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Electrophoresis, Vol.35, No.9, 1375-1385, 2014
Accurate LC-ESI-MS/MS quantification of 2-deoxymugineic acid in soil and root related samples employing porous graphitic carbon as stationary phase and a C-13(4)-labeled internal standard
For the first time the phytosiderophore 2-deoxymugineic acid (DMA) could be accurately quantified by LC-MS/MS in plant and soil related samples. For this purpose a novel chromatographic method employing porous graphitic carbon as stationary phase combined with ESI-MS/MS detection in selected reaction monitoring was developed. Isotope dilution was implemented by using in-house synthesized DMA as external calibrant and C-13(4)-labeled DMA as internal standard (concentration levels of standards 0.1-80 M, determination coefficient of linear regression R-2 > 0.9995). Sample preparation involved acidification of the samples in order to obtain complete dissociation of metal-DMA complexes. Excellent matrix related LOD and LOQ depending on different experimental setups were obtained in the range of 3-34 nM and 11-113 nM, respectively. Standard addition experiments and the implementation of the internal C-13(4)-DMA standard proved the accuracy of the quantification strategy even in complex matrices such as soil solution. The repeatability of the method, including sample preparation, expressed as short- and long term precision was below 4 and 5% RSD, respectively. Finally, application in the context of plant and soil research to samples from rhizosphere sampling via micro suction cups, from soil solutions and soil adsorption/extraction studies revealed a DMA concentration range from 0.1 to 235 M.
Keywords:C-13(4)-labeled internal standard;2-Deoxymugineic acid;Iron acquisition;LC-ESI-MS;MS;Rhizosphere