POSSIBILITIES FOR THE AUTOMATED-DETERMINATION OF TRACE CONCENTRATIONSOF URANIUM IN WATER SAMPLES BY ADSORPTIVE STRIPPING VOLTAMMETRY

The paper describes the development of two different techniques for th e automated determination of uranium by adsorptive stripping voltammet ry (AdSV). As a complex forming reagent 2,5-dichloro-3,6-dihydroxy-1,4 -benzoquinone (chloranilic acid) is used. The automation was performed in one case using an auto-batch system and in the second case by mean s of a flow-through cell. Sensitivities, reproducibilities and the fie lds of application are evaluated. The auto-batch technique, with the a utomatic standard addition capability as well as its logical decision- making capacity for selecting the correct type of working electrode ma kes it highly suitable for the determination of varying uranium concen trations above 1 mu g/l. The dilution of the sample, required by the m ethodology, makes determinations of uranium concentrations less than 1 mg/l unattainable. The flow-through technique is more suited to deter mine uranium at the ultra trace concentration level (above 70 ng/l). P rovided the matrix is reasonably constant, a pre-determined calibratio n curve can be used and, due to the higher slope of the calibration pl ot in the flow-through technique, the linear concentration range exten ds to a lower concentration compared to stationary conditions. Another advantage of the flow-through technique is the possibility of kinetic and mechanistic investigations of AdSV procedures.