Persulfate chemical wet oxidation method for the determination of particulate phosphorus in comparison with a high‐temperature dry combustion method

Abstract

A persulfate chemical wet oxidation (CWO) method for the determination of particulate phosphorus (PP) was improved and then compared with a conventional high-temperature dry combustion (HTDC) method. In the improved CWO method, the concentration of the digestion reagent, potassium persulfate, was increased from 0.5% to 3% (w/v); the method exhibited high recoveries of P from various test materials under commonly used autoclave conditions (at 120°C for 30 min). The recoveries of P relative to those of the HTDC method were 102 ± 6.7% from standard organic and inorganic P compounds, and 100 ± 3.8% from natural particulate matter analogues including riverine suspended particulate matter (SPM), sediments, plankton, and geochemical reference materials of rock. However, low recoveries of 14% to 69% were observed for reference samples of clay minerals. Comparison using many samples of estuarine and pelagic SPM showed that the CWO method produced PP values consistent with those obtained by the HTDC method, except for some estuarine samples enriched in inorganic matter. The low recoveries were ascribed to the presence of an inorganic P fraction highly recalcitrant to chemical digestion. The procedural blank was lower for the CWO method than for the HTDC method. The filter blanks showed large variation among the filter materials tested; aluminum oxide membrane filters were shown to contain a considerable amount of P that could cause significant contamination in both methods. Analytical precision was equivalent between the two methods. Considering its simplicity and its less time-consuming nature, the CWO method presented here is suitable for PP determination in aquatic environments.

Fractionation of Phosphorus in Steelmaking Slags and Aquatic Particulate Materials Using a Sequential Extraction Technique

“…For the Slags, the difference between the total extractable P determined by the sequential extraction method and the total P determined by the ignition method does not seem to be organic P; instead, it is probably inorganic P, perhaps in the similar form of some type of clay mineral that contains highly recalcitrant, inert inorganic P unable to be recovered by hydrochloric acid extraction. 32) As argued, the total P determined by the ignition method was comparable with that by the sequential extraction method (except S3) as well as that by the well-established X-ray fluorescence. Therefore, it can be considered that total P measurements in Slags by these three methods are consistent with each other.…”

“…31,32) Briefly, inorganic P was extracted with 1 M hydrochloric acid from the samples after combustion at 470°C for 90 min with addition of magnesium nitrate. The soluble reactive phosphate (SRP) concentration in the acid extract was determined by ascorbic-acid-reduction, molybdate-blue absorption spectrophotometry with a Seal Analytical QuAAtro Autoanalyser (2-HR, BLTEC) at a wavelength of 880 nm.…”

“…Although the ignition method used in this study has been widely used for total P analysis in aquatic sediments and particulate matter, 31,32) this seems to be the first application of the method to Slags. Previous studies have used other techniques for Slag analysis, including electron probe micro-analysis and X-ray fluorescence.…”

Characterisation of water quality in effluents of land-based abalone farms in the Western Cape, South Africa

“…Following digestion in an oven at 120°C for 2.5 h, an aliquot of the assay mixture was diluted 5 times with Milli-Q water and adjusted to pH 8 with Tris-HCl buffer to a final concentration of 0.01 M. Nitrate reduction was carried out on a cadmium column following the manual method of Nydahl (1976). Analyses of particulate P followed Suzumura (2008), with persulfate oxidation in an oven at 120°C for 2 h followed by manual PO 4 3− analyses (Grasshoff et al 1983). The present modification of employing oven digestion at 120°C for longer time periods than recommended in the original methods gave slightly better recoveries for N (p = 0.017), and similar recoveries for P, compared to autoclave digestion (Mann-Whitney rank sum tests).…”

Biogeography of globally distributed bacteria in temperate and boreal Québec lakes as revealed by tag pyrosequencing of 16S rRNA genes

“…Total phosphorus (TP) was measured using the molybdenum-blue method with potassium persulfate digestion (Suzumura 2008). Dissolved organic carbon (DOC) was measured on a total organic carbon (TOC) analyzer (OI Analytical) using a high-temperature persulfate oxidation method (Kaplan 1992).…”