Why are my NAD/NADH ratio readings erratic when compared to my standard solution?

Confirm that your readings are accurate and consistent-lack of calibration will render any readings unusable.

Most NAD+ standard solutions are unstable once mixed. Run assay as soon as possible after making the serial dilution (within 4 hours) for accurate comparison.

Check that your controls and standard solutions were prepared correctly. See our Serial Dilution Calculator for assistance.

Enzymatic activity can cause variable readings. If you suspect contamination (particularly esterase and caspase activity) run the assay again using fresh media.