Heavy metals

A plasma jet with a temperature of 9,000 degrees Celsius is injected into the sample. At such a high temperature, the metal atoms emit light. We determine the luminous intensity and the wavelength of the light emitted. The wavelength is characteristic of the element involved, while the luminous intensity indicates its concentration.

This method requires the sample to be present as a liquid and to be free of any solids. To meet this requirement, any solid specimens or sludge samples are dissolved using aqua regia. In some soil samples or construction material specimens, the soluble fraction of heavy metals is of interest. Where this is the case, water is used instead of aqua regia for extraction, and the eluates thus released are examined using ICP. Where particularly low detectable thresholds are called for, the specimen can be examined using graphite tube AAS.