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