Studies on the second reciprocal derivative constant-current stripping analysis

Theoretical and experimental investigation have been made on a method called the second reciprocal derivative constant-current stripping analysis (SRD-CCSA). The SRD-CCSA is based on the measurement of the d(2)t/dE(2) signal given by the curve of (d(2)t/dE(2)) versus the electrode potential (E). The d(2)t/dE(2)-E curve gives a maximum value (d(2)t/dE(2))(max) and a maximum value (d(2)t/dE(2))(min), which show as two peaks on the curve. Either of the heights of the peaks and the sum of absolute values of the two peaks are proportional to the bulk concentration of the analyte in solution, and they are much larger than (dt/dE)(p) in the first reciprocal derivative constant-current stripping analysis (FRD-CCSA). The ratio of peak-peak height in the SRD-CCSA to peak height in the FRD-CCSA is about 43n (where n represents the number of electrons transferred during the electrode process for the analyte). Potential difference (W-pp) between the two peaks is 48.2 mV n(-1) at 25 degrees C in the SRD-CCSA, which is noticeably smaller than the half-height width W-p/2 65.5 mv n(-1), in the FRD-CCSA. The theory was verified with a home-made multireciprocal derivative measuring instrument. The experimental results were in good agreement with the theoretical ones.