Essential oils are highly appreciated by the cosmetics industry because they have antimicrobial and antioxidant properties, among others. Since essential oils are natural products, their inclusion in cosmetic formulations is a common practice. Currently, low-quality and/or adulterated essential oils can be found on the market; therefore, analytical methods for control are required. Raman spectroscopy is a versatile technique that can be used for quality control tasks; the portability of modern devices expand the analytical possibilities also to in situ measurements. Fifteen essential oils of interest for the cosmetics industry were measured using a handheld Raman spectrometer, and the assignment of the main bands observed in their average spectra was proposed. In most cases, it is possible to distinguish the essential oils by a simple visual inspection of their characteristic Raman bands. However, for essential oils extracted from closely-related vegetable species and containing the same main component in a very high proportion, the visual inspection of the spectra may be not enough, and the application of chemometric methods is suggested. Characteristic Raman bands for each essential oil can be used to both identify the essential oils and detect adulterations.
OPEN ACCESSCosmetics 2015, 2 163
Honey is one of the oldest sweetening foods and has economic importance, making this product attractive to adulteration with cheap sugars. This can cause a critical problem in the honey industry and a possible health risk. The present work has the aim of evaluating the authenticity of honey commercialized in two different provinces of Ecuador (Pichincha and Loja) by performing physicochemical and spectroscopic analyses. For this study 25 samples were collected from different places and markets and characterized by water, sucrose, reducing sugars and electric conductivity measurement. Also, their Raman and Infrared (IR) spectra were recorded and analysed using a Principal Component Analysis (PCA) in order to verify the quality of the honeys. In addition, a screening of several pesticides was performed in order to verify possible chemical threats to human health and honey bees. It was found that 8 samples have a deviation from the Standard established parameters. Two of them have a high difference in the content of sucrose and reducing sugars, which are located deviated from all the other samples in the PCA of the applied vibrational spectroscopy (IR/Raman), shaping two clear clusters. The results show that Raman and IR spectroscopy is appropriate techniques for the quality control of honey and correlates well with the physicochemical analyses.
Essential oils are highly appreciated substances used as row materials in the food, cosmetics and pharmaceutical industry. Due to its biological activity and properties, the oil extracted from clove (Eugenia caryophyllus) has gained economic importance, and this is the main reason why adulterated clove essential oils have appeared in the market. The detection of adulteration is a fundamental task to ensure the quality of industrial products and, therefore, to protect the consumers from potential harmful products. In order to test the suitability of Raman spectroscopy to detect adulteration in essential oils, nineteen samples of commercial clove essential oil were measured with a handheld device and their Raman spectra analyzed. The Raman spectrum of a sample of authentic clove essential oil is dominated by bands of its main component eugenol. Principal component analysis (PCA) and independent component analysis (ICA) were applied in order to identify the adulterated samples and to assess the quality of the authentic samples. It was found that two samples were adulterated by the addition of benzyl alcohol and a third one by the addition of a vegetable oil. The adulteration by addition of benzyl alcohol is easy to detect by a quick inspection of the Raman spectrum, since this compound shows an intense band at 1003 cm‐1. However, the detection of adulteration by the addition of other substances (e.g., vegetable oils) requires the application of multivariable analysis, i.e., PCA or ICA. The results show that Raman spectroscopy is an appropriate technique for quality control of clove essential oil.
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