Abstract
Phosphite (P+III) is of emerging chemical interest due to its importance within the global phosphorus cycle. Yet, to date, precise/accurate measurements of P+III are still lacking due to the inherent analytical challenges linked to its instability/ease of oxidation and ultra-trace concentration. Here, we present the first in-situ sampling and speciation analysis method, for dissolved P+III, using the diffusive-gradients-in-thin-films (DGT) technique, combined with capillary-column-configured-dual-ion-chromatography (CC-DIC). Method optimization of the DGT elution regime, to simultaneously maximize desorption efficiency and CC-DIC sensitivity, along with the characterization of diffusion coefficients for P+III, were undertaken before full method validation. Laboratory-performance testing confirmed DGT-P+III acquisition to be independent of pH (3.0–10.0) and ionic strength (0–500 mM). The capacity for P+III was 45.8 μg cm−2, while neither P+V (up to 10 mg L−1) nor As+V (up to 1 mg L−1) impacted the DGT-P+III measurement. This novel method's functionality stems from the herein confirmed speciation preservation and double pre-concentration of P+III, resulting in quantification limits as low as 7.44 ng L−1 for a 3-day deployment. Applications of this method in various terrestrial/aquatic environments were demonstrated and simultaneous profiles of P+III and P+V across a sediment-water interface were captured at mm resolution in two contrasting redox-mesocosm systems.
Original language | English |
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Pages (from-to) | 281-289 |
Number of pages | 9 |
Journal | Water Research |
Volume | 137 |
Early online date | 13 Mar 2018 |
DOIs | |
Publication status | Published - 15 Jun 2018 |
Keywords
- DGT
- High-resolution
- In situ sampling method
- P
- Ultra-sensitivity analysis
ASJC Scopus subject areas
- Ecological Modelling
- Water Science and Technology
- Waste Management and Disposal
- Pollution