Considering all four test solutions, FASP II recovery varied between 24 and 40%, with the lowest value obtained for the 1 g/L BSA sample. This range is lower than that reported by Wisniewski
(∼50%) [28], though we note recoveries between 10 and nearly
100% have been reported [37]. Variation in recovery has been
attributed to the efficiency of tryptic digestion on the MWCO filter, particularly if any residual SDS is present [37]. The FASP II proto- col has also yielded variable success across different labs [38,39], noting that some proteins display much stronger interactions with the membrane, further reducing protein yields [40]. While some discrepancies are to be expected, the low recovery we observed through the FASP II protocol warrants further investigation.