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碱熔溶被视为测定土壤全磷的经典方法,但因分析手续繁琐而又费时,因此目前大都采用HClO_4消化测定,可是由于HClO_4造价昂贵、成本较高,又有易燃爆炸之危险,为此我们试用K_2S_2O_7、H_2SO_4和HNO_3混合消煑土壤,测定其全磷。经过多次试验研究,说明采用本法来测定土壤全磷不但结果准确,操作容易,速度较快,而且可以促使SiO_2充分脱水,避免铁还原性物质之干扰,同时药品易购,成本较低。 分析步骤:称取土样0.5克,K_2S_2O_71克左右置于150毫升凯庆烧瓶中。加入浓H_2SO_4 2毫升和浓HNO_33毫升。将凯氏烧瓶移置消化炉上,开始寸文火消化煑沸10分钟左右,视土色变白或淡灰色为度。待消化液稍冷,加15毫升蒸馏水消煑5分钟取出,连同沉淀物一并移入100毫升量瓶中定容后过滤,吸取
Alkali melting is regarded as the classical method for the determination of total phosphorus in soil. However, due to the cumbersome and time-consuming analysis procedures, HClO_4 digestion method is mostly used at present. However, due to the high cost and high cost of HClO_4 and the danger of flammable explosion, We tried K_2S_2O_7, H_2SO_4 and HNO_3 mixed eliminate soil, measured total phosphorus. After many experiments, it shows that the determination of total phosphorus in soil by this method is not only accurate, easy to operate and fast, but also can promote the dehydration of SiO 2 and avoid the interference of iron reducing substances. Analysis steps: Weigh 0.5 grams of soil samples, K_2S_2O_71 grams or so placed in 150 ml Kaiqing flask. Add concentrated H 2 SO 4 2 mL and concentrated HNO_ 33 mL. Kjeldahl flask will be relocated digestion furnace, began to Wen-diu boil boiling about 10 minutes, depending on soil color white or light gray for the degree. To be digestized slightly cold, add 15 ml of distilled water removed for 5 minutes removed, together with the precipitate into the 100 ml volumetric flask, filtered and pipetted