论文部分内容阅读
应用磷酸分解碳酸盐型样品以制取CO_2供质谱测定碳—氧同位素组成的方法中,规定所使用的磷酸必须是100％的正磷酸,如果有水存在就会使分析结果产生偏差。那么在磷酸中存在水,影响情况如何呢?对此我们做了如下试验: 将一个方解石样品磨细混匀,称取六等份样品分别在真空反应管中与100％的磷酸按方法要求在相同条件下反应完全,然后在真空系统中用液氮冷冻把CO_2分别转移到预先准备好的另外五支反应管中:1号空反应管,2号加有100％磷酸5毫升,3号加市售浓磷酸(含H_3PO_4≥85％)5毫升,4号加稀磷酸(H_3PO_4:H_2O=1:2)5毫升,5号加纯蒸馏水5毫升。然后将这5支反应管放入50℃水浴中恒温4小时后让其自冷20小时,再
The use of phosphoric acid to decompose carbonate-based samples to produce CO 2 for mass spectrometry for the determination of carbon-oxygen isotopic composition requires that the phosphoric acid used must be 100% orthophosphoric acid and that the analytical results will be biased in the presence of water. So in the presence of water in phosphoric acid, what is the effect? For this we have done the following test: A calcite sample is finely mixed, weighed six aliquots were vacuum reaction tube and 100% phosphoric acid according to the method requirements Under the same conditions, the reaction was complete, and then CO 2 was separately transferred to the other five reaction tubes prepared in advance by liquid nitrogen freezing in a vacuum system: an empty reaction tube No. 1, No. 2 plus 100 ml of phosphoric acid 5 ml, No. 3 plus Commercially available concentrated phosphoric acid (containing H_3PO_4 ≥ 85%) 5 ml, 4 plus dilute phosphoric acid (H_3PO_4: H_2O = 1: 2) 5 ml, 5 plus 5 ml of distilled water. Then the five reaction tubes into a water bath at 50 ℃ for 4 hours and then allowed to cool 20 hours, and then