The rate constant depends on the initial concentration of
pentoxifylline in solution: it is highest for the lowest
concentration and decreases with increasing concentration.
As mentioned before, the degradation is faster for lower
pentoxifylline initial concentration. However, the half-life
time for the decomposition of 25 mg/L pentoxifylline is less
than four times lower than for 150 mg/L, which results in
higher efficiency of the plasma treatment in case of the
higher initial concentrations of pentoxifylline, as seen also in
Fig. 4(b).