Why do concentration detectors require a higher purity of the carrier gas than mass detectors?
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As the title suggests, does anyone know why concentration detectors require a higher level of gas purity compared to mass detectors? :handshake
Because their principles are different. The commonly used concentration detector is the TCD, which uses the carrier gas as a reference to determine the components of the sample based on the difference in thermal conductivity between the sample and the carrier gas. So higher requirements are needed. You can look up the principles of these two detectors, TCD and FID, and compare them
Detectors with a general concentration-based detection mechanism do not have high selectivity; they are rather broad-spectrum detectors. To improve their detection sensitivity and reliability, it is necessary to reduce the background signal in order to effectively increase the signal-to-noise ratio. Quality detectors, on the other hand, generally exhibit good selectivity; aside from having strict requirements for specific impurities in the carrier gas, they do not have particularly high demands regarding other conditions of the carrier gas. Given the different characteristics of these two types of detectors, it would be best for the original poster to consult two professional textbooks, or refer to the chromatography section in analytical chemistry handbooks.