https://doi.org/10.1351/goldbook.09136
Voltammetry in which small potential pulses (constant height \(\pu{10 to 100 mV}\), constant width \(\pu{10 to 100 ms}\)) are superimposed onto a linearly varying potential or onto a staircase potential ramp. The current is sampled just before the onset of the pulse (e.g. \(\pu{10 to 20 ms}\)) and for the same sampling time just before the end of the pulse. The difference between the two sampled currents is plotted versus the potential applied before the pulse. Thus, a differential pulse voltammogram is peak-shaped.
Notes:
- The ratio of faradaic current to charging current is enhanced and the negative influence of charging current is partially eliminated in the same way as in normal pulse voltammetry (NPV). Moreover, subtraction of the charging current sampled before the application of the pulse further decreases its negative influence. Due to the more enhanced signal (faradaic current) to noise (charging current) ratio, the limit of detection is lower than with NPV. See figure.
- The sensitivity of DPV depends on the reversibility of the electrode reaction of the analyte.
- Differential pulse polarography is differential pulse voltammetry in which a dropping mercury electrode is used as the working electrode. A pulse is applied before the mechanically enforced end of the drop and the current is sampled twice: just before the onset of the pulse and just before its end. The pulse width is usually \(\pu{10 to 20\%}\) of the drop life. The drop dislodgement is synchronized with current sampling, which is carried out as in DPV.
(a) Potential waveform for differential pulse voltammetry (not to scale). Typical values for pulse parameters are $\tau$=1 s, $t_{\rm{p}}$=50 ms, $E_{\tau}$=50 mV, $E_{\rm{p}}$=2 mV. Sampling interval indicated by horizontal curly brackets is typically 15 ms. (b) Differential pulse voltammogram. $I$ is the difference between currents sampled at ‘2’ and ‘1’.
Source:
PAC, 2020, 92, 641. 'Terminology of Electrochemical Methods of Analysis (IUPAC Recommendations 2019)' on page 672 (https://doi.org/10.1515/pac-2018-0109)
PAC, 2020, 92, 641. 'Terminology of Electrochemical Methods of Analysis (IUPAC Recommendations 2019)' on page 672 (https://doi.org/10.1515/pac-2018-0109)