Table 1 Fractions (f) of unbound UCB species at different pH values, assuming low pKa values of 4.2 and 4.9*.

4.0

0.5847

0.3689

0.0464

4.5

0.2639

0.5265

0.2096

5.0

0.0656

0.4137

0.5208

5.5

9.96E-03

0.1988

0.7913

6.0

1.17E-03

0.0735

0.9253

6.5

1.23E-04

0.0245

0.9753

7.0

1.25E-05

7.88E-03

0.9921

7.5

1.26E-06

2.51E-03

0.9975

8.0

1.26E-07

7.94E-04

0.9992

8.5

1.26E-08

2.51E-04

0.9997

9.0

1.26E-09

7.94E-05

0.9999

9.5

1.26E-10

2.51E-05

0.99997

10.0

1.26E-10

7.94E-06

0.99999