Rapid size characterization of chromatographic silicas by flow field-flow fractionation

Ratanathanawongs, S. Kim; Giddings, J. Calvin

doi:10.1007/bf02277152

Cited by 26 publications

(16 citation statements)

References 26 publications

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“…The polydispersity value was represented by a percent coefficient of variation (%CV). The %CV value was obtained by calculating a percentage of the ratio of the standard deviation (r) in particle diameter to the mean diameter (d mean ) (Ratanathanawongs & Giddings, 1994). The r value is a half of the diameter range calculated by subtracting the diameter position at 15.85% total area from the diameter position at 84.15% total area (Siripinyanond & Barnes, 2002).…”

Section: Particle Size Information Of Milk Samplesmentioning

confidence: 99%

Sedimentation field-flow fractionation: Size characterization of food materials

Saeseaw

Shiowatana

Siripinyanond

2005

Food Research International

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Section: Particle Size Information Of Milk Samplesmentioning

confidence: 99%

Sedimentation field-flow fractionation: Size characterization of food materials

Saeseaw

Shiowatana

Siripinyanond

2005

Food Research International

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“…decreases i n total fluorescence were observed over the [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] h period The 145k Da deltran showed the greatest changes in molecular weight (Figure 2c compared to that at time-zero, and a broad peak was observed in the region of higher molecular weights (Figure 3c). This broad peak could be due to aggregation with DOM, such as the incorporation of the labeled dextran into high molecular weight carbohydrate mucus,ll or to the release of high molecular weight digestive fragments during flagellate grazing.36 The 2M Da dextran showed a consistent decrease in fluorescence intensity as a function of incubation time (Figure 3c).…”

Section: Resultsmentioning

confidence: 97%

Monitoring the Biological and Physical Reactivity of Dextran Carbohydrates in Seawater Incubations Using Flow Field-Flow Fractionation

Williams

Keil

1997

Journal of Liquid Chromatography & Related Technologies

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In order to better understand the factors that modulate the size and reactivity of high molecular weight organic matter dissolved in seawater, fluorescently labeled dextrans were used as the model compounds whose molecular weight distributions were monitored by flow field-flow fractionation (flow FFF or FIFFF) during incubations in seawater matrices. Two fluorescein isothiocyanate (FITC) labeled dextrans (145k and 2M Da) were incubated in whole seawater (natural microbial population and natural dissolved organic matter (DOM) present), 0.02 pm filtered seawater (all microorganisms removed, but natural DOM 2815 Copyright 0 1997 by Marcel Dekker, Inc. Downloaded by [Athabasca University] at 14:39 06 June 2016 2816 RATANATHANAWONGS WILLIAMS AND KEILlargely unaltered), and UV-oxidized seawater (no microorganisms or natural DOM present). Flow FFF fractograms of the two FITC-dextrans incubated in UV-oxidized seawater showed no changes, signifying that the dextrans did not undergo any alteration or aggregation. The dextrans incubated in filtered seawater with natural DOM present resulted in fractograms that are shifted to higher retention times, consistent with aggregation of the destran and natural DOM.In the whole seawater incubations, the complex changes in the fractograms over time indicated that the dextrans underwent both aggregation with natural DOM and degradation by hcterotrophic microorganisms. The latter was confirmed by microscopic examination of the collected fractions after selectively staining the microorganisms with the fluorescent dye 4,6-diamidino-2-phenylindole (DAPI). The FITC dextrans were observed to be "attached" to the bacteria's outer cell membrane where they are subsequently hydrolyzed into small low molecular weight fragments by extracellular enzymes. Some of these degraded dextrans are assimilated by the bacteria and the rest (-70%) are released into the seawater. Approximately half of the released degraded dextrans are of high enough molecular weight to be retained by flow FFF at the conditions employed in these studies. The data presented in this paper illustrate that, when used as both a qualitative and semipreparative tool, flow FFF can provide information on the relationships between natural and model DOM and microorganisms that would be difficult or impossible to obtain using other methods.

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“…(5). For FFF-based PSD analysis of silica samples, correction of the detector response into a frequency function has already been performed with the UV signal found to be proportional to the sample concentration in the specific range of interest [11] and with extinction coefficients taken as inversely dependent on particle size [26]. In Figure 2 the analytical response (UV signal) of diluted dispersions of silica samples continuously pumped through the detector cell, as described in Experimental, is shown as a func- tion of silica concentration for particles of different diameter with surfactant-free mobile phases.…”

Section: Determination Of Extinction Coefficientsmentioning

confidence: 99%

A quantitative approach to the analysis of supermicron dispersions by field-flow fractionation with UV-vis detectors. The application of an absolute method

1997

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SummaryQuantitative analysis in field-flow fractionation is becoming a necessary requirement for routine applications, instrumental optimization and scale-up to preparative separations. The use of detection systems which show complex dependence on sample characteristics (i.e. UV spectrometry) has hindered the application of quantitative methods of analysis in fieldflow fr actionation. A standardless model, shown valid in flow-through, homogeneous systems, is applied here to a heterogeneous system (dispersed supermicron particles) in field-flow fractionation by single peak area measurements. Absolute analysis in the fractionation of spherical silica particles for high-performance liquid chromatography column packing by gravitational fieldflow fractionation with UV-Vis detectors is presented. It has been shown that for such samples extinction coefficients are independent of sample concentration and are determined by the size and density of the particles. The accuracy of such an approach to absolute analysis is discussed.

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Rapid size characterization of chromatographic silicas by flow field-flow fractionation

Cited by 26 publications

References 26 publications

Sedimentation field-flow fractionation: Size characterization of food materials

Sedimentation field-flow fractionation: Size characterization of food materials

Monitoring the Biological and Physical Reactivity of Dextran Carbohydrates in Seawater Incubations Using Flow Field-Flow Fractionation

A quantitative approach to the analysis of supermicron dispersions by field-flow fractionation with UV-vis detectors. The application of an absolute method

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