Conductometric detectors, liquid chromatography

Since the output of the circuit is directly proportional to the conductance of the cell (1/Zcell in this case), the circuit may be used as a direct-reading detector for conductometric titration, reaction kinetic studies of fairly slow reactions, liquid chromatography, or ion-exchange chromatography. 

More recently, the description of a small-bore liquid chromatography by Manz et al. [83] on a 5 x 5 mm silicon chip revived the interest of the analytical chemical community. The chip incorporated an open tubular column of 6x2 pm cross section (column volume 1.8 nl) and a conductometric detector with a detection volume of only 1.2 pi. Although this work was an important benchmark study, the actual functioning of the chromatograph was never demonstrated with separations. 

With respect to chromatography, electrochemical detection means amperometric detection. Amper-ometry is the measurement of electrolysis current versus time at a controlled electrode potential. It has a relationship to voltammetry similar to the relationship of an ultraviolet (UV) detector to spectroscopy. Whereas conductometric detection is used in ion chromatography, potentiometric detection is never used in routine practice. Electrochemical detection has even been used in gas chromatography in a few unusual circumstances. It has even been attempted with thin-layer chromatography (TLC). Its practical success has only been with liquid chromatography (LC) and that will be the focus here. 

---