Speciation of Inositol Phosphates in Lake Sediments by Ion-Exchange Chromatography Coupled with Mass Spectrometry, Inductively Coupled Plasma Atomic Emission Spectroscopy, and 31P NMR Spectroscopy

A method for the detection and speciation of inositol phosphates (InsP(n)) in sediment samples was tested, utilizing oxalateoxalic acid extraction followed by determination by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLCMS/MS) using electrospray ionization (ESI) in negative mode. The chromatographic separation was carried out using water and ammonium bicarbonate as mobile phase in gradient mode. Data acquisition under MS/MS was attained by multiple reaction monitoring. The technique provided a sensitive and selective detection of InsP(n) in sediment samples. Several forms of InsPn in the oxalateoxalic acid extracted sediment were identified. InsP(6) was the dominating form constituting 0.250 mg P/g DW (dry weight); InsP(5) and InsP(4) constituted 0.045 and 0.014 mg P/g DW, respectively. The detection limit of the LCESI-MS/MS method was 0.03 mu M InsPn, which is superior to the currently used method for the identification of InsPn, P-31 nuclear magnetic resonance spectroscopy (P-31 NMR). Additionally sample handling time was significantly reduced.