Rapid solid phase extraction of dissolved organic matter

Abstract

Dissolved organic matter (DOM) is a complex mixture of molecules found ubiquitously in freshwater and saltwater environments. Its structures contain valuable information content on the sources of molecules as well as the mechanisms at work within an aquatic ecosystem. Recent advancements in high resolution mass spectrometry and liquid chromatography have made inroads into determinations of the molecular structures within DOM. Such analyses, however, generally require a prior step to concentrate/isolate DOM, and this step often limits the number of samples that can be analyzed. This study has developed a fast method to concentrate DOM on commercially available online solid phase extraction (SPE) cartridges, which can be directly eluted onto an HPLC‐MS system. This rapid solid phase extraction (RSPE) method requires less sample (10‐100 mL) than previous SPE methods for DOM isolation. Additionally, this study tested a suite of SPE phases to find a combination that improves DOM recovery as compared with commonly used approaches. When a polystyrene divinylbenzene phase (RP‐1) was coupled with an activated carbon (CAR) phase, recoveries were found to be significantly higher than in previous SPE studies relying upon single phases. RSPE was tested for a diverse set of salty and freshwater samples with recoveries ranging from 46% to 78% of the total DOC. It was also tested on a suite of model compounds (including caffeine) and should be applicable to anthropogenic compounds in aquatic environments, although, in such cases, optimization may be needed to minimize the natural organic matter signal that was maximized in this study.

Differential effects of solid‐phase extraction resins on the measurement of dissolved lignin‐phenols and organic matter composition in natural waters

“…All cartridges revealed comparable DOC extraction efficiency on the level of 56–60% for the river‐end‐member, which is in line with reported data (Roth et al ; Perminova et al ; Swenson et al ; Raeke et al ). There was not a significant difference ( p > 0.05) among the cartridges.…”

Concentration‐discharge relationships during an extreme event: Contrasting behavior of solutes and changes to chemical quality of dissolved organic material in the Boulder Creek Watershed during the September 2013 flood

“…[] demonstrated that a solid‐phase extraction protocol using modified styrene divinyl benzene polymer (PPL) type sorbents can recover a large fraction, about 65% in freshwaters, of both polar and nonpolar constituents of the total DOM pool. A PPL‐based sorbent was chosen based on its high recovery [ Simjouw et al ., ; Minor et al ., ; Swenson et al, ] and retention of N‐containing organic compounds. The PPL method preferentially sorbs more aromatic proteins and lignin‐like compounds, further necessitating the use of ancillary DOM isolate methods such as size separation (TFUF) and liquid chromatography (XAD) to identify any bias towards changes in these components [ Benner et al ., ].…”

Proposed Guidelines for Solid Phase Extraction of Suwannee River Dissolved Organic Matter

“…However, in natural environments, the concentration of DOM varied greatly, typically ranging from 5 to 20 mg/L in freshwater, with the exception of Suwannee River water (∼84 mg/L at the time of sampling) and other peatdraining waters at ∼80 mg/L. 27,38,39 Based on our results, dilution is suggested in the case of highly concentrated DOM such as sewage, and the use of larger volumes of freshwater is recommended at low DOC content within the capacity of the cartridge for meaningful SPE-based isolation of DOC. Samples with high contents of suspended solids and high ionic strength require centrifugation after filtration and dilution, respectively.…”