1 research outputs found
Optimized Demineralization Technique for the Measurement of Stable Isotope Ratios of Nonexchangeable H in Soil Organic Matter
To make use of the isotope ratio of nonexchangeable hydrogen
(δ<sup>2</sup>H<sub>n (nonexchangeable)</sub>) of bulk
soil organic matter (SOM), the mineral matrix (containing structural
water of clay minerals) must be separated from SOM and samples need
to be analyzed after H isotope equilibration. We present a novel technique
for demineralization of soil samples with HF and dilute HCl and recovery
of the SOM fraction solubilized in the HF demineralization solution
via solid-phase extraction. Compared with existing techniques, organic
C (C<sub>org</sub>) and organic N (N<sub>org</sub>) recovery of demineralized
SOM concentrates was significantly increased (C<sub>org</sub> recovery
using existing techniques vs new demineralization method: 58% vs 78%;
N<sub>org</sub> recovery: 60% vs 78%). Chemicals used for the demineralization
treatment did not affect δ<sup>2</sup>H<sub>n</sub> values as
revealed by spiking with deuterated water. The new demineralization
method minimized organic matter losses and thus artificial H isotope
fractionation, opening up the opportunity to use δ<sup>2</sup>H<sub>n</sub> analyses of SOM as a new tool in paleoclimatology or
geospatial forensics