Development of a new analytical protocol by stable carbon isotope ratio to identify and characterize the authenticity of commercial cleaning products formulated with biobased surfactants

The fast growth of cosmetic and detergent market and the problems associated with their environmental, social and economic impacts have stimulated research and development of ecofriendly and biobased formulations [1,2]. Stable carbon isotope analysis could be used to determine the origin of commercial surfactants and cleaning products, especially in quality process by chemical companies. Radiocarbon methodology is the standard method to assess and check the authenticity of biobased surfactants, but the high cost and time consuming of this technique are relevant disadvantages to its commercial application. Very recently, a few pioneering studies have described the possibility to use IRMS (Isotope ratio mass spectrometry) as alternative method to radiocarbon methodology [3]. Isotope mass spectrometry is an automated and useful tool with many applications in different scientific areas. The δ13C value was applied to commercial surfactants, such as ethoxylate alcohol, sodium lauryl sulfate, alkyl polyglucoside with different origin, that are the most common raw materials used in cleaning products. In this study, the isotopic analysis was performed on mixtures of commercial surfactants to simulate the commercial detergent formulations (handwashing, multisurface cleaner and degreaser) and then on bulk professional cleaning products to match relationship between isotope carbon composition and concentration of surfactants in real samples. This study demonstrated that δ13C was correlated to the origin of surfactants. In particular we analysed five samples of biobased surfactants, with δ13C value from -22,6 ‰ to -28,0‰, and six samples from carbon fossil raw material, with δ13C value from -28,5 ‰ to -32,0‰, which were the most common raw material used in commercial cleaning products. Isotope carbon composition was also analysed on mixtures of biobased and fossil surfactants to simulate and perform the method for stable carbon isotope analysis of commercial cleaning products. Furthemore the results assessed the relationship between stable carbon isotope ratio values and surfactant concentration in mixtures: for example in 50% mixtures of biobased (δ13C -22,6 ‰) and synthetic surfactant (δ13C -32,5 ‰), we found a δ13C value -28,00 ‰. The main advantage in using δ13C analysis is related to cheapness and easy-to-operate method in comparison to radiocarbon methodology.