Detector, atomic spectrometer electrochemical

The association of a spectrometer with a liquid chromatograph is usually to aid in structure elucidation or the confirmation of substance identity. The association of an atomic absorption spectrometer with the liquid chromatograph, however, is usually to detect specific metal and semi-metallic compounds at high sensitivity. The AAS is highly element-specific, more so than the electrochemical detector however, a flame atomic absorption spectrometer is not as sensitive. If an atomic emission spectrometer or an atomic fluorescence spectrometer is employed, then multi-element detection is possible as already discussed. Such devices, used as a LC detector, are normally very expensive. It follows that most LC/AAS combinations involve the use of a flame atomic absorption spectrometer or an atomic spectrometer fitted with a graphite furnace. In addition in most applications, the spectrometer is set to monitor one element only, throughout the total chromatographic separation. 

Any type of detector with a flow-through cell can be used for FIA. Photometric detectors are most often used in FIA (15-18, 25). However, many other analyses using fluorimeters (28, 29), refractometers (24), atomic absorption (30, 31), and inductively coupled plasma emission spectrometers (32) have been described. Electrochemical detectors based on potentiometry with ion-selective electrodes (15, 33), anodic stripping voltammetry (15, 34), potentiometric stripping (35), and amperometry (36) have also been used. 

The most common detectors in How-injection analysis are spectrophotometers, photometers, and fluorometers. Electrochemical systems, refractometers, atomic emission and atomic absorption spectrometers have also been used. 

In principle, any detection system which could be adapted for flow-through detection may be used as detectors for FIA. However, some detectors are inherently more suitable than others in the interfacing, and therefore are used more frequently in FI systems. These include the spectrophotometer (visible and UV), atomic absorption and ICP spectrometer, chemiluminescence and various electrochemical detectors, and will be discussed here in more detail. 

FI on-line column separation and/or preconcentration have been applied to various detection systems, including atomic absorption and ICP spectrometers, spectrophotometers and electrochemical detectors. The basic components of the manifolds for different detection systems are quite similar, usually consisting of the following parts ... 

Derivatization procedures have been used to enhance the sensitivity of different solutes to a variety of other detecting systems. Reagents have been suggested for rendering solutes amenable to electrochemical detection, radioactivity detection and even atomic absorption spectrometers when used as detectors. However, further discussion on precolumn derivatization techniques is outside the scope of this book and those interested are recommended to read the book by Frei and Lawrence (41) that deals exclusively with derivatization procedures. 

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