Preliminary Study on Dissolved Organic Phosphorus Determination by ICP-AES Method in Lake Taihu

Samples collected from Lake Taihu on May 27,2010 were used in removal experiment to validate the removal rates of representative dissolved organic phosphorus(DOP) such as glyphosate and phytic acid with C18 column,and role of digestion in measurement of total soluble phosphorus(TSP) by ICP-AES was also discussed.Different phosphorus fractions in samples were indirectly measured based on ICP-AES coupled with preliminary treatment with C18 column.Compared with traditional molybdenum-antimony anti-spectrophotometric methods on DOP determination,results showed that more than 96% of DOP can be successfully removed with C18 column.TSP concentrations determined by ICP-AES after digestion ranged from 0.025 mg/L to 0.095 mg/L,while samples without digestion were determined in the range of 0.009~0.03 mg/L,suggesting that digestion was necessary for DOP determination of water samples containing high levels of organophosphorus by ICP-AES method.Concentrations of DOP ranging from 0.014 mg/L to 0.069 mg/L were observed in samples by ICP-AES pretreated with C18 column,which were obviously higher than those determined by traditional methods as DOP ranging from 0.026 mg/L to 0.083 mg/L.It was evident that DOP levels determined by traditional method were overvalued;on the contrary,a much more accurate measurement on DOP could be obtained by ICP-AES coupled with C18 column pretreatment.