Analysis of Soil Organic Matter by Wet Combustion
Reagents
In 1 L volumetric flask
- 49.04 g Potassium Dichromate (K 2 Cr 2 O 7 )
Bring to volume with DI water.
- 36 N Sulfuric Acid (H 2 SO 4 )
Standard (H3)
In 1 L volumetric flask
- 9.5 g Sucrose
Bring to volume with DI water.
- Add 1, 2, 4, 6, and 8 ml of the 4 mg C ml -1 sucrose standard solution into five 250 ml Erlenmeyer flasks.
- Add 10 mL Potassium Dichromate, swirl.
- Add 20 mL Sulfuric Acid.
- Add 100, 99, 98, 96, 94, and 92 ml of H 2 O to the 0, 4, 8, 16, 24, and 32 mg C standards.
Standards: 0, 4, 8, 16, 24, and 32 mg C
Procedure
Add the following to 250 mL Erlenmeyer flask
- 1.0 g Soil (0.5 g if samples is dark)
- 10 mL Potassium Dichromate
Swirl. (Make sure soil is completely covered.)
- 20 mL Concentrated H 2 SO 4
Swirl & let sit for 10 minutes.
- 100 mL DI water
Centrifuge for 5 minutes at 2000 rpm.
Using a pipette, transfer supernatant 200 µl into each well in one column on a clear well plate.
Measure absorbance at 620 nm.
Created: 6/25/07