Several areas around the world rely on seawater desalination to meet drinking water needs, but a detailed analysis of dissolved organic matter (DOM) changes and disinfection by-product (DBP) formation due to chlorination during the desalination processes has yet to be evaluated. To that end, DOM composition was analyzed in samples collected from a desalination plant using bulk measurements ( e.g. dissolved organic carbon, total dissolved nitrogen, total organic bromine), absorbance and fluorescence spectroscopy, and ultrahigh resolution mass spectrometry (HRMS). Water samples collected after chlorination ( e.g. post pretreatment (PT), reverse osmosis (RO) reject (brine wastewater) (BW), RO permeate (ROP), and drinking water (DW)), revealed that chlorination resulted in decreases in absorbance and increases in fluorescence apparent quantum yield spectra. All parameters measured were low or below detection in ROP and in DW. However, total solid phase extractable (Bond Elut Priority PolLutant (PPL) cartridges) organic bromine concentrations increased significantly in PT and BW samples and HRMS analysis revealed 392 molecular ions containing carbon, hydrogen, oxygen, bromine (CHOBr) and 107 molecular ions containing CHOBr + sulfur (CHOSBr) in BW PPL extracts. A network analysis between supposed DBP precursors suggested that the formation of CHOBr formulas could be explained largely by electrophilic substitution reactions, but also HOBr addition reactions. The reactions of sulfur containing compounds are more complex, and CHOSBr could possibly be due to the bromination of surfactant degradation products like sulfophenyl carboxylic acids (SPC) or even hydroxylated SPCs. Despite the identification of hundreds of DBPs, BW did not show any acute or chronic toxicity to mysid shrimp. High resolution MS/MS analysis was used to propose structures for highly abundant bromine-containing molecular formulas but given the complexity of DOM and DBPs found in this study, future work analyzing desalination samples during different times of year ( e.g. during algal blooms) and during different treatments is warranted.
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Lignin phenol quantification from machine learning‐assisted decomposition of liquid chromatography‐absorbance spectroscopy data
Analysis of lignin in seawater is essential to understanding the fate of terrestrial dissolved organic matter (DOM) in the ocean and its role in the carbon cycle. Lignin is typically quantified by gas or liquid chromatography, coupled with mass spectrometry (GC‐MS or LC‐MS). MS instrumentation can be relatively expensive to purchase and maintain. Here we present an improved approach for quantification of lignin phenols using LC and absorbance detection. The approach applies a modified version of parallel factor analysis (PARAFAC2) to 2ndderivative absorbance chromatograms. It is capable of isolating individual elution profiles of analytes despite co‐elution and overall improves sensitivity and specificity, compared to manual integration methods. For most lignin phenols, detection limits below 5 nmol L−1were achieved, which is comparable to MS detection. The reproducibility across all laboratory stages for our reference material showed a relative standard deviation between 1.47% and 16.84% for all 11 lignin phenols. Changing the amount of DOM in the reaction vessel for the oxidation (dissolved organic carbon between 22 and 367 mmol L−1), did not significantly affect the final lignin phenol composition. The new method was applied to seawater samples from the Kattegat and Davis Strait. The total concentration of dissolved lignin phenols measured in the two areas was between 4.3–10.1 and 2.1–3.2 nmol L−1, respectively, which is within the range found by other studies. Comparison with a different oxidation approach and detection method (GC‐MS) gave similar results and underline the potential of LC and absorbance detection for analysis of dissolved lignin with our proposed method.
more » « less- NSF-PAR ID:
- 10424047
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Limnology and Oceanography: Methods
- Volume:
- 21
- Issue:
- 8
- ISSN:
- 1541-5856
- Page Range / eLocation ID:
- p. 508-528
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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