LC-MS/MS method validation for the quantitation of 1-kestose in wheat flour

Fructan analysis is challenging due to several mono-, di-, and oligosaccharides as well as starch and proteins present in wheat grains which interfere with the analysis. So far, a sensitive and fully validated LC-MS/MS method is missing although even small amounts of short-chain fructans such as 1-kestose are suggested to elicit gastrointestinal symptoms in patients suffering from irritable bowel syndrome. Therefore, the aim of this study was to validate a LC-MS/MS method for the detection of 1-kestose in a complex wheat matrix according to international guidelines. The chromatographic separation was performed on a C18 column coupled with a triple quadrupole MS in MRM mode using the transition m/z 503 -> m/z 119 for the quantitation of 1kestose. Accuracy of 1-kestose quantitation in an aqueous solution was 105.5 %. However, the poor recovery of 64.1 % in a complex wheat matrix demonstrated the great impact of proteins and other constituents present in wheat. Nevertheless, the proposed method allows precise quantification of 1-kestose amounts >= 0.1 ppm. The robustness of the method was confirmed by the results being within 6.03 % of the target value. The validated method was successfully applied for the measurement of 10 different wheat samples with 1-kestose amounts between 7.0 and 50.2 ppm.