A comparison of extraction methods of phenolic acids in wheat and American ginseng soil

We compared and evaluated different solvents [water, dichloromethane, 1 M and 2M sodium hydroxide solution (NaOH)] to extract the phenolic acids in wheat (Triticumaestivum L.) and American ginseng (Panax quinquefolium L.) cultivated soil. All samplesolutions, with or without concentrating, were tested with HPLC. Nine individual phenolicacids (p-hydroxybenzoic acid, vanillic acid, syringic acid, vanillin, p-coumaric acid, ferulicacid, benzoic acid, salicylic acid and cinnamic acid) were detected in 1 M and 2 M NaOHextracts with concentrating, while only 5-phenolic acids (p-hydroxybenzoic acid, vanillicacid, vanillin, p-coumaric acid and ferulic acid) were detected without concentrating.However, the contents of p-hydroxybenzoic acid, vanillin and p-coumaric acid detected afterconcentrating were significantly less. Only 5-individual phenolic acids in American ginsengsoil (p-hydroxybenzoic acid, vanillic acid, syringic acid, vanillin and p-coumaric acid) and 4-in wheat soil (p-hydroxybenzoic acid, vanillic acid, syringic acid and vanillin) were detectedin water extracts and none in dichloromethane extracts. The results indicated that NaOH andwater recovered different phenolic acids from soil and concentrating might cause loss ofcertain phenolic acids. Besides, concentrating may make more individual phenolic acidsdetectable in NaOH extract