Separation and characterization of particles in natural water and soil using flow field-flow fractionation

Flow field-flow fractionation (FlFFF) is used to characterize particles in natural water (ground and surface water) and soil. The opposed flow sample concentration (OFSC) mode of FlFFF (OFSC-FlFFF) is employed, where the colloidal sample is continuously fed into the channel so that the particles are focused into a narrow band near the inlet of the FlFFF channel before the separation is initiated. There is no need for stopping the flow for the sample relaxation, which is usually required in conventional FlFFF operations. First, the OFSC-FlFFF is tested with mixtures of polystyrene latex spheres. Then the OFSC-FlFFF procedure is optimized for the analysis of particles in natural water and soil by varying various experimental parameters including the flow rates. Ground water of up to 100 mL has been successfully loaded, concentrated, and characterized by OFSC-FlFFF. Results show that the OFSC-FlFFF provides a simplified alternative to existing off-line concentration procedures, and it shows high potential for application to analysis of dilute colloidal particles in environmental water. The composition of the samples was analyzed using atomic absorption spectrometry.