High-performance anion-exchange chromatography (HPAEC) coupled with pulsed amperometric detection
(PAD) is an efficient method to quantify carbohydrates in natural samples and food products [15–21]. In fact, due to
their weak acidic properties (pKa ≈12), carbohydrates can be ionized in strong basic conditions. Thus, an accurate
separation of carbohydrates can be achieved by using a strong anion exchange stationary phase and hydroxide
solutions as eluent. PAD is an electrochemical method based on the oxidation of carbohydrates on a gold electrode by
application of a positive potential. It provides high sensitivity and selectivity, without any time-consuming derivatization
step. However, in plant extracts, as in many natural samples, the high complexity of the matrix may lead to coelution
and excessive noise. Consequently, interferences between the matrix components and the target compounds can
strongly affect the results by hindering peak attribution and integration. The mass spectrometric detection is highly
selective and sensitive, and can therefore solve a lot of chromatographic troubles. However, MS is commonly considered
to be incompatible with the highly alkaline eluents used in HPAEC. Technical improvements allowing the MS
analysis of carbohydrates by HPAEC and results obtained on drought-stressed poplar are described in this work