Lipstick traces: FTIR calibration
- Published: Oct 15, 2016
- Author: David Bradley
- Channels: Chemometrics & Informatics
Lipstick is a widely used cosmetic the world over. However, it is commonly formulated with animal fat, and lard in particular, which does not sit comfortably for some people with particular ethical, moral and religious beliefs. A new approach to extraction and analysis by multivariate calibration of Fourier transform infrared (FTIR) spectroscopy has been demonstrated by researchers in Indonesia.
Dri Waskitho, Endang Lukitaningsih, Sudjadi and Abdul Rohman of Gadjah Mada University, in Yogyakarta and The National Agency of Drug and Food Control, in Central Kalimantan, Indonesia, point out that lard is commonly used as an emulsifying agent and to improve viscosity of lipstick, eyebrow pencils, eyeliner, and other products. Lard and its derivatives are regulated in the same way as any other cosmetic ingredient and are deemed safe. However, regulations do not necessarily take into account religious or other beliefs and as such there is an issue for certain sectors of society in using such products, perhaps unwittingly. There is a need for a rapid and straightforward test for authentication studies to ensure a given product complies with religious and ethical thought, for instance.
Lipsticks are composed of mainly oils, fats and colouring agents. Sometimes scent compounds are used or other additives to give a different glossy, sparkly or other finish and texture. Castor oil is widely used in manufacture because of its high viscosity and ready uptake of the dye compounds commonly used. The use of lard is widespread and can be analysed using FTIR spectroscopy, differential scanning calorimetry, gas chromatography, high performance liquid chromatography (HPLC), a so-called electronic nose, for instance. FTIR is the most powerful and rapid of the various techniques used to analyse fats and oils in cosmetics and food, it is also non-destructive.
However, to make analysis more tenable in a real-world environment calibration of FTIR spectroscopy (in the wavenumber region 1200 to 800 cm-1) combined with multivariate analysis, partial least square (PLS）and principal component analysis（PCA）can be used for quantification and classification of oils and fats. The Indonesian team has now demonstrated proof of principle of this approach to the analysis of lard specifically in lipstick for halal authentication studies.
Saponification and extraction
They used their calibration process to test which of three extraction methods is most suitable for such testing. First, they investigated a saponification method followed by liquid/liquid extraction with hexane/dichloromethane/ethanol/water. The second approach involved saponification followed by liquid/liquid extraction with dichloromethane/ethanol/water. Finally, the Bligh and Dyer method using chloroform/methanol/water as extracting solvent. The latter was found to be the most capable of identifying and quantifying lard extracted from various commercial lipstick formulations. "The results can be extended to various types of topical cosmetic preparations using oils as a base in their formulation," the team adds in their paper in the Journal of Oleo Science published by the Japan Oil Chemists' Society.
J Oleo Sci 2016, 65, 815-824: "Analysis of Lard in Lipstick Formulation Using FTIR Spectroscopy and Multivariate Calibration: A Comparison of Three Extraction Methods"
Article by David Bradley
The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.
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