Application of Raman spectroscopy in the rapid detection of waste cooking oil

Raman spectra were used to distinguish waste cooking oil from edible vegetable oils. Signals at 869, 969, 1302 and 1080 cm−1 were found to be crucial to distinguish waste cooking oil from five edible oils using PCA. When waste cooking oil was added to soybean or olive oil, PCA could separate adulterated and pure oils, when the adulteration proportions reached 10% and 20%, respectively. Peaks at 969 (R2 > 0.951), 1267 (R2 = 0.987) and 1302 (R2 > 0.984) cm−1 responded linearly to adulteration. Heating assays and 1H NMR analysis revealed that differences between the Raman spectra of waste cooking oil and edible oils at 969 and 1267 cm−1 were directly related to heat treatment. This work highlights the potential for Raman spectroscopy to detect waste cooking oil.