
Vlad Orlovsky
HELIX Chromatography
My opinions might be bias, but I have about 1000 examples to support them. Check our website for new science and applications
www.helixchrom.com
ELSD/ CAD, very niche detectors with very high maintenance. They require huge amounts of pure gas to operate (and exhaust all the solvent fumes back out, so direct to a fume hood). CAD is not better than ELSD. Both used for the same applications. Both have many of the same concerns and cons. Best for advanced users only. Super easy to collect invalid data.

100% NOT UNIVERSAL DETECTORS (this comes from adverts and marketing mis-info, not facts). Much of the sales literature is just made up or taken out-of context.

My boss was involved in the development and testing of both of these units many years ago. He developed hundreds of application notes, white papers, published journal articles, updates for them plus provided professional training/consulting. He often states that he does not recommend them for most users. Would not use in a validated methods/application(s) as documenting repro can be a challenge and you must optimize the detector to each and every sample (as resp is different for each). All of your samples get baked onto the inside, then flake off over time resulting in very high noise levels (must internally clean on a regular basis). Most users have little to no training in how to optimize, clean or operate them.

More info can be found in this linked article. "Evaporative HPLC Detectors; CAD (Charged Aerosol Detector) and ELSD (Evaporative Light-Scattering Detector)": https://hplctips.blogspot.com/2017/12/e ... arged.html
Multidimensional wrote:
ELSD/ CAD, very niche detectors with very high maintenance. They require huge amts of pure gas to operate (and exhaust all the solvent fumes back out, so direct to a fume hood). CAD is not better than ELSD. Both used in same applications. Both have many of the same concerns and cons. Best for advanced users only. Super easy to collect invalid data.

100% NOT UNIVERSAL DETECTORS (this comes from adverts and marketing mis-info, not facts). Much of the sales literature is just made up or taken out-of context.

My boss was involved in the development and testing of both of these units many years ago. He developed hundreds of application notes, white papers, updates for them plus provided professional training/consulting. He often states that he does not recommend them for most users. Would not use in a validated methods/application(s) as documenting repro can be a challenge and you must optimize the detector to each and every sample (as resp is different for each). All of your samples get baked onto the inside, then flake off over time resulting in very high noise levels (must internally clean on a regular basis).

More info can be found in this linked article. "Evaporative HPLC Detectors; CAD (Charged Aerosol Detector) and ELSD (Evaporative Light-Scattering Detector)": https://hplctips.blogspot.com/2017/12/e ... arged.html


I can't say that I agree. I think that ELSD is the most simple detector, it does not require any maintenance except changing bulbs and cleaning nebulizer may be once a year. Operating ELSD is much easier than any other detectors. I personally like Sedex from Sedere. If you dedicate one system for ammonium buffers and another one for TFA, you should not have much less issues with noise. I cannot imagine not having this tool in the lab. We have two Coronas and two ELSD. I like ELSD more because in my opinion it has less issues when doing a gradient and it is impossible to flood it like CAD. Just my opinion.
Vlad Orlovsky
HELIX Chromatography
My opinions might be bias, but I have about 1000 examples to support them. Check our website for new science and applications
www.helixchrom.com
10 posts Page 1 of 1

Who is online

In total there is 1 user online :: 0 registered, 0 hidden and 1 guest (based on users active over the past 5 minutes)
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm

Users browsing this forum: No registered users and 1 guest

Latest Blog Posts from Separation Science

Separation Science offers free learning from the experts covering methods, applications, webinars, eSeminars, videos, tutorials for users of liquid chromatography, gas chromatography, mass spectrometry, sample preparation and related analytical techniques.

Subscribe to our eNewsletter with daily, weekly or monthly updates: Food & Beverage, Environmental, (Bio)Pharmaceutical, Bioclinical, Liquid Chromatography, Gas Chromatography and Mass Spectrometry.

Liquid Chromatography

Gas Chromatography

Mass Spectrometry