In either case, t s1 is a good indicator of the lag time, which is roughly the amount of time it takes for ṗ to reach its maximum (see Fig. ). Fig. When tc 2 /ts 1 is near unity but ts 1 /ts 2 is very small, the QSSA cannot be imposed until after the completion of the indicator reaction. In this case the transient buildup of c 2 is best modeled by (44b). In this figure, the solution to the mass action equations (7a)-(7d) is the thick black line, and the vertical dashed line corresponds to t = ts 1 . The dashed blue line is the numerical solution to (44b), and the dashed red line is the numerical solution to (44d). Parameter values for numerical solutions are: s 0 1 = 100, s 0 2 = 0, e 0 1 = 1, e 0 2 = 1, k 1 = 10, k 2 = 100, k -1 = 1, k 3 = 0.1, k 4 = 0.1 and k -3 = 1 (units have been omitted). Time has been mapped to the t∞ scale: t∞(t) = 1 -1/ ln(t + e).