JPH02118450A - Multi-dimensional chromatography system - Google Patents

Abstract

PURPOSE: To achieve the on-line multidimensional analysis of nonvolatile or high-polarization compound by providing a switching valve for sampling a fractionation to be eluted from a microsize elimination chromatography and a size elimination chromatography. CONSTITUTION: A chromatography system 10 includes a liquid chromatography 12 and the liquid chromatography 12 has a solvent pump 14, an injection valve 16, at least one column 18, and a detector 20. The liquid chromatography 12 separates a sample containing nonvolatile component to an important fraction containing the nonvolatile component. Also, a switching valve 22 directly moves a sample sampling fraction to a thermal decomposition probe 24 and the thermal decomposition probe 24 produces a volatile fragment for indicating a nonvolatile component from a sample sampling fractionation. Then, a gas chromatography 48 receives an eluted gas from the thermal decomposition probe 24 and separates it into components, thus achieving the on-line multidimensional analysis of a sample containing nonvolatile components.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to multidimensional chromatography, and more particularly to on-line coupled LC/GC systems that can provide information regarding compounds containing non-volatile components.

Multidimensional chromatography is a powerful separation tool, especially when dealing with complex matrices that require unattainably high theoretical plate numbers for adequate resolution. Similarly, multidimensional chromatography has been found to be very useful when working with samples that require lengthy washing steps before analysis. The combination of liquid chromatograph (LC) and gas chromatograph (GC) in on-line formation is described in the following literature;
[On-line multidimensional chromatography using packed capillary liquid chromatography and capillary gas chromatography]
international Chromatography Us
ing Packed Capillary Liquor
idChromatography And Capi
gas chromatography)
J.

11RC&CC8 (1985) 485 pages; H.
[Determination of trace amounts of chlorinated benzene in fuel oil by online multidimensional chromatography using packed capillary liquid chromatography and capillary gas chromatography]
f TraceChlorinated Benzene
as in Full 011 by On line
Multidimensional Chromato
graphy Llsing PackedCapil
lary Liquid Chromatograph
y and Capillary Gas Chroma
J, Journal of Chromatography
matography).

349 (1985) p. 55; and Etsch, J./Cortez et al., "On-line multidimensional chromatography using micro HPLC-capillary GC" Con-LineMu
ltidimensional chromatogr
aphy Llsing MierOllPLc -C
apillarary GC) J, Chromatography Forum (Chromatography F
orum) 4. (198B) p.29.

As disclosed in these documents, high performance liquid chromatography (HPLC) columns are mainly used in online format for the quantification of trace components in complex matrices, in which case liquid chromatography (L
C) forms a highly efficient washing step, and the chromatogram portion containing the components of interest is transferred to GC for further resolution and quantification. Duquet et al. [Micro-LC tubules and GC as a powerful tool for complex mixture analysis]
Coupling of Micro LC-Cap
illary GCasPowerful Tool
for the Analysis of CompI
ex old xtures) J HRC&CC,If(
A similar system has been used to classify components, as described on page 252 (1988).

Nevertheless, a major limiting factor to the use of this LC/GC technology is the type of components analyzed by GC. In other words, such compounds must be volatile and must be chromatographically analyzable in the gaseous state. Non-volatile or highly polar compounds can be analyzed by GC when chemically treated (derivatized) and added to the appropriate form. Regarding this, please refer to KyBlau.
etc.

[reyden & so
Handbook of Derivatives for Chromatography (Handbook, Ltd.) London (1978)
of Derivatives ForChromat
see) J. However, the need to chemically treat these compounds makes it extremely difficult to perform online or continuous multidimensional analysis of such non-volatile or highly polar compounds.

Another alternative is to use pyrolysis gas chromatography to examine volatile pyrolysis fragments of non-volatile molecules. In polymer characterization, the combination of size exclusion chromatography (S E C') and pyrolysis gas chromatography allows for the determination of average polymer composition as a function of molecular size/molecular weight. However, it is difficult to obtain this kind of data, the reason being that S
This is because the fractions eluted from the EC system are usually manually collected, evaporated, redissolved in a suitable solvent, and manually transferred to the pyrolysis probe by syringe.

It is therefore a first object of the present invention to provide a coupled liquid chromatography/gas chromatography system that allows on-line multidimensional analysis or quantification of non-volatile or highly polar compounds. In this regard, the term "non-volatile" as used herein refers to compounds that are non-volatile and/or highly polar.

Coupling size exclusion chromatography (SEC) and pyrolysis gas chromatography in an online system to enable quantification of average polymer composition as a function of molecular size/molecular weight, as well as to understand polymer properties and polymerization chemistry. It is another object of the present invention to obtain valuable information that can be used for

It is yet another object of the present invention to provide an online multidimensional system that allows automatic collection of the fractions of interest from the SEC and transfer of these fractions to an interface where GC analysis can be performed.

To achieve the above objectives, the present invention forms an on-line multidimensional system that includes a microsize exclusion chromatograph and a switching valve for sampling the fraction eluting from the SEC. The switching valve transfers the sampled fraction directly to the pyrolysis probe, which produces volatile fragments representing non-volatile components from the sampled fraction. The system also includes a gas chromatograph that provides molecular size/molecular weight distribution information from volatile fragments. The present invention also allows for a valve, pyrolysis probe, and chromatograph combination that can be used as an automatic injector when no SEC or other LC is coupled to the system.

A switching valve couples the separate sample circuit and solvent flush circuit and allows the carrier fluid to continuously carry the contents of these circuits to the pyrolysis probe. The pyrolysis probe includes a pyrolysis ribbon coaxially disposed within a glass housing. The pyrolysis probe housing includes a side hole portion that directs the collection fraction to a region of the pyrolysis ribbon. The pyrolysis probe housing also allows for the introduction of an auxiliary carrier fluid to increase the rate of solvent evaporation and minimize the chance of solvent spreading along the pyrolysis ribbon.

More particularly, the invention relates to a liquid chromatograph for separating a sample containing non-volatile components into important fractions containing said non-volatile components; a pyrolysis device; and a transfer of the fraction in question eluting from the liquid chromatograph to a pyrolysis device. and a gas chromatograph arranged to receive and separate into components a gas effluent stream from a pyrolysis device.

The invention also includes the steps of: separating a sample into fractions of interest; transferring said fractions online to a pyrolysis device; pyrolyzing said sample fractions to form volatile fragments; and chromatographically separating said volatile fragments and detecting the separated fractions.

The invention further provides a transfer device for receiving a sample containing non-volatile components; a pyrolysis device in communication with said transfer means for producing volatile fragments representing said non-volatile components from said sample; and said pyrolysis device. The present invention also relates to an automated injector comprising a gas chromatograph for receiving at least a portion of said volatile fragments from said volatile fragments and for analyzing said volatile fragments.

The invention also relates to a size exclusion chromatograph; a valve for sampling a fraction eluting from said size exclusion chromatograph; a valve for producing a volatile fragment representing said non-volatile components from said sampled fraction; a pyrolysis device in communication with a valve; and a gas chromatograph for receiving at least a portion of said fragments from said pyrolysis device for volatile fragment analysis. chromatography apparatus.

Other advantages and features of the invention will become apparent from reading the detailed description of the preferred embodiments with reference to the drawings.

In FIG. 1, an online multidimensional chromatography system 10 according to the invention is shown. System 10 is liquid chromatograph 1
2, which has a solvent pump 14, an injection valve 16, one or more columns 18, and a detector 20.

In one embodiment according to the invention, the solvent pump is an Isco micro-LC operated at constant flow rate.
ro-LC) 500 solvent supply system [Isco
, Lincoln, Nebraska, USA]. Similarly, the injection valve 16 is 200 nanoliters (n, lll)
Valco model Nl4W with injection volume of
Injection valve [Valco Insulmen]
Struments), Hyeuston, Texas, USA]. Furthermore, the detector 20 is equipped with a Jasco Uvidc cell equipped with a modified cell whose illumination intensity is calculated to be 6 nN from the tube diameter and slit size.
c) V detector [Jusco International (J
Asco International), Japan].

Such an improved cell was developed by F., G., and Young (P., J.
, Yang) [Fused silica, fine-pore microparticle photonic column
arrowBore Microparticle P
acked Column HPLC) J.

Journal of Chromatography
chromatography), 23B(
(1982), p. 265.

Column 18 is a fused silica capillary tube (Polymicrotechno sheath) with a column length of 50 cm and an inner diameter of 250 micrometers (μm).
(Fuenox, Alisina, USA).

H, J, Cortes
"Porous Ceramic Bed Support for Fused Silica Capillary Columns for Liquid Chromatography"
ramic Bed 5upports for Fu
sed 5ilica CapillaryColumn
ns tlsed in Liquid Chrom
atography) J.

A porous ceramic bed support was used, as described in HRC & CC10 (1987), 446.

Column 18 was filled with Zorpax (Zorba) with a particle size of 7 μm.
x) PSM-1000 was packed as a slurry in acetonitrile to a pressure of 6000 psig (41,470 kPa).

Liquid chromatograph 12 is preferably a microSEC system (eg, for polymer characterization). However, the choice of column dimensions and type will be determined by the sample and desired information, and there is no intent to limit the broad aspects of the invention to micro-based or size exclusion chromatography. In this context, a microSEC system was chosen as the LC12, since the important components are diluted in very small volumes compared to regular SEC columns.

This feature allows testing of polymers in a relatively small number of analyses. However, if a more detailed examination is desired, smaller cuts or fractions can be analyzed. Alternatively, fine-bore columns or conventional columns can also be used.

Therefore, the analysis can yield many measurements for narrow molecular size intervals. Because SEC separates molecules based on size, and molecular size is proportional to molecular weight, the term "molecular size/molecular weight" as used herein generally refers to molecular size and/or molecular weight.

System 10 includes a multiport switching valve for transferring important fractions eluted from microSEC system 12 to pyrolysis probe 24.
alve).

In one implementation, aspect of the invention, valve 22 is a bulk 10 port valve model N I 10WT. As shown in Figures 2A and 2B, this valve has a 1.0 μg sample loop 26.
and a 5.0 μg solvent flush loop 28. Both of these loops 26 and 28 are 50-solvent 1. D. Manufactured from silica tubing. This short length of tubing was also used as the conduit 30 that connects the valve 22 to the pyrolysis probe 24 and the conduit 32 that connects the valve 22 to the detector 20 of the Micro5EC12.

FIG. 2A shows the valve 22 in the loaded state, forming a separate sample loop and a flush loop. In contrast, FIG. ” valve 22 is shown in the state. Under load conditions, the elution flow from the SEC detector 20 flows through the sample loop 26 through conduit 32. The effluent stream from sample loop 26 is stored or transferred to a waste receptacle. Similarly, when valve 22 is under load, a suitable solution (e.g., THF) is supplied to flush loop 28.
flows through and flows out.

Switching the valve 22 to the injection state couples the sample loop 26 with the flash loop 28 so that the contents of these loops are carried to the pyrolysis probe by a suitable carrier fluid (eg, helium). Additionally, other gases, such as air, can also be introduced to flush the system. Although other suitable switching valve arrangements may be used in suitable applications, the use of a flush loop is preferred as it allows the transfer line from the Micro 5EC 12 to the pyrolysis probe 24 to be cleaned before the next sample collection.

Although the preferred valve arrangement is such that the sample loop initially withdraws a predetermined amount of elution stream from 5EC12, other suitable valve arrangements may be used for suitable applications. For example, a valve structure can be used that allows the elution stream to select either the injection mode or the short-circuit mode so that it reaches the pyrolysis probe unless it is bypassed or short-circuited to the waste receptacle. If the elution stream is to be diverted, a carrier fluid can be used to carry the elution stream through the valve to the pyrolysis probe.

Pyrolysis probe 24 generally consists of a pyrolysis ribbon 34 disposed coaxially within a glass chamber of housing 36 . In one embodiment of the invention, a Heulet Paracard (Ilew) operated for 1 second at a temperature of 700°C
Lett Packard) Model 18580A Proprobe [Llewlett Paracard Instruments
ents), Avondahl, Pennsylvania, USA] is used as the pyrolysis apparatus. Housing 36 includes a cylindrical portion 38 through which pyrolysis ribbon 34 extends, and lateral cylindrical portions 40 extending generally perpendicularly from the cylindrical portion. The housing 36 is wrapped by a heating tape 41 which is heated to a temperature of approximately 180° C. (
(external surface temperature).

According to one aspect of the invention, the lateral portion 4 of the housing 36
A recess or hole portion 43 is formed in the pyrolytic ribbon 34 directly below the pyrolytic ribbon 34 . Hole portions 43 in pyrolysis ribbon 34 are used to receive the individual sampled fractions of interest conveyed through conduit 30 from valve 22 . In this regard, the holes 43 serve to confine this fluid flow to specific parts of the pyrolysis ribbon. Therefore, the holes 43 transfer the transferred fraction to the pyrolysis ribbon 34.
will be deposited on a constant, reproducible portion of the sample.

The inlet 42 in the side portion 40 also allows an auxiliary carrier gas (eg helium, nitrogen or air) to enter the housing 36 from a conduit 44. The flow m of this auxiliary carrier gas can be adjusted to control the evaporation rate of the solvent transferred to the pyrolysis probe 24. This feature can increase the evaporation rate, thereby minimizing the opportunity for solvent and sample to spread onto the pyrolysis ribbon.

The housing 36 of the pyrolysis probe 24 also includes an outlet 46 that allows the transfer of volatile fragments produced by the pyrolysis ribbon 34 to a gas chromatography device 48 . A short capillary 50 extends from the outlet 46. Capillary tube 5 to divide the exhaust stream from pyrolysis probe 24
0 to the lower dead space of the three-way T-joint 54 (Low dead v
olume) by a fitting 52. A portion of this flow is transferred to column 5 of the gas chromatography device 48.
6, while the remaining portion is discharged through conduit 58. A micro-dosing valve 60 is coupled to conduit 58 to direct the exhaust flow/
Control the split ratio of GC transfer fluid. Instead of this, use the special switching valve of Parco model N4WT at the housing outlet 50.
and the split-T fitting 54 to quickly drain the solvent.

In one aspect of the invention, the gas chromatography apparatus used includes a Parian (Vari) flame ionization detector 62.
a) Model 3700 gas chromatograph (Varian Associates, Allnut Creek, California, USA).

Similarly, the analytical column 56 is made of phenylmethyl silicone (50 m x 0.20 mm inner diameter) with a film thickness of 0.3 hm.
) (Heuret-Barackard, Avondahl, Pennsylvania, USA). The temperature program used was 5.
0°C for 6 minutes; then ramped to 220°C at 10°C or 20'C/min intervals. This temperature program was carried out during pyrolysis, preferably after the solvent had eluted from the system. The carrier gas used was helium, and the detector 62
The make-up gas was nitrogen (20 ml/min).

Before conducting the experiment, anionic polystyrene standard reagents with narrow molecular weight distribution [Polymer La
bs), UK] was used to evaluate and calibrate SEC column 18. Column performance was determined by Kirkland
[Introduction to Modern Liquid Chromatography (Int.
production to Modern Liqui
d Chromato-graphy) J. Wiley & Sons (J, Wiley & 5o
(1979), by measuring the asymmetry factor. In the case of toluene as a perfectly permeable molecule, the asymmetry factor is 1.04 and the column efficiency is 38,000
It turned out to be 1 plate/m. The resolution was evaluated by the following formula: R=D(7=(d(l og
M/dv (ΔV)]=d ρog M where is the slope of the calibration curve, σ is the standard deviation of toluene, ■ is the elution amount, and M is the molecular weight. In the embodiment, the obtained resolution factor
factor) was 0.034.

The elution volume of SEC systems is known to increase with sample concentration due to changes in the hydrodynamic teeth of the polymer solution with concentration. Furthermore, high sample concentrations are thought to lead to band expansion due to viscous flow of the solute band. Therefore, for a particular polymer and conditions, it is preferred that the amount of polymer injected into SEC column 18 does not exceed 2 micrograms (μg) in order to obtain an accurate molecular weight distribution based on the assay method described above.

The preferred mobile compatibilizer used for this particular application is H
PLC grade tetrahydrofuran [Fisher Scientific
), Firelawn, New Chassis, USA]. In this regard, the solvent flow rate was 2.01 μ/min, which produced a column head pressure of 1300 psfg (9087 kPa). It is known that instrument flow rate fluctuations cause large errors in calculated sample molecular weights. Therefore, it is preferred to add a small amount of toluene to the polymer solution to be injected to form an internal standard in order to compensate for the flow fluctuations experienced.

The application of on-line SEC/pyrolysis GC system 10 to the characterization of styrene-acrylonitrile copolymers is shown in FIGS. 3 and 4. Figure 3 shows the microSEC chromatogram obtained for the polymer prepared by dissolving lomg/ml in THF. The various fractions transferred to the pyrolysis interface 24 are shown in the chromatogram. Figure 4 shows the capillary GC chromatogram obtained after pyrolysis of fraction No. 1 from Figure 3 whose molecular weight is within the range of 1.800,000 to 450,000; GC obtained after pyrolysis of appropriate parts of the distribution
considered typical of a chromatogram.

By measuring the area ratio between the generated acrylonitrile peak and the styrene peak, the relative composition of the copolymer soluted in each fraction was calculated.

This information is valuable when calculating relative composition as a function of molecular size. In this context, the morphology of the pyrolysis probe was found to influence changes in area ratio data. When performing pyrolysis, platinum ribbon 34 bends and rarely returns to its initial position. Therefore, due to this orientation change, it is difficult to deposit important fractions at the same site as previous fractions. Because the ribbon 34 is not heated uniformly over its length, the fractions being transferred will experience different pyrolysis temperatures, resulting in variable results. However, as discussed above, the provision of holes 43 in the pyrolytic ribbon 34 will confine the transferred fraction to a reproducible region, resulting in an acceptable standard deviation of area ratios (e.g., 2. 4%)
.

Ideally, all fractions to be pyrolyzed should be transferred to GC column 56. However, it has been found that in order to obtain a relatively sharp peak, a high gas flow rate must be blown through the pyrolysis probe 24. This situation is
The C column 56 generates a relatively high pressure and the pyrolysis probe 2
It is further complicated by the fact that it limits the use of high flow rates from 4. In this connection, the split Tt
It should be noted that the provision of the I-hand 54 is appropriate to enable achieving sufficiently high flow rates. Alternatively, the use of a large internal diameter capillary allows for rapid transfer of fragmented components to the column 56 without resorting to split ratio systems.
The splitting function can also be performed by using a trap such as a solid absorber (cheme) or a solid absorber, for example.

5A-5D, T-joint 54 is shown under control of valve 60.
A series of GC chromatograms are shown to illustrate the experimental effects of various split ratios on In these experiments, samples are prepared by dissolving 70 mg of polystyrene homopolymer and heating the GC probe to minimize condensation of the fragments of interest and avoid poor chromatography. With respect to the multidimensional system 10 according to the present invention, FIGS. 6A and 6B illustrate the effects of two types of pyrolysis interface temperatures. Both of these GC chromatograms were obtained by chromatographic analysis of the pyrolysis products of styrene homopolymer formed and deposited on the pyrolysis ribbon 34 by the method described above for studying the effects of various split ratios. It is something that

Figure 6A represents the chromatogram obtained at an interfacial temperature of 25°C, and Figure 6B shows the results obtained at an interfacial temperature of 180°C. As shown in these figures, a high interfacial temperature significantly improves the peak shape. However, if the transfer is carried out while heating the interface 24, the sample tends to splatter and some of the polymer is deposited on the interface wall rather than on the pyrolysis ribbon 34. This led to decreased sensitivity and made the reproducibility of results unpredictable. Therefore, depending on the solvent used, it is preferable to carry out the transfer of the important fractions at a temperature that does not cause excessive boiling.

Once the transfer is complete, the probe 24 is heated to, for example, 180°C.
Heat to an appropriate temperature.

Once those skilled in the art are given the idea of the above disclosure, it will be readily apparent that modifications to the specific embodiments described herein may be made without departing from the essence of the invention.

Such modifications are considered to be within the scope of this invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the online multidimensional system according to the invention; FIGS. 2A and 2B are schematic diagrams of the load position and injection position of the multiport switching valve shown in FIG. 1; FIG. is a micro-SEC chromatogram of a styrene-acrylonitrile copolymer; FIG. 4 is a graph representing a capillary GC chromatogram obtained from the pyrolysis product of the styrene-acrylonitrile fraction shown in FIG. 3; Figures 5-5D are graphs representing capillary GC chromatograms obtained from polystyrene homopolymer at various split ratios; Figures 6A-6B are graphs representing capillary GC chromatograms obtained from styrene homopolymer at two different interfacial temperatures. This is a graph representing grams. 10... System 12... Liquid chromatograph 14... Solvent pump 16... Injection valve 18
... Column 20 ... Detector 24 ... Pyrolysis probe 34 ... Pyrolysis ribbon 48 ... Gas chromatograph 54 ... Printing of T-joint drawing (no change in content) GinPIFl (here) 10CJ9゜06C 50℃ 10℃14+ 906C Father ℃ 501IC10℃~190℃

Claims (1)

[Scope of Claims] 1. A chromatography device for performing on-line multidimensional analysis of a sample containing non-volatile components; for separating a sample containing non-volatile components into fractions of interest containing said non-volatile components; a liquid chromatograph; a pyrolysis device; means for transferring the fraction of interest eluting from the liquid chromatography to the pyrolysis device; and a gas chromatograph arranged to receive and separate the gaseous effluent stream from the pyrolysis device into components. equipment containing. 2. The apparatus of claim 1, wherein said transfer means is a valve for selectively sampling a predetermined amount of said fraction eluting from said liquid chromatograph and transferring said sampled fraction to said pyrolysis device. 3. The valve is a multi-port switching valve having a load position and an injection position, the load position forming a separate sample loop and a flush loop, and the injection position coupling the sample loop and the flush loop. 2. The apparatus of claim 1, wherein the contents of the sample loop and the flash loop are conveyed continuously to the pyrolysis device by a carrier fluid. 4. The apparatus of claim 2, wherein said valve is a switching valve having an injection type and a short circuit type for transferring liquid chromatography effluent directly to the pyrolysis device. 5. The pyrolysis device includes a pyrolysis ribbon having a recess to confine the transfer portion to a reproducible region, and the housing containing the ribbon receives the sampled fraction from the liquid chromatograph. 5. Apparatus according to any preceding claim, having an inlet for transporting product fragments to the gas chromatograph and an outlet for transferring product fragments to the gas chromatograph, said inlet also comprising an inlet for receiving a supplementary carrier fluid. 6. Any one of claims 1 to 5, wherein the gas chromatograph includes a splitter for discharging a portion of the gas elution stream from the pyrolysis device and transferring the remainder of the gas elution stream to the column of the gas chromatograph. The device described. 7. A method for performing online multidimensional analysis of a sample containing non-volatile components, comprising the following steps: separating the sample into fractions of interest; transferring the fractions online to a pyrolysis device; A method comprising the steps of pyrolyzing to form volatile fragments; transferring said volatile fragments on-line to a gas chromatograph; and separating said volatile fragments by chromatography and detecting the separated fractions. 8. The sample is a polymer sample, the polymer sample is separated by size exclusion chromatography to obtain molecular weight/molecular size information, and the chromatographically analyzed fraction of the sample is pyrolyzed to determine the volatile components of the pyrolysis products. 8. The method of claim 7, wherein the molecules are separated by gas chromatography to provide molecular weight/molecular size versus composition information. 9. The method of claim 7 or 8, wherein said first transfer step comprises forming separate sample loops and flash loops and then combining said sample loops and said flash loops. 10. A method according to any of claims 7 to 9, wherein said second transferring step comprises discharging at least a portion of said volatile fragments resulting from said pyrolysis step. 11. The following elements: a transfer device for receiving a sample containing non-volatile components; a pyrolysis device in communication with said transfer means for producing volatile fragments representing said non-volatile components from said sample; An automated injector device comprising a gas chromatograph for receiving at least a portion of said volatile fragments from a decomposition device and for decomposing said volatile fragments. 12. A chromatography device for performing online multidimensional analysis of compounds containing non-volatile components,
the following elements: a size exclusion chromatograph; a valve for sampling the fraction eluting from said size exclusion chromatograph; said valve for forming volatile fragments representing said non-volatile components from said sampled fraction; Communicated pyrolysis equipment;
and a chromatography device comprising a gas chromatograph receiving at least a portion of the fragments from the pyrolysis device for analyzing the volatile fragments.