Extraction of low molecular weight components and their identification using 1H Nuclear Magnetic Resonance Spectroscopy (1H NMR).

Extraction of low molecular weight organic components: Five g of soil is placed into a 100 mL flask and extracted overnight with 50 mL of 0,5 M hydrochloric acid using an end-over-end shaker at 100 rpm and at 65°C. The resulting solution is filtered through nr. 42 Whatman filter paper and free-dried before analysis. Analysis: The 1HNMR spectra are obtained on 0,5 M sodium deuterate solution of lyophilized material (20-30 mg) with a Bruker ACF 250 spectrometer (Karlsruhe, Germany) at room temperature (22+-1°C) with a 5-mm multinuclear probe. The spectra are accumulated with 16 K data point, one pulse sequence, 40° pulse angle, 3 s relaxation delay and a sweep width of 2.5 kHz. To obtain a satisfactory signal to noise ratio 1000-2000 scans are needed. Gated irradiation is applied between acquisitions to presaturate the residual water peak. Chemical shifts are relative to 3-trymethylsilyl tetradeutero propionate (TSP).