Asymmetric flow field flow fractionation with light scattering detection - an orthogonal sensitivity analysis.
Asymmetric flow field flow fractionation (AF4) has several instrumental factors that may have a direct effect on separation performance. A sensitivity analysis was applied to ascertain the relative importance of AF4primary instrument factor settings for the separation of a complex environmental sample. The analysis evaluated the impact of instrumental factors namely, cross flow, ramp time, focus flow, injection volume, and run buffer concentration on the multi-angle light scattering measurement of natural organic matter (NOM) molar mass (MM). A 2(5-1)orthogonal fractional factorial design was used to minimize analysis time while preserving the accuracy and robustness in the determination of the main effects and interactions between any two instrumental factors. By assuming that separations resulting in smaller MM measurements would be more accurate, the analysis produced a ranked list of effects estimates for factors and interactions of factors based on their relative importance in minimizing the MM. The most important and statistically significant AF4instrumental factors were buffer concentration and cross flow. The least important was ramp time. A parallel 2(5-2)orthogonal fractional factorial design was also employed on five environmental factors for synthetic natural water samples containing silver nanoparticles (NPs), namely: NP concentration, NP size, NOM concentration, specific conductance, and pH. None of the water quality characteristic effects or interactions were found to be significant in minimizing the measured MM; however, the interaction between NP concentration and NP size was an important effect when considering NOM recovery. This work presents a structured approach for the rigorous assessment of AF4instrument factors and optimal settings for the separation of complex samples utilizing efficient orthogonal factional factorial design and appropriate graphical analysis.
Gillings School of Global Public Health, Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC 27599, USA. Electronic address: galyean@mines.edu.
Anne A
AA
Galyean
Statistical Engineering Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA. Electronic address: james.filliben@nist.gov.
James J
JJ
Filliben
Materials Measurement Science Division (Present: Nano Research Group), National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA. Electronic address: dave.holbrook@nist.gov.
R David
RD
Holbrook
Biomolecular Measurement Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA. Electronic address: wyatt.vreeland@nist.gov.
Wyatt N
WN
Vreeland
Gillings School of Global Public Health, Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC 27599, USA. Electronic address: howard_weinberg@unc.edu.
Howard S
HS
Weinberg
D002623:Chemistry Techniques, Analytical / Q000379:methods*; D031521:Fractionation, Field Flow; D008027:Light; D053758:Nanoparticles / Q000032:analysis*; D010316:Particle Size; D012542:Scattering, Radiation; D012834:Silver / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis
D014874:Water Pollutants, Chemical; D012834:Silver
Asymmetric flow field-flow fractionation; Light scattering; Nanoparticles; Natural organic matter; Separation optimization