Fig. 4
The effect of dilution of Humulin®R in the experiments of simple mixing in vials. Humulin®R was diluted 5-fold with saline (a) and PBS (pH 7.4) (b). Turbidity (●), fluorescence intensity (■), and pH (▲) were evaluated. The isoelectric point of human insulin in Humulin®R and the pH range in the original formulation of Humulin®R are expressed as a dotted line and filled area in grey. Each value is expressed as the mean ± S.D. (n = 3–5). Significantly lower pH value (*) than the lower standard pH value of Humulin®R (P < 0.05)