Detect total content of NAD+ and NADH Ethanol generates acetaldehyde under the action of enzyme. Meanwhile, NAD+ is reduced to NADH, NADH, under the action of hydrogen transmitter, transfer electrons to WST-8 to produce the yellow product, which has a characteristic absorption peak at 450 nm. Therefore, the total content of NAD+ and NADH can be quantified by measure the OD value at 450 nm. Detect NADH After treating sample, heat at 60oC water bath for 30 min. the NAD+ of the sample is decomposed and only NADH remains. NADH reduces WST-8 to form yellow product, and the amount of NADH is determined by measure the OD value at 450 nm. Detect NAD+ and NAD+/NADH The content of NAD+ and the ratio of NAD+/NADH in the sample can be obtained according to the total content of NAD+ and NADH obtained of the first two steps as well as the separate content of NADPH. Note: NADP+ and NADPH have no effect on the determination results.