Humic substances, including humin fraction, play a key role in the fate of organic and inorganic xenobiotics contaminating the environment. Humin is an important fraction of humic substances, which has been the least studied to date. This is due to the difficulties connected with its isolation that pose a number of methodological problems. Methods of humin fraction isolation can be divided into following main groups: (1) digestion of mineral soil components with HF/HCl followed by alkali extraction of HA and FA; (2) alkali extraction of HA and FA followed by extraction of humin by different organic solvents; and (3) alkali extraction of HA and FA followed by HF/HCl digestion of mineral soil components. Nevertheless, each of these methods has different limitations. We described in detail a useful procedure of humin isolation, in which this fraction was not extracted, but isolated from the soil by removing its soluble organic and mineral components. A modified method of HA and FA extraction with 0.1 M NaOH, according to the International Humic Substances Society, was used in the first step. Then, the mineral components in the residue were digested with the 10% HF/HCl. Unlike the procedures oriented to increase the concentration of organic matter, samples were treated several times with the HF/HCl mixture until the mineral fraction was almost completely digested. The main assumption of the method modification was to obtain the highest yield with the lowest possible ash content, but without affecting humin chemical structure. The results showed that the proposed procedure is characterized by a high efficiency and recovery and, therefore, it can be used to isolate high amounts of humin from soil.

腐殖质，包括腐殖质部分，在污染环境的有机和无机外源生物的命运中起着关键作用。腐殖质是腐殖质的重要组成部分，迄今为止研究最少。这是由于与它的隔离相关的困难造成了许多方法问题。腐殖质部分分离的方法主要分为以下几类： (1) 用 HF/HCl 消化矿质土壤组分，然后碱提取 HA 和 FA；(2) 碱提HA和FA，然后用不同的有机溶剂提取腐殖质；(3) 碱提HA和FA，然后用HF/HCl消化矿质土壤成分。然而，这些方法中的每一种都有不同的局限性。我们详细描述了一种有用的腐殖质分离程序，其中该部分没有被提取，而是通过去除其可溶性有机和矿物质成分从土壤中分离出来。根据国际腐殖物质协会的规定，第一步使用改进的 HA 和 FA 提取方法，使用 0.1 M NaOH。然后，用 10% HF/HCl 消化残渣中的矿物质成分。与旨在增加有机物浓度的程序不同，样品用 HF/HCl 混合物处理数次，直到矿物部分几乎完全消化。方法修改的主要假设是在不影响胡敏化学结构的情况下，以尽可能低的灰分获得最高产量。结果表明，所提出的程序具有高效率和回收率的特点，因此，