Qualitative and quantitative differentiation of species from Vaccinium by NMR spectroscopy in automation

The genus Vaccinium contains approximately 450 species including bilberry, blueberry, cranberry, lingonberry, and huckleberry. The fruit of Vaccinium are widely eaten and touted for their health benefits, attributed to antioxidants and micronutrients. Blueberry leaf extract is a traditional medicine of the Cree people, believed to have anti-diabetic properties. Extracts from Vaccinium plants are commonly added to foods, dietary supplements, and cosmetics. Given their widespread use in humans, it is important to have methods to verify the identity and purity of Vaccinium extracts. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for characterizing mixtures such as plant extracts in full automation. Discrimination of different species, absolute identification & quantification of key compounds and verification if the determined parameters are in the allowed range is the basis for the quality control of a sample. The automation of this process minimizes failures in the analysis. A comprehensive report makes the results easy to interpret. An NMR spectrum, such as a 1D¹H spectrum, shows the superposition of the characteristic signals of all of the compounds in the mixture. When enough samples of a specific material are available, chemometric models can be build. Then new samples can be classified against the model to determine whether they represent the same material. The result is represented in different ways, e.g. as quantile plot. Identifying and quantitating of key compounds from a mixture spectrum can be based on spectral analysis or using PLS-1. Both results can be used to verify if the sample is in the allowed range. We will demonstrate the power of these techniques using examples from our ongoing study of Vaccinium.