Differential Pulse Anodic Stripping Voltammetry has been one of the most sensitive techniques for the analysis of trace metal ions. Especially for the heavy metal ions like iron, cadmium, copper, zinc, lead etc. The use of Hanging Mercury Drop Electrode is recommended for these analyses as each analysis is performed on a new drop of mercury. With the availability of atomic spectroscopy techniques, which offer higher sample throughput, polarography has lagged behind in recent years as the system of choice. However, for some analyses, voltammetry is still the technique of choice. When everything else fails, people turn to voltametric techniques and are surprised by the sensitivity of the technique. It is a technique complimentary to atomic spectroscopy and many times used as confirmatory technique for results obtained with the atomic spectroscopy technique.
Some of the advantages of voltametric techniques are summarized below
Inexpensive technique compared to
atomic spectroscopy technique costing below 10K Euro. The Flame atomic absorption spectrometer costs ~ 20K USD and offers results in the range of ppm. For results in the range of ppb, graphite furnace with autosampler is required. In addition, each element requires a separate hollow cathode lamp. ICP and ICP MS offer wider dynamic range and better detection limits compared to AAS techniques, but cost in excess of USD 100K.
Samples with high salt content
like sea water or plating bath are no problem for voltametric analysis. Parts per billion level detection limits can be easily achieved for analysis of ions in sea water. For AAS system a graphite furnace with Zeeman background correction is required.
Sample with complex backgrounds
can be easily analyzed. For example, lead in blood can be easily analyzed. For AAS, the sample needs to be digested with acid to decompose all organic matrix or AAS with Zeeman Background correction is required. For analysis of impurities in zinc, voltammetry is preferred technique.
For analysis of ions in two different oxidation states, voltammetry can be used. For example Fe+2 and Fe+3, Cr+6 and Cr+3, Sulphide, sulphite and thiosulphate in a single analysis.
Heavy metal ions, as well as some anions like sulphite, nitrite, cyanide, chloride can be analyzed. Some organics can also be analyzed like thiourea in copper plating bath, vitamin C in fruit juice, some pesticides etc. Low cost of the instrument as well as low cost of operation. Only mercury and nitrogen gas are required for operation. One bottle of mercury can be used for one year. It can be purified and reused. One nitrogen cylinder is sufficient for at least one week of continuous use.
Amel Model 4330 Voltammetric Analyzer is supplied by us. It can be fitted with a Hanging Mercury Drop Electrode as well as solid electrodes or screen printed electrodes. It can also be fitted with a Rotating Disk Electrode which is required for analysis of arsenic in ppb range. For more details on the Amel Model 4330, please contact us.