US EPA

2077455 

Journal Article 

Assessment of the folin and Ciocalteu's method for determining soil phenolic carbon 

Ohno, T; First, PR 

1998 

Yes 

Journal of Environmental Quality
ISSN: 0047-2425
EISSN: 1537-2537 

BIOSIS/98/25711 

27 

4 

776-782 

English 

BIOSIS COPYRIGHT: BIOL ABS. Previous studies have shown that phenolic compounds are potentially allelopathic and present at low concentrations in soil solution. This study was conducted to evaluate the Folin and Ciocalteu's method for determining concentrations of phenolic C in aqueous and citrate extracts of soils containing 7.1 to 57.9 g kg-1 organic C. Soils were reacted for 1-8 h with a 0.3 mM phenolic acid mixture or DI-H20 to serve as a control. Folin and Ciocalteu's reactive-phenolic C content in the DI-H2O control extracts suggested positive interference from dissolved organic matter rather than free phenolic compounds desorbed from the native soils. The absorptivity of the Folin and Ciocalteu's reduced complex was 1128 | 25 L mol-1 cm-1 for the phenolic acid mixture and 45 | 8 L mol-1 cm-1 for soluble organic matter ligands. Although the method has much higher sensitivity to phenolic acids than to organic matter, the higher concentration of organic matter results in substantial backgroun