Determination of Siderophores in Seawater by High Performance Liquid Chromatography-Tandem Mass Spectrometry Coupled with Solid Phase Extraction

Siderophores are produced and secreted by marine microorganisms as a kind of specific iron binding organic ligand with high affinity. In this study, a liquid chromatography-tandem mass spectrometric method coupled with solid phase extraction pretreatment was developed for the determination of siderophores in seawater. The seawater samples were filtered through a 0.22-μm PES membrane, extracted with an ENVI-18 extraction cartridge, and eluted with methanol. The eluted sample was separated on a reversed phase SB-C18 column using a gradient elution program with 0.1% (V/V) formic acid and methanol as the mobile phases. Qualitative analysis was performed with mass spectrometry under multiple-reaction monitoring mode. Good linearity (R2 > 0.99) was obtained for pyoverdines-Fe, ferrichrome and ferrioxamine E at linear concentration ranges of 0.001–3.00 μg mL−1, 0.005–15.00 μg mL−1, 0.001–3.00 μg mL−1, respectively. The instrumental detection limits of the three analytes were 0.08, 1.76 and 1.36 ng mL−1, and the limits of quantification were 0.27, 5.87 and 4.53 ng mL−1, respectively. As for the standard addition experiments in seawater, the relative standard deviations of the three analytes were lower than 12%, while the recoveries were 12.1%–18.6% for pyoverdines-Fe, 82.0%–97.7% for ferrichrome and 70.0%–98.3% for ferrioxamine E.

Typical hydroxamate siderophores, ferrichrome (FC), ferrioxamine E (FO E) and pyoverdines-Fe (PVDs-Fe), in seawater were extracted on an ENVI-18 cartridge, eluted with methanol and determined using HPLC-tandem MS. With MS technique, the chemical structure of the target molecules could also be qualitatively analyzed.Figure optionsDownload as PowerPoint slide