Quantitation of Mi-saponin A in adulterated Quillaja and contaminated Gypsophila saponin extracts by high performance liquid chromatography/quadrupole time-of-flight mass spectrometry

Abstract

• Development of a semipreparative HPLC method for the isolation of Mi-saponin A. • New HPLC / Q-ToF method for quantitation of Mi-saponin A in various saponin extracts. • Detection of Mi-saponin A in currently purchased Quillaja and Gypsophila extracts. • Quantitation of Mi-saponin A in these adulterated Quillaja and Gypsophila extracts. Plant saponin extracts are currently of increasing importance for the environment and climate. Saponin extracts are used for the regeneration of soils contaminated by environmental pollutants such as polycyclic aromatic hydrocarbons. Furthermore, as feed additives they may have the potential to reduce the release of the greenhouse gas methane in ruminants, or to reduce ammonia emissions in pigs and broilers. Quillaja extracts play a major role in emission reduction. Some commercially available Quillaja extracts have been adulterated by blending with an inexpensive Madhuca saponins extract. Since a quantitation has not been performed so far, the present work aims at the development of a quantitative method for the determination of the main ingredient Mi-saponin A of Madhuca . For this purpose, a semi-preparative HPLC method for the isolation of Mi-saponin A from mahua seed cake, which is the press residue of the seed kernels of Madhuca longifolia , was developed. Using 1 H NMR, 13 C NMR, and high resolution mass spectrometry, the identity was unambiguously confirmed and the purity was excellent. It was used as standard for quantitation of Mi-saponin A in various currently purchased commercially available Quillaja saponin extracts. The concentration of Mi-saponin A was between 1.68 and 2.65 % (w/w), which reveals that the blending of Quillaja saponin extracts with Madhuca is still relevant. Moreover, the developed method for the quantitation of Mi-saponin A is also suitable for lower concentration. Thus, Mi-saponin A was found at a concentration of 0.10 % (w/w) in Gypsophila saponin extracts, confirming that there was a contamination with this Madhuca saponin.