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EP0104668A2 - Filmeinsatz für einen Sedimentationskraftfeld-Fraktionierungskanal für ein fliessendes Medium - Google Patents

Filmeinsatz für einen Sedimentationskraftfeld-Fraktionierungskanal für ein fliessendes Medium Download PDF

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Publication number
EP0104668A2
EP0104668A2 EP83109765A EP83109765A EP0104668A2 EP 0104668 A2 EP0104668 A2 EP 0104668A2 EP 83109765 A EP83109765 A EP 83109765A EP 83109765 A EP83109765 A EP 83109765A EP 0104668 A2 EP0104668 A2 EP 0104668A2
Authority
EP
European Patent Office
Prior art keywords
channel
film
ring
particulates
outer ring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP83109765A
Other languages
English (en)
French (fr)
Other versions
EP0104668A3 (de
Inventor
Donald Richard Johnson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EIDP Inc
Original Assignee
EI Du Pont de Nemours and Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Publication of EP0104668A2 publication Critical patent/EP0104668A2/de
Publication of EP0104668A3 publication Critical patent/EP0104668A3/de
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B5/00—Other centrifuges
    • B04B5/04—Radial chamber apparatus for separating predominantly liquid mixtures, e.g. butyrometers
    • B04B5/0407—Radial chamber apparatus for separating predominantly liquid mixtures, e.g. butyrometers for liquids contained in receptacles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
    • B03B5/00—Washing granular, powdered or lumpy materials; Wet separating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B5/00—Other centrifuges
    • B04B5/04—Radial chamber apparatus for separating predominantly liquid mixtures, e.g. butyrometers
    • B04B5/0442—Radial chamber apparatus for separating predominantly liquid mixtures, e.g. butyrometers with means for adding or withdrawing liquid substances during the centrifugation, e.g. continuous centrifugation
    • B04B2005/045—Radial chamber apparatus for separating predominantly liquid mixtures, e.g. butyrometers with means for adding or withdrawing liquid substances during the centrifugation, e.g. continuous centrifugation having annular separation channels

Definitions

  • Field flow fractionation is a versatile technique for the high resolution separation of a wide variety of particulates suspended in a fluid medium.
  • the particulates include macromolecules in the 10 5 to the 10 13 molecular weight (O.DO1 to 1 ⁇ m) range, colloids, particles, micelles, organelles and the like.
  • the technique is more explicitly described in U.S. Patent No. 3,449,938, issued June 17, 1969 to John C. Giddings and U.S. Patent No. 3,523,610, issued August 11, 1970 to Edward M. Purcell and Howard C. Berg.
  • SFFF sedimentation field flow fractionation
  • the'mobile phase or solvent is fed continuously from one end of the channel, it carries the sample components through the channel for later detection'.at the outlet of the channel. Because of the shape of the laminar velocity profile of the solvent within the channel and the placement of particulates in that profile, solvent flow causes smaller particulates to elute first, followed by a continuous elution of components in the order of ascending particulate mass.
  • the channels are usually formed of two mating rings. This creates a problem in that leaks can occur at the interface between the rings.
  • an apparatus is constructed for separating particulates suspended in a fluid medium according to their effective masses.
  • This apparatus includes an annular, cylindrical channel having a cylinder axis, means for rotating the channel about the axis, means for passing the fluid medium circumferentially through the channel, and means for introducing the particulates into the medium for passage through the channel.
  • the channel is defined by an outer support ring having a constant inner radius, and a unitary inner ring mating with the outer ring to define the channel therebetween.
  • This channel is improved according to this invention by constructing the channel to have a replaceable, thin film disposed between the rings and in contact with the outer ring forming the outer channel wall. This greatly facilitates cleaning of the channel.
  • the outer support ring need not have a microfinish; rather it can rely simply upon the film to provide such finish.
  • the film is particularly useful in that it aids in sealing the channel to prevent leakage at the interface between the rings.
  • the particular film may be selected according to the particulates to be separated, the objective being to prevent the particles from adhering to the film surface of the outer wall.
  • the outer ring or wall may be formed either by a separate ring or by the inner wall of a conventional zonal rotor centrifuge.
  • the inner ring may be continuous or split.
  • the film may be coated with a material or its surface may be modified using known techniques to reduce adhesion of the particulates to the outer support ring.
  • the film may be a polymeric material that is flat, smooth, of a desired surface chemically to reduce particulate adhesion, resilient, insoluble in the solvents normally used, and noncorroding.
  • split ring, SFFF channels 10 are constructed to have an outer ring 12, which is in the form of a band having a constant inner radius and functions to support an inner ring 13.
  • the outer ring 12 may be supported by a spider, bowl, or disc which is driven directly by a rotor 14 acting through a linkage depicted by the dashed line 16.
  • the Romanauskus patent describes one such mounting in which the outer ring is supported by compression washers which follow the expansion of the ring during centrifugation.
  • the outer ring may be eliminated and a bowl type rotor substituted. In this event, the bowl rotor has a cylindrical inner surface formed thereon to provide the outer channel wall.
  • the inner ring 13 is split, i.e., its longitudinal circumference is divided or separated to have a gap 18 with the-longitudinal ends 20 of the inner ring 13 slightly tapered to facilitate the use of wedges 22.
  • the wedges 22 retain the inner ring sufficiently expanded to maintain contact with the outer ring 12 at all times even when stopped.
  • the radially outer wall 24 of the inner ring 12 and the radially inner wall 26 of the outer ring 56 are formed to define the channel 10. Normally these walls are formed as by polishing, for example, or by coating the surfaces with a suitable material to have a microfinish. This smooth finish tends to reduce the possibility that particles will stick to the walls or become entrapped in small crevices or depressions and also insures that the expected sample retention takes place.
  • a groove 28 may be formed in the outer wall 24 of the inner ring 13 form the flow channel 10.
  • subsidiary grooves 30 may be formed to accommodate a resilient seal 32, such as an 0-ring, which completely surrounds and tracks along the edges of the channel, including the end sections.
  • the upper edge of the inner ring is formed with a radial, outwardly extending flange 34, as is seen most clearly in FIG. 2, such that the inner ring may rest upon and be supported by the outer ring against axially downward displacement.
  • Inlet and outlet conduits 36 communicate with the ends of the channel 10 through the inner ring. As is known, fluids containing particulate samples are passed through these conduits.
  • the outlet conduit is coupled to a detector (not shown).
  • the thickness of this channel 10 is relatively small, typically being in the order of 0.1 cm or less. The dimensions of the channel, both width and thickness must be very precisely maintained. The actual thickness is selected according to the separations to be performed as is known.
  • a thin, flat film 75 of a resilient, smooth surfaced material is positioned in-between the inner and outer rings 13, 12.
  • This film typically is placed over the inner ring, the ring compressed (the wedges 22 being removed) and placed within the outer ring (which of course may be the inside wall of a bowl rotor) and the inner ring allowed to release to expand and force the film in contact with the outer wall. The wedges are then reinserted to stabilize the inner ring as described by Grant.
  • This film which may be of any polymeric material or even aluminum or stainless steel, provides the smooth surface for the outer wall without the need for the normal polishing that would normally be required.
  • the film extends beyond the 0-ring seals to aid in sealing to prevent leakage of fluids from the channel. In fact, in many cases the seals may be omitted when a resilient film'insert is used.
  • the films that may be used should be flat, have a smooth surface and the desired surface chemical characteristics, be resilient, insoluble in the mobile phase used, noncorroding, and desirably colored for ease of handling.
  • the films that may be used are cellulose, polyethylene terephthalate, polytetrafluoroethylene, aromatic polyimide, polypropylene, polyvinyl acetates, and polyvinyl propionate polyesters. These tend to provide hydrophobic surfaces. If hydrophilic surfaces are desired, the above noted materials in many cases can be treated or coated.
  • Film thickness typically should exceed 0.005 cm. Thinner films than this have a tendency to wrinkle, which is highly undesirable for this purpose. Films up to .02 cm thickness have been used successfully.
  • Films significantly in excess of this thickness may be used but tend to be unnecessarily wasteful of the film material. Films having a thickness in the range of .01 cm are particularly desirable. They do not change the dimension of the channel's thickness, unless the channel is formed by a groove in the outer ring, since they simply serve to coat the inner wall of the outer ring.
  • Metal films that may be used include aluminum and stainless steel which may be gold plated if desired.
  • SFFF separations samples of particulates in suspension are introduced into a mobile phase which carries the particulates through the channel 10.
  • the particulate under test will determine the mobile phase and the type of film 75 that is used. Adhesion between the channel outer wall and the particulates is to be avoided--it reduces the resolution and sensitivity of the separation.
  • Adhesion can be avoided by properly selecting or coating or modifying the surface of a film.
  • Adhesion usually occurs where the surface charge of the particulate and the film's surface polarity are opposite. It also occurs where there is covalent bonding, chemical adsorption, or van der Waals forces. Ideally the channel should "look like" the mobile phase, i.e., be of the same polarity.
  • the mobile phase density be less than the particulate density and that the mobile phase wets the particulates. If the particulates are hydrophobic, the mobile phase should be nonaqueous. If the particulates are hydrophilic, the mobile phase should be aqueous. Although of secondary importance, it is desirable that the mobile phase wets the channel walls-In the event a hydrophilic surface is desired, many of the above noted polymeric films which are hydrophobic, may be surface modified. This typically is accomplished by forming OH or carboxyl groups on-the surface as by chemically bonding desired molecules to reactive sites on the surface.
  • hydrocarbons may be oxidized by a corona discharge
  • fluorocarbons may be reduced by sodium in ammonia
  • esters, amides and imides may be hydrolyzed.
  • Cellulose and polyvinyl alcohol have hydrophilic surfaces.
  • the replaceable film of this invention finds use with any double ring or other type SFFF channel which can be opened for cleaning and the like.
  • it may be used in the "floating" type channels described in the copending Dilks and Yau and Dilks, Yau and Kirkland applications mentioned above. These channels are formed with a continuous inner ring as is the Romanauskus channel.
  • Dilks and Yau describe a disklike channel 10 as seen in FIG. 3.
  • This channel 10 is formed by an inner ring or hub 76 and a mating outer ring 80 positioned in the bowl of a rotor 60.
  • the hub 76 and outer ring 80 are formed to have a diametrical interference fit of about 0.03 centimeters (cm) so that the outer ring 80 is in constant compressive contact with the hub 76 under static conditions.
  • the inner or mating surface 82 of the outer ring 80 has a channel or groove 84 formed therein leaving lands 81 on either side of the groove 84.
  • the outside portions 85 of the inner surface 82 are removed to limit the axial width of the lands 81 and thereby enhance their ability to seal the channel when they contact the peripheral surface of the hub 76.
  • This groove 84 may be formed to have different thicknesses, different widths, different lengths, different aspect ratios (width to thickness ratio).
  • a strip of film 75 is positioned against the inner wall of the outer ring 80. This is accomplished by coooling th einner ring, wrapping the film about the inner ring, inserting the inner ring 76 into the outer ring 80 while the film is maintained under tension, and allowing the inner ring to expand. Air may be removed from the inner wall of the outer ring by forming it with a matte finish. When liquid is later introduced into the channel 10, it will expand the film into the groove 84 to define the channel.
  • each channel and the manner in which fluids are fed to and withdrawn therefrom are preferably those described in U.S. Patent 4,284,498 issued to Grant et al. on August 18, 1981, the disclosures of which is incorporated herein by reference.
  • Fluids are fed through tubing 74 to circumferentially spaced radial bores 83 in the hub 76 to the beginning and end of the channel 10.
  • the beginning and end of the channel groove 84 is defined by a plastic shim (not shown) having a close fit with the channel axial width.
  • the shim has inverted V-shaped ends with the apex of the V slotted to encompass the respective bores 83.
  • the shim may be formed of a polyphenylene oxide plastic and be cemented into position. It may be slightly thicker than the depth of the channel groove 84. Thus, when it is compressed by the smooth outer peripheral surface of the hub 76, it seals and defines the beginning and end of the channel 10.
  • the interior of the bowl-type rotor 60 preferably is filled with a liquid of approximately the same density as the fluid medium that is forced to flow through the channel.
  • the outer ring 80 is formed to have a diameter slightly less than the interior diameter of the bowl 60 so that it does not contact the inside of the bowl even during centrifugation.
  • the hub 76 is configured so that it fits concentrically over the interior hub 94 of the rotor 60, so as to be mounted securely thereon, and to have a nib 96 that engages a receptacle 98 in the cover 70 to center the channel housing 76, 80.
  • the mid-portion 100 of the hub 76 may be in the form of.an annulus having a reduced thickness to facilitate the radially outward expansion of the hub 76 during centrifugation to facilitate its following the outer ring expansion.
  • Liquid typically water or other aqueous based liquid, thus surrounds essentially all of the channel housing 76, 80.
  • centrifugal force causes the liquid pressure exerted by the liquid in the rotor bowl 60, external to the channel, and that exerted internally by the fluid medium within the channel to be substantially equal. Since, leakage is essentially eliminated at the interface 81 between the hub and outer ring the width of the film may be selected to match the axial width of the groove 84. In this manner it finds use in reducing particulate adherence to the outer channel wall and the ability to remove and replace films according to the particulates to be separated.
  • the hub 76 and outer ring 80 preferably are each constructed of a suitable engineering plastic selected such that the effective density ⁇ to tensile modulus E ratio of the outer ring is somewhat less than the effective density ⁇ to tensile modulus E ratio of the hub.
  • the effective density ⁇ is the density of the channel material minus the density of the bowl filling liquid.
  • the effective density ⁇ of course can be negative. This is done so that the hub can expand outwardly to a greater extent than the outer ring to maintain a good contact, during centrifugation, with -the-outer ring and thereby maintain the integrity of the channel.
  • the density of the compensating liquid can be selected to be different from the density of the fluid medium and to lie between the densities of the hub and outer ring.
  • the compensating liquid density exceeds that of the outer ring, the outer ring will literally float under a force field and be forced to have closer contract with the inner ring.
  • the density of the outer ring is greater than that of the inner ring, then the use is limited to compensation liquid densities less than that of the hub or else the hub can separate from the outer ring under some operating conditions.
  • the effective density ⁇ to tensile modulus E ratio of the outer ring less than the effective density ⁇ to tensile modulus E ratio of the hub, the hub will expand under centrifugal force at a faster rate than the outer ring and maintain good contact therebetween during centrifugal operation.
  • the density of the compensating liquid within the rotor is selected to be approximately equal to the density of the outer ring such that there is little expansion or contraction of the outer ring due to the effects of the liquid.
  • the films may be used typically to coat the inner wall of the outer ring of any particular channel whether the outer wall be formed by a zonal rotor, an outer ring or whatever.
  • the film is easily replaceable for cleaning the channel, to provide surface characteristics matching those of the particulates, end to reduce channel leakage.

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  • Investigating Or Analysing Biological Materials (AREA)
EP83109765A 1982-09-29 1983-09-29 Filmeinsatz für einen Sedimentationskraftfeld-Fraktionierungskanal für ein fliessendes Medium Withdrawn EP0104668A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US42747482A 1982-09-29 1982-09-29
US427474 1982-09-29

Publications (2)

Publication Number Publication Date
EP0104668A2 true EP0104668A2 (de) 1984-04-04
EP0104668A3 EP0104668A3 (de) 1985-05-15

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EP83109765A Withdrawn EP0104668A3 (de) 1982-09-29 1983-09-29 Filmeinsatz für einen Sedimentationskraftfeld-Fraktionierungskanal für ein fliessendes Medium

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EP (1) EP0104668A3 (de)
JP (1) JPS5980345A (de)
AU (1) AU1973183A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2524733A1 (de) * 2011-05-20 2012-11-21 Postnova Analytics GmbH Vorrichtung zur Durchführung einer zentrifugalen Feldflussfraktionierung, Keildesign zur Verwendung in solch einer Vorrichtung und Verfahren zur Herstellung solch einer Vorrichtung und zur Verwendung in solch einer Vorrichtung konstruierter Rotor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1185228A (en) * 1964-05-13 1970-03-25 Baxter Laboratories Inc Apparatus and Method for Washing Cells
US3698626A (en) * 1971-05-17 1972-10-17 Atomic Energy Commission Centrifuge separator
FR2404470A1 (fr) * 1977-10-03 1979-04-27 Ibm Ensemble formant rotor de centrifugeuse et reservoir de fluide pour utilisation dans un tel ensemble
US4283276A (en) * 1980-02-29 1981-08-11 E. I. Du Pont De Nemours And Company Rotor for sedimentation field flow fractionation

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1185228A (en) * 1964-05-13 1970-03-25 Baxter Laboratories Inc Apparatus and Method for Washing Cells
US3698626A (en) * 1971-05-17 1972-10-17 Atomic Energy Commission Centrifuge separator
FR2404470A1 (fr) * 1977-10-03 1979-04-27 Ibm Ensemble formant rotor de centrifugeuse et reservoir de fluide pour utilisation dans un tel ensemble
US4283276A (en) * 1980-02-29 1981-08-11 E. I. Du Pont De Nemours And Company Rotor for sedimentation field flow fractionation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2524733A1 (de) * 2011-05-20 2012-11-21 Postnova Analytics GmbH Vorrichtung zur Durchführung einer zentrifugalen Feldflussfraktionierung, Keildesign zur Verwendung in solch einer Vorrichtung und Verfahren zur Herstellung solch einer Vorrichtung und zur Verwendung in solch einer Vorrichtung konstruierter Rotor

Also Published As

Publication number Publication date
JPS5980345A (ja) 1984-05-09
AU1973183A (en) 1984-04-05
EP0104668A3 (de) 1985-05-15

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