Detection in IC

As discussed earlier, the majority of IC separations are performed in conjunction with conductivity detection. However, two further modes of detection, namely indirect UV spectrophotometry and post-column reaction with visible spectrophotometry, also find widespread use. Each of these detection modes will be described briefly.

The normal mode of operation of a detector in IC is the monitoring of a signal (due to the analyte), which appears as an increase above the background signal arising from the eluent alone. This is called direct detection, and is a useful detection mode whenever the background detector signal due to the eluent alone is small enough to be offset by the zeroing control on the detector. An alternative, namely indirect detection, is also possible and involves the measurement of a decrease in detector signal when the analyte is eluted and is generally used with eluents that give a high background signal. To function correctly, indirect detection requires that the background composition of the mobile phase must alter in the presence of the eluted analyte and it is this change, rather than a specific characteristic of the analyte itself, that is monitored. Ion exchange chromato-graphy is the most important example of a separation mode that is suited to indirect detection.

Solar Panel Basics

Solar Panel Basics

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