An alternating pulse current technique for potentiometric stripping analysis (APC-PSA).
The response signal in PSA measurements - the transition time tau - can be considerably amplified by using a special pulse technique which we call "alternating pulse current (APC)". The sensitivity of the method is thereby considerably increased. This is achieved by modulating the current with a high frequency in a square wave mode during the stripping phase in such a way, that cathodic and anodic pulses alternate, so that the species to be determined is stripped and - at least partially - redeposited during the procedure. The transition time tau is not affected by the absolute values of the currents and of the times they flow. The amplification is determined by their respective ratios only. The equations holding are derived and proven experimentally by measurements on very dilute Pb solutions. The APC-PSA technique has also been applied for systems termed 'irreversible' such as U and Tc, where also a considerable amplification could be achieved. The probable reasons are discussed and future developments and investigations are depicted.
Beck
H P
HP
Institute of Inorganic and Analytical Chemistry and Radiochemistry, Universität des Saarlandes, Postfach 15 11 50, D-66041, Saarbrücken, Germany.
Schiestel
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