Figure 1.

(a) Number of publications found in Scopus, which contain spectroscopy tools in the title, abstract and/or keywords of studies on phenolic compounds. The keywords were “phenolic compound” and “fluorescence” (FL), “ultraviolet” (UV), “mass spectrometry” (MS), “infrared” (IR), “nuclear magnetic resonance” (NMR), “ion mobility” (IMS) or “Raman” (RS) were used. (b) The keywords were “phenolic compound” “mass spectrometry” and “ambient”, “liquid chromatography” or “gas chromatography”.