Spin at high speed to dry column.

Transfer spin unit to fresh eppendorf tube.

Add 30 mL Buffer EB to center of filter and allow to sit 3 minutes at RT.

Spin at 13K rpm for 1 minute.

Repeat elution step again with another 30 mL of Buffer EB.

Pool eluates.

Add 20 mL (20 mg) Cot DNA (Gibco).

Add 420 TE and apply to fresh Microcon-30 filter.

Spin 12,000g to a volume of 29 mL or less.

For 38 mL array hybridization:

29 mL cDNA probe in TE

* Slight modifications to original protocol by Mitch Garber and Anatoly Urisman.