Determination of Available Silicon in Soil by Inductively Coupled Plasma Atomic Emission Spectrometry with Ultrasonic Extraction

The study mentioned by the title was conducted for problems including long soaking extraction time and susceptibility of detection results to chromogenic time, chromogenic temperature, and soil acidity by silicon molybdenum spectrophotometry in standard methods of LY/T 1266-1999 or NY/T 1121.15-2006 to detect the available silicon in soil. The 5.00 g of sample and 50.00 mL of 0.025 mol·L^-1 citric acid solution were added into a plastic bottle. After capping the bottle and vortexing, the above mixture was extracted at 30℃ for 2.0 h under 300 W ultrasound power. The extract was filtered with qualitative filter paper, and the filtrate was introduced into the inductively coupled plasma atomic emission spectrometer. The available silicon in soil was determined at the conditions of radio frequency power of 1 150 W, atomizing gas flow of 0.55 L·min^-1, and analytical spectral line of 251.611 nm. As found by the results, linear relationship between values of the mass concentration and response intensity of silicon was kept within 100.0 mg·L^-1, and detection limit (3s) was 0.012 mg·kg^-1. The proposed method was used for the analysis of 19 soil reference materials with different acidity, giving determined values within the uncertainty ranges of the certified values, and RSDs (n=12) of the determined values less than 10%. There was no significant difference between the proposed method and silicon molybdenum spectrophotometry given by the above standard methods, indicating the proposed method was suitable for accurate and rapid determination of available silicon in large batches of soil with different acidity.