The phase-resolved photoacoustic method to indicate chemical assignments of paracetamol

•Photoacoustic spectroscopy was used to identify chemical assignments of paracetamol in NIR.•Phase-resolved photoacoustic method is applied to characterization of paracetamol.•The peaks centered at 1398 and 1225 nm were assigned to a C–H combination from a CH3 structure.•The peak centered at 1305 nm was assigned to a C–H combination from the aromatic ring.

In this work, the phase-resolved photoacoustic method was applied to provide specific information on the chemical assignments of paracetamol in the near-infrared region. Two broad bands, centered at 1370 and 1130 nm, were well-resolved using this method, making it possible to assign the peaks centered at 1398, 1355 and 1295 nm to a C–H combination from a CH3 structure and the peak at 1305 nm to a C–H combination from the aromatic ring. This information represents a new finding in chemical studies regarding this medicament.

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