Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/483—Physical analysis of biological material
  • G01N33/487—Physical analysis of biological material of liquid biological material
  • G01N33/49—Blood
  • G01N33/491—Blood by separating the blood components
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/25—Chemistry: analytical and immunological testing including sample preparation
  • Y10T436/25375—Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]

Definitions

• This invention relates to a method of separating serum/plasma included in a certain volume of blood, said volume of blood being introduced into a test tube, in which a so-called separating body is also present, after which the test tube is centrifugalized, the blood being separated into a heavy phase containing red blood corpuscles and a light phase containing serum or plasma, the separating body being given such a specific gravity that upon centrifugation it enters a position in the boundary layer between the heavy and light phase.
• the invention also relates to a device for separation according to the above.
• a plurality of various technical methods are known to provide separation of a sample of blood enclosed in a test tube to a heavy phase containing red blood corpuscles and a light phase containing serum.
• a general method is arranging a silicon compound having a specific gravity between that of the heavy phase and the light phase on the bottom of a test tube. Upon centrifugation of the sample the silicon compound will form a barrier between the heavy phase and the light phase so that the light phase, i.e. the serum/plasma can be removed from the test tube while the heavy phase, i.e. the red blood corpuscles, remains in the test tube.
• this technique does not provide any mechanical barrier between the two phases and, moreover, the accumulation of leukocytes and tr ⁇ mbocytes in the boundary layer between the two phases is not taken charge of, meaning that the serum/plasma will be "contaminated” by these leukocytes and tromb ⁇ cytes.
• the mechanical separating bodies have different types of seals bearing on the walls of the test tube. However, these seals cannot be made too efficient as the separating body must be able to slide within the test tube.
• the accumulation of leukocytes and trombocytes in the boundary layer between the heavy and the light phase is not taken charge of but will "contaminate" the serum/plasma.
• the separating body is arranged in a test tube open at both ends, said ends being sealed by means of elastic members and, as a result of thi3, vacuum prevailing in the test tube.
• Fig. 1 shows a test tube in which a separating body according to the invention is placed and the test tube is in a position of sampling
• Fig. 2 shows the test tube according to Fig. 1 in a position for separation
• Fig. 3 shows the test tube according to Fig. 1 after separation
• Fig. 4 shows an alterna tive embodiment of the separating body according to the invention.
• the test tube 1 shown in Figs. 1-3 is open at its two ends.
• One end (the upper one in Fig. 1) of the test tube 1 is sealed by means of a plug 2 of an elastic material, said plug 2 being of a type that can be penetrated a plurality of times by a cannula 3 without losing its sealing ability upon removal of the cannula 3.
• a relatively thin membrane 4 of an elastic material is arranged which is threaded onto said end of the test tube 1 to provide a sealing closure.
• a separating body 5 is also placed within the test tube 1.
• This separating body 5 consists of an outer shell of a shape-permanent material, e.g. rigid plastic, the material of the shell also having the property not to react with blood.
• the shell has a cup-shaped recess 6, which is associated with a cylindrical recess 8 by way of a passage 7.
• a viscous or, as an alternative, fine granular mass 9 having a specific gravity somewhat higher than the specific gravity of the shell is placed within the cylinder-shaped recess 8.
• test tube 1 with its associated separating body 5 described above is used as follows. In the starting position shown in Fig. 1 the separating body 5 is located in connection with the membrane 4, i.e. at the lower end of the test tube 1.
• a sample of blood 10 is thereafter supplied to the test tube 1 by way of the cannula 3 in Fig. 1, the blood being sucked into the test tube 1 thanks to the vacuum prevailing therein.
• the cannula 3 is removed, and the plug 2 will close the test tube 1 sealingly at its upper end in Fig. 1.
• test tube Before separation of the sample of blood through centrifugation of the test tube 1 the test tube is turned upside down so that it enters the position shown i Fig. 2, i.e. the sample 10 is located beneath the separating body 5.
• the sample of blood Upon centrifugation the sample of blood will substantially be separated into a heavy phase 11 and a light phase 12, see Fig. 3.
• the heavy phase consists of red blood corpuscles, erythrocytes, while the light phase consists of serum or plasma.
• the separating body 5 which, thus, consists of the shell and the viscous or fine granular mass, will also seek out a balance position in the test tube corresponding to its specific gravity which is intermediary in relation to the specific gravity of the red blood corpuscles and that of the serum/plasma.
• the separating body 5 By giving the separating body 5 a specific gravity substantially corresponding t o that o f the leukocyt es and the t rombocyt es the s eparating body 5 will enter a balance position on a level with the layer of leukocytes and trombocytes between the heavy and the light phase.
• the mass 9 placed in the recess 8 will move downwards out of the recess 8 during the continued centrifugation. Due to a high viscosity and frictional force this will not take place earlier during the centrifugation.
• the mass 9 has a somewhat higher specific gravity than the shell of the separating body 5 but a somewhat lower specific gravity than the heavy phase 11 meaning that the mass 9 will flow at least partly around the lower edge of the shell and seal the space between the separating body 5 and the wall of the test tube.
• the recess 8' has a relatively small outlet opening for the mass 9' meaning that a mass of a somewhat lower viscosity than in the illustrative example described above can be used in this illustrative example.
• the separating body of this invention provides a mechanical barrier between the separated phases through the sealing effect of the mass 9 against the wall of the test tube and that the accumulation of leukocytes and trombocytes is sucked into the recess 8 in the separating body 5 at least partly.
• the separating body according to the invention is placed in a test tube which is open at both its ends and sealed there by elastic members. Vacuum prevails within the test tube.
• This arrangement has several advantages as has been stated above. However, it is also possible to use the separating body of the invention at other types of test tubes, but handling thereof, will be somewhat more awkward.
• the dimensions of the separating body must be adapted to the type of test tube used. As far as the play between the wall of the test tube and the outer periphery of the separating body is concerned a suitable size of this appears to be about 0.5 mm. Of course this is only an indication for the sake of exemplification.

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Citations (7)

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• 1985
  • 1985-08-27 SE SE8503991A patent/SE448323B/sv not_active IP Right Cessation
• 1986
  • 1986-08-27 JP JP61504781A patent/JPS63500679A/ja active Granted
  • 1986-08-27 AU AU62897/86A patent/AU590616B2/en not_active Ceased
  • 1986-08-27 EP EP86905469A patent/EP0235244B1/en not_active Expired - Lifetime
  • 1986-08-27 WO PCT/SE1986/000381 patent/WO1987001457A1/en active IP Right Grant
  • 1986-08-27 US US07/050,298 patent/US4853137A/en not_active Expired - Fee Related
• 1987
  • 1987-04-23 FI FI871792A patent/FI84404C/sv not_active IP Right Cessation

Patent Citations (7)

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