NAD+ vs NADH: Chemistry, Identity and COA Documentation
Published 2026-10-30 · Last updated: 2026-10-30 · By: Index Peptides technical team
NAD+ and NADH are the oxidised and reduced forms of the same coenzyme, nicotinamide adenine dinucleotide. They are not two names for one material: they differ in structure at the nicotinamide ring, in charge, in molecular formula and in mass, so each has its own identity record. NAD+ is CAS 53-84-9, molecular formula C₂₁H₂₇N₇O₁₄P₂, molecular weight about 663.4 g/mol, and that CAS number refers to the beta-anomer free acid. For a research buyer the practical consequence is simple: a certificate of analysis (COA) has to name the exact form that was tested, and a result for one form is not evidence about the other.
Research use only. Not for human or animal consumption. This page covers chemistry, identity and documentation only.
NAD+ vs NADH at a glance
| NAD+ | NADH | |
|---|---|---|
| Form | Oxidised | Reduced |
| Nicotinamide ring | Pyridinium ring carrying a positive charge | 1,4-dihydropyridine ring, no positive charge |
| CAS number | 53-84-9 (beta-anomer free acid) | A separate registry entry |
| Formula and molecular weight | C₂₁H₂₇N₇O₁₄P₂, about 663.4 g/mol | A different formula and mass |
| UV absorbance | Near 260 nm | Near 260 nm and near 340 nm |
| Interchangeable on a COA? | No | No |
What NAD+ is
NAD+ is a coenzyme, not a peptide. Structurally it is two nucleotides joined through their phosphate groups: one carries an adenine base and the other carries nicotinamide, and the two phosphates form a diphosphate bridge between the halves. The "+" in the name refers to the positive charge on the nitrogen of the nicotinamide ring in the oxidised form.
Its reference identifiers are:
- CAS number: 53-84-9, the beta-anomer free acid.
- Molecular formula: C₂₁H₂₇N₇O₁₄P₂.
- Molecular weight: about 663.4 g/mol as average mass; the monoisotopic mass is about 663.1.
The beta-anomer detail pins the CAS number to one stereochemical form at the bond between the nicotinamide and its ribose sugar. Salt forms, such as a sodium salt, are different documented materials with a different formula weight. The reference chemistry Index works from explicitly warns against confusing the free acid with NADH or with the disodium salt.
How NADH differs
NADH is the reduced form. The change sits entirely in the nicotinamide ring: the oxidised pyridinium ring of NAD+ becomes a 1,4-dihydropyridine ring in NADH, which carries no positive charge. In chemical terms the pair is a redox couple, with NAD+ as the electron-accepting form and NADH as the electron-donating form; the conversion between them involves two electrons and one proton, the equivalent of a hydride ion.
That structural change has three documentation consequences:
- Different formula and mass. NADH is a distinct molecule with its own formula, molecular weight and CAS entry. An NAD+ reference value cannot serve as the expected value for NADH, or the other way round.
- Different UV absorbance. Both forms absorb near 260 nm because of the adenine ring, but only NADH has a second absorbance band near 340 nm. This is why UV-based methods can tell the two apart.
- Separate chromatographic behaviour. With a suitable HPLC method the two forms are resolved as separate peaks, so a purity result is tied to the peak identified as the named form.
A third pair is worth knowing because the names are so close. NADP+ and NADPH carry an extra phosphate group on the adenosine ribose. They are separate compounds again, so a label reading NADP+ describes a different material from NAD+.
Why the form matters on a COA
The identity section of a COA has to state exactly which material was tested: NAD+ as the free acid, a named salt, or NADH. Every figure below it depends on that line. A purity result of, say, 98% NAD+ is a statement about the oxidised form; it is not a figure for NADH, and a certificate issued for an NADH lot is not evidence about an NAD+ lot. The batch record for the specific lot is the authority.
When reading an NAD+ certificate, check:
- Name and form: NAD+ (oxidised), with the salt form stated if it is not the free acid.
- CAS number: 53-84-9 for the beta-anomer free acid.
- Formula and molecular weight: C₂₁H₂₇N₇O₁₄P₂ and about 663.4 g/mol, with the mass basis clear. How formula and weight are derived is covered in peptide molecular weight and formula; the same arithmetic applies to a coenzyme.
- Lot number: identical to the number on the vial label.
- Method, result and report date: the purity method named, the result reported against it, and a date.
How identity is confirmed
Purity and identity answer different questions. An HPLC purity figure reports how much of the detected signal belongs to the main peak; it does not prove what that peak is. Identity is normally confirmed by mass spectrometry, typically LC-MS: the expected mass is calculated from the formula, and the detected mass from the instrument is compared against it on the same basis, average or monoisotopic. For NAD+ the expected value comes from C₂₁H₂₇N₇O₁₄P₂. Because NADH has a different formula, a correctly matched mass result distinguishes the two forms. The comparison is explained in full in LC-MS identity confirmation explained.
Storage as recorded
Index's NAD+ compound page lists the material as a lyophilised powder stored at -20°C, desiccated and protected from light. NAD+ is hygroscopic, meaning it takes up moisture from the air, which is why the desiccated condition appears on the record. The label and batch record for the lot are the authority, so store as stated on the label.
NAD+ documentation at Index
Index documents NAD+ the same way as every other catalogue item, even though it is a coenzyme rather than a peptide. The NAD+ compound overview sets out the chemistry, and the NAD+ buying guide compares the 500mg and 1000mg formats. Batch records and certificates are published at /coa, and any lot can be looked up on the public batch verification page. Review the record for the exact lot and the analyses it actually reports: an HPLC purity result does not on its own confirm identity, so if a required identity result is not published, ask before ordering. Orders dispatch from the UK.
FAQ
What is the difference between NAD+ and NADH?
NAD+ is the oxidised form and NADH the reduced form of nicotinamide adenine dinucleotide. The difference sits in the nicotinamide ring, which is a positively charged pyridinium ring in NAD+ and an uncharged 1,4-dihydropyridine ring in NADH. They have different formulas, masses and CAS entries, so they are documented as separate materials.
What are the CAS number and molecular weight of NAD+?
NAD+ is CAS 53-84-9, which refers to the beta-anomer free acid. Its molecular formula is C₂₁H₂₇N₇O₁₄P₂ and its molecular weight is about 663.4 g/mol. Salt forms and NADH are different materials with different values.
Can an NAD+ certificate of analysis be used for NADH?
No. A COA describes the specific material and lot that was tested. An NAD+ purity or identity result is a statement about the oxidised form only, and a certificate for an NADH lot is not evidence about an NAD+ lot. The identity section should name the exact form tested.
How can a laboratory tell NAD+ and NADH apart?
By identity and spectral data. Mass spectrometry distinguishes them because their formulas and masses differ. UV absorbance also separates them: both absorb near 260 nm, but only NADH has a band near 340 nm. A suitable HPLC method resolves them as separate peaks.
What should an NAD+ COA record?
The compound name and exact form, CAS 53-84-9, the formula and molecular weight with the mass basis stated, the lot number matching the vial label, the purity method and result, any identity result with expected and detected mass, and the report date. Research use only. Not for human or animal consumption.
Research use only. Not for human or animal consumption.