Elucidating the redox cycle of environmental phosphorus using ion chromatography

Historically, it was assumed that reactive, inorganic phosphorus present in pristine environments was solely in the form of orthophosphate. However, this assumption contradicts theories of biogenesis and the observed metabolic behavior of select microorganisms. This paper discusses the role of ion chromatography (IC) in elucidating the oxidation-reduction cycle of environmental phosphorus. These methods employ suppressed-IC, coupled with tandem conductivity and electrospray mass spectrometry detectors to identify and quantify phosphorus oxyanions in natural water, synthetic cosmochemical, and biological samples. These techniques have been used to detect phosphite and orthophosphate in geothermal hot springs. Hypophosphite, phosphite, and orthophosphate have been detected in synthetic schreibersite corrosion samples, and termite extract supernatant. Synthetic schreibersite corrosion samples were also analyzed for two poly-phosphorus compounds, hypophosphate and pyrophosphate, and results show these samples did not contain concentrations above the 1.3 and 2.0 μM respective 3σ limit of detection. These methods are readily adaptable to a variety of matrices, and contribute to the elucidation of the oxidation-reduction cycle of phosphorus oxyanions in the environment. In contrast to most studies, these techniques have been used to show that phosphorus actively participates in redox processes in both the biological and geological world.