Metrohm has developed a new method of determining chromium (VI) levels in cement, using the voltammetry technique.
The chromium present in cement during clinker burning is partially oxidised to the toxic hexavalent form.
EC legislation has been introduced to prevent allergic contact dermatitis, a condition that can lead to permanent disability, which can occur when wet cement containing chromium (VI) touches skin.
Construction workers and workmen laying concrete floors are most likely to be at risk, but this condition can also occur in members of the public that use either cement or products containing cement.
From 2005, manufacturers have added a reducing agent to their products to bring chromium concentrations down to permitted levels (2 parts per million).
Voltammetry (VA) is an established technique, but recent advances made from Metrohm have improved the measuring cell, electrodes and control interface, making VA a reliable and robust technique for the determination of heavy metals at low concentrations for a limited number of samples.
The Metrohm method uses an acid extraction before the chromium (VI) is determined using a tartrate electrolyte with the Multimode Electrode.
Usually the determination is done automatically with intelligent Dosino technology employed to add the chromium (VI) standard automatically to semi automate the process.
By using standard addition as a means of calibration, the analysis is then calibrated on every determination to give added confidence and eliminate any matrix effects.
Voltammetry offers comparable detection limits to ICP for a lower price and ongoing running costs are favourable, requiring only a source of ultra pure water and an inert gas to provide an oxygen-free environment for the analysis.
The instrument occupies less than one metre and does not require the specialist extraction fuming required by spectroscopic techniques.
