Detectable Substances and Selectivity

6 Technique Specification of Filter and Photoacoustic IR Detectors 8.2.6.1 Detectable Substances and Selectivity 

IR radiation at another frequency to supplement or confirm the detection observed in the first analysis. A third wavelength can be used, if necessary, to further enhance detection reliability. 

Unlike other techniques in which samples can be continually introduced into the detector, these two techniques use pulsed sampling methodology. The sample is introduced into the sample cell, which is then closed during the analysis. Sample volume can be rather large. Therefore, no GC separation technique is coupled with these types of detectors currently. 

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