No. NAD+ is a dinucleotide coenzyme made of two nucleotides joined through a pyrophosphate bridge, with no amino acids at all. It is often sold alongside peptides and tested by some of the same instruments, but methods built for peptides need adapting, and tests such as amino acid analysis or peptide mapping do not apply to it.

Can a test tell NAD+ from NADH?

Yes. Their masses differ, 663.4 g/mol for NAD+ against 665.4 g/mol for NADH in PubChem, and their UV spectra differ: NADH absorbs at 340 nm while NAD+ does not. A chromatographic method with mass or dual-wavelength detection reports how much of each is present, which tells you whether a vial sold as NAD+ contains reduced material.

Why does water content matter so much for NAD+?

PubChem, citing the Merck Index, describes NAD+ as highly hygroscopic. The powder absorbs moisture from the air, which adds weight without adding NAD+. A Karl Fischer water result lets the laboratory express the assay on a dry basis, so a damp sample is not mistaken for a degraded or underfilled one. The water content lesson covers the method.

What mass should an NAD+ certificate show?

PubChem lists NAD+, under the name nadide, at an average molecular weight of 663.4 g/mol and a monoisotopic mass of 663.11 Da. A mass spectrometer may report an ion slightly above or below that depending on its ionisation mode. A main mass near 665 instead suggests NADH, the reduced form, rather than NAD+.

Does a liquid NAD+ product test differently from a powder?

It can. A 43-day study of NAD+ and NADH in solution found that degradation depended on pH, temperature and buffer, with NAD+ breaking down faster in phosphate or HEPES than in Tris. A liquid product's result therefore reflects its formulation and storage history. The test still answers what is in the bottle, but it is less likely to match a fresh powder.

One of the 30 compound testing profiles

NAD+

NAD+ is a dinucleotide coenzyme, not an amino acid chain (C21H27N7O14P2, average mass 663.4 g/mol); a test should confirm that mass, show the material is the oxidised NAD+ form rather than NADH, and measure water, because the powder is highly hygroscopic.

NAD+ (nicotinamide adenine dinucleotide, nadide) is not a peptide but a dinucleotide coenzyme, built from ribosylnicotinamide 5'-diphosphate joined to adenosine 5'-phosphate through a pyrophosphate linkage (PubChem).

Test your NAD+

Identity card

Formula: C21H27N7O14P2
Average mass: 663.4 g/mol
Monoisotopic mass: 663.11 Da
Length: Not applicable
Modifications: None listed
Also sold as: NAD, Nicotinamide adenine dinucleotide, Nadide, beta-NAD, Coenzyme I
Note: NAD+ has no amino acid sequence. PubChem records it under the name nadide. The reduced form, NADH, is a separate record (CID 439153, C21H29N7O14P2, average mass 665.4 g/mol).

Source: Nadide (NAD+) compound record (CID 5892), NADH compound record (CID 439153).

Compare the mass printed on a certificate with the values above. The mass checker explains charge states and which mass a lab usually reports.

What usually goes wrong with NAD+. Documented failure modes, with sources.

Peptide methods do not transfer directly

Most peptide testing is built around reversed-phase HPLC, which separates molecules by how strongly they cling to an oily stationary phase. NAD+ is small, highly polar and carries phosphate groups, and pyridine nucleotides are poorly retained on conventional reversed-phase columns without ion-pair reagents (Røst et al., 2020). Published methods use either ion-pairing, for example tetrabutylammonium in the buffer with UV detection (Bernocchi et al., 1994), or zwitterionic HILIC with tandem mass spectrometry. A certificate that runs a generic peptide gradient on NAD+ without either adaptation deserves a closer look.

NAD+ and NADH confused or mixed

NAD+ is the oxidised form and NADH the reduced form, and the two differ by two hydrogen atoms: PubChem lists 663.4 g/mol for NAD+ and 665.4 g/mol for NADH (PubChem, NAD+; PubChem, NADH). A label reading simply "NAD" does not say which. The two forms also absorb light differently: NADH absorbs strongly at both 260 and 340 nm, while NAD+ absorbs at 260 nm but not at 340 nm (Wolfe et al., 2024). A 340 nm signal in a sample sold as NAD+ is therefore a quick sign that reduced material is present.

A highly hygroscopic powder

PubChem's physical description, drawn from the Merck Index, calls NAD+ a highly hygroscopic white solid (PubChem). Water it picks up adds weight that is not NAD+, so two vials filled to the same powder weight can hold different amounts of coenzyme if one was handled in humid air. A useful report gives the water content, usually by Karl Fischer titration, and states whether the assay is on an as-is or dried basis. Without both, a low assay could mean degraded material or simply a damp sample.

Degradation that depends on pH and buffer

NAD+ and NADH break down by opposite routes: the oxidised form undergoes base-catalysed degradation at high pH, while the reduced form undergoes acid-catalysed degradation at low pH (Wolfe et al., 2024). In the same 43-day study, NAD+ degraded faster in sodium phosphate or HEPES than in Tris. For a pre-mixed liquid product, formulation and storage therefore shape what a test finds.

Interconversion during the analysis itself

Interconversion between the oxidised and reduced forms, and their different pH lability, make the pyridine nucleotides hard to quantify (Røst et al., 2020). One validated method used acid extraction for the oxidised nucleotides and a separate alkaline extraction for the reduced ones, and found autooxidation and interconversion of the reduced forms almost insignificant (Bernocchi et al., 1994). A report that names its sample preparation lets you judge whether its NAD+ to NADH ratio describes the vial or the method.

Which tests matter most

LC-MSConfirms the 663.11 Da monoisotopic mass of NAD+ and separates it from NADH and breakdown products by mass.
HPLC-UVWith ion-pairing or HILIC rather than a peptide gradient, gives purity, and a 340 nm channel reveals any NADH.
Karl Fischer titrationNAD+ is highly hygroscopic, so water content is needed before the assay can be compared with a label weight.
Appearance and solubilityA white powder that dissolves cleanly is expected; discoloration or residue is a cue to look harder at degradation.

Reading NAD+ results

Because NAD+ is not a peptide, there is no sequence to confirm and no amino acid analysis to run. Identity rests on mass (663.4 g/mol average, 663.11 Da monoisotopic, per PubChem), on retention time against an NAD+ reference standard, and on the UV spectrum. A report that gives all three is stronger than one that gives any single check.

A single 260 nm absorbance reading is a weak NAD+ assay: acid-catalysed NADH degradation products, with a hydroxyl added to the ring, also absorb at 260 nm (Wolfe et al., 2024). Chromatographic separation before detection, or mass spectrometry, avoids counting those products as NAD+.

Public Tested.ph results

No public NAD+ records yet

Each public NAD+ record will appear here with its identity, HPLC purity and measured amount against the label, once the first vial is tested.

FIG 13Amount against the label

Questions about testing NAD+

Is NAD+ a peptide?: No. NAD+ is a dinucleotide coenzyme made of two nucleotides joined through a pyrophosphate bridge, with no amino acids at all. It is often sold alongside peptides and tested by some of the same instruments, but methods built for peptides need adapting, and tests such as amino acid analysis or peptide mapping do not apply to it.
Can a test tell NAD+ from NADH?: Yes. Their masses differ, 663.4 g/mol for NAD+ against 665.4 g/mol for NADH in PubChem, and their UV spectra differ: NADH absorbs at 340 nm while NAD+ does not. A chromatographic method with mass or dual-wavelength detection reports how much of each is present, which tells you whether a vial sold as NAD+ contains reduced material.
Why does water content matter so much for NAD+?: PubChem, citing the Merck Index, describes NAD+ as highly hygroscopic. The powder absorbs moisture from the air, which adds weight without adding NAD+. A Karl Fischer water result lets the laboratory express the assay on a dry basis, so a damp sample is not mistaken for a degraded or underfilled one. The water content lesson covers the method.
What mass should an NAD+ certificate show?: PubChem lists NAD+, under the name nadide, at an average molecular weight of 663.4 g/mol and a monoisotopic mass of 663.11 Da. A mass spectrometer may report an ion slightly above or below that depending on its ionisation mode. A main mass near 665 instead suggests NADH, the reduced form, rather than NAD+.
Does a liquid NAD+ product test differently from a powder?: It can. A 43-day study of NAD+ and NADH in solution found that degradation depended on pH, temperature and buffer, with NAD+ breaking down faster in phosphate or HEPES than in Tris. A liquid product's result therefore reflects its formulation and storage history. The test still answers what is in the bottle, but it is less likely to match a fresh powder.

Sources

Nadide (NAD+) compound record (CID 5892), PubChem, US National Library of Medicine
NADH compound record (CID 439153), PubChem, US National Library of Medicine
Wolfe KD et al. Long-term stability of nicotinamide cofactors in common aqueous buffers. Molecules. 2024;29(22):5453, Molecules (PMC)
Røst LM et al. Zwitterionic HILIC tandem mass spectrometry with isotope dilution for quantification of pyridine nucleotides. J Chromatogr B. 2020;1144:122078, Journal of Chromatography B (PubMed)
Bernocchi P et al. Extraction and assay of creatine phosphate, purine, and pyridine nucleotides in cardiac tissue by reversed-phase HPLC. Anal Biochem. 1994;222(2):374-9, Analytical Biochemistry (PubMed)

Last reviewed 6 Oct 2026.