Analysis of Nitraria Tangutourum Bobr-Derived Fatty Acids with HPLC-FLD-Coupled Online Mass Spectrometry

Fatty acids (FAs) are basic components in plants. The pharmacological significance of FAs has attracted attentions of nutritionists and pharmaceutists. Sensitive and accurate detection of FAs is of great importance. In the present study, a pre-column derivatization and online mass spectrometry-based qualitative and quantitative analysis of FAs was developed. Nineteen main FAs were derivatized by 2-(7-methyl-1H-pyrazolo-[3,4-b]quinoline-1-yl)ethyl-4-methyl benzenesulfonate (NMP) and separated on reversed-phase Hypersil BDS C8 column with gradient elution. All FAs showed excellent linear responses with correlation coefficients more than 0.9996. The method obtained LOQs between 0.93 ng/mL and 5.64 ng/mL. FA derivatives were identified by both retention time and protonated molecular ion corresponding to m/z [M + H](+). A comparative study based on FA contents in peel and pulp, seeds and leaves of Nitraria tangutourum Bobr (NTB) from different geographical origins was performed with the established method. Results indicated that NTB were rich in FAs, and the types and contents of FAs varied among tissues. On the other hand, the same tissue of NTB from different geographical areas differed in the content, but not in type, of FAs.