Determination of total phosphorus in sediments by means of high-pressure bombs and ion chromatography

The traditional standard method for the determination of total phosphorus is performed by oxidizing of phosphorus to phosphate in a strong acidic media. The determination of total phosphorus in natural waters using potassium persulphate provides an alkaline environment optimum for breaking the phosphorus bonds under high pressure and temperature. This work describes a methodology for the determination of total phosphorus in sediments using a mixture of potassium persulphate and NaOH. A Dionex Model 2000i/SP ion chromatograph, with an anion pre-column (Dionex AG4A), an anion separator column (Dionex AS4A), a suppressor column (Dionex AMMS-II) and a conductivity detector was used. The mobile phase (2 ml min(-1)) was 1.7 mM NaHCO3-1.8 mM Na2CO3. Results were compared with the traditional HCl method showing a relative standard deviation of 5%. Precision of the proposed methodology between 5 samples analyzed by triplicate was 4.61%. The method is of low cost and has an easy procedure.