Filtration and Solid Phase Extraction

Filtration is accelerated either with the aid of pressure or vacuum. For vacuum filtration the regulation and ultimate vacuum requirements are generally modest. With vacuum filtration at 100 mbar, 90% of the atmospheric pressure is available as the driving force for filtration. Improving the vacuum level even further has only a minor impact on the process. However, in some cases two-stage pumps with their high pumping speed may accelerate the filtration process. In these cases control of the vacuum, e.g., by a manual vacuum regulator valve unit with a vacuum gauge is recommended to avoid evaporation of solvents from the filtration bottle.

Process requirements

  • modest vacuum, at best medium requirements
  • depending on filter size and leakage rate, the pumping speed of the pump is an important parameter
  • the speed of filtration is partly influenced by the consistency of the filter cake
  • limited need for vacuum control for filtration
  • for solid-phase extraction, a defined flow or drip rate is needed that may require control

Pump requirements

  • single-stage diaphragm pump with up to 70 mbar ultimate vacuum is ideal
  • outstanding chemical resistance and superior vapor tolerance for solid phase extraction or filtration samples containing solvents
  • for a defined flow or drip rate, a manual control valve and a vacuum gauge is helpful
  • vacuum inlet catch pot (AK) recommended to protect the pump from particles and liquid droplets
  • emission condenser for solvent recovery to minimize the impact of solvent vapors on environmental and laboratory air
  • the automation of a filtration process is possible with chemistry pumping units that are equipped with electronic vacuum controllers