Colloid characterization by sedimentation field-flow fractionation:  correction for particle-wall interaction.

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Sedimentation field-flow fractionation (FFF) is a powerful technique for separating and characterizing particles.
• Particle-wall interactions can influence retention times and affect the accuracy of particle size determination in FFF.
• A quantitative method to account for these interactions is needed for improved FFF performance.

Purpose of the Study:

• To introduce and validate a semiempirical parameter, δ(w), for describing particle-wall interaction effects in sedimentation FFF.
• To present a practical experimental method for determining the δ(w) parameter.
• To enable more accurate particle diameter measurements by incorporating δ(w) into FFF data analysis.

Main Methods:

• Experimental determination of retention ratios for particle standards across a range of field strengths.
• Analysis of retention data to extract the δ(w) parameter from a linear plot.
• Validation of δ(w) as a system-independent constant under specific conditions.

Main Results:

• The particle-wall interaction parameter, δ(w), with units of length, effectively describes retention behavior in sedimentation FFF.
• A straightforward method for experimentally determining δ(w) from retention data is demonstrated.
• The parameter δ(w) was found to be independent of field strength.

Conclusions:

• The δ(w) parameter provides a robust means to correct for particle-wall interactions in sedimentation FFF.
• Accurate particle size determination is achievable by incorporating δ(w) into retention time calculations.
• δ(w) has the potential to serve as a universal constant for specific FFF instrument configurations, enhancing inter-instrument comparability.