电感耦合等离子体光谱法测定土壤中的全硫

硫元素在植物中属于重要的中量元素，是继氮、磷、钾后第4位主要营养成分，是所有植物生长发育不可缺少的元素之一。硫在植物生长发育及代谢过程中具有重要的生理功能。土壤中全硫能够反映出土壤硫的生态和环境效应，因此，对土壤中全硫的测定显得至关重要。以硝酸-双氧水为消解体系，对土壤样品进行消解，将土壤中不同形态的硫转化为可溶性无机硫，利用电感耦合等离子体发射光谱仪测定土壤中全硫含量。称取0.25 g土壤样品，加入10 mL硝酸、5 mL双氧水，在150℃电热板上消解样品，剩余体积为2 mL左右时取下，样品冷却至室温后定容至25 mL，用电感耦合等离子体光谱仪测定硫含量。实验结果表明，分析谱线为182.037 nm时具有灵敏度好、干扰少的优点，以硫含量为横坐标，强度为纵坐标建立线性回归曲线，其线性回归曲线为Y=0.001195C+0.037420，线性相关系数R2为0.9999。在优化的条件下，方法的检出限和定量限分别为7和23 mg/kg。为了验证方法精密度，选择不同含量级别的国家标准物质平行测定6次，结果显示，相对标准偏差为2.2%～6.8%；绝对偏差为2～171 mg/kg，

Determination of total sulfur in soil by inductively coupled plasma spectrometry

Sulfur is an important medium element in plants. It is the fourth major nutrient after nitrogen，phosphorus and potassium，and is one of the indispensable elements for the growth and development of all plants. Sulfur plays an important role in plant growth，development and metabolism. The total sulfur in soil can reflect the ecological and environmental effects of soil sulfur，so the detection of total sulfur in soil is very important. The soil sample was digested with nitric acid-hydrogen peroxide as the acid digestion system，different forms of sulfur in the soil was converted into soluble inorganic sulfur. The content of sulfur in soil was determined by inductively coupled plasma emission spectrometer. 0.25 g of soil sample was added to 10 mL of nitric acid and 5 mL of hydrogen peroxide，the sample was digested on a 150℃ electric heating plate，and was taken down at the remaining volume of about 2 mL. After the sample was cooled to room temperature，the volume was fixed to 25 mL，and determined the sulfur content by inductively coupled plasma spectrometer. The test results showed that when the spectral analysis line was 182.037 nm，it had the advantages of good sensitivity and less interference. A linear regression curve was established with the sulfur content of the sample as the abscissa and the strength as the ordinate. The linear regression curve was Y=0.001195C+0.037420，and the linear correlation coefficient R² was 0.9999. Under the optimized conditions， the detection limit and quantitative limit of the method were 7 and 23 mg/kg，respectively. In order to verify the precision of the method，the national standard materials of different content levels were selected for parallel determination for six times，and the results showed that the relative standard deviation was 2.2%-6.8%. The absolute deviation was 2-171 mg/kg， all test results met the recommended values of national standard materials.