Before the invention of the Charged Aerosol Detector (CAD), liquid chromatographers relied on detectors such as refractive index, low wavelength UV absorbance, and evaporative light scattering for quantitative analyses.
While these detection methods helped chromatographers analyze compounds incompatible with traditional detectors, they were also limited by low sensitivity and quantitation challenges, severely impacting method development and research progression.
Then in the early 2000s, a group of analytical scientists did what scientists do best. They created a more sensitive and universal detection method, which led to the award-winning invention of the CAD.
The Corona CAD was first introduced to the scientific community at the Pittsburgh Conference in 2005 and received both the Pittsburgh Conference Silver Pittcon Editor’s Award and the R&D 100 award in recognition of its potential.
All CADs utilize evaporative technology and the conversion of an analyte to a detectable signal involves the same successive steps:
1. Nebulization: Charged Aerosol Detection begins by nebulizing the column eluent into droplets and subsequently drying the droplets into particles. The particle size increases with the amount of analyte.
2. Charging: a stream of ionized nitrogen gas collides with the analyte particles in the mixing chamber. The charge transfers from the ionized gas to the analyte particles. The larger the particle, the greater the charge.
3. Detection: charged aerosol particles transfer to a collector, where an extremely sensitive electrometer measures the aggregate charge. This process generates a signal directly proportional to the mass of the analyte present.
Our cutting-edge CAD technology combined with modern separation technology empowers scientists to measure the previously unmeasurable. Our Thermo Scientific Charged Aerosol Detectors offer you:
Charged Aerosol Detectors utilize evaporative technology. The conversion of an analyte to a detectable signal involves (1) nebulization of the eluent stream, (2) drying of the nebulized droplet aerosol into analyte particles, (3) transfer of positive charge from ionized gas to the evaporated analyte particles, and (4) detection of the charged analyte particles.
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