title: Confirmation and determination of carboxylic acids in root exudates using LC-ESI-MS.
abstract: Reversed-phase liquid chromatography with UV detection is of limited applicability in the separation and identification of carboxylic acids because of the column's poor separation efficiency and the non-selective nature of the UV detector. To address this issue, RP-LC with electrospray ionization mass spectrometry has been explored for the confirmation and determination of carboxylic acids in plant root exudates, with ESI-MS providing structural information, high selectivity, and high sensitivity. The separation of 10 carboxylic acids (pyruvic, lactic, malonic, maleic, fumaric, succinic, malic, tartaric, trans-aconitic, and citric acid) was performed on a C(18) column using an eluent containing 0.1% (v/v) acetic acid within 10 min, where the acidic eluent not only suppressed the ionization of the carboxylic acids to be retained on the column, but was also compatible with ESI-MS detection. In addition, an additional standard was used to overcome the matrix effect. The results showed that peak areas correlated linearly with the concentration of carboxylic acids over the range 0.05-10 mg/L. The detection limits of target acids (signal-to-noise S/N ratio of 3) ranged from 20 to 30 microg/L. Finally, the proposed method was used for the confirmation and determination of low-molecular-weight carboxylic acids in plant root exudates, and provided a simple analytical procedure, including sample processing, fast separation, and high specificity and sensitivity.
authors.affiliation: School of Chemistry and Materials Science, Fujian Normal University, Fuzhou, China. ZLchen@fjnu.edu.cn
authors.forename: Zuliang
authors.initials: Z
authors.lastname: Chen
authors.forename: Xiaoyin
authors.initials: X
authors.lastname: Jin
authors.forename: Qinqping
authors.initials: Q
authors.lastname: Wang
authors.forename: Yuman
authors.initials: Y
authors.lastname: Lin
authors.forename: Li
authors.initials: L
authors.lastname: Gan
authors.forename: Caixing
authors.initials: C
authors.lastname: Tang