COBALT(III) PRETREATMENT FOR TOTAL PHOSPHORUS DETERMINATION

A fast and simple pretreatment method of phosphorus compounds using Co3+ has been studied for the spectrophotometric determination of total phosphorus in water samples. Sample was mixed with a pretreatment solution (0.05 mol dm-3 CoSO4 in 1 mol dm-3 H2SO4) in an electrolytic cell at the volume ratio...

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Bibliographic Details
Published in:Phosphorus Research Bulletin 2015, Vol.30, pp.26-29
Main Authors: Kubo, Hiroya, Miyazaki, Azumi, Kuritani, Kazunori, Takeuchi, Masaki, Tanaka, Hideji
Format: Article
Language:English
Subjects:
Co3+ pretreatment
Determination of total phosphorus
flow injection analysis
organic phosphorus
polyphosphate
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Summary:A fast and simple pretreatment method of phosphorus compounds using Co3+ has been studied for the spectrophotometric determination of total phosphorus in water samples. Sample was mixed with a pretreatment solution (0.05 mol dm-3 CoSO4 in 1 mol dm-3 H2SO4) in an electrolytic cell at the volume ratio of 4:1. Highly reactive Co3+ was continuously generated through the electrolysis of Co2+ during the pretreatment. Aliquot of the solution was injected to the system of flow injection - Molybdenum Blue spectrophotometry in order to evaluate phosphate ion (PO43-) produced. Organic phosphorus compounds are completely decomposed to PO43- within 2 min by Co3+ under moderate condition (70°C). The Co3+ is also effective for the acid hydrolysis of polyphosphates; diphosphate and tripolyphosphate are converted to PO43- within 8 min through the pretreatment. Possible mechanisms of the pretreatment are discussed based on the strong oxidizing activity and the Lewis acid nature of Co3+.
ISSN:0918-4783
1882-2363
DOI:10.3363/prb.30.26