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. 2021 Sep 9;16(9):e0252806. doi: 10.1371/journal.pone.0252806

Fig 2. FTIR-ATR spectra of reference standards used for calibration—genuine (pure) beeswax, and adulterants (paraffin—Paraffinum solidum, stearic acid—Acidum stearicum).

Fig 2

Wavenumber, the number of waves per unit distance; cm, centimetre; a.u. is for the absorbance unit.