Problem | Possible reason | Solution |
---|---|---|
The centrifugal unit spun all the protein sample. No sample left on the membrane. | Faulty filter | Collect the filtrate and place it onto a new tested and conditioned spin filter |
Filter membrane displaced due to the tight insertion of the filter into the collection tube | Find a collection tube where a new tested and conditioned filter can be inserted with no friction. Collect the filtrate onto it. | |
Low peptide recovery in the filtrate (<40 %) | Severe filter clogging | Pipette gently up and down to homogenize when adding a new solution, without touching the filter membrane |