Figure A3.

Linear relationship between pH and absorbance at 557 nm in M9U. The effect on absorbance at 557 nm and 630 nm when the pH of M9U is gradually increased. A linear fit and the corresponding R² value are shown for the absorbance at 557 nm between pH 6.8 and 8.5 (indicated in red). The linear relationship can be described by the function A₅₅₇ = 0.497 pH—3.3169