Determination of phosphate in seawater by ion chromatography inductively coupled plasma sector field mass spectrometry

Abstract

Phosphate in three seawater certified reference materials developed in previous work was not certified because it was only determined by continuous flow analysis (CFA). To obtain certified values for phosphate, we developed a novel method for the analysis of phosphate in seawater via inductively coupled plasma sector field mass spectrometry (ICP-SFMS) combined with anion exchange ion chromatography (IC). With use of a Jet-sampler cone and an X-skimmer cone on the ICP-SFMS instrument, the 31 P sensitivity derived from phosphate was enhanced by a factor of 18 compared to that of standard cones. To reduce the severe saline-generated matrix effect, an IC with a switching-valve system that separates phosphate from saline was employed. By adding an internal standard element (As) to the seawater samples, time-dependent fluctuation of the 31 P sensitivity was corrected and a better calibration curve was obtained. The developed method was applied to the analysis of three types of seawater. Although NMIJ CRM 7601-a could not be determined because its concentration after dilution for the IC separation is lower than the detection limit (0.005 μmol kg À1 ), the analytical results for NMIJ CRM 7602-a and 7603-a are in good agreement with the values obtained via CFA, considering their expanded uncertainties with the coverage factor of 2. The developed method was validated by analyzing an existing certified reference material (MOOS-3). This method enabled the measurement of sub-μmol kg À1 levels of phosphate with high accuracy and sensitivity.

Highly sensitive colorimetric detection and effective adsorption of phosphate based on MOF-808(Zr/Ce)

“…So far, the determination of phosphate methods include high-performance liquid chromatography (HPLC), 3 flow injection analysis (FIA), 4 and so on. 5,6 However, there exist many limitations in these methods, such as intricate operation steps, lengthy detection cycles, and expensive detection costs, which limit their practical applications. Due to the property of being intuitive, simple, and low cost, colorimetric analysis has been widely used.…”

Atomic Spectrometry Update: review of advances in elemental speciation

“…The NMIJ have added the phosphate ion to the certified analytes in two existing seawater CRMs, 7602-a and 7603-a. 26 In the original certification exercise, phosphate was determined by continuous flow analysis (CFA), due to the analyte levels being too low for an ICP-MS based approach. Due to the potential for interferences ( e.g.…”

“…Recent work involving the certification of phosphate in three seawater CRMs (National Metrology Institute of Japan (NMIJ) CRM 7601-a, 7602-a, and 7603-a) has used IC coupled to SF-ICP-MS. 26 The use of AE separation allowed for the reduction of the severe matrix effects due to the high concentration of Cl present in seawater, such that phosphate could be completely separated from Cl in the chromatograms for a 10% and 1% dilution of seawater. This separation was achieved using an IonPac AS23 AE analytical column (4 × 250 mm, Dionex) with an IonPac AG23 guard column (4 × 5 mm, Dionex).…”

Potentiometric Phosphate Ion Sensor Based on Electrochemically Modified All-Solid-State Copper Electrode for Phosphate Ions’ Detection in Real Water

“…The phosphor molybdenum blue spectrophotometric method is currently the most widely used phosphate detection method [11,12]. With the advancement of instrumentation, ion chromatography has gradually become a common method for determining phosphates [13,14]. The methods mentioned above possess good sensitivity and reliability.…”