Asymmetric flow field flow fractionation with light scattering detection - an orthogonal sensitivity analysis

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Asymmetric flow field flow fractionation (AF⁴) is crucial for separating complex environmental samples.
• Instrumental factors can significantly influence AF⁴ separation performance and accuracy.

Purpose of the Study:

• To determine the relative importance of AF⁴ instrumental factors for complex environmental sample separation.
• To optimize AF⁴ settings for accurate molar mass (MM) determination of natural organic matter (NOM).

Main Methods:

• A 2^(5-1) orthogonal fractional factorial design was used to assess five instrumental factors (cross flow, ramp time, focus flow, injection volume, buffer concentration).
• A parallel 2^(5-2) design evaluated five environmental factors for silver nanoparticle (NP) samples.
• Sensitivity analysis ranked factor importance based on minimizing measured MM.

Main Results:

• Buffer concentration and cross flow were the most significant AF⁴ instrumental factors affecting NOM MM.
• Ramp time was the least important instrumental factor.
• Environmental factors (NP concentration, size, NOM concentration, specific conductance, pH) did not significantly impact NOM MM, but NP concentration and size interaction affected NOM recovery.

Conclusions:

• A structured approach using orthogonal fractional factorial design effectively assesses AF⁴ instrument factors for complex sample analysis.
• Optimized AF⁴ settings are essential for accurate separation and characterization of environmental samples, particularly NOM and nanoparticles.