Poor DNA recovery could be due to one or more of the following:

• Plasmid did not propagate.

  Ensure that the appropriate growth medium, supplements, and antibiotics were used for the host cell and plasmid of interest.

• Inoculum cell culture was old.

  Old bacterial cells are a poor source of plasmid DNA. Bacterial cell inoculum should be prepared from fresh single colonies, grown in a test tube overnight, and immediately used for inoculum preparation. Prolonged incubation or storage of culture in the fridge almost guarantees poor results.

• Insufficient lysis of cells.

  The Lysis Buffer N may have formed precipitates. Warm and mix gently before use.

• Cell resuspension was incomplete.

  Pelleted cells should be completely resuspended in the Resuspension Solution AZ. Do not add Lysis Buffer N until a homogeneous suspension is obtained.

• Elution Buffer was not placed directly over the column’s membrane.

  It is important that the Elution Buffer be placed directly over the column’s membrane to ensure uniform passing of the buffer through the column. Do not pipette the Elution Buffer K onto the side of the column.

• Proper Elution Buffer was not used.

  The provided Elution Buffer has been optimized for high elution recoveries for respective plasmid DNA isolation kits. If water is used, ensure that the pH is between 7 and 8.

If the DNA does not perform well in downstream applications, it may be due to one or more of the following:

• Bound DNA was not washed properly.

  Traces of salt from the binding step may remain in the sample if the column is not washed with Wash Buffer E (for miniprep) or Wash Buffer J (for maxiprep) / magnetic beads are not washed with 70% ethanol (freshly prepared). Salt may interfere with downstream applications and thus must be washed from the magnetic beads.

• Dry spin not performed.

  The dry spin must be performed after the wash step in order to remove all traces of ethanol.

• The appropriate amount of ethanol was not added to the Wash Solution E / Wash Solution J.

  The Wash Solution E (miniprep) / Wash Solution J (maxiprep) has been specifically designed to contain the appropriate amount of components. Ensure that the Wash Solution was prepared using the correct amount of ethanol.

• A different elution buffer was used.

  If a different elution buffer other than the one provided in the kit was used, the buffer should be checked for any components that may interfere with the application. Common components that are known to interfere are high salts (including EDTA), detergents, and other denaturants. Check the compatibility of your elution buffer with the intended use.