Method and apparatus for optimizing the separation of small particles using the asymmetric flow field flow fractionation method
AssigneeWyatt Technology Corporation
InventorsPhilip J. Wyatt, Michelle H. Chen, David N. Villalpando
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Abstract
A new type of asymmetric flow field flow fractionator, A4F, is described permitting improved sample fractionation means by providing a range of available channel lengths within the same A4F unit. With such an apparatus, samples may be optimally separated by performing such fractionations as a function of channel length. The ability to vary channel length within the same A4F unit has heretofore been unavailable.
Claims19
A method to improve the characterization of particles separated by an asymmetric flow field flow fractionation unit, A4F, whose structure comprises
- i. a top plate assembly containing ports,
- ii. a spacer containing two or more cavities separating said top plate assembly from a bottom plate assembly,
- iii. a membrane preventing particles from entering
- iv. a supporting fit structure, and
- v. a bottom plate assembly to which said top plate assembly can be rigidly attached sealing, thereby, said cavity between said membrane and said top plate;
- comprising the steps of
- A. assembling a channel structure which provides a plurality of cavities of different cavity configurations by using one spacer containing a plurality of cavities of different cavity configurations therein;
- B. creating a suspension of said particles to be characterized;
- C. injecting an aliquot of said particles into a first cavity configuration of said A4F channel means;
- D. fractionating said injected aliquot by said first cavity configuration;
- E. measuring said fractionated aliquot by detector means;
- F. injecting successively a plurality of aliquots of said particles into said corresponding plurality of additional cavity configurations within said same channel structure without the need to disassemble said channel structure;
- G. fractionating successively each said injected aliquot by means of said corresponding subsequent cavity configuration selected;
- H. measuring successively said fractionated aliquots of said particles by said detector means;
- and
- I. combining all such measurements collected from all aliquots so measured to provide improved characterization of said particles.
An improved A4F unit for the fractionation of a sample of particles suspended in fluid means comprised of
- A. a bottom plate incorporating a porous fit;
- B. a membrane permeable only to said fluid means carrying said particles suspended therein;
- C. a spacer containing two or more cavities;
- D. a top plate containing a set of associated port means providing each said cavity with
- 1. a port means for injecting mobile phase fluid;
- 2. a plurality of port means for injecting samples of said particles to be fractionated;
- each of said injection port means providing sample injection locations at different distances from said mobile phase injection port;
- and
- 3. an exit port means for carrying said sample after fractionation to detector means.
An A4F system for the fractionation of a sample of particles suspended in fluid means, comprising
- A. a top plate comprising an array of fluid ports arranged in a plurality of rows and columns extending horizontally and vertically over the accessible area of said top plate wherein each said row and column contains two or more of said fluid ports, any of which may act as a mobile phase injection port, a sample injection port, or an outflow port, as long as said sample injection port is downstream from said mobile phase injection port and upstream from said outflow port, all unused ports being made inaccessible, where the region beneath said mobile phase injection port, sample injection port, and outflow port has a properly positioned
- B. spacer containing two or more cavities separating said top plate from
- C. a membrane permeable to said fluid means lying on;
- D. a porous frit incorporated into a bottom plate;
- and
- E. means whereby said top plate is connected and sealed to said bottom plate.
Dependencies are inferred from the claim text.