(a)
(b)
(c)
(d)
(e)
Figure 6: Optimization of parameters for the colorimetric system. Acetate buffer at pH 4.0 was optimal for TMB oxidation (a). MNP concentration of 400 μg/mL (b), TMB concentration of 40 μM (c), H2O2 concentration of 35 mM (d), and incubation time of 10 min (e) yielded optimal effectiveness.