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Publication numberUSH896 H
Publication typeGrant
Application numberUS 07/052,170
Publication dateMar 5, 1991
Filing dateMay 19, 1987
Priority dateMay 31, 1983
Publication number052170, 07052170, US H896 H, US H896H, US-H-H896, USH896 H, USH896H
InventorsJulius J. Szakasits, Robert E. Robinson
Original AssigneeShell Oil Company
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Separating column for gas chromatography
US H896 H
Abstract
A method of fabricating an elution chromatography separating column from an elongated capillary tube, such column having a layer comprising a plurality of disunited particles of porous solid material disposed on an inner surface of the tube. The method comprises the steps of: preparing a suspension comprising a dispersive liquid and particles of the solid material; filling an elongated capillary tube with prepared suspension; and flowing an inert gas through the tube to dry the tube thereby leaving a layer comprising a plurality of disunited particles of the solid material attached to the inner surface of the tube.
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Claims(9)
What is claimed is:
1. A method of fabricating an elution chromatography separating column from an elongate capillary tube comprising:
preparing a suspension comprising a single component dispersive liquid and particle of porous solid material,
filling an elongated capillary tube with the prepared suspension followed by,
flowing an inert gas through said tube to evaporate said dispersive liquid and leave a plurality of disunited particles of said porous solid material adhering to the inner surface of the capillary tube, and then
flowing an elevated temperature inert gas through the tube to condition the tube and solid material adhering thereto.
2. A method as recited in claim 1, wherein said step of filling an elongated capillary tube with the prepared suspension comprises pushing the suspension into the tube under pressure.
3. A method as recited in claim 1, wherein said solid material comprises 13 molecular sieve material.
4. A method as recited in claim 3, wherein said dispersive liquid is water.
5. A method as recited in claim 2, wherein said solid material is 13 molecular sieve material and said dispersive liquid is water.
6. An elution chromatography separating column comprising:
an elongated capillary tube having an inner surface; and
a layer of a plurality of disunited particles of porous solid material attached to the inner surface of said tube by filling said tube with a suspension of a single component dispersive liquid and particles of said solid material, followed by attaching said particles to the inner surface of said tube by flowing an inert gas through said tube to dry said tube, and then flowing an elevated temperature inert gas through said tube to condition said tube and said particles.
7. A column as recited in claim 6, wherein said solid material comprises 13 molecular sieve material.
8. A column as recited in claim 7, wherein said dispersive liquid comprises water.
9. A column as recited in claim 8, wherein said capillary tube is made of stainless steel.
Description

This is a continuation of Ser. No. 602,626, filed Apr. 23, 1984, now abandoned, which is a continuation of application Ser. No. 499,123, filed May 31, 1983, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates generally to separating columns for gas chromatography and, more particularly, to a molecular sieve coated open tubular column for gas chromatography.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a method of fabricating an elution chromatography separating column from an elongated capillary tube, such column having a layer comprising a plurality of disunited particles of porous solid material disposed on an inner surface of the tube. The method comprises the steps of: preparing a suspension comprising a dispersive liquid and particles of the solid material; filling an elongated capillary tube with the prepared suspension; and flowing an inert gas through the tube to dry the tube thereby leaving a layer comprising a plurality of disunited particles of the solid material attached to the inner surface of the tube.

In addition, the present invention provides an elution chromatography separating column comprising: an elongated capillary tube; and a layer comprising a plurality of disunited particles of porous solid material disposed on an inner surface of the tube by filling the tube with a suspension comprising a dispersive liquid and particles of the solid material and flowing an inert gas through the tube to dry the tube thereby leaving a layer comprising a plurality of disunited particles of the solid material attached to the inner surface of the tube.

In the preferred embodiment of the present invention, finely ground 13 molecular sieve is combined with water to form a slurry which is pressured through a clean length of stainless steel capillary tubing. A purge is maintained to dry the column, thereby leaving the 13 sieve particles attached to the wall of the tubing. The layer of finely divided particles provides a high resolution, type separation of naphthenes, isoparaffins and paraffins boiling up to 255 C. However, in other embodiments other finely ground adsorption agents, such as carbon black and firebrick, can also be used, and the capillary tube can be made of other materials, for example, nickel, fused silica, borosilicate and soda lime glass.

Other objectives, advantages and applications of the present invention will be made apparent by the following detailed description of the preferred embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section through an elution chromatography separating column according to the present invention.

FIG. 2 is a chromatogram obtained with the column of the present invention.

FIG. 3 is a chromatogram obtained with the column of the present invention.

FIG. 4 is a chromatogram obtained with a conventional packed column.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Suspension of the solid particles in the liquid can be achieved by means of stirring or vibrating the slurry. Usually, a treatment of two to three minutes is sufficient if not additional comminution of the solid is desired. Before the slurry or suspension is pressed into the capillary tube it is advantageous to pass it through a pressure sieve in order to eliminate coarser agglomerates which could lead to cloggings in the capillary tube. A preferred method of separating the desired sized particles is to allow the larger particles to settle during a predetermined time interval in the range of 30-120 minutes. One half to two thirds of the upper portion of the slurry is then pipetted into a separate container. The finely ground solid particles can be any powdery substance usable as an adsorption agent, for example, carbon black, firebrick, and so forth; however, the preferred embodiment employs molecular sieve type 13. The capillary is filled by means of a pressure vessel and an inert gas, such as nitrogen, helium, argon and so forth. The pressure to be used depends on the diameter and the length of the capillary and on the viscosity of the suspension; usually the pressure is between 4-12 psig. The capillary tube should be cleansed from impurities by washing it thoroughly, such as by using 0.1-0.3N HCl followed by water which is followed by acetone and finally water again, prior to filling. The purging of the tube is performed by flowing an inert gas, such as helium, through the tube to dry it thereby leaving a layer of material attached to the inner surface or wall of the tube. Usually a purge of 0.1-1 ml./min. is maintained for approximately two to five hours to dry the tube. Next the column is stabilized at 420-440 C. for about twice as long as the drying period.

The following examples are presented to provide a more complete understanding of the invention. The specific techniques, conditions, materials, proportions and reported data set forth to illustrate the principles and practice of the invention are exemplary and should not be construed as limiting the scope of the invention.

EXAMPLE 1

Fifteen meters of a stainless steel capillary tube with an inner diameter of 0.5 millimeters were conditions with 8 ml. of 0.1N HCl and washed with water which was followed by acetone and finally water again. Next, 2.14 g. of finely divided 13 molecular sieve were suspended in 50 ml. of deionized H2 O and stirred rapidly. The slurry was allowed to settle for 60 minutes; then 10 ml. of the slurry containing a 1:1000 w. ratio 13/H2 O were pressed into the capillary tube at a pressure of 6 psig while venting the excess to waste at a rate of 5-7 drops per minute. After the tube had been filled, the gas pressure on the slurry was gradually decreased to obtain a purge of N2 at a rate of 0.5 ml./min. which was maintained on the tube for two hours to dry it. The tube was then conditioned with a stream of He passing through the tube at a rate of 6 ml./min. and at a temperature of 440 C. for five hours. The column produced in this way contains about 1 mg. of 13 molecular sieve material, and the particle size in the column ranges from 0.4-12.0 microns.

EXAMPLE 2

Thirty-eight meters of a stainless steel capillary tube with an inner diameter of 0.38 millimeters were rinsed with 0.3 N HCl and washed with water which was followed by acetone and finally water. Then 5.75 g. of finely ground 13 molecular sieve material were suspended in 250 ml. H2 O by stirring. The slurry was allowed to settle for 60 minutes. then 10 ml. of the slurry were separated and pressed into the capillary tube at a pressure of 11 psig., venting the excess to waste. After the tube had been filled in this manner, a purge of He at a rate of 0.2-0.3 ml./min. for two hours was maintained on the tube. The tube was then conditioned with a stream of He passing through the tube at a rate of 4 ml./min. and at a temperature of 440 C. for six hours. The column produced in this way contains abut 1 mg of 13 molecular sieve material, and the particle size in the column ranges from 0.4-12.0 microns.

FIG. 1 illustrates a cross section through a stainless steel capillary tube according to the present invention. Stainless steel tubing 2 has a layer 4 consisting of disunited, detached solid residue from a suspension of finely subdivided 13 molecular sieve material in H2 O per Example 1 above. The important improvement achieved by the present invention is demonstrated by FIG. 2 and 3 which illustrate the chromatograms obtained with columns prepared according to Examples 1 and 2 respectively. The temperature program used with each of the columns to obtain the chromatograms in FIGS. 2 and 3 was as follows: the column was maintained at an initial temperature of 100 C. for five minutes; the temperature was then increased at a rate of 10.0 C./min. until 150 C. was reached; the temperature was maintained at 150 C. for one minute; the teperature was then increased at a rate of 2.5 C./min. until 288 C. was reached; the temperature was then increased at a rate of 1.5 C./min. until 440 C. was reached; and the temperature was maintained at 440 C. for forty-two minutes. For purposes of comparison, FIG. 4 illustrates a chromatogram obtained with a conventional 13 molecular sieve packed column which was one meter long and had an inside diameter of 1.27 ; millimeters and which was packed with 13 material having a size in the range of 60 to 80 mesh. The temperature program used with the packed 13 column to obtain the chromatogram in FIG. 4 was as follows: the column was maintained at an initial temperature of 178 C. for five minutes; the temperature was then increased at a rate of 10.0 C./min. until 198 C. was reached; the temperature was then increased at a rate of 4.0 C./min. until 330 C. was reached; the temperature was then increased at a rate of 1.5 C./min. until 390 C. was reached; the temperature was then increased at a rate of 2.0 C./min. until 410 C. was reached; the temperature was then increased at a rate of 2.5 C./min. until 445 C. was reached; and the temperature was maintained at 445 C. for sixteen minutes.

From FIG. 4 it is apparent that the carbon number of separation on a packed column for paraffins/naphthenes is quantitative through C8 partially quantitative for C9 and useful for C10. However, for C11 and C12 saturates fractions there is increasing overlap between the naphthene and paraffin bands that prevents accurate measurement of their relative distribution. Comparing the results obtained with the column of the present invention as invention as illustrated in FIGS. 2 and 3, it is readily apparent that the column of the present invention distinctly separates the isoparaffins and paraffins. Moreover, quantitative measurement of the paraffin/naphthene fractions is carried out with baseline or near-baseline separation throughout the entire sample. A number of individual naphthenes and paraffins of interest can also be identified up to C8. The column of the present invention also provides good peak shape through C14 for better integration and quantitative measurement in the C9 + region. In addition, separation of the various hydrocarbon groups is generally carried out at a lower column temperature with the present invention, thus reducing the risk of oxidizing the sample as it is being separated.

Non-Patent Citations
Reference
1Hawley, The Condensed Chemical Dictionary, Eighth Edition, New York, Van Nostrand, 1971, p. 591.
2Mikes, Chromatographic and Allied Methods, Ellis Horwood Limited, 1979, pp. 225 & 226.
3Snyder, "Introduction to Modern Liquid Chromatography", John Wiley & Sons, Inc., pp. 202-218, 1979.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5599445 *Jun 7, 1995Feb 4, 1997Supelco, Inc.Nucleophilic bodies bonded to siloxane and use thereof for separations from sample matrices
US5607580 *Jun 7, 1995Mar 4, 1997Supelco, Inc.Nucleophilic bodies bonded to siloxane and use thereof for separations from sample matrices
US5609756 *Jun 7, 1995Mar 11, 1997Supelco, Inc.Nucleophilic bodies bonded to siloxane and use thereof for separations from sample matrices
US5620603 *Jun 7, 1995Apr 15, 1997Supelco, Inc.Nucleophilic bodies bonded to siloxane and use thereof for separations from sample matrices
US5630937 *Jun 7, 1995May 20, 1997Supelco, Inc.Nucleophilic bodies bonded to siloxane and use thereof for separations from sample matrices
US5653875 *Jul 29, 1994Aug 5, 1997Supelco, Inc.Nucleophilic bodies bonded to siloxane and use thereof for separations from sample matrices
US5858241 *May 15, 1997Jan 12, 1999Hewlett-Packard CompanyFilling stationary phase packing material into capillary, immobilizing by applying thermal treatment along entire length while applying pressure to inlet side
US5997746 *May 29, 1998Dec 7, 1999New Objective Inc.Evaporative packing of capillary columns
US6190559Aug 2, 1999Feb 20, 2001Valaskovic Gary ASlurry of packaging material in volatile solvent
US6395183Jan 24, 2001May 28, 2002New Objectives, Inc.Forcing slurry liquid (but not solid) through frit; chromatography
US8101998 *Mar 30, 2009Jan 24, 2012Oki Semiconductor Co., Ltd.MOSFET and manufacturing method thereof
WO1999062610A1 *Apr 16, 1999Dec 9, 1999New Objective IncEvaporative packing of capillary columns
WO2005039106A1 *Oct 20, 2004Apr 28, 2005Nortel Networks LtdMethod and apparatus for performing routing operations in communications network
Classifications
U.S. Classification210/198.2, 96/101, 210/656, 95/88
International ClassificationG01N30/38, G01N30/60, G01N30/56
Cooperative ClassificationG01N30/6078, G01N2030/387, G01N30/56
European ClassificationG01N30/56, G01N30/60D8B