PORTABLE CAPILLARY-ELECTROPHORESIS INSTRUMENT WITH POTENTIOMETRIC DETECTION

Portable instrumentation has become of increasing interest in analytic al chemistry, because on-site analysis has various advantages. In this report we describe the construction of a field-portable capillary ele ctrophoresis instrument with potentiometric detection. The apparatus i s contained in a PVC case of 340 x 175 x 175 mm size and a total weigh t of 7.5 kg and can therefore be carried easily by one person. Two lea d-acid batteries provide the power for a high voltage module capable o f 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 ho lder cell without the need for a microscope. Data acquisition is carri ed out by a small analog-to-digital converter board, which is integrat ed into the unit, and a palmtop personal computer. The instrument was tested on the banks of the river Rhine. As examples, alkali and alkali ne earth metal cations and inorganic monovalent anions were analysed i n the river water.