Table 1.

Selection protocol

Round	No. col. vols. of washes	No. pre-elutions	Time of each pre-elution	% surviving 6 col. vols.	% eluted and amplified
1	6	0	—	0.1	0.1
2	6	0	—	0.04	0.04
3	6	0	—	0.4	0.4
4	6	0	—	7.5	7.5
5	20	0	—	20	10
6	10	2	0.5 min	45	5
7	10	3	4 min	50	1
8	10	3	4 min	60	4.7
9	10	3	4 min	71	13
10	10	4	10 min	76	13