Hollow-fiber flow/hyperlayer field-flow fractionation for the size characterization of airborne particle fractions obtained by SPLITT fractionation

Abstract

Hollow-fiber flow field-flow fractionation (HF FlFFF) was applied for the separation and size characterization of airborne particles which were collected in a municipal area and prefractionated into four different-diameter intervals >5.0, 2.5-5.0, 1.5-2.5, <1.5 microm) by continuous split-flow thin (SPLIIT) fractionation. Experiments demonstrated the possibility of utilizing a hollow-fiber module for the high-performance separation of supramicron-sized airborne particles at steric/hyperlayer operating mode of HF FlFFF. Eluting particles during HF FlFFF separation were collected at short time intervals (approximately 10 s) for the microscopic examination. It showed that particle size and size distributions of all SPLITT fractions of airborne particles can be readily obtained using a calibration and that HF FlFFF can be utilized for the size confirmation of the sorted particle fraction during SPLITT fractionation.

Tracking the Transformation of Nanoparticulate and Ionic Silver at Environmentally Relevant Concentration Levels by Hollow Fiber Flow Field-Flow Fractionation Coupled to ICPMS

“…Briefly, the whole analytical run cycle consist of three on-line steps: (I) focusing/relaxation of AgNPs and isolation of Ag­(I) species, (II) fractionation, characterization, and quantification of AgNPs, and (III) quantification of Ag­(I) species. Given that particle retention in HF5 is dependent on the size, the particle size or size distribution of the target particles can be calculated with standard particles (e.g., AuNPs). , Considering the material-dependent retention behavior possibly due to the particle–particle and particle–accumulation-wall interactions, in step II the AgNPs size was obtained with a calibration curve obtained by plotting t R measured under the same fractionation conditions against the known size of standard AuNPs (Figure S2A), the acceptable standard metallic NPs, from ICPMS fractograms of the Au ( 197 Au) and Ag ( 107 Ag) signals (Figure S2B), and concentrations of fractioned AgNPs were acquired by ICPMS (7700 series, Agilent Technologies, Palo Alto, CA). Free Ag­(I), newly formed Ag­(I) complex, and AgNPs with diameter less than the HF pore size, namely, tiny AgNPs, could be quantified respectively as follows: Free Ag­(I) ions or weak Ag­(I) complexes adsorbed onto the Amberlite IR120 resin through ion-exchange with Na + in minicolumn concentration (MCC) during step I were desorbed by Na 2 S 2 O 3 and quantified by ICPMS detector in step III.…”

“…Given that particle retention in HF5 is dependent on the size, the particle size or size distribution of the target particles can be calculated with standard particles (e.g., AuNPs). 40,42 Considering the materialdependent retention behavior possibly due to the particle− 45 a series of aqueous solutions of NaClO 4 and Ca(ClO 4 ) 2 were chosen to evaluate the influences of mono-and divalent cations on the aggregation of AgNPs (10 ng/mL) in NOM solutions. First, the influences of focusing time and NOM concentration on the size of AgNP aggregates were investigated to confirm the capability of HF5 to maintain AgNPs intact in complex matrices through the whole separation.…”

Size Selectivity in Field-Flow Fractionation: Lift Mode of Retention with Near-Wall Lift Force

“…Though most S d determinations in FlFFF have been made with classical symmetrical systems with independent controls of the axial and cross-flow rates, a few studies were performed with other FlFFF configurations, such as hollow fiber FlFFF − or asymmetrical FlFFF (channels with a single flow inlet). , The S d values obtained with these alternative systems are comparable with the classical ones, although the hollow fiber system provided the highest reported S d values. However, the situation in these alternative FlFFF systems is more complicated than that of the symmetrical systems, due to the variation of the focusing position resulting with the decrease of the carrier axial flow rate and flow velocity with increasing distances from channel inlet.…”