Analysis of aquatic-phase natural organic matter by optimized LDI-MS method.
The composition and physiochemical properties of aquatic-phase natural organic matter (NOM) are most important problems for both environmental studies and water industry. Laser desorption/ionization (LDI) mass spectrometry facilitated successful examinations of NOM, as humic and fulvic acids in NOM are readily ionized by the nitrogen laser. In this study, hydrophobic NOMs (HPO NOMs) from river, reservoir and waste water were characterized by this technique. The effect of analytical variables like concentration, solvent composition and laser energy was investigated. The exact masses of small molecular NOM moieties in the range of 200-1200 m/z were determined in reflectron mode. In addition, spectra of post-source-decay experiments in this range showed that some compounds from different natural NOMs had the same fragmental ions. In the large mass range of 1200-15,000 Da, macromolecules and their aggregates were found in HPO NOMs from natural waters. Highly humic HPO exhibited mass peaks larger than 8000 Da. On the other hand, the waste water and reservoir water mainly had relatively smaller molecules of about 2000 Da. The LDI-MS measurements indicated that highly humic river waters were able to form large aggregates and membrane foulants, while the HPO NOMs from waste water and reservoir water were unlikely to form large aggregates.
College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China; Water Desalination and Reuse Center (WDRC), 4700 King Abdullah University of Science and Technology, Kingdom of Saudi Arabia.
Ren-Qi
RQ
Wang
Katharina
K
Druckenmüller
Gereon
G
Elbers
Klaus
K
Guenther
Jean-Philippe
JP
Croué
D001578:Benzopyrans / Q000032:analysis* / Q000737:chemistry; D004784:Environmental Monitoring; D006812:Humic Substances / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods*; D045483:Rivers / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*
D001578:Benzopyrans; D006812:Humic Substances; D062065:Wastewater; C005023:fulvic acid
humic substances; hydrophobic acid; laser desorption/ionization mass spectrometry; natural organic matter; post-source-decay