Accessory for robotic sample processor will seal sample vessels with a chemical-resistant cover, which is lifted automatically just before analysis to prevent premature evaporation
Samples that undergo changes on exposure to the air or other external influences must be protected.
This applies in particular when the samples cannot be analysed immediately, but must stand around for some time - eg on a sample changer.
Critical samples are, for example, alkaline solutions (as their concentration would be reduced due to absorption of carbon dioxide from the atmosphere), producing incorrect titration results.
Bad odours from sample solutions or titrants, such as may occur during non-aqueous titrations, are also unpleasant.
Although the evaporation of solvents does not normally have a negative effect on the analysis, work needs to be carried out under a fume hood to minimise health risks.
All these problems can now be avoided by using a new accessory to the Metrohm robotic sample processors - the Dis-Cover system, says Metrohm.
The principle is simple: the sample vessels are sealed with chemical-resistant covers that are automatically removed just before analysis.
The Dis-Cover extension is mounted on the 786 Swing Out Head of the robotic sample processor, and the sealed sample vessels are placed onto the sample rack as usual.
Just before a sample is analysed the cover is , moved to an external park position.
Once the titration has taken place, the cover is repositioned, and the sample sealed.
