Browse reference spectra from the USGS Spectral Library Version 7 and other curated sources. Each spectrum includes interactive plots, metadata, and downloadable data.
Have an unknown spectrum? Match it against this entire library with HQI similarity scoring — no install, no data leaves your machine.
Identify My SampleLearn more about how spectral matching works, HQI scoring, and building a personal reference library on the Spectral Library Search page.
| Formula | Modality | Category | Source | ||
|---|---|---|---|---|---|
| 4-VINYLGUAIACOL | C9H10O2 | Mass Spec | Chemical | MassBank | |
| 4-Vinylpyridine | C7H7N | Mass Spec | Chemical | MassBank | |
| 4-[(3-oxobutanoyl)amino]benzenesulfonate | C10H11NO5S | Mass Spec | Chemical | MassBank | |
| 4-[(4-Aminophenyl)(4-iminocyclohexa-2,5-dien-1-ylidene)methyl]-2-methylaniline | C20H19N3 | Mass Spec | Chemical | MassBank | |
| 4-[(Diphenylhydrazinylidene)methyl]-N,N-diethylaniline | C23H25N3 | Mass Spec | Chemical | MassBank | |
| 4-[3-(4-Acetyl-3-hydroxy-2-propylphenoxy)propoxy]phenoxy-acetic acid | C22H26O7 | Mass Spec | Chemical | MassBank | |
| 4-amino-2-nitrophenol | C6H6N2O3 | Mass Spec | Chemical | MassBank | |
| 4-chloro-2-hydroxy-4-methoxybenzophenone | C14H11ClO3 | Mass Spec | Chemical | MassBank | |
| 4-chloro-N,N-dimethylaniline | C8H10ClN | Mass Spec | Environmental | MassBank | |
| 4-chloro-N-methylaniline | C7H8ClN | Mass Spec | Environmental | MassBank | |
| 4-guanidinobutanamide | C5H12N4O | Mass Spec | Pharmaceutical | MassBank | |
| 4-guanidinobutanoic acid | C5H11N3O2 | Mass Spec | Environmental | MassBank | |
| 4-heptylphenol | C13H20O | Mass Spec | Natural product | MassBank | |
| 4-hydroxy-benzoate | C7H6O3 | Mass Spec | Chemical | MassBank | |
| 4-hydroxyantipyrine | C11H12N2O2 | Mass Spec | Chemical | MassBank | |
| 4-methoxy-1H-indole-3-carbaldehyde | C10H9NO2 | Mass Spec | Natural product | MassBank | |
| 4-methyl-2-oxopentanoic acid | C6H10O3 | Mass Spec | Environmental | MassBank | |
| 4-methylumbelliferyl glucuronide | C16H16O9 | Mass Spec | Natural product | MassBank | |
| 4-n-Octylphenol | C14H22O | Mass Spec | Environmental | MassBank | |
| 4-nonylphenol | C15H24O | Mass Spec | Natural product | MassBank | |
| 4-tert-Butylbenzenesulfonamide | C10H15NO2S | Mass Spec | Environmental | MassBank | |
| 4-tert-Butylcatechol | C10H14O2 | Mass Spec | Chemical | MassBank | |
| 4-tert-Butylphenol | C10H14O | Mass Spec | Chemical | MassBank | |
| 4-tert-Octylphenol | C14H22O | Mass Spec | Environmental | MassBank | |
| 4-tert-pentylphenol | C11H16O | Mass Spec | Natural product | MassBank | |
| 4-{2-Oxo-2-[3-(trifluoromethyl)phenyl]ethyl}benzonitrile | C16H10F3NO | Mass Spec | Chemical | MassBank | |
| 4.4-DDE | C14H8Cl4 | Mass Spec | Environmental | MassBank | |
| 42FTS | C6H5F9O3S | Mass Spec | Natural product | MassBank | |
| 44m2PFOA | C8HF15O2 | Mass Spec | Natural product | MassBank | |
| 44m2PFOS | C8HF17O3S | Mass Spec | Natural product | MassBank | |
| 4:2-FTSA | C6H5F9O3S | Mass Spec | Natural product | MassBank | |
| 4A,6,9A-TRIMETHYL-1,2,3,4,4A,9A-HEXAHYDROPYRIDO(2,3-B)INDOLE | C14H20N2 | Mass Spec | Chemical | MassBank | |
| 4A,9,9A-TRIMETHYL-1,2,3,4,4A,9A-HEXAHYDROPYRIDO(2,3-B)INDOLE | C14H20N2 | Mass Spec | Chemical | MassBank | |
| 4A-METHYLDECAHYDRO-2-NAPHTHOL | C11H20O | Mass Spec | Chemical | MassBank | |
| 4A-METHYLDECAHYDRO-2-NAPHTHOL-2-D | C11H20O | Mass Spec | Chemical | MassBank | |
| 4ABETA-ETHYLENEDIOXYMETHYL-(1BETA),6-DIMETHYL-(1ALPHA)-(4-METHYL-3-PENTENYL)-1,2,3,4,4A,7,8,8A-OCTAHYDRONAPHTHALENE-5(6H)-ONE | C21H34O3 | Mass Spec | Chemical | MassBank | |
| 4ALPHA-ACETYL-1(2H)-METHYLENE-6(7H)-OXO-3,4,4AALPHA,5,8,8ABETA-HEXAHYDRO NAPHTHALENE6-ETHYLENE ACETAL | C15H22O3 | Mass Spec | Chemical | MassBank | |
| 4ALPHA-DEUTERO-7-METHOXYISOFLAVAN-4-OL | C16H16O3 | Mass Spec | Chemical | MassBank | |
| 4BETA-ACETYL-1(2H),6(7H)-DIOXO-3,4,4ABETA,5,8,8AALPHA-HEXAHYDRONAPHTHALENE 6-ETHYLENE ACETAL | C14H20O4 | Mass Spec | Chemical | MassBank | |
| 4BETA-DEUTERO-7-METHOXYISOFLAVAN-4-OL | C16H16O3 | Mass Spec | Chemical | MassBank | |
| 4BETA-FORMYL-1(2H)-METHYLENE-6(7H)-OXO-3,4,4ABETA,5,8,8AALPHA-HEXAHYDRONAPHTHALENE 6-ETHYLENE ACETAL | C14H20O3 | Mass Spec | Chemical | MassBank | |
| 4H,5H-1-TERT-BUTYL-3-METHOXYCARBONYL-4-(1-METHOXYPYRROL-2-YL)METHYLENE-PYRAZOL-5-ONE | C16H19N3O5 | Mass Spec | Chemical | MassBank | |
| 4H,5H-3-METHOXYCARBONYL-4-(1-METHOXYCARBONYLPYRROL-2-YL)METHYLENE-1-PHENYLPYRAZOL-5-ONE | C18H15N3O5 | Mass Spec | Chemical | MassBank | |
| 4HR | C12H18O2 | Mass Spec | Environmental | MassBank | |
| 4IPPDPP | C21H21O4P | Mass Spec | Natural product | MassBank | |
| 4MeC13SPC | C20H32O5S | Mass Spec | Chemical | MassBank | |
| 4XI,11XI-DIPHENYLTRICYCLO(5.3.1.0(3,8))UNDECANE-2,6-DIONE | C23H22O2 | Mass Spec | Chemical | MassBank | |
| 4`-Aminoacetanilide | C8H10N2O | Mass Spec | Environmental | MassBank | |
| 4`-Bromacetanilide | C8H8BrNO | Mass Spec | Environmental | MassBank | |
| 4`-Hydroxy Diclofenac | C14H11Cl2NO3 | Mass Spec | Environmental | MassBank |