One of the biggest challenges liquid chromatographers currently face with analyte detection is no single method can reliably measure all compounds. Often, analytes respond more strongly to one form of detection than another, like UV versus MS, or do not respond at all.
What is most needed is the ability to detect a wide range of analytes—from small molecules to antibodies—with a response that delivers accurate quantitation.
For complex separations where multiple analytes in a sample are incompatible with UV and MS detectors, like when compounds lack a chromophore or cannot ionize, liquid chromatographers can turn to a universal detection approach called Charged Aerosol Detection (CAD).
The Charged Aerosol Detector provides a uniform analyte response and standard relative quantitation capable of detecting all non-volatile and many semi-volatile compounds irrespective of the chemical structure.
By meeting the flexibility and performance needs for analytical R&D studies and the simplicity and reproducibility demands for manufacturing quality control in QA/QC studies, CAD gives chromatographers more confidence in every LC analysis.
Charged Aerosol Detectors utilize evaporative technology. The conversion of an analyte to a detectable signal involves the same successive steps:
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.
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.
The charged 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.
Before the invention of CAD, liquid chromatographers relied on detectors such as refractive index, low wavelength UV absorbance, and evaporative light scattering for quantitative analyses.
While these HPLC detection methods helped analyze compounds incompatible with traditional UV-Vis detectors, they were also limited because of low sensitivity and quantitation challenges, severely impacting method development and research progression.
The first Charged Aerosol Detector, the Thermo Scientific Corona CAD, was introduced to the scientific community at the Pittsburgh Conference in 2005 and became commercially available soon after. The Corona CAD received both the Pittsburgh Conference Silver Pittcon Editor’s Award and the R&D 100 award in recognition of its potential.
CAD is now a preferred universal LC detector for both routine and complex analyses, driven by the need for sensitive, near-universal analyte response and standard-free quantitation.
The most impactful technology advancement happened in 2013 when the detector was fully redesigned and introduced by Thermo Scientific as the Thermo Scientific Corona Veo RS Charged Aerosol Detector, and later the Thermo Scientific Vanquish Charged Aerosol Detectors.
These major redesigns markedly improved the detector performance and user-friendliness in a few ways:
The most desired feature of a near-universal detector like CAD is the ability to both quantitatively measure compounds incompatible with UV-Vis and MS detection and relative amounts of compounds when certified standards are not available for a single calibrant quantification.
The Charged Aerosol Detector also increases the efficiency of existing analytical operations and may open up entirely new possibilities by exploiting a range of analytes unseen by other detection methods.
Major benefits of using CAD include:
This collection of publications is a resource to demonstrate the analytical capabilities of CAD by highlighting the breadth and scope of the different analytical applications found in the literature.
The Chared Aerosol Detector delivers versatility and allows chromatographers to use traditional HPLC, UHPLC, and nano-flow separations. In many cases, CAD can eliminate the need for derivatization or sample pretreatment, providing dilute-and-shoot simplicity.
Scientists in diverse areas like pharmaceuticals, food and beverage, natural products, fundamental research, and environmental testing rely on this detection method for complete analyses.
These publications cover analysis of small and large APIs, counterions, excipients and adjuvants, liposome characterization, QC library measurement, degradants/impurities, analyte purity, and stability.
These articles cover many disciplines relevant to the study of living organisms including the fields of biochemistry, biology, microbiology, and physiology.
Articles include the measurement of different classes of compounds found in plant extracts, many of which are used in traditional medicines. Some highlight CAD for analyte quantitation when reference standards are unavailable.
Includes publications describing the use of the CAD for measurement of analytes like carbohydrates and lipids, plus metabolomic approaches for determining product authenticity and adulteration.
This section spans many industries including agriculture and farming, petrochemical, environmental, and the production and use of plastics and polymers.
Includes topics such as tissue drug measurement in fresh and post-mortem samples, effects of drugs, and how disease progression affects metabolism.
Articles include fundamentals, operating principles, detector optimization, detector comparison, method development, and evaluation of columns.
Cutting-edge detection technology combined with modern instrumentation empowers liquid chromatographers to measure the previously unmeasurable and deliver results without compromise.
Our Thermo Scientific Charged Aerosol Detectors seamlessly combine with Thermo Scientific HPLC and UHPLC systems, leading column technologies, and advanced data handling to help you:
Vanquish Charged Aerosol Detectors and Corona Veo Charged Aerosol Detectors provide:
More information: Discover what you’re missing with Thermo Scientific Charged Aerosol Detectors, Brochure BR70735
Dive into the technical capabilities of our unique HPLC/UHPLC detector. Hear from industry experts in pharma/biopharma and food/beverage how you can easily apply the CAD in your analyses along with tips, tricks, pointers, and advice from our guest speakers.
Access our full CAD symposium webinar series on-demand here.
“The Vanquish CAD system is intuitive to work with and requires minimal maintenance, which gives it potential to be used by industry for in-house testing.”
– Hilary G.| UC Davis Olive Oil Center
“We are living a love story with Vanquish Duo + CAD. In addition to sensitivity, its robustness and reliability keep our relationship secure. Coupled with CAD, we go further with this love story that reveals precisely unknown compounds … streamlining processes, reducing costs with maximum quality.”
– Emilia G. | GM Regulatórios
Charged Aerosol Detectors utilize evaporative technology. The conversion of an analyte to a detectable signal involves (i) nebulization of the eluent stream, (ii) drying of the nebulized droplet aerosol into analyte particles, (iii) transfer of positive charge from ionized gas to the evaporated analyte particles, and, (iv) detection of the charged analyte particles.
Both CAD and ELSD are evaporative aerosol detectors able to detect non-volatile and many semi-volatile compounds. But how the particles are detected differs between the two technologies. CAD measures particle charge while ELSD measures the ability of the particle to scatter light.
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