Solid phase extraction techniques for the isolation of siderophores from aquatic environments

Abstract

To study the ecological role of siderophores in the natural environment, it is necessary to enrich the sample by several orders of magnitude. Solid phase extraction techniques are excellently suited for this type of application. Adsorption of three siderophores (Desferal, rhodotorulic acid, deferriferrichrome A) and EDTA were studied using 12 solid phase resins. These included traditional silica and C‐18 cartridges, polar (e.g., diol or amine) cartridges, non‐silica polymeric cartridges (e.g., MP‐1, MP‐2 and MP‐3) and ion exchange cartridges (e.g., SAX, CBA, SCX). Using iron‐55 labeled siderophores as probes, considerable variation was observed between the cartridge types and similar cart‐ridges from different manufacturers. For most applications, traditional or polymeric C‐18 reverse cartridges were preferred. Recoveries for EDTA and RA were low, while recoveries for DES and FCA were generally greater than 40%. C‐18 cartridges worked equally well when freshwater or seawater was the starting matrix. We conclude that solid phase extraction techniques may be suitable for the enrichment of siderophores from natural systems.

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