A specific and sensitive method for quantification of small quantities of a standardized
Dry Grape Extract in complete feed based on UHPLC-MS/MS has been developed and validated.
The standardized Dry Grape Extract studied is a natural commercial feed additive (Nor-Grape®,
Nor-Feed, France) used in animal nutrition, consisting of a complex mixture of grape
seed extracts and grape skin extracts in which malvidin-3-O-glucoside (M3OG) has been
identified and quantified. M3OG was used as phytomarker for the quantification of
the additive in feed. Key steps in the preparation of the sample are the use of several
successive and selective extractions allowing firstly to eliminate a large number
of undesirable molecules and in a second time to recover and concentrate the anthocyanins
of the additive present in the sample. The use of an internal standard (cyanidin-3-O-sambubioside)
makes it possible to compensate for the losses of the analyte during sample work-up.
M3OG quantification is performed by the standard addition method to compensate ion suppression during HPLC-MS/MS analysis. The method was developed and validated in-house in accordance with the guidelines
recommended by IUPAC (selectivity, calibration and linearity, trueness, precision,
recovery, limit of quantification, measurement uncertainty) [1] for the quantification of a small dose of the standardized Dry Grape Extract in
complete feed (30ppm). This patented method of analysis has all the prerequisites
to be used by European authorities as part of the registration of a feed additive
[2].
