Each lot of poorly defined crude or enriched collagenase is unique because it represents the enzymatic activities present in the C. histolyticum culture supernatant. The enzyme activities listed on the Certificate of Analysis can be used as a guide but they are not sufficient to predict the effectiveness of a specific lot to recover cells. Lot pre-qualification enables the user to evaluate the performance of the new lot against the collagenase lot that is currently in use. If the new lots do not give acceptable results, then additional lots are evaluated. Once an acceptable or “good” lot is identified, then the cell isolator purchases an amount of product sufficient to perform > 1 year of cell isolations.