THE DIFFERENT FORMS IN WHICH p-HYDROXYBENZOIC, VANILLIC, AND FERULIC ACIDS EXIST IN A PEAT SOIL

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Abstract
The extraction of 3 different forms, A, B and C, in which p-hydroxybenzoic, vanillic and ferulic acids exist in peat soil were studied. Form A is designated a free form and was isolated with hot ethyl acetate by repeated reflux; form B is a combined form, which was extractable with hot ethyl acetate; and form C is another combined form, which was unextractable with hot ethyl acetate, but was isolated with hot 2 M NaOH by repeated extraction, and apparently is bound to the soil matrix and does not move easily in the soil environment. The amounts of the 3 different forms of the 3 phenolic acids in peat soil was determined by GLC, and their distributions were studied. For p-hydroxybenzoic acid, forms A, B and C were 11, 69 and 980 .mu.g/g soil, respectively; those with vanillic acid were 85, 130 and 860 .mu.g/g soil, respectively; and those with ferulic acid were 53, 450 and 2700 .mu.g/g soil, respectively. The total amounts of the 3 forms for p-hydroxybenzoic, vanillic and ferulic acids were 1200, 1100 and 3200 .mu.g/g soil, respectively. The largest amount of forms A, B and C was for p-hydroxybenzoic, ferulic and ferulic acids, respectively. Form A, which is important for allelopathic studies, was 2% (for ferulic acid) to 10% (for p-hydroxybenzoic acid) in distribution, and form C was > 80%.