A vial labeled NAD+ is only as useful to a research protocol as the analytical work that stands behind it. Because the coenzyme is a small, well-defined dinucleotide rather than a peptide chain, purity testing for it looks somewhat different from the assays run on the amino-acid-based products in this catalog.
Separating NAD+ from what it isn't
High-performance liquid chromatography is the primary tool for resolving intact NAD+ from closely related molecules — unreacted nicotinamide or adenine nucleotides, and hydrolysis products formed if the dinucleotide bond has broken down. Because these related compounds can be structurally similar to NAD+ itself, chromatographic separation followed by UV detection at the appropriate wavelength is used to generate a purity percentage for the batch. Background on how this separation works in general is covered in understanding HPLC purity.
Confirming identity, not just purity
A clean chromatographic peak only tells you that one component dominates the sample — it doesn't by itself confirm that component is NAD+. Identity confirmation typically pairs the separation step with mass-based detection, comparing the observed mass against NAD+'s known molecular weight. Because NAD+ has no amino acid sequence to verify, this mass-based check plays the role that sequence confirmation plays for peptide products. Some testing protocols supplement this with a spectrophotometric ratio check, since NAD+ has a well-characterized UV absorbance profile that shifts in a predictable way if the sample contains significant amounts of degraded or unrelated material.
Why degradation products matter here
Because the coenzyme's glycosidic bond can hydrolyze under heat, moisture, or pH stress, a purity assay for NAD+ is implicitly also a stability check: a batch that has been mishandled during production, shipping, or storage will often show measurable hydrolysis products even if the intact NAD+ peak still appears dominant. This is one reason purity figures are tied to a specific lot and a specific test date rather than treated as a fixed, permanent property of the compound.
What ends up on the certificate of analysis
Results from these assays are compiled into a batch-specific certificate of analysis, which should report the measured purity, the method used to obtain it, and identity confirmation for that specific lot — not a generic specification sheet reused across batches.
Independent verification
Where possible, results are cross-checked through independent, third-party laboratory testing, giving a reference point beyond a supplier's own internal analysis and reducing reliance on any single lab's determination.
NAD+ vials sold with lot-specific documentation of this kind are available at NAD+ research vials.
Research Use Only. Supplied strictly for laboratory research and development — not for human or veterinary use, consumption, or any therapeutic or diagnostic purpose. This article is research education, not usage guidance.