Determination of cation exchange capacity and exchangeable cations in soils by means of cobalt hexamine trichloride. Effects of experimental conditions
Determination of cation exchange capacity and exchangeable cations in soils by means of cobalt hexamine trichloride. Effects of experimental conditions
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DOI：
10.1051/agro:19970101
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发表时间：
1997-01-01
期刊：
影响因子：
--
通讯作者：
Sterckeman, T
中科院分区：
文献类型：
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作者：
Ciesielski, H;Sterckeman, T
本文比较了用六氨合钴[Co（NH3）（6）]Cl-3溶液测定土壤样品阳离子交换容量（CEC）和交换性阳离子数量的不同方法。首先，检查用于测量与土壤交换反应后留在溶液中的Cohex离子的残留浓度的各种技术。钴的测定采用火焰原子吸收光谱法，氨氮的测定采用分光光度法。然而，在425 nm处直接分光光度法测定有色Cohex离子被证明是更容易进行的，具有良好的重复性，只要事先适当地校正非特异性洗脱。该方法被保留以比较三种离子交换程序：单次萃取、连续萃取和渗滤。后一项研究使我们能够选择一个特定的程序，了解其局限性，优点和缺点。尽管反应产率略低，但用单次提取获得的结果仍然非常适合量化交换反应的大小。
Different ways of using solutions of cobalt-hexamine (Cohex) trichloride, [Co(NH3)(6)]Cl-3, to determine the cation exchange capacity (CEC) and the quantity of exchangeable cations in soil samples are compared. First, various techniques for measuring the residual concentration of Cohex ions left in solution after the exchange reaction with soil are examined. Cobalt can be determined by flame atomic absorption spectrometry and ammonium nitrogen by spectrocolorimetry. However, a direct spectrocolorimetric determination of the coloured Cohex ions at 425 nm proves to be easier to carry out with a good repeatability, provided that non-specific absorptions have been properly corrected in advance, That method was retained to compare three procedures of ion exchange: single extraction, successive extractions and percolation. The latter study allows us to chose a particular procedure with a knowledge of its limitations, advantages and disadvantages. In spite of a slightly lower reaction yield, results obtained with a single extraction remain quite appropriate to quantify the magnitude of the exchange reactions.