Electrochemical Detection of Trace Concentrations of Cadmium and Lead with a Boron‐Doped Diamond Electrode: Effect of KCl and KNO₃ Electrolytes, Interferences and Measurement in River Water

Abstract

Parts-per-billion levels of cadmium and lead were detected using square-wave anodic stripping voltammetry with a boron-doped diamond electrode. Calibration plots (10-minute deposition time) in KCl and KNO 3 were non-linear at low concentrations (1 ± 5 ppb) due to the deposition mechanism of these metals. The preferred electrolyte for cadmium was KCl, while lead could be measured in either electrolyte. The lowest concentrations included in the linear portion of the calibration plot (5 minute deposition time) for cadmium were 10 ppb and 50 ppb in KCl and KNO 3 , respectively, and 10 ppb for lead in KNO 3 . The presence of either lead or copper suppressed the cadmium stripping peak, but the lead stripping peak was unaffected by cadmium, and enhanced by the addition of copper. A river water sample was analyzed for cadmium and lead, and the cadmium results were confirmed using ICP-AES spectrometry. It was determined electrochemically that a fraction of lead in the river sample was bound by complexing material in the sample.

Anodic Stripping Voltammetry of Heavy Metals at Nanocrystalline Boron‐Doped Diamond Electrode

“…Formation of intermetallic species was also suspected at intermediate Cu/Zn ratio. Cu-Zn intermetallic was noticed in other studies [10,41], and same for Cu-Cd [33]. This proposal is in agreement with what is observed in figure 4 representing the overlay of stripping voltammograms before and after adding Cu to Cd and Zn initial solution.…”

“…Similar study was made in tap water giving sub-ppb detection of Pb too [32]. Other studies treating single metal analysis of Pb and Cd at BDD have mentioned 10 ppb quantification limit for both metals for 5 min accumulation at À 1 V (Pb) and À 1.1 V (Cd) with 0.1 M KCl as electrolyte [33]. Microwave enhanced anodic stripping detection of Pb seams to have advantageous effects on the sensitivity of analysis [34].…”

Application of Modified Tafel Analysis to the Identification of Corrosion Products on Archaeological Metals Using Voltammetry of Microparticles

“…Additionally, it should be noted that in our case, copper is the first metal deposited during the experiment. It is known that copper deposition notably influences the deposition of other metals like Cd [68], Pb [69] and Zn [70] as a result of the formation of intermetallic compounds and often by appearance of a misleading extra peak due to hydrogen evolution at freshly exposed copper under stripping conditions at low pH values [71]. For instance, metal-metal interaction during stripping experiments results in the drop of peaks for cadmium and zinc when copper was added [72].…”

Effect of the sp2/sp3 Ratio in a Hybrid Nanocarbon Thin Film Electrode for Anodic Stripping Voltammetry Fabricated by Unbalanced Magnetron Sputtering Equipment

“…In contrast, an sp 3 dominant BDD electrode was reported to achieve a low detection limit due to its low noise current. [16][17][18][19][20][21][22][23]27 Diamond-like carbon (DLC) and nitrogen doped DLC were also used as an electrode for ASV; 28,29 however, the ASV performance of DLC is reported to be poorer than that of BDD. This is because DLC is generally amorphous and not electrochemically active, and so cannot efficiently preconcentrate metal ions on a DLC surface.…”

“…Unfortunately, they did not perform as well as the Hg electrode. More recently, various carbon electrodes, such glassy carbon (GC), [11][12][13] screen-printed carbon, 14 carbon nanotube 15 and boron doped diamond (BDD) [16][17][18][19][20][21][22][23][24][25] electrodes, have been employed for ASV. Table 1 summarizes their performance as regards sensitivity, background current and detection limit.…”