CA2000637A1 - Viscosity detection method for liquid chromatography systems with carrier liquids having time-varying viscosity - Google Patents
Viscosity detection method for liquid chromatography systems with carrier liquids having time-varying viscosityInfo
- Publication number
- CA2000637A1 CA2000637A1 CA002000637A CA2000637A CA2000637A1 CA 2000637 A1 CA2000637 A1 CA 2000637A1 CA 002000637 A CA002000637 A CA 002000637A CA 2000637 A CA2000637 A CA 2000637A CA 2000637 A1 CA2000637 A1 CA 2000637A1
- Authority
- CA
- Canada
- Prior art keywords
- time
- function
- viscosity
- delta
- carrier liquid
- 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.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
- G01N11/02—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by measuring flow of the material
- G01N11/04—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by measuring flow of the material through a restricted passage, e.g. tube, aperture
- G01N11/08—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by measuring flow of the material through a restricted passage, e.g. tube, aperture by measuring pressure required to produce a known flow
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/62—Detectors specially adapted therefor
- G01N2030/621—Detectors specially adapted therefor signal-to-noise ratio
- G01N2030/625—Detectors specially adapted therefor signal-to-noise ratio by measuring reference material, e.g. carrier without sample
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/26—Conditioning of the fluid carrier; Flow patterns
- G01N30/28—Control of physical parameters of the fluid carrier
- G01N30/32—Control of physical parameters of the fluid carrier of pressure or speed
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/44—Resins; rubber; leather
- G01N33/442—Resins, plastics
Abstract
TITLE
VISCOSITY DETECTION METHOD FOR LIQUID CHROMATOGRAPHY
SYSTEMS WITH CARRIER LIQUIDS HAVING TIME-VARYING
VISCOSTY
A method for measuring the inherent viscosity of individual solute components in a multicomponent sample in solution with a solvent.
VISCOSITY DETECTION METHOD FOR LIQUID CHROMATOGRAPHY
SYSTEMS WITH CARRIER LIQUIDS HAVING TIME-VARYING
VISCOSTY
A method for measuring the inherent viscosity of individual solute components in a multicomponent sample in solution with a solvent.
Description
fi;~7 TITL~
VISCOSITY DETECTION METHOD FOR LIQUID CHROMATOGRAPHY
SYSTEMS WITH CARRIER LIQUIDS HAVING TIME-VARYING
S VISCOSITY
RACKG~Q~ND OF TH~_L~V~NTTON
United States Patent No. 4,793,174 discloses a method for determining the intrinsic or inherent viscosity of a solute in solution with a solvent. In one embodiment, a gel permeation column separates a multicomponent sample into its separate solute components, each of wh~ch is subject to a separate viscosity determination.
In some applications, it may be desirable to separate a multicomponent sample into its separate solute components based on partitioning and chemical interaction, rather than molecular Qize. In such ; 20 ca~es, the gel permeation column described in the above-identified application could be~replaced, for example, with a column containing a packing mate~ial capable of binding each component of the multicomponent sample. The solvent flowing through the column could then be changed continuously with respect to some relevant chemical property, causing each component of the solute to elute sequentially under desired conditions of analysis time and experimental resolution. Under such circumstances, the viscosity of the solvent may, itself, vary from an initial to a final value, causing a varying "background" against which the solute viscosity is measured. It is an ob~ect of the present invention to provide a method for measuring the intrinsic or inherent viscosity of a solute in solution with such a solvent of varying viscosity.
.
, .- ~, .
,~ .r~ 7 SUMMARY OF ~HE TNvENTTON
The present invention provides a method for ; measurins the inherent viscosity of individual solute components in a multicomponent sample in solution with a solvent, comprising:
passing a stream of a carrier liquid having a viscosity which varies as a function of time at a flow rate R sequentially through ~1) means for separating said sample into its individual solute components~ (2) a first capillary tube and (3) a second capillary tube, which tubes are separated from each other by an offset volume ~V, where O~VSRT, where T is as defined below;
introducing into said stream of carrier liquid, upstream of said means for separating said sample lnto its individual solute components, a predetermined volume of a solut~on comprising the sample and the solvent, whereby said sample is separated ~nto its individual solute components, measuring, as a function of time, pressure differences oPl(t) and aP2(t) across said first and second capillary tubes, respectively, sa$d aPl(t) and ~P2(t) being characterized by a rise time T;
. 25 measuring, as a function of time, the concentration C(t) of the individual solute components : in the carrier liquid;
obtaining a function S(t), where S(t) - ln [~Pl~t)/~P2(t)~;
obtaining a function So(t), where So(t) - ln ~Pl(t)~P2(t)l when only carrier liquid is flowing through both the first and second capillary tubes;
obtaining a function I(t), where Itt) - ¦~S(t)-So~t)~dt; and relating C~t), I~t) and ~v to the inherent viscosity o~ the individual solute components.
:
"
":
.. : , . . . . . .... ... .
..
.. , ~, ... ..
'' ' . ` ~ . ' ':
`' " ::` ~' ' BRTEF DESC~L~ION QE T~_DRAWINGS
FIG. 1 is a stylized view of apparatus for carrying out the method of the present invention.
s FIG. 2 is a stylized plot showing viscosity, ~, of carrier liquid as a function of time, t.
FIG. 3 is a stylized plot of concentration, C, as a function of time, t, for the single solute component whose pressure difference effects are shown in FIG. 4.
FIG. 4 is a stylized plot of pressure differences oPl, and oP2 across first and second capillary tubes as functions of time, t, for a single solute component.
FIG. 5 is a stylized plot of ~Pl/~P2 as a function of time, t.
FIG. 6 is a stylized plot of the function S
as a function of time, t.
FIG. 7 is a stylized plot of the function SO
as a function of time, t.
FIG. ô is a stylized plot of the function [S-SO] as a function of time, t.
FIG. 9 is a stylized plot of the function I
as a function of time, t.
:
; 35 FIG. 10 is a stylized plot of inherent viscosity, ~nh, as a function of t~me, t.
.
.
, .~ :.
-, ' '~ :
- . ~ - . . ~
: ,: : , , ~f~ 37 D~E~ DE:SCRIPTION OF THE INVENTION
~eferring now to the drawing, in which like S reference numerals indicate li~e elements, there is seen in Flgure 1 an apparatus 10 in accordance with -, the present invention. Carrier liquids 12, 12' having viscosities ~1 and ~2, respectively, are pumped from - reservoirs 14, 14' by a pump/mixer 16 through a pulse dampener 18 to a sample injection valve 22. The pump/mixer iq set to mix the two carrier liquids 12, 12' at a predetermined rate. Figure 2 depicts a plot showing visco~iity of the mixed carrier liquid as a funct~on of time. The plot shows a linear increase from a predetermined minimum to a predetermined maximum. Nonlinear functions may also be used.
Referring again to Figure 1, the pump/mixer 16 may be any type of pump/m~xer which is used conventionally in liquid chromatography. An example of a suitable pump/mixer 16 ~s a Hewlett-Packard Modél 1050. The dampener 18 i-~ required only if a reciprocal piston-type pump is used. Typically, the dampener will be chosen to dampen high frequency pulses without impeding the overall flow rate of the mixed carrier : 25 liquids 12, 12'. The tubing utilized in the apparatus is not critical. Generally, any small internal diameter tubing which is substantially chemically inert with respect to the carrier liquids and solute may be utilized. Preferred tubings are made of stainless steel or Teflon~ ~polytetrafluoroethylene), which is available from i. E. I. du Pont de Nemours and Company, Wilmington, ,t,. Delaware.
The sample injection valve 22 may be a 2-position 6-port valve. A suitable valve is sold by Valco Instruments, Inc. (Houston, Texas) under the designation CV6UHPA.
.
. ~ . . , , : ~ , .
. : . :
. ,~. .:, . ~, .
IP~7 Conveniently, a syringe 24, containing a multicomponent solute in solvent t~sample solution"), may be utilized to fill sample loop 26 with sample solution. The sample injection valve 22 will be set to "load" position, which allows the mixed carrier liquid 12, 12' to flow across the valve, while allowing sample loop 26 to be filled from syringe 24.
After sample loop 26 is filled with sample solutio~, valve 22 will be set to "inject" position, which diverts the flow of mixed carrier liquid 12, 12' to sample loop 26. The sample solution will then be introduced into the flowing stream of mixed carrier liquid 12, 12', as a substantially localized volume.
Alternat~vely, the sample solution may be in~ected directly into the flowing stream of mixed carrier liquid 12, 12'.
The stream of flowing mixed carrier liquid 12, 12' havlng a t~me varying viscosity and containing the multicomponent solute will pass through means for separating the multicomponent solute into lts ~ndividual solute components. A preferred separating means is column 52 which may contain a packing material for which the individual solute components in ; the sample have varying affinities. Suitable packing materials include Zorbax~_ODS. Other suitable separating means include Zorbax~ C-8 columns; both are ! commercial products from E. I. du Pont de Nemours and Company, Wilmington, Delaware.
After entering column 52, the individual solute components will elute one by one as the viscosity of the carrier liquid changes from a first value ~A to a second value ~ A may be equal to ; or may equal some predetermined viscosity based on some initial composition using liquids 12 and 12'.
Similarly, ~8 may be equal to ~2 or may equal some predetermined viscosity based on a final composition using liquids 12 and 12'. It should be understood . .
. . ~ -.
.
~ .~ ,, .
lDfi37 that it is not necessarily the change in carrier liquid viscosity which causes sequential elution of the individual components, but rather the changing chemical and/or physical composition of the carrier liquid, which may, in turn, result in an unavoidable change in viscosity. It should also be understood that it is not necessary to change the chemical composition of carrier liquid for eluting solute components sequentially. Chromatographic separations using a carrier liquid of constant composition are called isocratic separations. Isocratic separations may often result in excessive analysis time and very uneven experimental resolution. These problems can sometimes be avoided by employing so-called temperature programming by which the temperature of the carrier liquid is changed with time, thereby resulting in a viscosity change with time.
The stream of flow~ng mixed carrier llquid 12, 12', now containing separated individual solute components, can be split at a ~unction 30, so that a portion of the stream passes through a concentration detector 32 into a waste receptacle 34 and another portion passes to first and second capillary tubes, discussed below. Alternatively, the concentration detector 32 can be place~ in series with the capillary tubes 36 and 42, discussed below. The concentration detector 32 may be any type of detector which is ` typically used in liquid chromatography. A preferred concentration detector 32 is a differential refractometer. Other types of concentration detectors such as ultraviolet or infrared devices also may be used, depending upon the particular type of solute whose viscosity is being measured. Figure 3 depicts the output of the concentration detector 32 as a function of time for an individual solute component.
Refarring again to Figure 1, the flowing mixed carrier liquid 12, 12' -- containing separated lndividual solute components -- will pass through a " . , - .
. ~; ,.
:-fi;~7 first capillary tube 36, across which differences in pressure as a function of time will be detected by transducer 38. The carrier liquid will continue to flow through an offset volume element 40 into a second capillary tube 42, across which differences in pressure as a function of time will be detected by transducer 44. Finally, the carrier liquid will be emptied into a waste receptacle 46.
The internal diameter of the capillary tubes 36, 42 is not critical. Generally, the internal diameter will be chosen to maximize the performance of the pressure transducers associated with each capillary tube. Generally, the internal diameter will be larger than 7~mil. It is preferred that capillary tubes 36 and 42 be as close to physically identical as possible.
The pressure transducers can be the well-known diaphragm type such as those manufactured by Celesco Transducers Products, Inc. (Conoga Park, California). Typically, the transducers 38, 44 are connected across their respective capillary tubes 36, 42 by means of "T" connectors. Each pressure transducer 38, 44 $s connected to its own amplification means 38', 44', respectively, with variable gain control. Preferably the amplification means comprises a DC amplifier. The variable gain controls are used to control the magnitude of the outputs from the two pressure transducers.
Specifically, the two gains will be adjusted to ` 30 provide equal outputs when the same carrier liquid is flowing through capillary tubes 36 and 42. Figure 4 depicts the pressure changes across capillary tubes 36, 42 as a function of time. It should be noted that the curves are identical except for a time offset.
Advantageously, the fluid circuit defined by the apparatus 10 will be placed in a bath (not shown) at a preselected temperature. The bath will .
:.
, . ~ . ~ .
. , : , - .
;37 help to minimize temperature gradients within the apparatus.
Referring again to Figure 1, the outputs from transducers 38 and 44 can be applied to the inputs (not shown) of a differential logarithmic amplifier 48. A suitable amplifier is a Burr Brown Log 100 JP. The output signal of the differential logarithmic amplifier 48 can be expressed by the following equation:
S(t) = ln loPl(t)/~P2(t)]
This output is a function of time. The output S(t) is then integrated over time.
The apparatus depicted in Figure 1 allows a stream of carrier liquid containing individual solute components to pass sequentially through two capillary tubeQ separated by a small offset volume. As each component passes through each capillary tube, the pressure difference across the tube wiil rise from a baseline to a maximum value ~n a characteristic rise time (T). As each compone~t leaves each capillary tube, the pressure difference across the tube will decay back to baseline in a characteristic decay time, which should approximate the rise time. After each component has passed through both capillary tubes, the respective pressure transducers will have generated two substantially identical pressure versus time curves, which curves are separated from one anotber by a time difference, aT, which is equal to the offset volume av divided by the flow rate R. When aT is sufficiently small, the two pressure versus time curves will be slightly displaced from one another, thereby allowing one curve to be used to approximate a 3s value on the other curve. Generally, this condition will be achieved when the offset volume ~v lies between O and RT.
.
, ~ ~ , fi3 To compensate for the contribution of ~P1~t~
and ~P2~t) which is caused not by the individual solute component, but by the change in viscosity of the mixed carrier liquid 12, 12', it is necessary to determine a function So(t) which reflects only the contribution of the mixed carrier liquid 12, 12' to aPl~t) and ~P2~t~. A convenient way to determine this function is to extrapolate the baseline of the S~t) curve through any sin~soidal responses. The resulting curve will represent So~t). Figure 7 depicts the result of such an extrapolation. The sinusoidal response of the solute is shown in dotted line~. The solid line represents the function So~t).
To calculate inherent viscosity, a new function [S(t)-So~t)] is formed. This function essentially subtracts the mixed carrier liquid 12, 12' baseline from the S~t) curve. Fiqure 8 depicts this new function, in which the sinuaoidal response ha~
been lowered to the baseline.
Next a function I~t) is obt~ined:
I~t)- ¦~S(t)-So(t)]dt.
Such a function is depicted in Figure 9.
Finally, for each individual solute component, the function I~t) is divided by C~t) fox that component.
; The height of the resulting curve represents inherent viscosity. The integration can be done by well-known manual computational methods or by an electronic integrator or digital computer.
:
,~:
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.: , ~ . , . , ., ,: : .
~, .......... .
: - . . , . . : ~ ~ . ~ . :
-: ..
- . ~ - -.
, ~ ~ . . : ,.
,, . . : ~ .
VISCOSITY DETECTION METHOD FOR LIQUID CHROMATOGRAPHY
SYSTEMS WITH CARRIER LIQUIDS HAVING TIME-VARYING
S VISCOSITY
RACKG~Q~ND OF TH~_L~V~NTTON
United States Patent No. 4,793,174 discloses a method for determining the intrinsic or inherent viscosity of a solute in solution with a solvent. In one embodiment, a gel permeation column separates a multicomponent sample into its separate solute components, each of wh~ch is subject to a separate viscosity determination.
In some applications, it may be desirable to separate a multicomponent sample into its separate solute components based on partitioning and chemical interaction, rather than molecular Qize. In such ; 20 ca~es, the gel permeation column described in the above-identified application could be~replaced, for example, with a column containing a packing mate~ial capable of binding each component of the multicomponent sample. The solvent flowing through the column could then be changed continuously with respect to some relevant chemical property, causing each component of the solute to elute sequentially under desired conditions of analysis time and experimental resolution. Under such circumstances, the viscosity of the solvent may, itself, vary from an initial to a final value, causing a varying "background" against which the solute viscosity is measured. It is an ob~ect of the present invention to provide a method for measuring the intrinsic or inherent viscosity of a solute in solution with such a solvent of varying viscosity.
.
, .- ~, .
,~ .r~ 7 SUMMARY OF ~HE TNvENTTON
The present invention provides a method for ; measurins the inherent viscosity of individual solute components in a multicomponent sample in solution with a solvent, comprising:
passing a stream of a carrier liquid having a viscosity which varies as a function of time at a flow rate R sequentially through ~1) means for separating said sample into its individual solute components~ (2) a first capillary tube and (3) a second capillary tube, which tubes are separated from each other by an offset volume ~V, where O~VSRT, where T is as defined below;
introducing into said stream of carrier liquid, upstream of said means for separating said sample lnto its individual solute components, a predetermined volume of a solut~on comprising the sample and the solvent, whereby said sample is separated ~nto its individual solute components, measuring, as a function of time, pressure differences oPl(t) and aP2(t) across said first and second capillary tubes, respectively, sa$d aPl(t) and ~P2(t) being characterized by a rise time T;
. 25 measuring, as a function of time, the concentration C(t) of the individual solute components : in the carrier liquid;
obtaining a function S(t), where S(t) - ln [~Pl~t)/~P2(t)~;
obtaining a function So(t), where So(t) - ln ~Pl(t)~P2(t)l when only carrier liquid is flowing through both the first and second capillary tubes;
obtaining a function I(t), where Itt) - ¦~S(t)-So~t)~dt; and relating C~t), I~t) and ~v to the inherent viscosity o~ the individual solute components.
:
"
":
.. : , . . . . . .... ... .
..
.. , ~, ... ..
'' ' . ` ~ . ' ':
`' " ::` ~' ' BRTEF DESC~L~ION QE T~_DRAWINGS
FIG. 1 is a stylized view of apparatus for carrying out the method of the present invention.
s FIG. 2 is a stylized plot showing viscosity, ~, of carrier liquid as a function of time, t.
FIG. 3 is a stylized plot of concentration, C, as a function of time, t, for the single solute component whose pressure difference effects are shown in FIG. 4.
FIG. 4 is a stylized plot of pressure differences oPl, and oP2 across first and second capillary tubes as functions of time, t, for a single solute component.
FIG. 5 is a stylized plot of ~Pl/~P2 as a function of time, t.
FIG. 6 is a stylized plot of the function S
as a function of time, t.
FIG. 7 is a stylized plot of the function SO
as a function of time, t.
FIG. ô is a stylized plot of the function [S-SO] as a function of time, t.
FIG. 9 is a stylized plot of the function I
as a function of time, t.
:
; 35 FIG. 10 is a stylized plot of inherent viscosity, ~nh, as a function of t~me, t.
.
.
, .~ :.
-, ' '~ :
- . ~ - . . ~
: ,: : , , ~f~ 37 D~E~ DE:SCRIPTION OF THE INVENTION
~eferring now to the drawing, in which like S reference numerals indicate li~e elements, there is seen in Flgure 1 an apparatus 10 in accordance with -, the present invention. Carrier liquids 12, 12' having viscosities ~1 and ~2, respectively, are pumped from - reservoirs 14, 14' by a pump/mixer 16 through a pulse dampener 18 to a sample injection valve 22. The pump/mixer iq set to mix the two carrier liquids 12, 12' at a predetermined rate. Figure 2 depicts a plot showing visco~iity of the mixed carrier liquid as a funct~on of time. The plot shows a linear increase from a predetermined minimum to a predetermined maximum. Nonlinear functions may also be used.
Referring again to Figure 1, the pump/mixer 16 may be any type of pump/m~xer which is used conventionally in liquid chromatography. An example of a suitable pump/mixer 16 ~s a Hewlett-Packard Modél 1050. The dampener 18 i-~ required only if a reciprocal piston-type pump is used. Typically, the dampener will be chosen to dampen high frequency pulses without impeding the overall flow rate of the mixed carrier : 25 liquids 12, 12'. The tubing utilized in the apparatus is not critical. Generally, any small internal diameter tubing which is substantially chemically inert with respect to the carrier liquids and solute may be utilized. Preferred tubings are made of stainless steel or Teflon~ ~polytetrafluoroethylene), which is available from i. E. I. du Pont de Nemours and Company, Wilmington, ,t,. Delaware.
The sample injection valve 22 may be a 2-position 6-port valve. A suitable valve is sold by Valco Instruments, Inc. (Houston, Texas) under the designation CV6UHPA.
.
. ~ . . , , : ~ , .
. : . :
. ,~. .:, . ~, .
IP~7 Conveniently, a syringe 24, containing a multicomponent solute in solvent t~sample solution"), may be utilized to fill sample loop 26 with sample solution. The sample injection valve 22 will be set to "load" position, which allows the mixed carrier liquid 12, 12' to flow across the valve, while allowing sample loop 26 to be filled from syringe 24.
After sample loop 26 is filled with sample solutio~, valve 22 will be set to "inject" position, which diverts the flow of mixed carrier liquid 12, 12' to sample loop 26. The sample solution will then be introduced into the flowing stream of mixed carrier liquid 12, 12', as a substantially localized volume.
Alternat~vely, the sample solution may be in~ected directly into the flowing stream of mixed carrier liquid 12, 12'.
The stream of flowing mixed carrier liquid 12, 12' havlng a t~me varying viscosity and containing the multicomponent solute will pass through means for separating the multicomponent solute into lts ~ndividual solute components. A preferred separating means is column 52 which may contain a packing material for which the individual solute components in ; the sample have varying affinities. Suitable packing materials include Zorbax~_ODS. Other suitable separating means include Zorbax~ C-8 columns; both are ! commercial products from E. I. du Pont de Nemours and Company, Wilmington, Delaware.
After entering column 52, the individual solute components will elute one by one as the viscosity of the carrier liquid changes from a first value ~A to a second value ~ A may be equal to ; or may equal some predetermined viscosity based on some initial composition using liquids 12 and 12'.
Similarly, ~8 may be equal to ~2 or may equal some predetermined viscosity based on a final composition using liquids 12 and 12'. It should be understood . .
. . ~ -.
.
~ .~ ,, .
lDfi37 that it is not necessarily the change in carrier liquid viscosity which causes sequential elution of the individual components, but rather the changing chemical and/or physical composition of the carrier liquid, which may, in turn, result in an unavoidable change in viscosity. It should also be understood that it is not necessary to change the chemical composition of carrier liquid for eluting solute components sequentially. Chromatographic separations using a carrier liquid of constant composition are called isocratic separations. Isocratic separations may often result in excessive analysis time and very uneven experimental resolution. These problems can sometimes be avoided by employing so-called temperature programming by which the temperature of the carrier liquid is changed with time, thereby resulting in a viscosity change with time.
The stream of flow~ng mixed carrier llquid 12, 12', now containing separated individual solute components, can be split at a ~unction 30, so that a portion of the stream passes through a concentration detector 32 into a waste receptacle 34 and another portion passes to first and second capillary tubes, discussed below. Alternatively, the concentration detector 32 can be place~ in series with the capillary tubes 36 and 42, discussed below. The concentration detector 32 may be any type of detector which is ` typically used in liquid chromatography. A preferred concentration detector 32 is a differential refractometer. Other types of concentration detectors such as ultraviolet or infrared devices also may be used, depending upon the particular type of solute whose viscosity is being measured. Figure 3 depicts the output of the concentration detector 32 as a function of time for an individual solute component.
Refarring again to Figure 1, the flowing mixed carrier liquid 12, 12' -- containing separated lndividual solute components -- will pass through a " . , - .
. ~; ,.
:-fi;~7 first capillary tube 36, across which differences in pressure as a function of time will be detected by transducer 38. The carrier liquid will continue to flow through an offset volume element 40 into a second capillary tube 42, across which differences in pressure as a function of time will be detected by transducer 44. Finally, the carrier liquid will be emptied into a waste receptacle 46.
The internal diameter of the capillary tubes 36, 42 is not critical. Generally, the internal diameter will be chosen to maximize the performance of the pressure transducers associated with each capillary tube. Generally, the internal diameter will be larger than 7~mil. It is preferred that capillary tubes 36 and 42 be as close to physically identical as possible.
The pressure transducers can be the well-known diaphragm type such as those manufactured by Celesco Transducers Products, Inc. (Conoga Park, California). Typically, the transducers 38, 44 are connected across their respective capillary tubes 36, 42 by means of "T" connectors. Each pressure transducer 38, 44 $s connected to its own amplification means 38', 44', respectively, with variable gain control. Preferably the amplification means comprises a DC amplifier. The variable gain controls are used to control the magnitude of the outputs from the two pressure transducers.
Specifically, the two gains will be adjusted to ` 30 provide equal outputs when the same carrier liquid is flowing through capillary tubes 36 and 42. Figure 4 depicts the pressure changes across capillary tubes 36, 42 as a function of time. It should be noted that the curves are identical except for a time offset.
Advantageously, the fluid circuit defined by the apparatus 10 will be placed in a bath (not shown) at a preselected temperature. The bath will .
:.
, . ~ . ~ .
. , : , - .
;37 help to minimize temperature gradients within the apparatus.
Referring again to Figure 1, the outputs from transducers 38 and 44 can be applied to the inputs (not shown) of a differential logarithmic amplifier 48. A suitable amplifier is a Burr Brown Log 100 JP. The output signal of the differential logarithmic amplifier 48 can be expressed by the following equation:
S(t) = ln loPl(t)/~P2(t)]
This output is a function of time. The output S(t) is then integrated over time.
The apparatus depicted in Figure 1 allows a stream of carrier liquid containing individual solute components to pass sequentially through two capillary tubeQ separated by a small offset volume. As each component passes through each capillary tube, the pressure difference across the tube wiil rise from a baseline to a maximum value ~n a characteristic rise time (T). As each compone~t leaves each capillary tube, the pressure difference across the tube will decay back to baseline in a characteristic decay time, which should approximate the rise time. After each component has passed through both capillary tubes, the respective pressure transducers will have generated two substantially identical pressure versus time curves, which curves are separated from one anotber by a time difference, aT, which is equal to the offset volume av divided by the flow rate R. When aT is sufficiently small, the two pressure versus time curves will be slightly displaced from one another, thereby allowing one curve to be used to approximate a 3s value on the other curve. Generally, this condition will be achieved when the offset volume ~v lies between O and RT.
.
, ~ ~ , fi3 To compensate for the contribution of ~P1~t~
and ~P2~t) which is caused not by the individual solute component, but by the change in viscosity of the mixed carrier liquid 12, 12', it is necessary to determine a function So(t) which reflects only the contribution of the mixed carrier liquid 12, 12' to aPl~t) and ~P2~t~. A convenient way to determine this function is to extrapolate the baseline of the S~t) curve through any sin~soidal responses. The resulting curve will represent So~t). Figure 7 depicts the result of such an extrapolation. The sinusoidal response of the solute is shown in dotted line~. The solid line represents the function So~t).
To calculate inherent viscosity, a new function [S(t)-So~t)] is formed. This function essentially subtracts the mixed carrier liquid 12, 12' baseline from the S~t) curve. Fiqure 8 depicts this new function, in which the sinuaoidal response ha~
been lowered to the baseline.
Next a function I~t) is obt~ined:
I~t)- ¦~S(t)-So(t)]dt.
Such a function is depicted in Figure 9.
Finally, for each individual solute component, the function I~t) is divided by C~t) fox that component.
; The height of the resulting curve represents inherent viscosity. The integration can be done by well-known manual computational methods or by an electronic integrator or digital computer.
:
,~:
'`
: . .
.: , ~ . , . , ., ,: : .
~, .......... .
: - . . , . . : ~ ~ . ~ . :
-: ..
- . ~ - -.
, ~ ~ . . : ,.
,, . . : ~ .
Claims
1. A method for measuring the inherent viscosity of individual solute components in a multicomponent sample in solution with a solvent, comprising:
passing a stream of a carrier liquid having a viscosity which varies as a function of time at a flow rate R sequentially through (1) means for separating said sample into its individual solute components, (2) a first capillary tube and (3) a second capillary tube, which tubes are separated from each other by an offset volume .DELTA.V, where O<.DELTA.V?RT, where T is as defined below;
introducing into said stream of carrier liquid, upstream of said means for separating said sample into its individual solute components, a predetermined volume of a solution comprising the sample and the solvent, whereby said sample is separated into its individual solute components;
measuring, as a function of time, pressure differences .DELTA.P1(t) and .DELTA.P2(t) across said first and second capillary tubes, respectively, said .DELTA.P1(t) and .DELTA.P2(t) being characterized by a rise time T;
measuring, as a function of time, the concentration C(t) of the individual solute components in the carrier liquid;
obtaining a function S(t), where S(t) = ln [.DELTA.p1(t)/.DELTA.P2(t)];
obtaining a function So(t), where So(t) = ln [.DELTA.P1(t)/.DELTA.P2(t)] when only carrier liquid is flowing through both the first and second capillary tubes;
obtaining a function I(t), where I(t) = ?[S(t)-So(t)]dt; and relating C(t), I(t) and .DELTA.V to the inherent viscosity of the individual solute components.
passing a stream of a carrier liquid having a viscosity which varies as a function of time at a flow rate R sequentially through (1) means for separating said sample into its individual solute components, (2) a first capillary tube and (3) a second capillary tube, which tubes are separated from each other by an offset volume .DELTA.V, where O<.DELTA.V?RT, where T is as defined below;
introducing into said stream of carrier liquid, upstream of said means for separating said sample into its individual solute components, a predetermined volume of a solution comprising the sample and the solvent, whereby said sample is separated into its individual solute components;
measuring, as a function of time, pressure differences .DELTA.P1(t) and .DELTA.P2(t) across said first and second capillary tubes, respectively, said .DELTA.P1(t) and .DELTA.P2(t) being characterized by a rise time T;
measuring, as a function of time, the concentration C(t) of the individual solute components in the carrier liquid;
obtaining a function S(t), where S(t) = ln [.DELTA.p1(t)/.DELTA.P2(t)];
obtaining a function So(t), where So(t) = ln [.DELTA.P1(t)/.DELTA.P2(t)] when only carrier liquid is flowing through both the first and second capillary tubes;
obtaining a function I(t), where I(t) = ?[S(t)-So(t)]dt; and relating C(t), I(t) and .DELTA.V to the inherent viscosity of the individual solute components.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US302,899 | 1989-01-30 | ||
| US07/302,899 US4876882A (en) | 1989-01-30 | 1989-01-30 | Viscosity detection method for liquid chromatography systems with carrier liquids having time-varying viscosity |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2000637A1 true CA2000637A1 (en) | 1990-07-30 |
Family
ID=23169685
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002000637A Abandoned CA2000637A1 (en) | 1989-01-30 | 1989-10-13 | Viscosity detection method for liquid chromatography systems with carrier liquids having time-varying viscosity |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4876882A (en) |
| EP (1) | EP0380864B1 (en) |
| JP (1) | JPH02208540A (en) |
| AT (1) | ATE108901T1 (en) |
| CA (1) | CA2000637A1 (en) |
| DE (1) | DE68916934T2 (en) |
| ES (1) | ES2056225T3 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4972701A (en) * | 1989-08-31 | 1990-11-27 | E. I. Du Pont De Nemours And Company | Osmotic method for determining the molecular weight of solutes in solution with a solvent |
| US5306734A (en) * | 1993-09-08 | 1994-04-26 | Shell Oil Company | Use of viscosity as an in-line diagnostic for high internal phase emulsion generation |
| DE4421423C2 (en) * | 1994-06-18 | 1998-08-20 | Barnikol Wolfgang | Method and device for determining the viscosity in microliter samples |
| US5637790A (en) * | 1996-02-28 | 1997-06-10 | De Corral; Jose L. | Three capillary flow-through viscometer |
| US6720186B1 (en) * | 1998-04-03 | 2004-04-13 | Symyx Technologies, Inc. | Method of research for creating and testing novel catalysts, reactions and polymers |
| US5847268A (en) * | 1997-03-19 | 1998-12-08 | Ball; Dean M. | Viscosity measuring apparatus and method |
| US6260407B1 (en) | 1998-04-03 | 2001-07-17 | Symyx Technologies, Inc. | High-temperature characterization of polymers |
| DE19848687B4 (en) * | 1998-10-22 | 2007-10-18 | Thermo Electron (Karlsruhe) Gmbh | Method and device for the simultaneous determination of shear and extensional viscosity |
| US6553812B2 (en) * | 2000-05-02 | 2003-04-29 | Kavlico Corporation | Combined oil quality and viscosity sensing system |
| US6609431B1 (en) | 2000-09-29 | 2003-08-26 | Xellogy, Inc. | Flow measuring device based on predetermine class of liquid |
| US6856251B1 (en) | 2001-04-26 | 2005-02-15 | Xsilogy, Inc. | Systems and methods for sensing pressure |
| US6992590B1 (en) | 2001-04-27 | 2006-01-31 | Xsilogy, Inc. | Systems and methods for sensing a fluid supply status |
| WO2006029017A1 (en) | 2004-09-03 | 2006-03-16 | Symyx Technologies, Inc. | System and method for rapid chromatography with fluid temperature and mobile phase composition control |
| JP5200507B2 (en) * | 2007-11-30 | 2013-06-05 | 東ソー株式会社 | Viscometer for liquid chromatograph |
| FR2973828B1 (en) * | 2011-04-11 | 2014-04-18 | Snf Sas | SET OF MEASURING EQUIPMENT AND REGULATION OF HIGH PRESSURE ONLINE VISCOSITY |
| DE102015220966A1 (en) * | 2015-10-27 | 2017-04-27 | Bayerische Motoren Werke Aktiengesellschaft | Apparatus and method for determining viscosity |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4286457A (en) * | 1980-03-06 | 1981-09-01 | Shell Oil Company | Viscosity measurement |
| US4463598A (en) * | 1982-12-10 | 1984-08-07 | Haney Max A | Capillary bridge viscometer |
| US4578990A (en) * | 1984-11-07 | 1986-04-01 | E. I. Du Pont De Nemours And Company | Differential pressure capillary viscometer for measuring viscosity independent of flow rate and temperature fluctuations |
| US4627271A (en) * | 1984-11-07 | 1986-12-09 | E. I. Du Pont De Nemours And Company | Differential pressure capillary viscometer for measuring viscosity independent of flow rate and temperature fluctuations |
| US4644781A (en) * | 1984-12-07 | 1987-02-24 | The United States Of America As Represented By The Secretary Of The Army | Fluid property measuring device |
| US4793174A (en) * | 1987-10-05 | 1988-12-27 | E. I. Du Pont De Nemours And Company | Differential pressure capillary viscometer |
-
1989
- 1989-01-30 US US07/302,899 patent/US4876882A/en not_active Expired - Fee Related
- 1989-10-13 ES ES89310518T patent/ES2056225T3/en not_active Expired - Lifetime
- 1989-10-13 CA CA002000637A patent/CA2000637A1/en not_active Abandoned
- 1989-10-13 DE DE68916934T patent/DE68916934T2/en not_active Expired - Fee Related
- 1989-10-13 AT AT89310518T patent/ATE108901T1/en not_active IP Right Cessation
- 1989-10-13 EP EP89310518A patent/EP0380864B1/en not_active Expired - Lifetime
- 1989-10-16 JP JP1266374A patent/JPH02208540A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| ATE108901T1 (en) | 1994-08-15 |
| EP0380864A2 (en) | 1990-08-08 |
| EP0380864A3 (en) | 1991-03-06 |
| JPH02208540A (en) | 1990-08-20 |
| EP0380864B1 (en) | 1994-07-20 |
| DE68916934T2 (en) | 1994-11-03 |
| DE68916934D1 (en) | 1994-08-25 |
| US4876882A (en) | 1989-10-31 |
| ES2056225T3 (en) | 1994-10-01 |
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