INVESTIGATING THE IMPACTS OF SOLID PHASE EXTRACTION ON DISSOLVED ORGANIC MATTER OPTICAL SIGNATURES AND THE PAIRING WITH HIGH-RESOLUTION MASS SPECTROMENTRY DATA

Advancing our understanding of dissolved organic matter (DOM) in aquatic systems requires cross-platform integration of data streams. Recent studies have shown interest in pairing high resolution molecular data with optical data, an approach that would increase the information capacity of optical data with potential utility in sensor networks. However, solid phase extraction (SPE) pretreatments that accompany high resolution molecular analyses can bias the measured signals, leading to concerns over the ability to adequately derive linkages across platforms. We address this concern by assessing the impact of SPE on the pairing of high-resolution data with optical signatures for 47 samples collected from stream network of varying DOM sources. Pre- and post-SPE samples were characterized by excitation-emission fluorescence with parallel factor analysis (PARAFAC). PARAFAC models were then coupled with complimentary Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) data. A comparison of PARAFAC models revealed no systematic qualitative differences in the DOM composition, although quantitative biases were observed post-SPE due to a better recovery of “humic-like” signatures.  Despite the observed quantitative differences, the molecular fingerprint associated with pre- and post-SPE fluorescence components were consistent suggesting that broad-scale linkages could be inferred reliably across FTICR-MS and optical platforms. This work represents a key step forward in the evaluation of cross platform linkages for the characterization of DOM in freshwater systems.

Primary Presenter: Alan Roebuck, Pacific Northwest National Laboratory (alan.roebuck@pnnl.gov)

Authors:

Alan Roebuck, Pacific Northwest National Laboratory  (alan.roebuck@pnnl.gov)

Allison Myers-Pigg, Pacific Northwest National Laboratory  (allison.myers-pigg@pnnl.gov)

Vanessa Garayburu-Caruso, Pacific Northwest National Laboratory  (vanessa.garayburu-caruso@pnnl.gov)

James Stegen, Pacific Northwest National Laboratory  (james.stegen@pnnl.gov)