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US 4,285,810 AGranted
Method and apparatus for field flow fractionation
AssigneeE. I. Du Pont de Nemours and Company
InventorsJoseph J. Kirkland, Wallace W. Yau
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AssigneeE. I. Du Pont de Nemours and Company
InventorsJoseph J. Kirkland, Wallace W. Yau
Estimating the term…
The method described is useful in field flow fractionation techniques for reducing separation times and improving the convenience and accuracy of measuring sizes or molecular weights of particulates. In field flow fractionation, the particulates (particles or macromolecules) are subjected to a force field and a mobile phase while passing through a flow channel. This field strength is decreased exponentially as a function of time. Alternatively the flow velocity is increased exponentially as a function of time. The initiation of the change in field strength or flow velocity may be delayed a period of time. If this time delay is made equal to the time constant of the exponential decay, the range of particulate retention time that is linearly related to the logarithm of the particle size or molecular weight is increased. An apparatus for implementing the method is also described and teaches the use of a function generator for providing the desired exponential decay and delay time. The apparatus is described in implementations involving a force field.
A method for separating particulates, including macromolecules and particles, by introducing a sample of said particulates into a fluid medium, passing the fluid medium with sample suspended therein through a narrow flow channel, establishing a force field that influences a characteristic of said particulates across said flow channel to partition said particulates within said flow channel by selectively retarding different particulates according to their interaction with said influencing field and said fluid medium, comprising the step of:
In an apparatus for separating particulates, including macromolecules and particles, suspended in a fluid medium, said apparatus having a narrow flow channel, means for establishing a force field across said channel that influences a characteristic of said particulates, means for passing said fluid medium through said flow channel, means for introducing a sample of said particulate into said fluid medium for passage through said flow channel, the improvement wherein said field-establishing means includes programming means for decreasing the field strength exponentially as a function of time to reduce the separation time and better equalize particle size separation.
In an apparatus for separating particulates, including macromolecules and particles, suspended in a fluid medium, said apparatus having a narrow flow channel, means for establishing a force field across said channel that influences a characteristic of said particulates, means for passing said fluid medium through said flow channel, means for introducing a sample of said particulates into said fluid medium for passage through said flow channel, the improvement wherein said means for passing said fluid medium through said flow channel includes programming means for increasing the flow velocity of said fluid medium exponentially as a function of time to reduce the separation time and better equalize particle size separation.
Dependencies are inferred from the claim text.