About nmr-impurities

Almost every NMR spectrum contains signals that are not the compound you made — residual solvent, water, the ether or ethyl acetate from your workup, grease from a ground glass joint. Assigning them normally means scanning a dense printed table across twelve solvent columns.

This site makes that table queryable. Enter the shift you cannot assign and it returns the impurities that resonate there in your solvent, ranked by how close they are. The spectrum view shows the whole impurity landscape of a solvent at once.

All chemical shift values are reproduced from a single published compilation:

Fulmer, G. R.; Miller, A. J. M.; Sherden, N. H.; Gottlieb, H. E.; Nudelman, A.; Stoltz, B. M.; Bercaw, J. E.; Goldberg, K. I. NMR Chemical Shifts of Trace Impurities: Common Laboratory Solvents, Organics, and Gases in Deuterated Solvents Relevant to the Organometallic Chemist. Organometallics 2010, 29, 2176-2179. doi:10.1021/om100106e

The dataset covers 46 compounds, 158 distinct signals and 1753 individual shift values across ¹H and ¹³C{¹H} in 12 deuterated solvents. The measured values are experimental facts, but the compilation is the authors’ work and deserves the citation above. This site is an independent tool, not affiliated with or endorsed by the authors or the American Chemical Society.

Δ ppm is the signed distance from your query to the listed shift; results are sorted by its magnitude. For a signal reported as a range, any query inside the range counts as an exact match.

Tolerance starts at ±0.3 ppm for ¹H and ±1.0 ppm for ¹³C, which roughly reflects how much a shift realistically moves with concentration, temperature and referencing. Narrow it once you have a candidate; widen it when nothing turns up.

The shift filter is applied last, so before you type anything the table already lists every signal for your nucleus, solvent and selection. Note also that a solvent’s own protic form is not listed twice: in CDCl₃ the 7.26 ppm peak appears once, as the solvent residual signal, rather than also as “chloroform”.

Superscript letters are the publication’s own footnotes — hover or tap one to read it. Shifts do move with sample conditions, so treat a close hit as a strong candidate rather than proof.

The site is completely static and every calculation runs in your browser: the nucleus, solvent and shift you enter are never transmitted anywhere. There are no cookies and no third-party fonts.

Reach is measured with Vercel Web Analytics, which is cookieless and records only aggregated page views. The privacy policy sets out what that covers and what the host logs.

Made by PODSchu.