CA1311624C - Material layer volume determination with correction band - Google Patents
Material layer volume determination with correction bandInfo
- Publication number
- CA1311624C CA1311624C CA000570818A CA570818A CA1311624C CA 1311624 C CA1311624 C CA 1311624C CA 000570818 A CA000570818 A CA 000570818A CA 570818 A CA570818 A CA 570818A CA 1311624 C CA1311624 C CA 1311624C
- Authority
- CA
- Canada
- Prior art keywords
- tube
- annulus
- float
- band
- measured
- 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.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
- B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
- B01L3/502—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures
- B01L3/5021—Test tubes specially adapted for centrifugation purposes
- B01L3/50215—Test tubes specially adapted for centrifugation purposes using a float to separate phases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/04—Investigating sedimentation of particle suspensions
- G01N15/05—Investigating sedimentation of particle suspensions in blood
Abstract
ABSTRACT OF THE DISCLOSURE
A centrifuge tube is used to hold a mixture of several constituents, and also contains a generally cylindrical float. The float settles, after cen-trifugation, into the zone occupied by the constituent whose volume is to be measured. The constituent layer will settle, after centrifugation, into the annular space between the tube bore and the outside of the float and will be expanded axially due to the restricted volume of the annular space. The degree of expansion is dependent upon the respective sizes of the float O.D. and the tube bore ID, both of which must be closely controlled for accurate results. A
known volume of a control material is placed in the tube to settle into the annular space during centrifugation in an area thereof outside of the constituent layer zone. The length of the band of the control material is measured after centrifugation and is compared to a known length which will result if the annular space is of the proper target volume. A
correction factor is thus obtained and applied to all of the other constituent layers which were measured.
The band thus forms a varying reference which reflects the actual volume of the annulus.
A centrifuge tube is used to hold a mixture of several constituents, and also contains a generally cylindrical float. The float settles, after cen-trifugation, into the zone occupied by the constituent whose volume is to be measured. The constituent layer will settle, after centrifugation, into the annular space between the tube bore and the outside of the float and will be expanded axially due to the restricted volume of the annular space. The degree of expansion is dependent upon the respective sizes of the float O.D. and the tube bore ID, both of which must be closely controlled for accurate results. A
known volume of a control material is placed in the tube to settle into the annular space during centrifugation in an area thereof outside of the constituent layer zone. The length of the band of the control material is measured after centrifugation and is compared to a known length which will result if the annular space is of the proper target volume. A
correction factor is thus obtained and applied to all of the other constituent layers which were measured.
The band thus forms a varying reference which reflects the actual volume of the annulus.
Description
This invention relates to the measurement of one or more constituent layers in a complex material mixture, and more particularly, to volumetric measurements in a centrifuged sample, with the application of correction factors to correct for dimensional variations in the paraphenalia used to contain the sample.
A technique has been developed to measure constituent layers in a complex material mixture by centrifuging a sample of the material mixture in a capillary or other tube which contains a float. The float is preferably cylindrical and of a specific gravity which causes it to settle into the centrifuged mixture to a degree which creates a free volume annulus in the tube into which the layer, or layers to be measured will settle. The layers to be measured are thus physically elongated, and can be more easily and accurately measured. This technique is described in U. S. Patent Nos. 4,027,660, issued June 7, 1977;
4,082,085 issued April 4, 1978; 4,156,570, issued May 29, 1979; and others.
This technique, as c1esc^ibed in the prior art, depends on the manufacture-'s ability &O hold the capillary tube ID's and the float OD's to very tight tolerances. The magnification factor for the elongated constituent layers, when the technique is used as preferred in its commercial form, is about 10.5. This means that any layer which is expanded by the technique will be 10.5 times longer using the float than it would be without using the float. In order to achieve this magnitude of elongation, the ' ~ tube ID will be maintained at 0.06605 inch, and the float OD will be maintained at 0.06285 inch. Thus the annulus is preferably only sixteen ten thousandths of ; 35 an inch thick. It will be appreciated that minor :
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: ~ : -- 2 - t3116~4 variations in either the tube ID or the float OD, especially if additive, can result in changes in the annulus thickness which can cause inaccurate readings.
For example, a tube ID which is slightly oversize, i.e., 0.00016 inch too large, plus a slightly undersized floa-t, i.e., 0.00011 too small will result in a reduction of the observed band lengths in the annulus of 8%.
This invention relates to a technique for providing an internal standard correction band in the tube which resides in the annulus after cen-trifugation, but separate from any constituent layers of the material which are to be measured. In a blood sample, the correction band may, for example, float on top of the lightest of the constituents being measured, i.e., the platelets, and would thus form an additional visible band adjacent to the platelets which band would have its length measured. The correction band is formed by placing a known volume of artificial beads, (or some other flowable material such as a liquid or gel which is immiscible with the ; blood, or other material being measured) which can be made from plastic, in the tube prior -to cen-trifugation. The beads will have a common controlled size, or a statistically repeatable heterogeniety and may be differentially colored, preferably fluorescent, so as to be readily contrasted with the other colored bands in the tube formed by the stained layered material constituents. The material from which the beads are made will have a specific gravity such that the beads will float on one of the constituent material layers away from those being measured, so as not to interfere with the constituent measurements being performed. As previously noted, in the blood ~ 35 sample, the beads will be made to float on the : ;
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_ 3 - I 3 1 ~ ~24 platelet layer. The volume of beads placed in the tube will be constant, such that the beads will form a correction band of known length when the tube ID and the float OD are made to specification. Any variations in the tube and float which enlarge or shrink the annulus will be reflected in the length of the correction band. The measurements can be made and the corrections applied in an instrument such as that disclosed in U. S. Patent No. 4,156,570; or that disclosed in U.S. Patent No. 4,558,947.
It is therefore an object of this invention to provide an improved technique for measuring centrifuged material constituent layers which employs means for identifying incorrect readings resulting from dimensional variations in the paraphenalia used to contain the samples.
It is a further object to provide an improved technique of the character described wherein ~; a correction band is formed in the tube which contains the sample being measured.
It is an additional object of this invention to provide an improved technique of the character described wherein the correction band is formed with a preset volume of artificial beads which settle into the measurement area of the tube but outside of the constituent layers which are being measured.
It is another object of this invention to provide an improved technique of the character described wherein the correction band expands or 30 ~ contracts in response to dimensional variations in the measurlng zone whereupon appropriate corrections can he made to the measured lengths of the constituent ; layers.
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In accordance with a particular embodiment of the invention there is provided, for use in measuring volumes of constituent material layers in a centrifuged material mixture having at least first and second adjacent material layers of different specific gravities, apparatus comprising a transparent tube having a bore which is of substantially constant diameter and an elongated float in said tube bore, said float having a substantially constant cross sectional area which is smaller than the cross sectional area of said tube bore, said float combining with said tube bore to form a free space annulus in said tube, said free space annulus being operable to receive and elongate at least one of said constituent `
layers, and means in said tube forming a known volume reference band whose length, as measured axially of the tube, varies inversely to the volume of the annulus, said band being positioned outside of any constituent material layers which are being measured, and said band, by reason of observed changes in its length, providing a correction factor for calculating true volumes of constituent material layers being measured.
In accordance with a further embodiment of the invention there is provided, for use in measuring blood constituent counts in a centrifuged sample of :blood, apparatus comprising a transparent tube h;aving : a bore which is of substantially constant diameter, and an elongated float in said tube bore, said float ~having a substantially constant cross sectional area which is smaller than the cross sectional area of said bore tube whereby a free space annulus is provided : between said float and said tube bore, said float and ~: ~ : tube bore being sized to provide said annulus with a 35~ theoretlcal target thickness, and said float having a :::: :: :
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- 3b -specific gravity such that said float will be buoyant in the red cell layer of a centrifiged blood sample and extend upwardly through the white cell and plate-let layers in the blood sample and into the plasma layer, whereby the white cell and platelet layers will be situated in said annulus and will be physically elongated in the direction of the axis of the tube, and means in said tube forming a reference band having a known volume such that said reference band, when disposed in said annulus, will have a predetermined standard target length when said annulus has said theore-tical target thickness so that variations in the actual measured length of said band will vary inversely to variations in the thickness of said annulus, whereby a correction factor for use in calculati.ng true blood counts of layers measured can be derived by dividing the measured band length into said band predetermined standard target length.
From a different aspect and in accordance with the invention there is provided a method for measuri.ng volumes of constituent material layers in a centrifuged material mixture, said method comprising the steps of:
(a) providing a transparent tube;
~: 25 (b) placing the material mixture in said tube;
(c) providing an elongated float in said tube which is operable to combine with said tube to form an annulus in said tube, said tube and said float : 30 being sized so as to provide said annulus with a ~ ~ . theoretical target thickness defined by a nominal OD
:~ ~ : on:the float and a nominal ID in the tube;
(d) providing a known volume of a material for forming a reference band in said tube, said materiaI having a specific gravity which will cause .
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- 3c - 1 3 1 1 6 24 said material to coalesce in said annulus to form said reference band therein, and said reference band having a standard target length when said annulus has said theoretical target thicknessi 5(e) centrifuging said tube;
(f) measuring lengths of any constituent material layers formed in said annulus and measuring the length of said reference band in said annulus; and (g) comparing the measured length of said 10reference band with said standard target length thereof to determine whether the thickness of said annulus deviates from said theoretical target thick-ness and then applying any resultant correction factor to -the measured lengths of the constituent material 15layers to determine the true lengths of the con-stituen-t material layers.
In accordance with a still further embodi-ment of the invention there is provided a method for determining whether an annulus has a radial thickness 20which deviates from a predetermined target thickness, said method comprising the steps of:
(a) providing a transparent tube;
(b) providing an elongated float in said tube, said float and said tube combining to form said 25annulus in said tube with the radial thickness of said annulus being defined by the difference between the ID
of said tube and the OD of said float;
(c) positioning a known volume of a flowable material in said annulus and confining said flowable 30material to said annul:us so that said flowable material forms a reference band in said annulus which reference band has a length as measured axially of : said tube which equals a predetermined standard target length when the radial thickness of the annulus equals 35sald predetermined target thickness; and ~ :.
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~ , -`` 131 1624 - 3d -(d) measuring the actual length of said reference band to determine whether the actual measured length of the band deviates from the standard target length thereby providing an indication of the manner and extent of any deviations of the annulus radial -thickness from the predetermined target thick-ness of said annulus.
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These and other objects and advantages will become more readily apparent from the following detailed description of a preferred embodiment of the invention when taken in conjunction with the accompanying drawing which is an enlarged elevational view of a tube and float combination incorporating a correetion band in aeeordance with the invention.
In the drawing, the tube 2 is a glass eapillary tube whieh is formed with a nominal target ID or bore diameter of 0.066050 inch, the tube bore being designated by the broken lines 4. The bottom of the tube 2 is closed with a cap 6 after the blood sample has been drawn into the tube 2. The float 8 is formed from a plastic material having a specifie gravity whieh causes it to float in the red cell layer when the blood sample is centrifuged and is formed with a nominal target OD of 0.06285 ineh. After eentrifugation, the white eell layer, or buffy coat, will layer out into three separate bands on top of the red cell layer 10. The buffy coat 12 will layer out into a granulocyte layer 14, a leukocyte/monocyte layer 16, and a platelet layer 18. These buffy coat constituent layers 14, 16 and 18 will be differ-entially eolored beeause of a fluoreseent stain whieh ~; 25 is added to the blood sample prior to eentrifugation.
Above the buffy eoat eonstituents is the plasma layer 20, whieh is basieally water. The eorreetion band is denoted by the numeral 22, and is eomposed of a predetermined volume of plastie beads whieh have a mean specific gravity of about 1.035. The aetual volume of the beads in the tube 2 is relatively :":
unimportant, so long as enough beads are included to ereate a change in the length of the band 22 which is able to mirror signifieant variations in the thiekness of the annulus between the tube 2 and float 8, whieh ~`::
, variations are caused by dimensional variations in the tube and float. When the tube and float are at their nominal target diameters, the length of the correction band will be assigned a value of 100 in the micro-processor software. Thus, if the annulus has a thickness that is less than the nominal target thickness, then the correction band will be longer than the assigned 100 value. If, for example, the measured band length is 110, then the microprocessor will know that the other true band lengths will be calculated by dividing their apparent lengths, as measured, by 1.10, the relative measured length of the correction band. The microprocessor will be pre-programmed to perform this correction calculation for all of the measured layers. It will be appreciated that this use of a correction band which reflects variations from the norm in the annulus will result in accurate and true constituent layer measurements.
; An example of the operation of this inven-tion is as follows. A blood sample when run in a tube and float combination which had been formed with the target dimensions to produce an annulus of normal thickness displayed a hematocrit of 47.0; a granulocyte count of 4.0; a lymphocyte/monocyte count of 2.0; a platelet count of 350; and a control band of 100. When the same sample is run in a tube which is 0.00016 inch oversized in its bore, and a float which has an OD which is 0.00011 undersized, the following apparent counts will be made. The hematocrit count will measure 46.9; the granulocyte count will measure 3.68; the lymphocyte/monocyte count will measure 1.84;
the platelet count will measure 322; and a control band cound of 92. In every reading the microprocessor will compare the measured control band count to 100.
Thus, the comparison between 92 and 100 is made, and ::
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, '` . ' ~ .' ' : ,: , the microprocessor calculates the appropriate correction factor and applies it to the other band measurements to determine and display the true WBC
constituent (and to-tal WBC) counts as well as the platelet count. It will be noted that the hematocrit amount is not significantly altered by errant annulus dimensions because of ~he thickness of the RBC band, and because the float does not sink into the red blood cells to a significant extent.
It will be readily appreciated -that the technique of this invention will result in a considerable relaxation of manufacturing tolerances as applied to the tube bore diameter and the float OD.
The use of the self-adjusting control band provides the user with confidence that the displayed cell counts are accurate and statistically sound. The correction band is formed from microspheres which have a specific gravity that will ensure that the band will coalesce in an area in the tube which is outside of the constituent bands which are being measured. In a blood sample, for example, the red blood cells will have a mean specific gravity of about 1.0793; the granulocytes will have a specific gravity of about 1.0747; the lymphocyte/monocyte layer will have a specific gravity of about 1.0632; the platelets will have a specific gravity of about 1.0490; the beads, or other material forming the control will have a ;~ ~ specific gravity of about 1.0350; and the plasma has a specific gravity of about 1.0280.
Since many changes and variations of the disclosed embodiment of this invention may be used without departing from the inventive concept, it is not intended to limit the invention otherwise than as required by the appended claims.
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A technique has been developed to measure constituent layers in a complex material mixture by centrifuging a sample of the material mixture in a capillary or other tube which contains a float. The float is preferably cylindrical and of a specific gravity which causes it to settle into the centrifuged mixture to a degree which creates a free volume annulus in the tube into which the layer, or layers to be measured will settle. The layers to be measured are thus physically elongated, and can be more easily and accurately measured. This technique is described in U. S. Patent Nos. 4,027,660, issued June 7, 1977;
4,082,085 issued April 4, 1978; 4,156,570, issued May 29, 1979; and others.
This technique, as c1esc^ibed in the prior art, depends on the manufacture-'s ability &O hold the capillary tube ID's and the float OD's to very tight tolerances. The magnification factor for the elongated constituent layers, when the technique is used as preferred in its commercial form, is about 10.5. This means that any layer which is expanded by the technique will be 10.5 times longer using the float than it would be without using the float. In order to achieve this magnitude of elongation, the ' ~ tube ID will be maintained at 0.06605 inch, and the float OD will be maintained at 0.06285 inch. Thus the annulus is preferably only sixteen ten thousandths of ; 35 an inch thick. It will be appreciated that minor :
:, :
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: ~ : -- 2 - t3116~4 variations in either the tube ID or the float OD, especially if additive, can result in changes in the annulus thickness which can cause inaccurate readings.
For example, a tube ID which is slightly oversize, i.e., 0.00016 inch too large, plus a slightly undersized floa-t, i.e., 0.00011 too small will result in a reduction of the observed band lengths in the annulus of 8%.
This invention relates to a technique for providing an internal standard correction band in the tube which resides in the annulus after cen-trifugation, but separate from any constituent layers of the material which are to be measured. In a blood sample, the correction band may, for example, float on top of the lightest of the constituents being measured, i.e., the platelets, and would thus form an additional visible band adjacent to the platelets which band would have its length measured. The correction band is formed by placing a known volume of artificial beads, (or some other flowable material such as a liquid or gel which is immiscible with the ; blood, or other material being measured) which can be made from plastic, in the tube prior -to cen-trifugation. The beads will have a common controlled size, or a statistically repeatable heterogeniety and may be differentially colored, preferably fluorescent, so as to be readily contrasted with the other colored bands in the tube formed by the stained layered material constituents. The material from which the beads are made will have a specific gravity such that the beads will float on one of the constituent material layers away from those being measured, so as not to interfere with the constituent measurements being performed. As previously noted, in the blood ~ 35 sample, the beads will be made to float on the : ;
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_ 3 - I 3 1 ~ ~24 platelet layer. The volume of beads placed in the tube will be constant, such that the beads will form a correction band of known length when the tube ID and the float OD are made to specification. Any variations in the tube and float which enlarge or shrink the annulus will be reflected in the length of the correction band. The measurements can be made and the corrections applied in an instrument such as that disclosed in U. S. Patent No. 4,156,570; or that disclosed in U.S. Patent No. 4,558,947.
It is therefore an object of this invention to provide an improved technique for measuring centrifuged material constituent layers which employs means for identifying incorrect readings resulting from dimensional variations in the paraphenalia used to contain the samples.
It is a further object to provide an improved technique of the character described wherein ~; a correction band is formed in the tube which contains the sample being measured.
It is an additional object of this invention to provide an improved technique of the character described wherein the correction band is formed with a preset volume of artificial beads which settle into the measurement area of the tube but outside of the constituent layers which are being measured.
It is another object of this invention to provide an improved technique of the character described wherein the correction band expands or 30 ~ contracts in response to dimensional variations in the measurlng zone whereupon appropriate corrections can he made to the measured lengths of the constituent ; layers.
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In accordance with a particular embodiment of the invention there is provided, for use in measuring volumes of constituent material layers in a centrifuged material mixture having at least first and second adjacent material layers of different specific gravities, apparatus comprising a transparent tube having a bore which is of substantially constant diameter and an elongated float in said tube bore, said float having a substantially constant cross sectional area which is smaller than the cross sectional area of said tube bore, said float combining with said tube bore to form a free space annulus in said tube, said free space annulus being operable to receive and elongate at least one of said constituent `
layers, and means in said tube forming a known volume reference band whose length, as measured axially of the tube, varies inversely to the volume of the annulus, said band being positioned outside of any constituent material layers which are being measured, and said band, by reason of observed changes in its length, providing a correction factor for calculating true volumes of constituent material layers being measured.
In accordance with a further embodiment of the invention there is provided, for use in measuring blood constituent counts in a centrifuged sample of :blood, apparatus comprising a transparent tube h;aving : a bore which is of substantially constant diameter, and an elongated float in said tube bore, said float ~having a substantially constant cross sectional area which is smaller than the cross sectional area of said bore tube whereby a free space annulus is provided : between said float and said tube bore, said float and ~: ~ : tube bore being sized to provide said annulus with a 35~ theoretlcal target thickness, and said float having a :::: :: :
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131 162~
- 3b -specific gravity such that said float will be buoyant in the red cell layer of a centrifiged blood sample and extend upwardly through the white cell and plate-let layers in the blood sample and into the plasma layer, whereby the white cell and platelet layers will be situated in said annulus and will be physically elongated in the direction of the axis of the tube, and means in said tube forming a reference band having a known volume such that said reference band, when disposed in said annulus, will have a predetermined standard target length when said annulus has said theore-tical target thickness so that variations in the actual measured length of said band will vary inversely to variations in the thickness of said annulus, whereby a correction factor for use in calculati.ng true blood counts of layers measured can be derived by dividing the measured band length into said band predetermined standard target length.
From a different aspect and in accordance with the invention there is provided a method for measuri.ng volumes of constituent material layers in a centrifuged material mixture, said method comprising the steps of:
(a) providing a transparent tube;
~: 25 (b) placing the material mixture in said tube;
(c) providing an elongated float in said tube which is operable to combine with said tube to form an annulus in said tube, said tube and said float : 30 being sized so as to provide said annulus with a ~ ~ . theoretical target thickness defined by a nominal OD
:~ ~ : on:the float and a nominal ID in the tube;
(d) providing a known volume of a material for forming a reference band in said tube, said materiaI having a specific gravity which will cause .
, .: -:
:
- 3c - 1 3 1 1 6 24 said material to coalesce in said annulus to form said reference band therein, and said reference band having a standard target length when said annulus has said theoretical target thicknessi 5(e) centrifuging said tube;
(f) measuring lengths of any constituent material layers formed in said annulus and measuring the length of said reference band in said annulus; and (g) comparing the measured length of said 10reference band with said standard target length thereof to determine whether the thickness of said annulus deviates from said theoretical target thick-ness and then applying any resultant correction factor to -the measured lengths of the constituent material 15layers to determine the true lengths of the con-stituen-t material layers.
In accordance with a still further embodi-ment of the invention there is provided a method for determining whether an annulus has a radial thickness 20which deviates from a predetermined target thickness, said method comprising the steps of:
(a) providing a transparent tube;
(b) providing an elongated float in said tube, said float and said tube combining to form said 25annulus in said tube with the radial thickness of said annulus being defined by the difference between the ID
of said tube and the OD of said float;
(c) positioning a known volume of a flowable material in said annulus and confining said flowable 30material to said annul:us so that said flowable material forms a reference band in said annulus which reference band has a length as measured axially of : said tube which equals a predetermined standard target length when the radial thickness of the annulus equals 35sald predetermined target thickness; and ~ :.
,,: ~
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~ , -`` 131 1624 - 3d -(d) measuring the actual length of said reference band to determine whether the actual measured length of the band deviates from the standard target length thereby providing an indication of the manner and extent of any deviations of the annulus radial -thickness from the predetermined target thick-ness of said annulus.
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These and other objects and advantages will become more readily apparent from the following detailed description of a preferred embodiment of the invention when taken in conjunction with the accompanying drawing which is an enlarged elevational view of a tube and float combination incorporating a correetion band in aeeordance with the invention.
In the drawing, the tube 2 is a glass eapillary tube whieh is formed with a nominal target ID or bore diameter of 0.066050 inch, the tube bore being designated by the broken lines 4. The bottom of the tube 2 is closed with a cap 6 after the blood sample has been drawn into the tube 2. The float 8 is formed from a plastic material having a specifie gravity whieh causes it to float in the red cell layer when the blood sample is centrifuged and is formed with a nominal target OD of 0.06285 ineh. After eentrifugation, the white eell layer, or buffy coat, will layer out into three separate bands on top of the red cell layer 10. The buffy coat 12 will layer out into a granulocyte layer 14, a leukocyte/monocyte layer 16, and a platelet layer 18. These buffy coat constituent layers 14, 16 and 18 will be differ-entially eolored beeause of a fluoreseent stain whieh ~; 25 is added to the blood sample prior to eentrifugation.
Above the buffy eoat eonstituents is the plasma layer 20, whieh is basieally water. The eorreetion band is denoted by the numeral 22, and is eomposed of a predetermined volume of plastie beads whieh have a mean specific gravity of about 1.035. The aetual volume of the beads in the tube 2 is relatively :":
unimportant, so long as enough beads are included to ereate a change in the length of the band 22 which is able to mirror signifieant variations in the thiekness of the annulus between the tube 2 and float 8, whieh ~`::
, variations are caused by dimensional variations in the tube and float. When the tube and float are at their nominal target diameters, the length of the correction band will be assigned a value of 100 in the micro-processor software. Thus, if the annulus has a thickness that is less than the nominal target thickness, then the correction band will be longer than the assigned 100 value. If, for example, the measured band length is 110, then the microprocessor will know that the other true band lengths will be calculated by dividing their apparent lengths, as measured, by 1.10, the relative measured length of the correction band. The microprocessor will be pre-programmed to perform this correction calculation for all of the measured layers. It will be appreciated that this use of a correction band which reflects variations from the norm in the annulus will result in accurate and true constituent layer measurements.
; An example of the operation of this inven-tion is as follows. A blood sample when run in a tube and float combination which had been formed with the target dimensions to produce an annulus of normal thickness displayed a hematocrit of 47.0; a granulocyte count of 4.0; a lymphocyte/monocyte count of 2.0; a platelet count of 350; and a control band of 100. When the same sample is run in a tube which is 0.00016 inch oversized in its bore, and a float which has an OD which is 0.00011 undersized, the following apparent counts will be made. The hematocrit count will measure 46.9; the granulocyte count will measure 3.68; the lymphocyte/monocyte count will measure 1.84;
the platelet count will measure 322; and a control band cound of 92. In every reading the microprocessor will compare the measured control band count to 100.
Thus, the comparison between 92 and 100 is made, and ::
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.
, '` . ' ~ .' ' : ,: , the microprocessor calculates the appropriate correction factor and applies it to the other band measurements to determine and display the true WBC
constituent (and to-tal WBC) counts as well as the platelet count. It will be noted that the hematocrit amount is not significantly altered by errant annulus dimensions because of ~he thickness of the RBC band, and because the float does not sink into the red blood cells to a significant extent.
It will be readily appreciated -that the technique of this invention will result in a considerable relaxation of manufacturing tolerances as applied to the tube bore diameter and the float OD.
The use of the self-adjusting control band provides the user with confidence that the displayed cell counts are accurate and statistically sound. The correction band is formed from microspheres which have a specific gravity that will ensure that the band will coalesce in an area in the tube which is outside of the constituent bands which are being measured. In a blood sample, for example, the red blood cells will have a mean specific gravity of about 1.0793; the granulocytes will have a specific gravity of about 1.0747; the lymphocyte/monocyte layer will have a specific gravity of about 1.0632; the platelets will have a specific gravity of about 1.0490; the beads, or other material forming the control will have a ;~ ~ specific gravity of about 1.0350; and the plasma has a specific gravity of about 1.0280.
Since many changes and variations of the disclosed embodiment of this invention may be used without departing from the inventive concept, it is not intended to limit the invention otherwise than as required by the appended claims.
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,- - : :
Claims (11)
1. For use in measuring volumes of constituent material layers in a centrifuged material mixture having at least first and second adjacent material layers of different specific gravities, apparatus comprising a transparent tube having a bore which is of substantially constant diameter and an elongated float in said tube bore, said float having a sub-stantially constant cross sectional area which is smaller than the cross sectional area of said tube bore, said float combining with said tube bore to form a free space annulus in said tube, said free space annulus being operable to receive and elongate at least one of said constituent layers, and means in said tube forming a known volume reference band whose length, as measured axially of the tube, varies inversely to the volume of the annulus, said band being positioned outside of any constituent material layers which are being measured, and said band, by reason of observed changes in its length, providing a correction factor for calculating true volumes of constituent material layers being measured.
2. The apparatus of Claim 1 wherein said reference band is formed by a known volume of resinous particles placed in said tube prior to centrifuging the material mixture.
3. The apparatus of Claim 2 wherein said resinous particles are microspheres.
4. The apparatus of Claim 2 wherein said resinous particles have a specific gravity which is less than the specific gravity of the lightest of the constituent material layers being measured.
5. The apparatus of Claim 4 wherein said resinous particles are differentially colored.
6. For use in measuring blood constituent counts in a centrifuged sample of blood, apparatus comprising a transparent tube having a bore which is of substantially constant diameter, and an elongated float in said tube bore, said float having a sub-stantially constant cross sectional area which is smaller than the cross sectional area of said bore tube whereby a free space annulus is provided between said float and said tube bore, said float and tube bore being sized to provide said annulus with a theoretical target thickness, and said float having a specific gravity such that said float will be buoyant in the red cell layer of a centrifiged blood sample and extend upwardly through the white cell and platelet layers in the blood sample and into the plasma layer, whereby the white cell and platelet layers will be situated in said annulus and will be physically elongated in the direction of the axis of the tube, and means in said tube forming a reference band having a known volume such that said reference band, when disposed in said annulus, will have a predetermined standard target length when said annulus has said theoretical target thickness so that variations in the actual measured length of said band will vary inversely to variations in the thickness of said annulus, whereby a correction factor for use in calculating true blood counts of layers measured can be derived by dividing the measured band length into said band predetermined standard target length.
7. The apparatus of Claim 6 wherein said reference band is formed from a material having a specific gravity which is less than the specific gravity of the platelets in the blood sample.
8. The apparatus of Claim 7 wherein said reference band material has a specific gravity which is greater than the specific gravity of the plasma in the blood sample.
9. A method for measuring volumes of con-stituent material layers in a centrifuged material mixture, said method comprising the steps of:
(a) providing a transparent tube;
(b) placing the material mixture in said tube;
(c) providing an elongated float in said tube which is operable to combine with said tube to form an annulus in said tube, said tube and said float being sized so as to provide said annulus with a theoretical target thickness defined by a nominal OD
on the float and a nominal ID in the tube;
(d) providing a known volume of a material for forming a reference band in said tube, said material having a specific gravity which will cause said material to coalesce in said annulus to form said reference band therein, and said reference band having a standard target length when said annulus has said theoretical target thickness;
(e) centrifuging said tube;
(f) measuring lengths of any constituent material layers formed in said annulus and measuring the length of said reference band in said annulus; and (g) comparing the measured length of said reference band with said standard target length thereof to determine whether the thickness of said annulus deviates from said theoretical target thickness and then applying any resultant correction factor to the measured lengths of the constituent material layers to determine the true lengths of the constituent material layers.
(a) providing a transparent tube;
(b) placing the material mixture in said tube;
(c) providing an elongated float in said tube which is operable to combine with said tube to form an annulus in said tube, said tube and said float being sized so as to provide said annulus with a theoretical target thickness defined by a nominal OD
on the float and a nominal ID in the tube;
(d) providing a known volume of a material for forming a reference band in said tube, said material having a specific gravity which will cause said material to coalesce in said annulus to form said reference band therein, and said reference band having a standard target length when said annulus has said theoretical target thickness;
(e) centrifuging said tube;
(f) measuring lengths of any constituent material layers formed in said annulus and measuring the length of said reference band in said annulus; and (g) comparing the measured length of said reference band with said standard target length thereof to determine whether the thickness of said annulus deviates from said theoretical target thickness and then applying any resultant correction factor to the measured lengths of the constituent material layers to determine the true lengths of the constituent material layers.
10. The method of Claim 9 wherein the specific gravity of said material forming said band is less than the specific gravities of any of the constituent material layers being measured.
11. A method for determining whether an annulus has a radial thickness which deviates from a predetermined target thickness, said method comprising the steps of:
(a) providing a transparent tube;
(b) providing an elongated float in said tube, said float and said tube combining to form said annulus in said tube with the radial thickness of said annulus being defined by the difference between the ID
of said tube and the OD of said float;
(c) positioning a known volume of a flowable material in said annulus and confining said flowable material to said annulus so that said flowable material forms a reference band in said annulus which reference band has a length as measured axially of said tube which equals a predetermined standard target length when the radial thickness of the annulus equals said predetermined target thickness; and (d) measuring the actual length of said reference band to determine whether the actual measured length of the band deviates from the standard target length thereby providing an indication of the manner and extent of any deviations of the annulus radial thickness from the predetermined target thickness of said annulus.
(a) providing a transparent tube;
(b) providing an elongated float in said tube, said float and said tube combining to form said annulus in said tube with the radial thickness of said annulus being defined by the difference between the ID
of said tube and the OD of said float;
(c) positioning a known volume of a flowable material in said annulus and confining said flowable material to said annulus so that said flowable material forms a reference band in said annulus which reference band has a length as measured axially of said tube which equals a predetermined standard target length when the radial thickness of the annulus equals said predetermined target thickness; and (d) measuring the actual length of said reference band to determine whether the actual measured length of the band deviates from the standard target length thereby providing an indication of the manner and extent of any deviations of the annulus radial thickness from the predetermined target thickness of said annulus.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US068,572 | 1987-07-01 | ||
| US07/068,572 US4774965A (en) | 1987-07-01 | 1987-07-01 | Material layer volume determination with correction band |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1311624C true CA1311624C (en) | 1992-12-22 |
Family
ID=22083406
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000570818A Expired - Fee Related CA1311624C (en) | 1987-07-01 | 1988-06-30 | Material layer volume determination with correction band |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4774965A (en) |
| EP (1) | EP0297237A3 (en) |
| JP (1) | JPS6429766A (en) |
| CN (1) | CN1016644B (en) |
| BR (1) | BR8803213A (en) |
| CA (1) | CA1311624C (en) |
| DK (1) | DK361088A (en) |
| FI (1) | FI882663A (en) |
| NO (1) | NO881074L (en) |
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| US3741011A (en) * | 1971-05-28 | 1973-06-26 | Evertz E | Method and apparatus for measuring the internal volume of moulds and similar cavity members |
| US3920557A (en) * | 1974-02-27 | 1975-11-18 | Becton Dickinson Co | Serum/plasma separator--beads-plus-adhesive type |
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| US4141654A (en) * | 1977-05-23 | 1979-02-27 | James V. Massey, III | Standard for calibrating and/or verifying instrument accuracy |
| US4567754A (en) * | 1985-03-29 | 1986-02-04 | Wardlaw Stephen C | Measurement of small heavy constituent layer in stratified mixture |
-
1987
- 1987-07-01 US US07/068,572 patent/US4774965A/en not_active Expired - Fee Related
-
1988
- 1988-03-10 NO NO88881074A patent/NO881074L/en unknown
- 1988-04-25 EP EP88106605A patent/EP0297237A3/en not_active Ceased
- 1988-05-09 JP JP63110619A patent/JPS6429766A/en active Pending
- 1988-06-06 FI FI882663A patent/FI882663A/en not_active Application Discontinuation
- 1988-06-29 BR BR8803213A patent/BR8803213A/en not_active Application Discontinuation
- 1988-06-30 CN CN88104006A patent/CN1016644B/en not_active Expired
- 1988-06-30 DK DK361088A patent/DK361088A/en not_active Application Discontinuation
- 1988-06-30 CA CA000570818A patent/CA1311624C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1033695A (en) | 1989-07-05 |
| NO881074L (en) | 1989-01-02 |
| CN1016644B (en) | 1992-05-13 |
| DK361088A (en) | 1989-01-02 |
| US4774965A (en) | 1988-10-04 |
| DK361088D0 (en) | 1988-06-30 |
| EP0297237A3 (en) | 1990-06-27 |
| FI882663A0 (en) | 1988-06-06 |
| BR8803213A (en) | 1989-01-17 |
| FI882663A (en) | 1989-01-02 |
| JPS6429766A (en) | 1989-01-31 |
| NO881074D0 (en) | 1988-03-10 |
| EP0297237A2 (en) | 1989-01-04 |
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