U.S. patent number 3,780,935 [Application Number 05/270,278] was granted by the patent office on 1973-12-25 for serum separating method.
This patent grant is currently assigned to Lukacs & Jacoby Associates. Invention is credited to Ian H. Jacoby, Michel J. Lukacs.
United States Patent |
3,780,935 |
Lukacs , et al. |
December 25, 1973 |
SERUM SEPARATING METHOD
Abstract
The separation of a sample of blood into serum and clot portions
is accomplished by means of a sealant consisting essentially of a
silicone fluid and silica dispersed therein. The separation is
accomplished by inserting a device containing a supply of the
sealant into a container holding a sample of the blood, the device
being characterized by a nozzle portion which extends into the
sample. The container and device are centrifuged so that it
separates into serum and clot portions and the sealant, having a
specific gravity of at least 1.026, separates the two portions.
Inventors: |
Lukacs; Michel J. (Goshen,
NY), Jacoby; Ian H. (Franklin Lakes, NJ) |
Assignee: |
Lukacs & Jacoby Associates
(Goshen, NY)
|
Family
ID: |
23030661 |
Appl.
No.: |
05/270,278 |
Filed: |
July 10, 1972 |
Current U.S.
Class: |
494/37; 210/789;
436/17; 494/38; 422/73; 494/23 |
Current CPC
Class: |
G01N
33/491 (20130101); Y10T 436/107497 (20150115) |
Current International
Class: |
G01N
33/49 (20060101); B01d 021/26 () |
Field of
Search: |
;106/287SB
;210/65,83,DIG.23 ;233/1,26 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Zaharna; Samih N.
Assistant Examiner: Mukai; Robert G.
Claims
What is claimed is:
1. A method of separating a sample of whole blood into serum and
clot portions comprising the steps of:
placing a quantity of whole blood into a container adapted to be
centrifuged;
inserting into said container a supply of a thixotropic, water
insoluble, substantially non-toxic sealant consisting essentially
of a silicone fluid and an inert filler dispersed therein,
said sealant having a specific gravity in the range of 1.026 to
1.092; and
centrifuging the blood into serum and clot portions until the
sealant forms a separator between said portions.
2. A method as defined in claim 1 wherein the inert filler is
silica.
3. A method as defined in claim 1 wherein the sealant has a
specific gravity in the range of 1.030 to 1.050.
Description
BACKGROUND OF THE INVENTION
This invention relates to a method, apparatus and composition of
matter for separating a blood sample by centrifuging into clot
portions, so that the serum may be quickly and readily removed
without contamination by the clot portion.
In recent years, biomedical and hospital laboratories have been
faced with increasing demands for more and more routine, as well as
specialized, diagnostic tests of blood samples. To meet the demands
of these tests equipment has been devised which automatically takes
a sample or specimen of blood which has been placed in a cup and
subjects it to a series of programmed tests which eventuate in a
readout on a record member. While these analyzers have increased
the efficiency of performing the necessary tests, a problem has
continued in finding ways and means of separating the serum from
the clot portion and removing the serum for analysis. Various types
of tube and plug devices have been suggested by the prior art. For
example, in U.S. Pat. No. 3,512,940, issued May 19, 1970, a device
consisting of a tube with a filter at one end thereof is inserted
into a second but larger diameter tube containing a sample of the
material desired to be filtered. In U.S. Pat. No. 3,508,653, issued
Apr. 28, 1970, a piston in the form of a solid plug is driven
through a centrifuged blood sample so as to position itself between
the serum and clot portions of the centrifuged sample. The tube
within the tube concept of U.S. Pat. No. 3,512,940 suffers from the
apparent deficiency of being costly and not readily adaptable for
disposal after a single use. The plug arrangement of U.S. Pat. No.
3,508,653 has the shortcoming of utilizing a solid plug member
which when subjected to a substantial centrifugal force, may also
develop radial forces acting against the side of the sample tube,
thus creating the danger of breakage.
SUMMARY OF THE INVENTION
The present invention provides a method by which the serum and clot
portions of the blood sample are separated quickly and effectively
by use of a simple device containing a liquid sealant consisting
essentially of a silicone fluid and silica. The sealant has a
specific gravity of at least 1.026 and preferably in the range of
1.030 to 1.050. As such, it will normally be at the proper specific
gravity to divide the serum and clot portions of the centrifuged
sample, sealing the clot in the container while the serum is
removed.
Accordingly, it is an object of the present invention to provide a
simple and effective method of obtaining a serum sample during
centrifuging.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded partially sectional view of a sample tube and
dispenser to carry out the process of the present invention;
FIG. 2 is a partially sectional side view of a sample tube and
dispenser to carry out the process of the present invention with
the dispenser inserted into a supply of blood;
FIG. 3 is a partially sectional view similar to that of FIG. 2
wherein the blood, sample tube and dispenser have been partially
subjected to centrifuging;
FIG. 4 is a view similar to FIG. 2 wherein the blood, the sample
tube and dispenser have been subjected to the complete centrifuging
step;
FIG. 5 is a sectional view of the sample tube with the separator in
place overlying the clot portion with the serum portion
removed;
FIG. 6 is an enlarged sectional view of the sealant dispenser
showing the sealant contained therein;
FIG. 7 is a top view of the dispenser of FIG. 6; and
FIG. 8 is a bottom view of the dispenser of FIG. 6.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
Referring to the drawings, a container 10 for holding a blood
sample is illustrated as a straight side wall sample tube 10 with
an open top end 11. Into the open top 11 is inserted a dispenser
12. The dispenser 12 has a flange member 14 which overlies the top
edge 16 of the side wall 18 of the container. The dispenser 12
includes a body portion 19 consisting of three ring sections 20, 22
and 24. Extending from the body 19 is an elongated nozzle portion
26 and at the end of the nozzle 26 is a tip 28 having an opening 30
therein. The purpose of the three rings 20, 22 and 24 is to permit
the dispenser 12 to be used with containers of various diameters.
Ring 20 has a shoulder 32 and a side wall 33, ring 22 a shoulder 34
and a side wall 35, and ring 24 has a shoulder 36 and a side wall
37. When using a narrow container, the dispenser bears on the top
edge of the side wall of the container at one of the shoulders 32,
34 or 36 and the side wall of the next smaller ring is parallel
with the inner side wall of the container. During centrifuging the
relationship between the inner surface of the container and the
side wall of the ring insures stability of the dispenser during
this period.
By utilizing a dispenser as illustrated herein, it is possible to
use one dispenser for varying diameter containers.
The body portion 19 of the dispenser has an open end 37 over which
is placed a seal 38. The seal 38 has a small opening 40 therein.
The seal 38 is not placed over the open end until a sealant 42 has
been placed in the dispenser.
The sealant 42 consists essentially of a silicone fluid with an
inert filler, such as silica, dispersed therein. The sealant should
have a specific gravity of at least 1.026 and preferably in the
range of 1.030 to 1.050.
The normal specific gravity of blood as determined by the
pycnometric method is considered to be in the range of 1.048 to
1.066 with averages of 1.052 to 1.063. After centrifuging the
specific gravity of the blood serum which separates from the
remainder of the blood is at least 1.026 and in the range of 1.026
to 1.031. The specific gravity of the heavier portions such as the
erythrocytes is 1.092 to 1.095.
In selecting a sealant it is necessary to select one which has a
specific gravity greater than that of the serum portion.
Accordingly, the sealant should have a specific gravity of at least
1.026. However, its specific gravity should not be too high so as
to cause it to layer somewhere in the clot portion. Such layering
would be of no practical use towards obtaining a separated serum
portion. A preferred sealant would have a specific gravity in the
range of 1.030 to 1.050.
The sealant is also preferably thioxtropic, water insoluble,
substantially non-toxic as well as substantially chemically inert
with respect to the constituents of the blood sample, particularly
those in the serum portion.
A preferred sealant formulation is as follows:
EXAMPLE I
Parts by weight Silicone fluid (dimethylpolysiloxane) 100 Silica
(specific gravity 2.65) 8 Silica (specific gravity 2.3) 6
The silicone fluid used in Example I was a dimethyl-polysiloxane
polymer made by Union Carbide Corporation and identified by the
designation L-45. It had a viscosity of 12,500 centistokes and a
specific gravity of about 0.973 at 25.degree.C. The silica with a
specific gravity of 2.65 was an amorphous silica having a particle
size of at least 75 percent being less than 5.0 microns. It was
made by Whittaker, Clark & Daniels and identified by the
designation "No. 31 Lo Micron". The silica with a specific gravity
of 2.3 was a hydrophobic amorphous silica having an average
particle size of about 20 millimicrons. It was made by Degussa Inc.
and identified by the designation Aerosil R 972.
The silicone fluid and the silica were mixed together to a
thixotropic condition with a resultant specific gravity of 1.045 to
1.050 to form the sealant.
The sealant was then placed in a dispenser of the type illustrated
in FIG. 6 in particular. The diameter of the flange was 0.70 inches
and the overall length 1.75 inches with the nozzle and tip being
1.10 inches. The opening in the tip was 0.032 inches. The filled
dispenser was placed in a standard sample tube having an overall
length of 3.875 inches with the shoulder 32 of the first ring
resting on the top of the tube side wall. The tube had previously
been filled with a whole blood specimen to within 1.10 inches of
the open end of the tube. The extent of the dispenser from shoulder
32 to the end of the tip was 1.5 inches. Thus, the dispenser tip
and part of the nozzle extended well into the blood sample.
The tube with the blood sample and dispenser was centrifuged for
approximately 10 minutes. After 5 minutes substantially all of the
sealant had passed from the dispenser. The sealant did not disperse
but instead remained homogeneous and settled as a layer between the
serum and clot portions of the centrifuged blood. It was noted that
the sealant settled as a substantially even layer between the two
portions since its specific gravity of 1.045 to 1.050 was less than
that of the clot portion and greater than that of the serum
portion. The sealant formed a tight seal against the inner wall of
the tube. Also noted was the fact that the sealant had mixed into
it, particularly in the portion near the clot portion, fibrant
matter which had been filtered out of the serum portion as the
sealant settled to its own specific gravity level.
The use of the dispenser which extended into the blood sample
expedited the procedure since it was not necessary for the sealant
to overcome the surface tension of the blood sample.
With the sealant in place it was possible to merely decant off the
serum portion with the clot being trapped behind the sealant.
The specific gravity of the sealant was determined by using a
copper sulfate method. The procedure consists of letting drops of
the sealant fall into a graded series of solutions of copper
sulfate of known specific gravity and noting whether the drops rise
or fall. The series used were graded at 0.005 intervals. Merely by
observing the drops it was possible to determine that the sealant
had a specific gravity between 1.045 and 1.050.
Another sealant formulation is as follows:
EXAMPLE II
Parts by weight Silicone fluid (dimethylpolysiloxane) 100 Silica
(specific gravity 1.95) 14
The silicone fluid of Example II is the same dimethylpolysiloxane
polymer of Example I. The silica with a specific gravity of 1.05
has an average particle size of 16 millimicrons. It is made by
Henlig & Co. and identified by the designation TRI-SIL 404. The
specific gravity is from 1.045 to 1.050.
Still another sealant formulation is as follows:
EXAMPLE III
Parts by weight Silicone fluid (ethyltriethoxysilane) 100 Silica
(specific gravity 2.65) 8 Silica (specific gravity 2.3) 20
The silicone fluid of Example II is an ethyl-triethoxysilane
monomer made by Union Carbide Corporation and identified by the
designation A-15. The silicas are the same as those used in Example
I.
The filler serves the dual purpose of making the silicone fluid
thixotropic and of adjusting the specific gravity to that which is
desired for the resultant sealant. In place of silica other inert
fillers which may be used in a fine powdered form are bentoniate,
alumina and talc. Others will also occur to those skilled in the
art.
Another silicone fluid which may be used is made by Dow Corning
Corporation and identified as 200 Fluid.
In selecting silicone fluids and fillers, one should select
materials which when mixed together will give the desired specific
gravity, be substantially non-toxic, water insoluble and
substantially chemically inert with respect to the constituents of
at least the serum portion.
The dispenser serves to meter out the sealant gradually and this
gradual metering provides sufficient lead time for the
centrifugation to take effect before the sealant is in place. If
the sealant were allowed to be positioned too soon some unwanted
matter, such as red cells or fibrilar like material, may be trapped
in the serum portion by the sealant.
While various examples have been described herein and one
embodiment illustrated on the drawings, those skilled in the art
may practice the invention in its various forms by other examples
and embodiments without departing from the scope of the claims
herein.
* * * * *