The method of determining penetration rates of a test chemical through a membrane into a receptor solution, comprising the steps of:
- (a) providing a chamber having an open end for flowing the receptor solution past the membrane to be tested;
- (b) tilting the chamber so that bubbles in the receptor solution flow toward the open end;
- (c) providing a membrane holding chamber for holding the membrane against the open end of the chamber;
- (d) providing a cavity for holding the test chemical against the membrane;
- (e) providing an inlet to the chamber for supplying the flowing receptor solution and an outlet located substantially at the upper surface of the open end of the chamber for exiting the receptor solution;
- and,
- (f) analyzing the receptor solution for the presence of the test chemical.