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

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Organic Geochemistry

Background:

• Dissolved organic matter (DOM) isolation is crucial for water quality analysis.
• Solid phase extraction (SPE) with styrene-divinylbenzene copolymer (PPL) sorbent is a common DOM isolation technique.
• Existing SPE protocols require optimization for consistent DOM recovery and representative molecular composition.

Purpose of the Study:

• To propose improved guidelines for DOM isolation using PPL-SPE.
• To systematically investigate the impact of critical SPE variables on PPL sorbent selectivity.
• To enhance the reproducibility and accuracy of DOM analysis from natural waters.

Main Methods:

• Solid phase extraction (SPE) using a PPL sorbent.
• Systematic variation of loading mass, concentration, and flow rate.
• High-field Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) and proton nuclear magnetic resonance ((1)H NMR) spectroscopy for chemical analysis.
• Up-scaling of the SPE method.

Main Results:

• Optimized DOC/PPL mass ratio (1:800) achieved 89% DOC recovery at 20 mg/L concentration.
• Larger loading volumes resulted in lower retention of highly oxygenated compounds.
• Flow rate had minimal effect on extraction selectivity; up-scaling showed limited impact, except for increased methyl ester formation with methanol.
• SPE/PPL extracts closely matched original water and reverse osmosis sample characteristics.

Conclusions:

• The study provides refined SPE/PPL guidelines for reproducible DOM isolation.
• Optimized methods yield DOM extracts with representative molecular compositions.
• Findings minimize interlaboratory variability in DOM analysis across diverse water sources and concentrations.