Characterization of polyphosphates by electrospray mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) was applied for the char acterization of inorganic polyphosphates [orthophosphate, pyrophosphate, tr ipolyphosphate, trimetaphosphate, and tetrapolyphosphate]. The high selecti vity of ESI-MS allows the detection of different polyphosphate species with out preseparation by ion chromatography or capillary electrophoresis. Furth ermore, ESI-RIS does not require the incorporation of W-absorbing chromopho res into the analytical method for the detection of phosphates, unlike conv entional UV-chromatographic methods. Limits of detection by ESI-MS were est imated to range from similar to 1 to 10 ng/mL. The quantification of polyph osphate samples as single-component and multicomponent mixtures was investi gated. Linear signal response for single-component samples ranged from the limit of detection to similar to 10 mu g/mL. Quantification of polyphosphat e in streamwater is demonstrated using the standard addition method. The ef fect of multi-polyphosphate components and salts on signal response was als o studied. For concentrations less than 2.0 mu g/mL, signal response from a tetrapolyphosphate sample was comparable to those obtained from tetrapolyp hosphate-tripolyphosphate mixtures. Signal response obtained from tetrapoly phosphate in the presence of tripolyphosphate or NH4NO3 at higher concentra tions (similar to 50 mu g/mL and 35 mu g/mL, respectively) was significantl y lower relative to single-component standards (similar to 40%-70%).