Extraction of HS

The isolation of HS is a difficult problem that has challenged researchers for many years. The ideal extraction method should meet the following objectives (Stevenson 1994)  

The extracted HS are free of inorganic contaminants, such as clay and polyvalent cations. 

Extraction is complete, thereby ensuring the representation of fractions from the entire molecular-weight range. 

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The main results of the quantitative extraction of HS and of geochemical analyses of extracted organic fractions are ... 

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