Selective Solid Phase Extraction Using a Mixed-Mode Cation Exchange Cartridge Facilitates the Mass Spectrometry...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Biogeochemistry

Background:

• Dissolved organic nitrogen (DON) is a major nitrogen reservoir, vital for environmental nitrogen cycling and pollutant transport.
• Low environmental concentrations of DON pose challenges for detection and characterization.
• A standardized, efficient method for DON extraction from complex samples is lacking.

Purpose of the Study:

• To develop and validate an efficient solid-phase extraction (SPE) protocol for dissolved organic nitrogen (DON).
• To compare the effectiveness of different SPE cartridges for DON extraction and analysis.
• To facilitate a comprehensive understanding of DON's chemical composition and environmental impact.

Main Methods:

• Solid-phase extraction (SPE) using Bond Elut PPL, Waters HLB, and Waters MCX cartridges.
• One-step and three-step elution strategies were employed for DON extraction.
• Analysis of extracted DON using UV-Vis, fluorescence, mass spectrometry (MS), and GC-NCD.

Main Results:

• The stepwise elution with the MCX cartridge demonstrated superior DON recovery in both standard and environmental samples.
• The MCX method showed reduced interference from surfactants during MS analysis.
• MCX-extracted fractions revealed a higher number of DON molecular formulas with low O/C and high H/C ratios, including nitrosamine-type substances.

Conclusions:

• An efficient MCX-SPE protocol for DON extraction and analysis from environmental samples has been established.
• This method provides a reliable approach for studying DON's chemical composition.
• The findings support a deeper understanding of nitrogen-containing substances in the environment.