Journal article
On-line dynamic fractionation and automatic determination of inorganic phosphorous in environmental solid substrates exploiting sequential injection microcolumn extraction and flow injection analysi
Sequential injection microcolumn extraction (SI-MCE) based on the implementation of a soil containing microcartridge as external reactor in a sequential injection network is, for the first time, proposed for dynamic fractionation of macronutrients in environmental solids, as exemplified by the partitioning of inorganic phosphorous in agricultural soils.
The on-line fractionation method capitalises on the accurate metering and sequential exposure of the various extractants to the solid sample by application of programmable flow as precisely coordinated by a syringe pump. Three different soil phase associations for phosphorus, that is, exchangeable, Al- and Fe-bound and Ca-bound fractions, were elucidated by accommodation in the flow manifold of the 3 steps of the Hietjles-Litjkema (HL) scheme involving the use of 1.0 M NH4Cl, 0.1 M NaOH and 0.5 M HCl, respectively, as sequential leaching reagents.
The precise timing and versatility of SI for tailoring various operational extraction modes were utilised for investigating the extractability and extent of phosphorous re-distribution for variable partitioning times. Automatic spectrophotometric determination of soluble reactive phosphorous in soil extracts was performed by a flow injection (FI) analyser based on the molybdenum blue (MB) chemistry.
The 3σ detection limit was 0.02 mg P L-1 while the linear dynamic range extended up to 20 mg P L-1 regardless of the extracting media. Despite the variable chemical composition of the HL extracts, a single FI set-up was assembled with no need for either manifold re-configuration or modification of chemical composition of reagents.
The mobilization of trace elements, such as Cd, often present in grazed pastures as a result of the application of phosphate fertilizers, was also explored in the HL fractions by electrothermal atomic absorption spectrometry.
Language: | English |
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Year: | 2006 |
Pages: | 224-231 |
ISSN: | 18734324 , 00032670 and 00302670 |
Types: | Journal article |
DOI: | 10.1016/j.aca.2006.03.114 |