Liquid purification or separation – Processes – Chromatography
Reexamination Certificate
2003-11-07
2004-08-24
Therkorn, Ernest G. (Department: 1723)
Liquid purification or separation
Processes
Chromatography
C210S659000, C210S198200, C095S082000
Reexamination Certificate
active
06780326
ABSTRACT:
TECHNICAL FIELD
The invention pertains to systems for column-based separation, and to methods of forming and utilizing packed columns. In specific embodiments, the invention pertains to methods of separating sample components.
BACKGROUND OF THE INVENTION
Column-based separations are frequently used for selectively removing components from mixtures. A first step in utilizing column-based technology is to form a column. Such can be accomplished within a column chamber. An exemplary prior art column chamber
10
is illustrated in FIG.
1
. Column chamber
10
comprises a longitudinal tubular section
12
having ends
14
and
16
. An inlet
18
is provided at end
16
, and an outlet
20
is provided at end
14
. Outlet
20
is obstructed by a porous filter
22
. Filter
22
can comprise, for example, a porous fritted glass or ceramic material.
A packed column is formed within chamber
10
by flowing a slurry comprising a mixture of matrix material
15
and carrier fluid
17
into inlet
18
. Matrix material
15
comprises a plurality of particulates, such as, for example, beads. Filter
22
is permeable to the carrier fluid and impermeable to the matrix material. Accordingly, as the slurry is flowed into column chamber
10
, matrix material
15
stacks against filter
22
to form a packed column
19
within tubular portion
12
.
The composition of carrier fluid
17
and matrix material
15
vary depending on the components that are intended to be separated by the packed column, and on the mixtures (samples) within which such components are found. Example matrix materials are Sr-resin, TRU-resin, and TEVA-resin, all of which can be obtained from EIChrom Industries, Inc., of Darien, Ill. Such matrix materials can have particle sizes in the range of, for example, 20-100 micrometers. Sr-resin, TRU-resin, and TEVA-resin can be used for, for example, selectively retaining radioactive materials. Specifically, Sr-resin can selectively retain strontium, TRU-resin can selectively retain americium, and TEVA-resin can selectively retain technetium. Slurries utilized for forming packed columns of Sr-resin, TEVA-resin, or TRU-resin can comprise, for example, 0.074 gram/mL of Sr-resin in 3 M HNO
3
; 0.142 grams/mL of TEVA-resin in 4 M HNO
3
; or 0.076 grams/mL of TRU-resin in 0.1 M HNO
3
, respectively.
Other materials that can be separated utilizing column-based systems are, for example, biological materials, such as nucleic acids. For instance, Tepnel Life Sciences sells polymeric micro-beads in diameters of approximately 60-100 micrometers which are covalently linked to specific oligonucleotide capture probes. Such micro-beads can be utilized for selective purification of nucleic acid fragments from a biological sample. For purposes of interpreting this disclosure and the claims that follow, the term “nucleic acid” is defined to include DNA nucleotides and RNA nucleotides, as well as any length polymer comprising DNA nucleotides or RNA nucleotides.
In addition to the above-discussed exemplary uses for column-based separations, numerous other applications for column-based separations are known to persons of ordinary skill in the art. The column-based separations generally have in common that a mixture in a first physical state (typically either a gas phase or a liquid phase) is flowed across a column matrix in a second physical state (typically either a liquid phase or a solid phase) to separate a component of the mixture from other materials of the mixture. Accordingly, the physical state of the matrix is generally different than the physical state of the component that is to be separated.
It can be desired to quantitate and/or otherwise analyze an amount of a component retained by a column matrix in a packed column. Accordingly, it can be desired to extract a retained component from a matrix materia. A method of extracting a retained component is to subject the column matrix to conditions which disrupt interactions between the matrix material and the component to thereby elute the component from the matrix material. In some applications, it is desirable to elute the retained material from the matrix material while the matrix material is still within a packed column, and in other applications it is desirable to remove the matrix material from a packed column before eluting the retained component. Additionally, there are some applications in which it is desirable to remove a matrix material from a packed column and thereafter analyze the matrix material
11
directly to quantitate and/or otherwise analyze an amount of a component retained on the matrix material.
A difficulty in utilizing column-based separations is in removing matrix material from a column chamber and subsequently repacking additional matrix material in the chamber to re-form a packed column.
There are numerous reasons for removing matrix material from a chamber. For instance, a matrix material of a packed column can be rendered unusable after an initial separation, or after an initial series of separations. A matrix material can be rendered unusable if it is degraded by fluids passed through the material during a separation. Also, the matrix material can be rendered unusable if it becomes contaminated by materials within a sample because such contamination can pose a risk of cross-contamination. For one or more of the above-discussed reasons, it is frequently desirable to repeatedly pack and unpack a column chamber with matrix material. Because packing and unpacking of column chambers is a time-consuming and laborious process, disposable columns are generally used. However, disposable columns still require labor for column changeout. Accordingly, it is desirable to develop new methods for packing and unpacking column chambers.
A recent improvement is described with reference to an apparatus
30
in
FIGS. 2 and 3
. Referring to
FIG. 2
, apparatus
30
comprises a tubular column chamber
32
having an inlet end
34
and an outlet end
36
. Outlet end
36
terminates proximate a plate
38
. Plate
38
can comprise a window configured to enable light to pass through for spectroscopic measurement of materials eluting from column chamber
30
. A matrix material
40
forms a packed column
42
within column chamber
32
. Packed column
42
has a lateral periphery defined by tubular chamber
32
. Packed column
42
can be formed by flowing a slurry of matrix material
40
and a carrier fluid into column chamber
32
. Outlet end
36
of column chamber
32
is displaced from plate
38
by a distance “D” sufficient to enable the carrier fluid to pass between column chamber
32
and plate
38
. However, the distance is less than an average width of matrix material
40
. Accordingly, matrix material
40
is retained in column chamber
32
and stacks against plate
38
to form packed column
42
.
FIG. 3
illustrates a method for removal of matrix material
40
from packed column
42
. Specifically, column chamber
32
is raised to enable matrix material
40
to pass beneath column chamber
32
and over plate
38
. Subsequently, a fluid is flowed through chamber
32
to push matrix material
40
out of column chamber
32
.
System
30
is improved relative to other methods of packing and unpacking columns in that it can provide a quick method for releasing packed column material from a column chamber, and can also provide a quick method for resetting the column chamber to be repacked with fresh matrix material. A difficulty with column system
30
is that it can be problematic to move an entirety of column chamber
32
during transitions between packing and unpacking operations. Further, precise tolerances are needed to hold beads and may leak beads. Discharged beads can undesirably pass through a detector. It can become increasingly difficult to move the entirety of column chamber
32
as a column-based separation is scaled up for larger operations. Accordingly, it is desirable to develop alternative methods for conveniently packing and unpacking column chambers, wherein a column chamber is not moved in transitioning between packing and
Brockman Fred J.
Bruckner-Lea Cynthia J.
Chandler Darrell P.
Egorov Oleg B.
Grate Jay W.
Battelle (Memorial Institute)
McKinley, Jr. Douglas E.
Therkorn Ernest G.
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