A highly sensitive quantitative method for assaying nicotianamine (NA) and 2'-deoxymugineic acid (DMA) using liquid chromatography electrospray ionization time-of-flight mass spectrometry (LC-ESI-TOF-MS) was developed. This method requires fewer sample preparation steps than high-performance liquid chromatography (HPLC). The amino and hydroxyl groups of NA and DMA were derivatized using 9-fluorenylmethoxycarbonyl chloride, which improved their retention on a C18 reversed-phase column and facilitated separation. The amounts of NA and DMA in 10 μl of xylem sap from rice cultivated under Fe-sufficient and Fe-deficient conditions were quantified without concentration. In Fe-sufficient plants, the concentrations of NA and DMA were almost equal to that of Fe. In Fe-deficient plants, the concentration of NA did not change significantly, whereas that of DMA increased markedly
