duoPUR And subPUR

Think Pure. 

Reagent contaminations increase the background concentration of the analytes present in a sample. Because of this, laboratories purchase expensive high-purity acids for trace metal (element) analyses.  With small samples sizes it is critical to keep blank levels low for good reproducibility.  There is an alternative to the purchase of expensive high purity acids: Milestone has developed the DuoPUR and SubPUR, a sub-boiling distillation system which allows laboratories to make their own high purity acids at dramatically reduced costs.


The chemical reagents used during the analysis are an important source of the analytical blank.

Sub-boiling distillation has been demonstrated to be the best method of acid purification. It uses contactless infrared lamps to vaporize the surface liquid at a temperature typically 20 C below the boiling point.


The duoPUR consists of two quartz distillation units.Each unit contains two infrared heating elements (1), a water cooled condenser (2), a high-purity PFA collection bottle (3), and a fully automatic acid loading/discharge system. The vaporized liquid is collected on the inclined water-cooled condenser and drips into the collection bottle. The distillation process is microprocessor controlled, allowing the user to set the distillation time and power level by using a compact control terminal with easy-to-read, bright, full-color, touch-screen display.

The distillation rate ranges from 50 to 400 mL per hour, depending on the power setting and the temperature of the cooling water.

Watch how duoPUR works

Make Your Own Ultrapure Acids

In contrast to conventional distillation, where strong boiling action generating aerosolized particles results in contamination of the original liquid with the distillate, a gentle surface evaporation during sub-boiling distillation prevents the formation of spray or droplets and yields to a very high pure acid.


 The duoPUR offers an alternative to the purchase of expensive high purity acids for trace elemental.

 90% cost saving of ultra-pure acids by purifying low-cost reagent grade acids

 High productivity, up to 400 mL per hour (duoPUR) and up to 60 mL per hour (subCLEAN)

 On-demand acid purification

 Re-purification of contaminated acids