U.S. patent application number 14/041318 was filed with the patent office on 2014-03-06 for automated system and method for monitoring chromatography column performance, and applications thereof.
This patent application is currently assigned to Biogen Idec MA Inc.. The applicant listed for this patent is Biogen Idec MA Inc.. Invention is credited to Paul CUNNIEN, Joydeep GANGULY, Basav GHOSH, Asif LADIWALA, Robert SONG, Jorg THOMMES.
Application Number | 20140067308 14/041318 |
Document ID | / |
Family ID | 40901585 |
Filed Date | 2014-03-06 |
United States Patent
Application |
20140067308 |
Kind Code |
A1 |
CUNNIEN; Paul ; et
al. |
March 6, 2014 |
Automated System and Method for Monitoring Chromatography Column
Performance, and Applications Thereof
Abstract
The present invention provides automated systems and methods for
monitoring column performance in process chromatography, and
applications thereof. In an embodiment, column performance is
monitored by generating a plurality of process values such as, for
example, conductivity values or pH values with a detector during a
chromatography step transition between a first mobile phase liquid
and a second mobile phase liquid. The process values are
transformed to form transformed process values in which noise
present in the process values is suppressed. Column performance
parameters are calculated based on the transformed process values
and displayed during movement of the second mobile phase liquid
through the chromatography column. The displayed performance
parameters enable an operator to make a determination, for example,
regarding the quality of the chromatography column packing and
whether to continue the chromatography process or stop the
chromatography process until the chromatography column can be
repacked or replaced.
Inventors: |
CUNNIEN; Paul; (Cary,
NC) ; GANGULY; Joydeep; (Raleigh, NC) ; GHOSH;
Basav; (Cary, NC) ; LADIWALA; Asif; (San
Diego, CA) ; SONG; Robert; (Scituate, MA) ;
THOMMES; Jorg; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Biogen Idec MA Inc. |
Cambridge |
MA |
US |
|
|
Assignee: |
Biogen Idec MA Inc.
Cambridge
MA
|
Family ID: |
40901585 |
Appl. No.: |
14/041318 |
Filed: |
September 30, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12863955 |
Mar 10, 2011 |
8568586 |
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PCT/US09/00469 |
Jan 23, 2009 |
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14041318 |
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61023747 |
Jan 25, 2008 |
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Current U.S.
Class: |
702/100 |
Current CPC
Class: |
G01N 2030/562 20130101;
G01N 30/34 20130101; G01N 30/8617 20130101; G01N 2030/889 20130101;
G01N 33/00 20130101; G01N 30/88 20130101; G01N 30/8693
20130101 |
Class at
Publication: |
702/100 |
International
Class: |
G01N 33/00 20060101
G01N033/00 |
Claims
1. A method for monitoring or controlling chromatography column
performance, comprising: (1) generating a plurality of process
values with a detector during a chromatography step transition
between a first mobile phase liquid and a second mobile phase
liquid; (2) transforming the plurality of process values to form a
plurality of transformed process values, wherein the transforming
suppresses noise present in the plurality of process values by
reducing or filtering out spike noise; (3) calculating performance
parameters based on the plurality of transformed process values;
(4) displaying the performance parameters calculated in (3) during
movement of the second mobile phase liquid through the
chromatography column; and (5) making a determination that the
quality of the chromatography column packing is acceptable if a
performance parameter displayed in (4) is inside a specified range
of values.
2. The method of claim 1, wherein (1) comprises generating a
plurality of values selected from the group consisting of: a)
conductivity values; b) pH values; c) salt concentration values; d)
light absorption values; e) fluorescence values after excitation
with light of a suitable wavelength; f) refractive index values; g)
electrochemical response values; and h) mass spectrometry
values.
3. The method of claim 1, wherein (2) further comprises smoothing
the plurality of transformed process values.
4. The method of claim 1, wherein (2) further comprises calculating
a moving average for the plurality of transformed process
values.
5. The method of claim 1, wherein (3) comprises calculating one of
a plate number (N) value, a height equivalent to a theoretical
plate (HETP) value, and an asymmetry (As) value.
6. The method of claim 1, wherein (5) comprises making a
determination that the quality of the chromatography column packing
is unacceptable if a performance parameter displayed in (4) is
outside a specified range of values.
7. The method of claim 7, wherein said determination triggers an
automated alert system to notify users of said determination.
8. The method of claim 1, wherein transforming the plurality of
process values comprises applying a filter that operates by: (a)
comparing a process value (C.sub.i) with a corresponding process
value before (C.sub.i-1), and a corresponding process value after
(C.sub.i+1), and (b) replacing C.sub.i with C.sub.i+1 if C.sub.i+1
and C.sub.i-1 are identical or maintaining C.sub.i if C.sub.i+1 and
C.sub.i-1 are not identical.
9. The method of claim 1, wherein transforming the plurality of
process values comprises applying a filter that operates by: (a)
comparing a process value (C.sub.i) with a corresponding process
value before (C.sub.i-2), and a corresponding process value after
(C.sub.i+2), and (b) replacing C.sub.i with C.sub.i+2 if C.sub.i+2
and C.sub.i-2 are identical or maintaining C.sub.i if C.sub.i+2 and
C.sub.i-2 are not identical.
10. The method of claim 1, wherein transforming the plurality of
process values comprises applying a filter that operates by: (a)
comparing a process value (C.sub.i) with a corresponding process
value before (C.sub.i-2), and a corresponding process value after
(C.sub.i+1), and (b) replacing C.sub.i with C.sub.i+1 if C.sub.i-2
and C.sub.i+1 are identical or maintaining C.sub.i if C.sub.i+1 and
C.sub.i-2 are not identical.
11. The method of claim 1, wherein transforming the plurality of
process values comprises applying a filter that operates by: (a)
comparing a process value (C.sub.i) with a corresponding process
value before (C.sub.i-1), and a corresponding process value after
(C.sub.i+2), and (b) replacing C.sub.i with C.sub.i+2 if C.sub.1.,
and C.sub.i+2 are identical or maintaining C.sub.i if C.sub.i+2 and
C.sub.i-1 are not identical.
12. The method of claim 1, wherein transforming the plurality of
process values comprises applying one or more filters as defined in
any of claims 12-15 several times and in an alternating
fashion.
13. The method of claim 1, wherein transforming the plurality of
process values comprises applying a filter that operates by: (a)
comparing the sum of the process data values (.SIGMA..DELTA.C) and
the sum of the absolute process data values (.SIGMA. abs(.DELTA.C))
on each side of the maximum process sample value to identify the
presence of noise, and (b) replacing a process value (C.sub.i) that
includes noise with the minimum corresponding process value
selected from the group consisting of C.sub.i-3, C.sub.i-2,
C.sub.i-1, C.sub.i+1, C.sub.i+2 and C.sub.i+3.
14. The method of claim 1, wherein transforming the plurality of
process values comprises applying a filter that normalizes the
filtered process values.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of allowed U.S.
Non-Provisional application Ser. No. 12/863,955, having a
.sctn.371(c) date of Mar. 10, 2011, which is a national stage
application of PCT Application No. PCT/US09/00469, filed Jan. 23,
2009, which claims the benefit of U.S. Provisional Application No.
61/023,747, filed Jan. 25, 2008, all of which are incorporated
herein by reference in their entireties.
BACKGROUND OF THE PRESENT INVENTION
[0002] In the biopharmaceutical industry, process chromatography
using packed-bed columns is a key component in the manufacture of
complex biological products. In order to ensure product quality and
performance (e.g., biological activity), a high packing quality is
required. Accordingly, packing quality must be monitored and
packed-bed columns having an unacceptable packing quality must be
repacked or replaced.
[0003] Conventionally, three numeric parameters, namely, the number
of plates per column (N), height equivalent to a theoretical plate
(HETP), and asymmetry (As), are used to describe the quality of a
packed-bed column. These parameters are obtained by performing
pulse injections experiments or so-called HETP runs to assess the
degree of dispersion of an injected pulse of a non-adsorbed
solute.
[0004] In accordance with the pulse injection method for assessing
packing quality, a well-packed column should have a low HETP value
(e.g., less than 0.1 cm). A concept derived from N, HETP provides a
measure of broadening in relation to the distance a sample zone has
traveled in a chromatography column. A sample zone is the band of a
sample in the column, which appears as a peak when it exits the
column and is monitored by a detector (analyzer) that corresponds
to a certain property of the sample at the column outlet. The
mathematical definitions of N and HETP are:
N=V.sub.R.sup.2/.sigma..sup.2 (1),
and
HETP=L/N (2),
where V.sub.R is a retention volume, which is defined as the volume
delivered from the time when half the sample mass is applied to the
column to the time when half the sample mass has exited from the
column, .sigma..sup.2 is the variance of the exit volume
distribution, and N is a dimensionless number. L is the column
length (or height).
[0005] The injected tracer solution in the injected pulse method is
assumed to be a Dirac pulse, which has a height of C.sub.0 (the
initial tracer concentration) and, relative to the column volume,
an infinitesimal width. The initial condition corresponds to a
column containing only the mobile and stationary phase in
equilibrium but without any sample. The injected pulse method also
assumes that the distribution of the exit volume of the tracer in
the pulse follows, or closely follows, a normal (e.g., Gaussian)
distribution curve. Thus, the calculation of N is determined by
just three data points from the concentration-volume curve derived
during a pulse injection experiment (e.g., the volumes at the peak
and at the two points on the curve where the concentration of the
tracer is half of the peak concentration). For a normal density
function, the width of the curve at half peak height, W.sub.1/2, is
equal to 2.sigma. (2 ln 2).sup.1/2. Therefore,
.sigma.=W.sub.1/2/(2(ln 2).sup.2 (3).
Consequently, the calculation of N is given by:
N=V.sub.R.sup.2/(W.sub.1/2/(2(2 ln 2).sup.1/2).sup.2 (4),
N=V.sub.R.sup.2/(W.sub.1/2.sup.2/(4(2 ln 2))) (5),
N=5.545(V.sub.R/W.sub.1/2).sup.2 (6).
[0006] The value of HETP is obtained by using equation (2)
above.
[0007] The third parameter, As, used to describe the quality of a
packed-bed column, reflects the nature of the peak broadening (e.g.
fronting or tailing). As above, in the case of the pulse injection
method, just three data points from the entire dataset obtained
during a pulse injection experiment are used to determine the value
As. This value is calculated by taking the ratio (at 10 percent of
the peak height) of the distance between the peak apex and the back
side of the chromatographic curve to the distance between the peak
apex and the front side of the chromatographic curve. Accordingly,
an As value greater than 1 is a tailing peak, while an As value
less than 1 is a fronting peak. A well-packed column is assumed to
have an As value close to unity.
[0008] Because there are frequently situations where the peaks from
pulse injection experiments or HETP runs are not Gaussian, the N,
HETP, and As values calculated in accordance with the pulse
injection method often do not accurately describe the efficiency or
packing quality of a column. This is especially true for large
process chromatography columns, which routinely give peaks that do
not fit a Gaussian distribution. In fact, a calculation that is
based on a Gaussian distribution may be insensitive to changes in
bed condition or defects in column packing. The reason for this is
that if deviations occur somewhere in a transition other than at
the few data points used in the calculation, the deviations will
not be detected. For the same reason, the pulse injection method is
not robust because noise occurring at these critical points will be
weighted heavily and lead to incorrect calculations.
[0009] In addition to the above noted shortcomings, there are also
practical and economical reasons that make the pulse injection
method for determining packing quality poorly suited for use in
large-scale process chromatography. For example, when running a
pulse injection experiment, the volume of the pulse directly
affects the results. Since it is difficult to accurately introduce
a small pulse into a large column, the reproducibility of HETP runs
at the production scale is typically low, especially where subtle
changes in the column are concerned. This weakness can render the
parameters measured with the pulse injection method unsuitable for
use with statistical process control. Furthermore, HETP runs are
external to the manufacturing process, and the parameters derived
from them are not direct measures of the efficiency or packing
quality of the columns when the columns are actually used during
the manufacturing process. Column conditions can change between a
HETP run and an actual manufacturing process run. When the change
is sufficiently large, it can have potentially catastrophic effects
on the ensuing process chromatography. Finally, the pulse injection
method requires HETP runs to be performed on a regular basis to
check the efficiency of the column. These HETP runs consume process
resources and can cause delays in production.
[0010] What are needed are new monitoring systems and methods that
overcome the deficiencies noted above.
BRIEF SUMMARY OF THE PRESENT INVENTION
[0011] The present invention provides automated systems and methods
for monitoring column performance, and applications thereof. These
automated systems and methods are particularly well suited for
process chromatography.
[0012] In an embodiment, column performance is monitored by
generating a plurality of process values such as, for example,
conductivity values or pH values with a detector during a
chromatography step transition between a first mobile phase liquid
and a second mobile phase liquid. The process values are
transformed (e.g., by filtering and/or by smoothing) to form
transformed process values in which noise present in the process
values is suppressed. Column performance parameters are calculated
based on the transformed process values and displayed during
movement of the second mobile phase liquid through the
chromatography column. The displayed performance parameters enable
an operator to make a determination, for example, regarding the
quality of the chromatography column packing and whether to
continue the chromatography process or stop the chromatography
process until the chromatography column can be repacked or
replaced.
[0013] It is a feature of the present invention that it provides a
direct measure of chromatography column efficiency and/or packing
quality while a monitored column is being used to manufacture
product. It is also a feature of the present invention that it can
be used to determine chromatography column efficiency and/or
packing quality without interrupting or delaying product
manufacturing.
[0014] Particular embodiments of the present invention include, but
are not limited to a first method for monitoring chromatography
column performance, comprising: (1) generating a plurality of
process values with a detector during a chromatography step
transition between a first mobile phase liquid and a second mobile
phase liquid; (2) transforming the plurality of process values to
form a plurality of transformed process values, wherein the
transforming suppresses noise present in the plurality of process
values; (3) calculating performance parameters based on the
plurality of transformed process values; (4) displaying the
performance parameters calculated in (3) during movement of the
second mobile phase liquid through the chromatography column; and
(5) making a determination, based on the performance parameters
displayed in (4), regarding the quality of the chromatography
column packing.
[0015] In an embodiment, the present invention provides a second
method for controlling a chromatography process, comprising: (1)
generating a plurality of process values with a detector during a
chromatography step transition between a first mobile phase liquid
and a second mobile phase liquid; (2) transforming the plurality of
process values to form a plurality of transformed process values,
wherein the transforming suppresses noise present in the plurality
of process values; (3) calculating performance parameters based on
the plurality of transformed values during movement of the second
mobile phase liquid through a chromatography column; and (4)
stopping the chromatography process during movement of the second
mobile phase liquid through the chromatography column if a
performance parameter calculated in (3) is not within a specified
range of values.
[0016] In an embodiment of the present invention, step (1)
comprises generating a plurality of values selected from the group
consisting of (a) conductivity values; (b) pH values; (c) salt
concentration values; (d) light absorption values; (e) fluorescence
values after excitation with light of a suitable wavelength; (f)
refractive index values; (g) electrochemical response values; and
(h) mass spectrometry values.
[0017] In one embodiment of the present invention, step (2)
comprises filtering the plurality of process values. In another
embodiment, step (2) comprises smoothing the plurality of process
values. In still another embodiment, step (2) comprises calculating
a moving average for the plurality of process values.
[0018] In an embodiment of the present invention, step (3)
comprises calculating one of a plate number (N) value, a height
equivalent to a theoretical plate (HETP) value, and an asymmetry
(As) value.
[0019] In an embodiment, step (5) of the first method comprises
making a determination that the quality of the chromatography
column packing is unacceptable if a performance parameter
calculated in (4) is outside a specified range of values. In one
embodiment, an automated alert system is triggered to notify users
of the determination.
[0020] In an embodiment, step (5) of the first method comprises
making a determination that the quality of the chromatography
column packing is acceptable if a performance parameter calculated
in (4) is inside a specified range of values.
[0021] In embodiments, the chromatography column performance is
monitored during separation of a biomolecule or pharmacologic
compound. In one embodiment, the biomolecule or pharmacologic
compound is selected from the group consisting of (a) a protein;
(b) a nucleic acid; (c) a carbohydrate; (d) a lipid; (e) a
pharmacologically active small molecule; and (f) a hybrid or
variant form of any one of (a) through (e).
[0022] In embodiments, the chromatography method performed is
selected from the group consisting of (a) gas chromatography; (b)
liquid chromatography; (c) affinity chromatography; (d)
supercritical fluid chromatography; (e) ion exchange
chromatography; (f) size-exclusion chromatography; (g) reversed
phase chromatography; (h) two-dimensional chromatography; (i) fast
protein (FPLC) chromatography; (j) countercurrent chromatography;
(k) chiral chromatography; and (l) aqueous normal phase (ANP)
chromatography.
[0023] In an embodiment of the present invention, a first system
for monitoring chromatography column performance is provided. This
first system, comprising: a filter that operates on process values
corresponding to a chromatography step transition between a first
mobile phase liquid and a second mobile phase liquid and outputs
filtered process values; a smoothing module that operates on
filtered process values received from the filter and outputs
transformed process values; a parameter calculator that operates on
transformed process values received from the smoothing module and
outputs performance parameters indicative of a packing quality of
the chromatography column; and a display that displays the
performance parameters.
[0024] In an embodiment, the first system further comprising: a
data collection module that receives process values from a detector
and identifies which of the received process values correspond to
the chromatography step transition between the first mobile phase
liquid and the second mobile phase liquid.
[0025] In an embodiment of the first system, the data collection
module calculates normalized values for the received process values
corresponding to the chromatography step transition between the
first mobile phase liquid and the second mobile phase liquid.
[0026] In an embodiment of the first system, the smoothing module
calculates a moving average for the filtered values.
[0027] In an embodiment, the parameter calculator calculates one of
a plate number (N) value, a height equivalent to a theoretical
plate (HETP) value, and an asymmetry (As) value.
[0028] In an embodiment, the display is a computer monitor. The
display can include a graphical user interface that enables a user
to enter information regarding one of column volume and bed
height.
[0029] Further embodiments, features, and advantages of the present
invention, as well as the structure and operation of various
embodiments of the present invention, are described in detail below
with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES
[0030] The accompanying drawings, which are incorporated herein and
form a part of the specification, illustrate the present invention
and, together with the description, further serve to explain the
principles of the present invention and to enable a person skilled
in the pertinent art to make and use the present invention.
[0031] FIG. 1 is a diagram that illustrates an example process
chromatography system according to an embodiment of the present
invention.
[0032] FIG. 2 is a diagram that illustrates a portion of an example
process chromatography system according to an embodiment of the
present invention.
[0033] FIG. 3 is a diagram that illustrates an example system for
monitoring column performance according to an embodiment of the
present invention.
[0034] FIG. 4 and its continuation FIG. 4-1 are diagrams that
illustrate example process data for a chromatography step
transition.
[0035] FIG. 5A is a diagram that illustrates an example plot of a
chromatography step-up transition.
[0036] FIG. 5B is a diagram that illustrates an example normalized
plot of a chromatography step-up transition.
[0037] FIGS. 6A-B are graphs that illustrate example effects of a
filtering module according to the present invention.
[0038] FIGS. 7A-B are graphs that illustrate example effects of a
smoothing module according to the present invention.
[0039] FIGS. 8A-B are diagrams that illustrate example user
interfaces for a process chromatography system according to an
embodiment of the present invention.
[0040] The present invention is described with reference to the
accompanying drawings. The drawing in which an element first
appears is typically indicated by the leftmost digit or digits in
the corresponding reference number.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0041] The present invention provides automated systems and methods
for monitoring column performance, for example, in process
chromatography, and applications thereof. In the detailed
description of the present invention that follows, references to
"one embodiment", "an embodiment", "an example embodiment", etc.,
indicate that the embodiment described may include a particular
feature, structure, or characteristic, but every embodiment may not
necessarily include the particular feature, structure, or
characteristic. Moreover, such phrases are not necessarily
referring to the same embodiment. Further, when a particular
feature, structure, or characteristic is described in connection
with an embodiment, it is submitted that it is within the knowledge
of one skilled in the art to effect such feature, structure, or
characteristic in connection with other embodiments whether or not
explicitly described.
[0042] In an embodiment of the present invention, column
performance is monitored by generating a plurality of process
values such as, for example, conductivity values or pH values with
a detector during a chromatography step transition between a first
mobile phase liquid and a second mobile phase liquid. The process
values are transformed (e.g., by filtering and/or by smoothing) to
form transformed process values in which noise present in the
process values is suppressed. Column performance parameters are
calculated based on the transformed process values and displayed
during movement of the second mobile phase liquid through the
chromatography column. The displayed performance parameters enable
an operator to make a determination, for example, regarding the
quality of the chromatography column packing and whether to
continue the chromatography process or stop the chromatography
process until the chromatography column can be repacked or
replaced.
[0043] FIG. 1 is a diagram of an example process chromatography
system 100 according to an embodiment of the present invention. In
embodiments, system 100 is used, for example, to separate
biomolecules in a complex mixture, isolate a single biomolecule
and/or eliminate contaminants.
[0044] As shown in FIG. 1, system 100 includes a mobile phase
liquid supply system 102, a material injection system 104, a
chromatography or separation column 106, a process controller 108,
and an operator's station/computer 110 with a display 112. Mobile
phase liquid supply system 102 includes one or more reservoirs that
hold and supply the mobile phase liquid(s) used to drive raw
materials injected by material injection system 104 through column
106. Pumps belonging to mobile phase liquid supply system 102
impart a high pressure to the mobile phase liquid. In embodiments,
the pumps can be used to program the mobile phase liquid(s), for
example, by mixing two or more solvents in a particular ratio.
Material injection system 104 is used to inject, for example, raw
materials requiring separation and/or purification into the mobile
phase liquid(s). Chromatography separation column 106 is used to
separate and/or purify the injected raw materials.
[0045] In an embodiment, process controller 108 and operator's
station/computer 110 are used to control process chromatography
system 100. Process controller 108 and operator's station/computer
110, for example, react to operator inputs and control operation of
the various components of system 100 such as, for example, pumps
and valves. In embodiments, one or more elements of system 100, to
include portions of process controller 108 and/or operator's
station/computer 110, are implemented using a commercially
available digital automation system such as the DeltaV.TM. Digital
Automation System available from Emerson Process Management in
Austin, Tex.
[0046] In an embodiment, as described in more detail below, process
controller 108 and operator's station/computer 110 are used to
monitor the exit volume or output of column 106 and to make
determinations regarding the packing quality or efficiency of
column 106. If the packing quality or efficiency of a monitored
column is determined to be unacceptable, the operator can stop the
chromatography process until the questionable column is repacked or
replaced.
[0047] FIG. 2 is a diagram that illustrates an example detector 202
that is used to monitor the exit volume or output of chromatography
column 106 and provide process monitoring data to process
controller 108. The process data output by detector 202 is operated
upon by process controller 108 and/or operator's station/computer
110 to produce column dispersion parameters or performance
parameters. In an embodiment, the process data operated upon to
produce the performance parameters is data corresponding to a
chromatography step transition between a first mobile phase liquid
and a second mobile phase liquid. As used herein, a chromatography
step transition is a relatively abrupt change in the mobile phase
liquid provided to column 106 that is reflected by a change in a
measurable physical characteristic such as, for example,
conductivity, pH, etc. A step transition is typically in the form
of a breakthrough curve or a washout curve that is due to the
replacement of one mobile phase liquid (e.g., solution) by another
mobile phase liquid (solution) in a continuously flowing manner. As
shown in FIG. 5A, a step transition can be thought of as having
three phases (e.g., a baseline phase, a transition phase, and a
saturation or plateau phase), and is different than a pulse or a
gradient.
[0048] In embodiments, detector 202 can be any type of detector
that is capable of monitoring process properties useful for
determining the efficiency and/or packing quality of column 106. In
an embodiment, detector 202 is an electrical conductivity detector.
In other embodiments, detector 202 is an ultraviolet (UV) detector,
a fluorescence detector, a refractive detector, a pH detector,
etc.
[0049] FIG. 3 is a diagram that illustrates an example system 300
for monitoring column performance according to an embodiment of the
present invention. As shown in FIG. 3, system 300 includes a data
collection module 302, a filtering module 304, a smoothing module
306, a parameter calculator 308 and a memory 310. These modules
perform several functions, which include identifying series of
process values that correspond to chromatography step transitions,
suppressing/filtering out noise present in the process data values,
and calculating performance parameters that can be used to monitor
column performance.
[0050] As noted above, detector 202 is used to monitor liquid
exiting chromatography column 106 and output process monitoring
data. In an embodiment, the output of detector 202 (e.g.,
conductivity values) is provided to data collection module 302,
which may be a part of controller 108 and/or operator's
station/computer 110. Data collection module 302 temporarily stores
process data that it receives in a memory.
[0051] In embodiments, the exit volume or output of column 106 is
sampled on a regular basis and the sample values are sent to data
collection module 302. The sampling interval can be either a
time-based interval or a volume-based interval. This time-based
interval or volume-based interval is user selectable in embodiments
using a graphics user interface such as user interface 850
illustrated in FIG. 8B. In one embodiment, the default sample
interval is every two seconds, and data collection module 302 has
sufficient memory to store a minimum of 180 minutes of sampled data
(e.g., data collection module 302 can store at least 5400 sample
values). In an embodiment, a volume-based sample rate is used so
that the collected data and subsequent processing are not impacted,
for example, by starts and stops in the flow of mobile phase liquid
or by changes in the flow rate of the mobile phase liquid.
[0052] For the purpose of data collection to perform the transition
analysis described herein, the t=0 point (i.e., the 0th time point)
may be defined as the start of data collection in the phase and/or
the point at which the column is brought inline after a pump/system
flush. The actual start and end of data collection for transition
analysis purposes is an operator-defined transition window having a
default range of 0.2 to 2.2 column volumes, with the t=0 being the
origin point.
[0053] In embodiments of the present invention, the sampling rate
used to collect process data values during a chromatography step
transition is different (e.g., greater) than for other periods of
time so as to minimize the amount of memory needed to store data
collected for a particular process chromatography run.
[0054] FIG. 4 illustrates example data collected during a
chromatography step transition. As shown in FIG. 4, the data
includes conductivity values sampled using a volume-based sample
interval. In an embodiment, the step transition data that is used
for performance parameter calculations, as noted above, is chosen
to start at 0.2 column volume instead of at 0.0 column volume. This
is to avoid the response signals that are frequently present in the
0.0 to 0.2 column volume area due to a system flush but are not
related to the step transition.
[0055] In embodiments, the data range is selected to be within 0.2
to 2.2 column volumes because most step transitions are complete
within 2 column volumes. The extra 0.2 column volume at the end of
the range is to balance the distribution of data around the
retention volume (V.sub.R) since many step transitions have a
tailing. The retention volume is the volume delivered from the time
when half the sample mass is applied to the column to the time when
half the sample mass has exited from the column. A tailing is a
trailing shoulder of a main step transition. Potential causes of a
tailing include large void volume in the bed of a column as a
result of either uneven distribution of particle (e.g.,
chromatography medium) sizes or insufficient packing pressure, air
under the distribution net (frits), and partial clogging of nets
(frits) or chromatography media. In contrast to a tailing, a
fronting is a leading shoulder in front of a main step transition.
If a fronting is not seen in an original test (e.g., when the
column is freshly packed), but appears after reuse and is not
alleviated by column cleaning, the cause could be channeling in the
bed or development of headspace on top of the bed. Headspace could
be either the result of particle redistribution in the column or
compacting of the bed. Redistribution of particles happens if the
initial distribution of particle sizes in a pack bed is not uniform
throughout the column, for example, a column packed under gravity
settlement will form a particle size gradient, with large particles
settled at the bottom and fine particles on the top. Typically, if
a step transition takes more than 2.2 column volumes to complete,
the HETP value will be high and investigation is likely
warranted.
[0056] Filtering module 304 operates on process data received from
data collection module 302 and reduces/filters-out noise present in
the data. The filtering techniques implemented by filtering module
304 remove noise that might interfere with the accuracy of the
performance parameters calculated by parameter calculator 308 while
preserving the information contained in the data.
[0057] In an embodiment, filtering module 304 reduces or filters
out spike noise. Spike noise or spikes are typically present in
process data and can be caused, for example, by electrical surges
or other types of fluctuations in the electronic measuring
equipment of detector 202. These spikes are rises or dips in the
detector data that immediately fall back to the values before them.
Spikes usually have a relative small magnitude compared to the true
response signals. Any available filter or filter technique that
reduces/filters-out spike noise can be used.
[0058] In an embodiment of the present invention, filtering module
304 implements multiple cascading filters to eliminate/filter-out
noise. For example, in an embodiment, a first filter is applied to
process data values received from data collection module 302 that
operates by comparing the process value before (C.sub.i-1), and the
process value after (C.sub.i+1), the value being evaluated
(C.sub.i). If the values C.sub.i-1 and C.sub.i+1 are identical, the
value C.sub.i is replaced by the value C.sub.i+1, as shown in Table
1 below. If the values C.sub.i-1 and C.sub.i+1 are not identical,
the value C.sub.i is unchanged.
TABLE-US-00001 TABLE 1 Unfiltered Values Filtered Value C.sub.i-1
3.91 -- C.sub.i 3.92 3.91 C.sub.i+1 3.91 --
[0059] In the case of high density data sampling, which may occur,
for example, during chromatography step transitions, it may be
desirable to implement additional filtering as part of filtering
module 304. High density data sampling can lead to situations where
a spike may interfere with 2-3 process data values in a row. To
counter this, additional filtering can be implemented, for example,
by comparing a process value C.sub.i-2 before, and a process value
C.sub.i+2 after, the value C.sub.i being evaluated. If the values
C.sub.i-2 and C.sub.i+2 are identical, the value C.sub.i is
replaced by the value C.sub.i+2 as shown in Table 2 below. If the
values C.sub.i-2 and C.sub.i+2 are not identical, the value C.sub.i
is unchanged.
TABLE-US-00002 TABLE 2 Unfiltered Values Filtered Value C.sub.i-2
3.91 -- C.sub.i-1 3.92 -- C.sub.i 3.92 3.91 C.sub.i+1 3.91 --
C.sub.i+2 3.91 --
[0060] In embodiments, other filters are also applied to
suppress/filter-out spike noise such as the filters illustrated by
Table 3 and Table 4 below. For the filter illustrated by Table 3,
if the values C.sub.i-2 and C.sub.i+1 are equal, the value C.sub.i
is replaced by the value C.sub.i+1. For the filter illustrated by
Table 4, if the values C.sub.i-1 and C.sub.i+2 are equal, the value
C.sub.i is replaced by the value C.sub.i+2.
TABLE-US-00003 TABLE 3 Unfiltered Values Filtered Value C.sub.i-2
3.91 -- C.sub.i-1 3.92 -- C.sub.i 3.92 3.91 C.sub.i+1 3.91 --
TABLE-US-00004 TABLE 4 Unfiltered Values Filtered Value C.sub.i-1
3.91 -- C.sub.i 3.92 3.91 C.sub.i+1 3.92 -- C.sub.i+2 3.91 --
[0061] In embodiments, filters may also be implemented as part of
filtering module 304, for example, to suppress/filter-out noise
that may be present in the leading end or the trailing end of a
series of data values associated with a chromatography step
transition. Furthermore, the spike noise filters noted herein, as
well as other filters, may be applied to the process data values
received from data collection module 302 several times, and in an
alternating fashion, in order to further suppress/filter-out any
spike noise present in the process data values.
[0062] Because the influence of noise in calculating column
performance parameters is related to the distance of the noise from
V.sub.R, and the magnitude of the noise is of secondary importance,
filtering module 304 implements in embodiments one or more filters
that eliminates or suppresses random data spikes by pushing the
spikes outwards and away from the transition (e.g., a point one
column volume into the step transition). This is accomplished, for
example, by comparing the sum of the process data values
(.SIGMA..DELTA.C) and the sum of the absolute process data values
(.SIGMA. abs(.DELTA.C)) on each side of the transition to identify
the presence of noise, and forcing any identified noise outwards
away from the mid-point of the transition by replacing a value
(C.sub.i) that includes noise with the minimum value selected from
the values C.sub.i-3, C.sub.i-2, C.sub.i-1, C.sub.i+1, C.sub.i+2,
and C.sub.i+3. In embodiments, this filtering operation is used to
repeatedly operate on the process values to force the noise
outwards from the mid-point of the transition. In one embodiment
this filtering operation is repeated, for example, between five and
ten times. In embodiments, other filtering operations can be
interspersed with these five to ten filtering operations.
[0063] In one embodiment, a filtering operation that removes
concave and/or convex regions of step transition data is performed
ten times after the first occurrence of the above described filter
operation. Convex and/or concave regions, if present, are typically
found at the beginning and the end of a transition breakthrough
curve. The concave/convex removal filter is implemented by
adjusting identified convex and/or concave areas using adjacent
process values to adjust/flatten the concave/convex region.
[0064] In one embodiment, a filter is implemented that eliminates
or suppresses random data spikes by pushing the spikes outwards and
away from the point of the transition corresponding to the maximum
process sample value (e.g., the true mid-point of the step
transition rather than the one column volume transition point used
above). This filter is implemented similar to the filtering
technique described above by comparing the sum of the process data
values (.SIGMA..DELTA.C) and the sum of the absolute process data
values (.SIGMA. abs(.DELTA.C)) on each side of the maximum process
sample value to identify the presence of noise, and forcing any
identified noise outwards away from the maximum process sample
value by replacing a value (C.sub.i) that includes noise with the
minimum value selected from the values C.sub.i-3, C.sub.i-2,
C.sub.i-1, C.sub.i+1, C.sub.i+2, and C.sub.i+3.
[0065] As noted above, FIG. 5A is a diagram that illustrates an
example plot of a chromatography step-up transition. FIG. 5B is a
diagram that illustrates an example normalized plot of a
chromatography step-up transition. In an embodiment, the last
operation performed by filtering module 304 is to normalize the
filtered process values. As illustrated in FIG. 5B, normalized
values corresponding to a chromatography step transition can be
computed using the equation:
C.sub.normalized=(C-C.sub.min)/(C.sub.max-C.sub.min) (7)
where C.sub.normalized represents a normalized process (e.g.,
conductivity) value, C represents a data value that is to be
normalized, C.sub.min represents the minimum detector value of the
group of values being normalized, and C.sub.max represents the
maximum detector value of the group of values being normalized.
[0066] FIGS. 6A-B are graphs that illustrate example effects of a
filtering module 304 according to the present invention. Only the
first half of the step transition is shown for purposes of
clarity.
[0067] As illustrated by region 600 of the graph in FIG. 6A, the
raw process data output by a detector includes several spikes. As
illustrated by region 602 of the graph in FIG. 6B, these spikes are
removed when the raw process data is operated upon by filtering
module 304. The noise filtering performed by filtering module 304
removes spikes from the process data while leaving the trend
information contained in the transition unchanged. Importantly,
filtering module 304 eliminates the visible noise/spikes that, if
incorporated into the calculations performed by parameter
calculator 308, could have large influences on the outcome of the
calculations. Filtering module 304 enables the calculations
performed by parameter calculator 308 to be accurate and
robust.
[0068] Smoothing module 306 is used in embodiments to further
suppress noise present in the detector data values and to enhance
trend information. In one embodiment, smoothing module 306
accomplishes this by applying a moving average algorithm to
received data values. The degree of averaging used (e.g., the
number of data values averaged together to produce the moving
average) in embodiments is determined based on the density of the
data. Because the degree of noise reduction is proportional to the
square root of the number of data values that are being averaged,
noise suppression/reduction is not directly proportional to the
number of data values used in the moving average. In embodiments,
excessive averaging is avoided in order to ensure that trends in
the data are not obscured without an added benefit of increased
noise suppression. In embodiments, the number of data values used
to implement a moving average are varied depending on the product
being processed. Satisfactory results can be achieved using as few
as 2-4 data values to produce a moving average. In other
embodiments, as many as 10, 20 or 40 points can be used to provide
adequate smoothing without apparent flattening of the transition
data or degradation of the integrity of the data being
smoothed.
[0069] In one embodiment, smoothing module 306 takes a moving
average of every ten process data points for both volume values and
normalized process values to smooth the transition phase of a
chromatography step transition. The degree of averaging that allows
effective noise suppression is related to the density of the
data.
[0070] FIGS. 7A-B are graphs that illustrate example effects of a
smoothing module 306 according to the present invention. As
illustrated by the graph in FIG. 7A, the filtered process data does
not always clearly indicate a discernable trend (see, e.g.,
information in region 700). However, after smoothing by a smoothing
module 306 according to the present invention, trend data is
clearly shown in region 702 of the graph in FIG. 7B. The effect of
smoothing module 702 is to suppress or filter-out hidden noise and
enhance trending information contained in the process data.
[0071] As noted herein, in embodiments of the present invention,
filtering module 304 and smoothing module 306 can be programmed
using operator inputs that determine the type of filtering and
smoothing operations that are performed and how many iterations of
each filtering and smoothing operation are performed. Accordingly,
default values are specified for embodiments of the present
invention. In one embodiment, these operations and the default
values are as follows.
[0072] First, the process data received from data collection module
302 is filtered to remove random spikes in the data. For each
process value C.sub.i, process values C.sub.i+b and C.sub.i-c are
compared. If C.sub.i+b equals C.sub.i-c, the value C.sub.i+c is
used to replace the value C.sub.i. Otherwise, the value C.sub.i is
not altered. This filtering process is repeated (i.e., iterated) in
accordance with the width of an operator specified array [(b, c)].
If no input array is specified, the default array is Default: [(b,
c)]=[(1, 1), (2, 2), (1, 1), (2, 1), (1, 1), (1, 2), (1, 1), (1,
1)].
[0073] Next, the process data is filtered for noise by computing a
sum of the process values (.SIGMA..DELTA.C) and a sum of the
absolute process values (.SIGMA. abs(.DELTA.C)) on either side of
the volume equal to one column volume (e.g., a left hand side of
the transition (L: 0<V<1 Column Volume) and a right hand side
of the transition (R: V/1 Column Volume). For process value C.sub.i
on the left hand side, if .SIGMA..DELTA.C.sub.L,i=.SIGMA.
abs(.DELTA.C).sub.L,I, the value C.sub.i, is not altered.
Otherwise, C.sub.i is replaced with the minimum value
of(C.sub.i-n:C.sub.i+n), where n is a user-defined parameter. For
process value C.sub.i on the right hand side, if
.SIGMA..DELTA.C.sub.R,i=.SIGMA. abs(.DELTA.C).sub.R,I, the value
C.sub.i, is not altered. Otherwise, C.sub.i is replaced with the
maximum value of (C.sub.i-n:C.sub.i+n). This filtering operation is
repeated "r" times for different values of n, where r is an
operator-defined parameter. If no values are specified, the default
values are Default: n=3; r=1=width of array [n]
[0074] Concave and/or convex regions of the transition process data
are removed by computing values on the left side and the right side
of the one column volume value. These concaves or convexes are
typically caused by brief pauses in mobile phase liquid flow. For
the value C.sub.i on the left hand side, the value C.sub.i is set
to C.sub.i+1 if .DELTA.C.sub.i+1<0 and C.sub.i>C.sub.min.
Otherwise, C.sub.i is not altered. For the value C.sub.i on the
right hand side, C.sub.i is set to C.sub.i-1 if .DELTA.C.sub.i<0
and C.sub.i<C.sub.max. Otherwise, C.sub.i is not altered.
Finally, the new right hand side and left hand side values are
combined to get the new values for C. This filtering process is
iterated "m" times to smooth out convex/concave regions in the
transition data, where m is an operator-defined parameter. The
default value is Default: m=10.
[0075] The next noise filter to be applied is similar to that
described above. First, the values .SIGMA..DELTA.C and .SIGMA.
abs(.DELTA.C) are calculated on either side (i.e., left hand (L)
and right hand (R)) of the one column volume value. For C.sub.1 on
the left hand side, if .SIGMA..DELTA.C.sub.L,i=.SIGMA.
abs(.DELTA.C).sub.L,I, C.sub.i, is not altered. Otherwise, C.sub.i
is set to the minimum of (C.sub.i-n:C.sub.i+n). For C.sub.i on the
right hand side, if .SIGMA..DELTA.C.sub.R,i=.SIGMA.
abs(.DELTA.C).sub.R,I, C.sub.i is not altered. Otherwise, C.sub.i
is set to the maximum of (C.sub.i-n:C.sub.i+n). The filtering is
repeated "p" times for different values of n, where p and n are
operator-defined parameters. The default is Default: n=4, 5, 10,
20, 30, 30; p=6=width of array [n].
[0076] The next filtering technique applied is to compute
.SIGMA..DELTA.C and .SIGMA. abs(.DELTA.C) on either side of
V_.DELTA.C.sub.max (i.e., the volume value corresponding to
.DELTA.C.sub.max). For the value C.sub.i on the left hand side, if
.SIGMA..DELTA.C.sub.L,i=.SIGMA. abs(.DELTA.C).sub.L,I, the value
C.sub.i, is not altered. Otherwise, C.sub.i is set to C.sub.min.
For the value C.sub.i on the right hand side, if
.SIGMA..DELTA.C.sub.R,i=.SIGMA. abs(.DELTA.C).sub.R,I, C.sub.i is
not altered. Otherwise, C.sub.i is set to C.sub.max. The filtering
process is repeated "q" times, where q is an operator-defined
parameter. The default is Default: q=1.
[0077] After filtering by filtering module 304, the filtered
process values are normalized in the manner described above.
[0078] After normalization, the normalized, filtered process values
are smoothed by taking a moving average of the filtered process
values and the volume value to generate smoothed process values and
smoothed volume values. This is done using an N point moving
average algorithm where N is an operator-defined value. The default
value for N is Default: N=10.
[0079] In an embodiment, system 300 is capable of providing visual
representation (i.e., plots) for the following on display 112 of
C.sub.normalized (post-filtering) vs. V, .DELTA.C (post-filtering)
vs. V; and .DELTA.C (post-filtering and moving average smoothing)
vs. V. The operator has the option and flexibility to turn-on and
turn-off this plotting feature.
[0080] Parameter calculator 308 operates on the data values
received, for example, from smoothing module 306 and generates one
or more performance parameters 312 that can be used to evaluate the
packing quality and/or efficiency of chromatography column 106. In
an embodiment, parameter calculator 308 calculates one or more of
the performance parameters 312 (e.g., HETP, Skewness, N, Sigma,
Kurtosis, Tau, V.sub.R, etc.) illustrated in FIG. 3. Performance
parameters 312 are displayed in embodiments on a user interface
display so that an operator overseeing operation of chromatography
system 100 can monitor the performance parameters and determine
whether one or more performance parameter values exceed or are
outside of an acceptable range of values, thereby indicating that
chromatography column 106 may need to be repacked or replaced. In
an embodiment, when an operator identifies, for example, that a
performance parameter 312 exceeds or is outside of an expected
operating range of values, the operator checks the column or can
contact a more experienced individual such as, for example, a
supervisor to determine whether it is acceptable to continue the
chromatography process or whether the process should be
discontinued until the column can be repacked or replaced.
[0081] For purposes of calculating performance parameters 312,
process chromatography step transitions are treated as cumulative
frequency distribution curves of exit volume. Statistical
parameters of the exit volume distribution, and the subsequently
derived dispersion parameters, are directly calculated from the
step transition data, after being filtered and/or smoothed as
described herein. No assumption is made that the distribution of
exit volume follows any predetermined function. Thus, the present
invention can be adequately applied to step transitions of
different shapes. Furthermore, the Skewness parameter, which is
determined by taking into account the entire dataset from a step
transition without making any assumptions about the distribution of
the curve, is used to describe the asymmetry of the column. This is
markedly different from conventional asymmetry calculations, which
only uses the data points from a dataset.
[0082] In an embodiment, the values .DELTA.C and .DELTA.C/.DELTA.V
are computed based on the normalized process values
(C.sub.normalized) and the volume values (V) described above.
Calculations for N, HETP, Skewness, Kurtosis, .sigma..sup.2,
V.sub.R and V.sub.R1, .DELTA.C/.DELTA.V_max and .tau. (min) are
performed using the integral equations provided below, where C in
the equations refers to the normalized process values
(C.sub.normalized) described above.
V R 1 = V .DELTA. C max + .intg. 0 1 ( V - V .DELTA. C max ) C ( 8
) V R = .intg. 0 1 V C = V R 1 + .intg. 0 1 ( V - V R 1 ) C ( 9 )
.sigma. 2 = .intg. 0 1 ( V - V R ) C ( 10 ) Skewness = [ .intg. 0 1
( V - V R ) 3 c ] / ( .sigma. 2 ) 3 / 2 ( 11 ) Kurtosis = [ .intg.
0 1 ( V - V R ) 4 C ] / ( .sigma. 2 ) 2 ( 12 ) ##EQU00001##
[0083] Memory 310 is used to store performance parameters 312 as
well as other values that are useful for evaluating operation of
chromatography system 100. In embodiments, memory 310 can be any
type of available memory such as, for example, a computer hard
drive memory, flash memory, optical drive memory, tape memory, etc.
In an embodiment, memory 310 stores the transition analysis data
and the calculated results in an output file. This data can be
used, for example, to plot trends in the calculated transition
analysis parameters (e.g., N, HETP, Skewness, Kurtosis,
.sigma..sup.2, V.sub.R, etc.) across a set of process cycles and/or
batches. The operator has the option in embodiments to turn-on and
turn-off this plotting feature. In embodiments, calculated
performance parameters are stored in a continuous historian and a
batch historian data structure.
[0084] As will be understood given the description herein, system
300 can be used to cover both ends of each chromatography by
analyzing a step before a product/sample is loaded onto a column
and another step after the product/sample is eluted from the
column. Monitoring the step before loading enables an operator to
determine whether the column packing quality is sufficient for the
ensuing steps to continue. The monitoring step afterwards
indicates, for example, whether the packing quality was retained
throughout a purification process.
[0085] FIGS. 8A-B are diagrams that illustrate example user
interfaces for a process chromatography system according to an
embodiment of the present invention. In embodiments, the user
interfaces display performance parameters and other information
that enable a chromatography process operator to effectively and
efficiently manage operation of a chromatography system. In
particular, the performance parameters that are displayed permit an
operator to evaluate the quality of a chromatography column packing
and determine whether the column is performing as expected.
[0086] FIG. 8A is a diagram of an example graphical user interface
800. As shown in FIG. 8A, user interface 800 includes date-time
displays 802, performance parameter displays 804, a data collection
start button 806, and shortcut icons 808. The date-time displays
802 include a display that identifies the start date and time and
the stop date and time of the last chromatography transition
analysis run. Performance parameter displays 804 display several
performance parameters such as, for example, values for N, HETP,
skewness, etc. As described herein, the displayed performance
parameters provide process chromatography operators a reliable,
visual inspection of column performance, and they can be used to
determine when process adjustments are needed. The displayed
performance parameters also enable an operator to determination
whether the chromatography column should be repacked or replaced.
The data collection start ("Start Collection") button is used to
initiate the collection of process data. The shortcut icons 808 are
used to launch other applications and/or features of the present
invention described herein such as, for example, graphing and
control features.
[0087] FIG. 8B is a diagram of an example graphical user interface
850. As shown in FIG. 8B, user interface 850 includes date-time
displays 802, performance parameter displays 852, current
transition analysis status displays 854, and program adjustment
parameters 856. The date-time displays 802 display information
regarding the date and time of the last transition analysis run.
Performance parameter displays 852 display most or all of the
performance parameters described herein and includes several
parameters not shown on user interface 800. Current transition
analysis status displays 854 display the progress/status of a
current transition analysis run. Program adjustment parameters 856
are used for inputting and editing program parameters that control,
for example, operation of filtering module 304 and smoothing module
306 of system 300.
[0088] In embodiments of the present invention, user interfaces 800
and 850 can be modified to include additional features. For
example, in embodiments, when one of the displayed performance
parameters is outside of its normal operating range, the color of
the display is changed, thereby drawing the operator's attention to
the change.
[0089] As will become apparent to persons skilled in the relevant
art given the description herein, it is a feature of the present
invention that, in addition to being able to be used to recognize
conditions that require a column to be repacked such as, for
example, channel formation, a dried column, air bubble accumulation
under the flow distributor, etc., the invention can equally well be
used to confirm that a column does not require repacking. In many
instances, companies repack columns needlessly due to a lack of
objective evidence regarding the quality of the columns. By using
the present invention to confirm the quality of a column's packing,
companies can avoid the labor and material costs associated with
repacking columns that maintain their packing quality after
multiple reuses. In addition, the present invention can be used to
evaluate different packing procedures (e.g. gravity settlement
versus continuous flow of slurry).
[0090] Other features of the present invention described herein
include an ability to directly calculate column dispersion
parameters from a step transition without converting the transition
data into a peak, new techniques for reducing noise present in
process data, and using skewness to describe the asymmetry of a
transition. These features of the present invention, as well as
other features, enable one to calculate values of N, HETP, and
skewness accurately from step transition datasets. These calculated
values or performance parameters are both sensitive to subtle
changes that can develop in a column over time, and they are
capable of detecting gross integrity breaches in a column. The
performance parameters calculated in accordance with the present
invention can also be used, for example, to improve the statistical
process control (SPC) of production chromatography.
[0091] The systems and methods of the present invention are useful
for application to a wide-variety of chromatographic methods. For
example, some types of chromatographic methods that may be used
include, but are not limited to: gas; liquid (for example, but not
limited to, high performance liquid chromatography (HPLC));
affinity (for example, but not limited to, antibody affinity,
Fc-receptor affinity, and ligand-receptor affinity chromatography);
supercritical fluid; ion exchange; size-exclusion; reversed phase;
two-dimensional; fast protein (FPLC); countercurrent; chiral; and,
aqueous normal phase (ANP) chromatography.
[0092] The present invention is also particularly useful, for
example, in the production and manufacturing of biologics and
pharmaceutical (or pharmacological) compounds. For example, a small
sampling of the variety of different types of biologics and
pharmaceutical compounds that can be produced using methods and
systems of the present invention are shown below. The general
categories and specific examples of molecules and compounds listed
here are for purposes of exemplification only (to provide a
sampling of examples) and are not to be construed as limiting to
the present invention.
Examples of Biomolecules; Small and Large ("Macro") Molecules:
[0093] Proteins/polypeptides/peptides (for example, but not limited
to, recombinant proteins, recombinant fusion proteins,
antibodies/immunoglobulins, glycoproteins, peptide hormones,
complement proteins, coagulation factor proteins, enzymatic
proteins, receptor proteins, protein ligands, structural proteins,
metalloproteins);
[0094] Nucleic acids/polynucleotides (for example, but not limited
to, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
molecules including, for example, but not limited to, single-,
double-, triple-, and quadruple-stranded forms thereof, as well as
for example, but not limited to, A-, B- and Z-DNA forms of nucleic
acid molecules);
[0095] Carbohydrates/polysaccharides (for example, but not limited
to, monosaccharides, disaccharides, oligosaccharides,
polysaccharides);
[0096] Lipids (including, for example, but not limited to, fats,
oils, waxes, cholesterol, sterols, fat-soluble vitamins (such as
vitamins A, D, E, K), monoglycerides, diglycerides, phospholipids,
fatty acid esters, fatty acyls, glycerolipids,
glycerophospholipids, sphingolipids, sterol lipids, prenol lipids,
saccharolipids, polyketides);
[0097] Other small molecules, organic compounds, and
pharmacologically active molecules (for example, but not limited
to, amino acids, steroid hormones, amine-derived hormones);
and,
[0098] Hybrids and variants of any of the above (for example,
covalently-linked nucleic acid/polypeptide hybrids as wells as any
other combination or variation of the above compounds such as, for
example, labeled or "tagged" compounds (such as radiolabeled
compounds or compounds coupled with toxic or other therapeutic
components (e.g., pegylated compounds))).
[0099] The foregoing description of the specific embodiments will
so fully reveal the general nature of the invention that others
can, by applying knowledge within the skill of the art, readily
modify and/or adapt for various applications such specific
embodiments, without undue experimentation, and without departing
from the general concept of the present invention. Therefore, such
adaptations and modifications are intended to be within the meaning
and range of equivalents of the disclosed embodiments, based on the
teaching and guidance presented herein. It is to be understood that
the phraseology or terminology herein is for the purpose of
description and not of limitation, such that the terminology or
phraseology of the present specification is to be interpreted by
the skilled artisan in light of the teachings and guidance.
[0100] It is to be noted that while many of the examples features
described herein have made references to chromatography step-up
transitions, the present invention works equally well for both
step-up and step-down transition. Furthermore, the present
invention has been described above with the aid of functional
building blocks illustrating the implementation of specified
functions and relationships thereof. The boundaries of these
functional building blocks have been arbitrarily defined herein for
the convenience of the description. Alternate boundaries can be
defined so long as the specified functions and relationships
thereof are appropriately performed.
[0101] The breadth and scope of the present invention should not be
limited by any of the above-described exemplary embodiments, but
should be defined only in accordance with the following claims and
their equivalents. In addition, it is to be appreciated that the
Detailed Description section, and not the Summary and Abstract
sections, is intended to be used to interpret the claims. The
Summary and Abstract sections may set forth one or more but not all
exemplary embodiments of the present invention as contemplated by
the inventor(s), and thus, are not intended to limit the present
invention and the appended claims in any way.
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