Determination of Avaiable Phosphorus in Calcareous Soil by Inductively Coupled Plasma Emission Spectrometry with Ultrasonic Extraction

The inductively coupled plasma emission spectrometry (ICP-AES) with ultrasonic extraction method was used to achieve the fast, accurate and massive analysis of available phosphorus in calcareous soil. The mixture was extracted at 25 ℃ for 10 min at ultrasonic power of 400 W, and 3.50 g styrene cation exchange resin was used to reduce matrix interference. The available phosphorus was determined by ICP-AES at the analyzed spectral line of P 214.914 nm, radio frequency power of 1 150 W and carrier gas flow rate of 0.6 L/min. The results showed that the calibration curve was linear (correlation coefficient of 0.999 6) when the concentration of phosphorus was 0~5.00 mg/L, and the limit of detection was 0.072 mg/kg. The method was used to analyze the available state stardand materials in 4 different alkaline soils, the relative error were less than ±7%, the relative standard deviation were less than 10%, and it were close to the measured values of standard method (NY/T 1121.7—2014).