Table 15.

Transferring Samples to MWCO Filtration Units

Processing time	Step	Comments / Tips
15–30 minutes	Label a Vivacon-500 30 kDa MWCO filtration unit (filter and tube) for each sample and passivate by adding 20 μL 50 mM ABC + 1% SDC to the top of each filter.	Prepare (label and passivate) filtration units while samples are undergoing 20-minute alkylation reaction. The first collection tubes should be labelled “waste” as these will contain small molecules being washed from protein samples. A second set of collection tubes should be labelled “peptides” and set aside for post-digestion collection. Note that passivating MWCO filters before use is important to prevent protein loss in the FASP workflow.
	Transfer entire volume of each sample to appropriate filtration unit.
	Centrifuge sample-containing filtration units at 12,000 × g for 15 minutes.