The use of nitrogen-stable isotope technique to identify L-leucine extracted from human hair

Abstract

The production of L-leucine from pure botanical sources is expensive and time consuming. Hence, most fraudulent manufacturers in China use cheap and sometimes unwholesome sources of raw materials such as human hair and duck feathers in its production. Consequently, major concerns on health, economic, religious, legal and allergic reaction cases have been raised about this economically motivated adulteration. Notably, consumers of dietary supplements across the globe are beginning to request for non-animal and non-human sources. Hence, the prediction of the respective sources is essential for consumer protection. Therefore, this study provides discrimination between leucine derived from human hair and pure botanical sources as well as other sources such as duck feathers and pig fur by using the nitrogen stable isotope technique. An elemental analyzer which was connected to an isotope ratio mass spectrometer operated in the continuous flow mode was utilized. Statistical analysis was performed using descriptive statistics and one-way ANOVA. The results obtained showed δ15N values between 8.24 and 8.46 ‰ for the L-leucine extracted from human hair whereas ranges of 0.82–2.23, 5.41–5.47 and 5.88–6.01 ‰ were recorded for that of maize, pig fur and duck feather samples, respectively. It was shown that there is a clear difference between the δ15N composition of L-leucine extracted from human hair and the other sources. The difference confirms the predictable trophic enrichment of δ15N composition of organisms in a food web. This study adds to the efforts already in place to help curb food safety menace.