Water Extractable Organic Matter (WEOM)

Weigh out 6g of air-dried soil in triplicate into a labeled 50mL falcon tube

Add 30mLof Ultrapure DI (maintaining a 2g to 10mL ratio) using large pipette

Place samples onto orbital shaker for 2rpm

Once completed centrifuge samples at 6000rpm

If samples are still cloudy, centrifuge a second time

Transfer the supernatant to two centrifuge tubes and do not discard the soil pellet

5mL in a 15mL centrifuge tube for FT-ICR-MS

~20mLin a 50mL centrifuge tube for TOC/TN and LC-MS

Acidify the FT-ICR-MS subsample using2µL of concentrated phosphoric acid (37%)

Freeze the TOC/TN and LC-MS sample on the side at -20°C until filtration

Freeze FT-ICR-MS samples on their side in the -80°C until SPE 

SPE Protocol:Gilson Automated SPE Protocol

Thaw ~20mLsample prior to filtering

Using a new clean syringe for each sample, pull up 50mL up Ultrapure DI water

Attach a new 0.45 um filter to the syringe and press the water through the filter to rinse the filter.

Remove the filter without touching the tip and pull up the ~20mLof thawed sample

Re attach the rinsed filter and discard the first 1 - 2mLof sample filtered

Filter the sample into two falcon tubes, two 15mL tube labeled for TOC and LC-MS respectively.

Filter 10mL of solution into the LC-MS tube and all remaining sample into the TOC/TN tube.

If the filter becomes difficult to press sample through, rinse a new filter using a clean (DI ONLY syringe using steps 3 and 4) and attach the rinsed filter to the syringe with sample. Discard the first 1 - 2mL and continue filtering into the respective tubes.

Store filtered samples in the freezer prior to analyses.