Untargeted headspace gas chromatography - Ion mobility spectrometry analysis for detection of adulterated honey

The recognized properties of honey together with its price have, almost inevitably, led to economically motivated adulteration. In this work, headspace gas chromatography coupled to ion mobility spectrometry (HS-GC-IMS) is proposed for the differentiation of honey according to its purity and the level of adulteration by sugar cane or corn syrups. An easy and rapid sample treatment, consisting of incubating 1 g of honey at 100 °C for 15 min and then injecting 750 μL of the sample headspace into the GC-IMS system, is proposed. A 3-dimensional data map is obtained in 32 min. The proposed method was used for the analysis of 198 honey samples (56 pure honeys of different botanical origins, 71 honeys adulterated with sugar cane syrup and 71 adulterated with corn syrup). The influence of the adulterant on variations in the honey sample spectrum was studied. In order to obtain chemometric models for the detection of adulterated honey samples, the data obtained by HS-GC-IMS were processed selecting the significant markers of the spectrum fingerprint. OPLS-DA models were constructed using 80% of the samples, and the remaining 20% were used for method validation. The differentiation between pure and adulterated honeys had a validation success of 97.4%, and the assessment of adulterant content was obtained with a 93.8% validation success rate for both adulterant agents assayed. Nine commercial honey samples were analysed using the proposed methodology, and seven of them were classified as adulterated.