Detection of phosphorus oxyanions in synthetic geothermal water using ion chromatography–mass spectrometry techniques

Recent developments in microbiology suggest that reduced inorganic phosphorus oxyanions, including hypophosphite and phosphite, may be present in nature. These studies have inspired the development of specific and sensitive methods that detect phosphorus oxyanions in natural water. This paper will discuss a new technique that couples suppressed conductivity ion chromatography (Dionex AS17 analytical column and potassium hydroxide eluent) with electrospray mass spectrometry (IC/MS) with limits of detection nearly 200 times lower than those reported using suppressed conductivity detection. The technique was optimized for the detection of hypophosphite, phosphite, and phosphate in a synthetic geothermal water matrix. Samples were pre-treated with silver and sulfonic acid cartridges, and injection loop sizes as large as 800 μl were employed to enhance instrument sensitivity. All peaks were clearly resolved, and calibrations were linear with estimated 3σ limits of detection of 0.011, 0.0020, and 0.029 μM for hypophosphite, phosphite, and phosphate, respectively.