• Help section

    Frequently asked questions

    We have compiled the most frequently asked questions and answers about our biotech products for you here.

    • DMC is short for Digital Membrane Chromatography.

    • DMC elution is a novel approach that uses electrical potential for elution. This method enables rapid and gentle elution of biomolecules from chromatography membranes, avoiding the need of elution buffer adjustments. DMC makes the purification process more efficient, maintaining a stable environment that significantly reduces aggregation risks and enhances recovery yields.

    • To perform DMC elution with i3 DMC Membrane Absorber, you need i3 DMCControl with uniquely designed connecting cables and a chromatography system or a peristaltic pump. The Membrane Adsorber is equipped with Luer lock connectors. These connectors can be seamlessly integrated with a chromatography system using appropriate fittings.

      More detailed information about the equipment and installation of i3 DMC Membrane Adsorber and i3 DMCControl can be found here.

    • We recommend performing a bind/elute experiment using a purified analyte. This serves to verify the correct functionality of the system and is preferably used for determination of DBC.

      For bind/elute experiments, please use the recommended buffer systems listed under the next question on this site. More details can be found in the respective Instructions for Use.

    • Our i3 DMCAEX and i3 DMCCEX Membrane Adsorbers have been successfully tested with various buffer systems, particularly within our standard starting method using purified proteins. We recommend operating within the tested buffer ranges through the whole process.

      Buffer Concentration pH Added electrolyte
      Ammonium acetate 0.15 mM 6.1 0.15 mM NaCl
      HEPES 0.1 mM 7.1 0.15 mM NaCl
      MES 0.5 mM 6.1 –
      MES 0.1 mM 5.2 0.15 mM NaCl
      MOPS 0.5 mM 6.5 –
      MOPS 0.1 mM 6.6 0.15 mM NaCl
      PBS 0.24 mM* 7.4 –
      PBS 0.12 mM 6.9 –
      PBS 0.012 mM 6.8 0.15 mM NaCl

      *i3 standard PBS working solution: 0.24 mM phosphate buffer, 2.74 mM NaCl and 0.054 mM KCl

      Note:
      During DMC purification, pH values between 7 and 10 may occur. Immediately neutralize the samples by adding a small volume of a suitable neutralizing buffer. Depending on the further process, use buffer solutions such as PBS or ammonium acetate.

    • Our Protein A membrane is stable within a pH range of 3 to 10. Thus, the membrane can be directly loaded with clarified cell supernatant.
      DMC elution is dependent on ionic strength, buffer composition, and pH. The following DMC working solutions have been successfully tested for DMC elution:

      Buffer Concentration pH Added electrolyte
      Ammonium sulphate 0.15 mM 5.8 –
      PBS 0.24 mM* 7.4 –
      PBS 0.012 mM 6.8 0.15 mM NaCl

      *i3 standard PBS working solution: 0.24 mM phosphate buffer, 2.74 mM NaCl and 0.054 mM KCl

      Note:
      During DMC purification, pH values between 7 and 10 may occur. Immediately neutralize the samples by adding a small volume of a suitable neutralizing buffer. Depending on the further process, use buffer solutions such as PBS or ammonium acetate.

    • The level of Protein A leaching from the membrane adsorber depends on the experimental conditions.
      Under the recommended operating conditions, the leaching is typically <10 ppm.

    • Residual electrolytes from 20% ethanol/water storage solution within the membrane device may cause the DMCControl unit self-check to fail. Flush the unit extensively with ultrapure water.
      If the self-check remains unsuccessful after thorough wash, install a dummy adsorber to pass the self-check. Thereafter, prepare the Membrane Adsorber by applying recommended voltage without sample. Afterwards, a new purification cycle with the stored membrane adsorber can be initiated. We recommend performing a short pre-DMC step without sample (2 mL/min; 4 mL; +2 V) prior to loading.

      Note: It is recommended to connect the Membrane Adsorber to the FPLC only once for DMC purification runs. Incomplete post-run cleaning during storage can result in membrane fouling.