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用c(NH4 F) =0 .0 15mol/L的NH4 F和c(HCl) =0 .3mol/L的HCl浸提土壤样品中有效磷 ,以钼锑抗分光光度法测定有效磷的含量。在c(H2 SO4 ) =0 .2～ 0 .3mol/L的H2 SO4 和Sb3 + 存在下 ,磷酸与钼酸铵反应形成磷锑钼杂多酸 ,该杂多酸在常温下被抗坏血酸还原为磷钼蓝络合物 ,它的最大吸收波长于 70 0nm处 ,磷量在 0 .0～ 140 0 μg/L范围内服从比尔定律 ,检出限为 0 .0 2 4μg/mL。
The available phosphorus in soil samples was extracted with c (NH4F) = 0.15mol / L NH4F and c (HCl) = 0.3mol / L HCl, and the content of available phosphorus was determined by molybdenum-antimony spectrophotometry. In the presence of c (H2 SO4) = 0.2-2.3 mol / L of H2 SO4 and Sb3 +, phosphoric acid reacts with ammonium molybdate to form phosphorous antimony molybdenum heteropoly acid, which is reduced to ascorbic acid at room temperature to Phosphorus molybdenum blue complex, its maximum absorption wavelength at 70 0nm, phosphorus content in the range of 0. 0 ~ 140 0 μg / L obeys Bill’s law, the detection limit of 0. 0 2 4μg / mL.