Methods are described for the separate titration of total plasmin and of trypsin inhibitor in human blood serum. Azocoll was used as the substrate in all experiments.
When titrating the total plasmin, interference by trypsin inhibitor was minimized by mixing together serum, streptokinase, and substrate in the cold before incubation was commenced.
When titrating the trypsin inhibitor, interference by plasmin was avoided by using small quantities of serum and of crystalline trypsin.
Experimental results show that with the methods employed neither the trypsin inhibitor in the serum nor the inhibitor in the streptokinase nor the antistreptokinase in the serum significantly interfered with the results of titrations of total plasmin.