Portable capillary electrophoresis instrument with potentiometric detection

Portable instrumentation has become of increasing interest in analytical chemistry, because on-site analysis has various advantages. In this report we describe the construction of a field-portable capillary electrophoresis instrument with potentiometric detection. The apparatus is contained in a PVC case of 340 x 175 x 175 mm size and a total weight of 7.5 kg and can therefore be carried easily by one person. Two lead-acid batteries provide the power for a high voltage module capable of supplying up to 30 kV, and for the detection amplifier electronics. As detectors, miniature coated-wire ion-selective electrodes are used and a precise electrode alignment is achieved by a simple electrode holder cell without the need for a microscope. Data acquisition is carried out by a small analog-to-digital converter board, which is integrated into the unit, and a palmtop personal computer. The instrument was tested on the banks of the river Rhine. As examples, alkali and alkaline earth metal cations and inorganic monovalent anions were analysed in the river water.