done by monitoring of NADH or NADPH absorption at 340 nm. Based on the reading, we can calculate NADH concentration. ε = extinction coefficient of NADPH at: 340 nm = 6.3 [l × mmol-1 × cm-1] Hg 365 nm = 3.5 [l × mmol-1 × cm-1] Hg 334 nm = 6.18 [l × mmol-1 × cm-1] 1 Modified kinds of starch (phosphorylized or oxidized ones) do not react. After 10 min, the cover glass was removed and ≈50 μl of the liquid was analyzed by measuring the absorbance at 340 nm and the NADPH fluorescence. Monitoring NADPH-producing enzymes: activity and protein expression. The Amplite™ Colorimetric NADPH … … Though the detection of NAD(P)H absorption or fluorescence is useful … It is NADPH consumption that is measured by the decrease in absorbance at 340 nm. : not determined