Benefits of citrate over EDTA for extracting phenolic acids from soils and plant debris

The effectiveness of various citrate extractions to recover ferulic acid, a phenolic acid, from Cecil A(p) and B-t soil and plant surface debris (crimson clover, rye, subterranean clover, and wheat) was compared with that of EDTA extractions. Citrate extractions were equivalent to or better than EDTA in recovering phenolic acids from soil and plant debris. Citrate, unlike EDTA, did not interfere with the Folin & Ciocalteu's phenol reagent when determining total phenolic acid content in soil and plant debris extracts. Care, however, must be taken when using Folin & Ciocalteu's phenol reagent to estimate total phenolic acid content, particularly in the presence of soil organic matter. Citrate was also more effective in extracting phenolic acids from A-horizon soils. Thus, citrate extractions overcome some of the major limitations observed for EDTA extractions.