Methods in Determining Soluble Soil Phenolic Content

By Jared L. DeForest

Standard

In 1000 ml volumetric flask

• 50.0 mg Syringic acid
• Bring to volume.
• Mix concentrations: 100%, 75%, 50%, 25%, 10%, and 0%

Soluble Soil Phenolic Extraction

In a 50 ml centrifuge tube

• 5 g Soil sample
• 25 ml Distilled Water

Agitate on an orbital-action shaker for 18 h.

Centrifuge 15 m @ 900 rpm.

Filter with 0.45 µm nylon filters.

Folin-Ciocalteu Method

In a 15 ml test tube

• 5.0 ml Sample
• 0.75 ml Na₂CO₃ (1.9 M; 201.38 g L^-1)
• 0.25 ml Folin-Ciocalteu reagent

After 1 h @ 25°C in the dark, record the absorbance at 750 nm.

Created 7/20/2007