Optimizing size-exclusion chromatographic conditions using a composite objective function and chemometric tools:...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Chromatography

Background:

• Characterizing natural organic matter (NOM) is crucial for understanding environmental processes.
• Size-exclusion chromatography (SEC) is a key technique for assessing NOM molecular size distribution.
• Developing robust and accurate SEC methods for complex NOM samples remains a challenge.

Purpose of the Study:

• To propose a novel strategy for developing size-exclusion chromatography (SEC) methods for natural organic matter (NOM) analysis.
• To utilize a chromatographic response function (CRF) and response surface methodology for method optimization.
• To accurately determine the molecular size distribution of NOM from various environmental sources.

Main Methods:

• A central composite experimental design was employed to create a chromatographic response surface.
• Predictive polynomial and linear models were developed based on SEC studies with known organic compounds.
• The effects of mobile phase parameters (pH, organic solvent, salt concentration) on CRF were investigated.

Main Results:

• The study identified optimal mobile phase conditions for NOM analysis: pH 8.5, 11% acetonitrile, and 15 mM sodium chloride.
• A single linear effect of salt concentration on chromatographic separation quality was predicted and validated.
• Measured molecular size distributions for water-soluble organic matter and fulvic acids aligned well with published data.

Conclusions:

• The developed strategy provides a reliable and accurate method for describing size-exclusion profiles of NOM.
• This approach enhances the characterization of NOM from diverse environmental matrices.
• The CRF-based optimization strategy offers a systematic way to improve SEC method performance for NOM.