Cyanide and sulphide via IC
Chromatogram of 10 ppb cyanide and sulphide in water.
The trace determination of cyanide and sulphide require an alkaline eluent and amperometric detection. Metrohm presents an application note for the determination of cyanide and sulphide via ion chromatography using amperometric detection. This Application Note describes a new column/eluent combination for optimised separation. The combination consists of the Metrosep A Supp 10 – 100/4.0 column and a sodium hydroxide eluent containing a trace of EDTA for transition metal complexation. This yields in better peak shape and detection limits below 0.1 µg/L.
The most well-known method of amperometric measurement is direct current amperometry, which is also known as DC mode. It is used primarily to determine inorganic anions, but can also be used to determine organic substances such as phenols or catecholamines. When a constant working potential is applied between the working electrode and the reference electrode, the analytes are, for example, oxidised. Depending on their concentration, a current flows to the auxiliary electrode, which provides the measurement signal. In DC mode it is possible to measure without a specific range. For this, auto range is available.
DC amperometry is a highly sensitive analytical method that is characterised by detection limits in the lowest ng/L range. Another outstanding feature is its high selectivity, which enables matrix effects to be suppressed in the chromatogram, so reliable analysis can be carried out successfully even in the most difficult sample matrices.(e.g., glacial acetic acid, urine, wastewater).
To ensure optimum analysis of samples, Metrohm offers a wide selection of working electrode materials: gold (Au), silver (Ag), platinum (Pt), copper (Cu), and glassy carbon (GC). Complete cell equipments with an intelligent measuring cell, including the permanently installed auxiliary electrode, suitable working electrode, and reference electrode, are also available to users for the standard DC mode applications, such as cyanide determination, and for the analysis of inorganic anions.
