US3871826A

US3871826A - Method and apparatus for transporting discretely samples to be analyzed in a gel

Info

Publication number: US3871826A
Application number: US319525A
Authority: US
Inventors: Bohdan Bakay
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-12-23
Filing date: 1972-12-29
Publication date: 1975-03-18
Anticipated expiration: 1992-03-18

Abstract

A method and an apparatus for conveying samples of substances separated by a gel spacer which is squeezed into and wipes the inner wall of conduit free of contamination between samples transported therethrough, the spacer gel having high cohesive forces so as to return to its normal shape when free of compressive stress, is disclosed.

Description

0 United States Patent [1 1 [111 3,871,826 Bakay Mar. 18, 1975 [5 METHOD AND APPARATUS FOR I 3,523,756 8/1970 Loebl 23/253 x TRANSPORTING DISCRETELY SAMPLES 134/22 C U 0 era e a To BE ANALYZED IN A GEL 3,690,833 9/1972 Ferrari 23/230 R Inventor: Bohdan Bakay, 2967 Curie St., San

Diego, Calif. 92122 Filed: Dec. 29, 1972 Appl. No.: 319,525

Related US. Application Data Continuation-impart of Ser. No. 211,182, Dec 23, 1971, abandoned.

US. Cl. 23/230 R, 23/25.3 R, 134/22 C, 302/2, 302/66 Int. C1....B08b 9/00, GOln 31/08, GOln 33/00 Field of Search..... 23/230 R, 253 R; 134/22 C, 134/23, 166 C, 167 C, 168 C, 169 C; 15/104.06 A, 104.06 R; 302/2, 66; 222/183, 309

References Cited UNITED STATES PATENTS 11/1969 Smythe et a1.. 23/230 R 12/1969 Smythe et a1. 23/230 X ACRYLAMIDE SOLUTION OTHER PUBLICATIONS Chemistry of Acrylamide American Cyanamid Companyl969 pp. 18-19.

The Merck Index Eighth Edition pp. 24 and 484.

Primary ExaminerJoseph Scovronek Assistant Examiner-Michael S. Marcus Attorney, Agent, or FirmKnobbe, Martens, Olsen, Hubbard & Bear 57 ABSTRACT A method and an apparatus for conveying samples of substances separated by a gel spacer which is squeezed into and wipes the inner wall of conduit free of contamination between samples transported therethrough, the spacer gel having high cohesive forces so as to return to its normal shapewhen free of compressive stress, is disclosed.

17 Claims, 13 Drawing Figures SAMPLE SOLUTION CATALYST JPATEMIEWM 81975 SnLEI 1 BF 4 llll RESERVOIRS DATA '2 PRESENTATION REACTOR so INVENTOR. BOH DAN BAKAY 70 H 3 BY 03W & m WASTE ATTORNEYS PATENTEDIIIIII 8|975 3871 ,826

SI-LU 2 IF 4 RESERVOIRS RESERVOIRS A B c 0 E F e H J K sE L sE L 52 54 6O 58 56 v v P SEL. 72 MIX P IO M .Z 74

IQ m CHROMATOGRAPHY l2 COLUMN J I a2 50 94 96 GEL e2 O FRACTIONATOR T T QE AMPL O INJECTOR SAMPLE /9o OXIDIZER ea DATA PRESENTATION 6 AS 66 64 ANALYZER 9 REACTOR INJEcTIoN ANALYZER w PORT Ioo l INVENTOR. 4 BOHDAN BAKAY wAsTE BY BWXLYYLW ATTOR NEYS PATENTEDHAR 1 81% 3. 871 ,826

sum 3 of g CARRIER FLUID GEL CONTAINING CHEMICAL CONTAINING'CHEMICAL COMPOUND To BE COMPOUND TO ANALYZED BE ANA LYZED Fig. 5 Fig. 6

. SAMPLE SOLUTION ACRYLAMIDE CATALYST SOLUTION Fig. IO N PATENTEU W1 W5 SHEET U 0F 4 SOLUTION SAMPLE Fig. l2

SLOW FLOW DUE TO WALL FRICTION FASTER Fig. :3

1 METHOD AND APPARATUS FORTRANSPORTING DISCRETELY SAMPLES TO BE ANALYZED IN A GEL CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my earlier application, Ser. No. 211,182, filed Dec. 23, 1971 and now abandoned.

BACKGROUND OF THE INVENTION In the continuous flow analysis technique, liquid samples of the substances to be analyzed are usually transported through tubing in a fluid with successive samples hopefully being separated by air bubbles. The primary disadvantage of such systems is contamination,

. resulting from wetting of the inner wall of the conduit causing thin film deposits of the samples on the tubing walls, which are not completely removed by passage of the liquid and the separating air bubbles. The deposited film of the sample is in part taken up by the next successive sample, which thereby becomes contaminated. Various expediences have been utilized to reduce this cross contamination, an example of which is using air bubbles in combination with siliconizing the conduit wall. The main objective of separating the samples by segments of air or siliconizing the conduit has been to reduce wettng of the wall of the conduit by such samples as much as possible. In the analysis of some nonaqueous samples, siliconizing of the conduit is insufficient to prevent wetting of the conduit by the samples as silicon is soluble in the liquid of the sample. The further objective has been to reduce the spreading of the sample in the conduit caused by the friction adherence of the sample to the inner wall. Since no such adherence is in the center of the tube, a faster flow occurs in the center of the conduit than at the wall causing a conical flow in the conduit rather than discrete zonal flow. Neither of these objectives have been accomplished by the aforesaid approaches and cross-contamination and conical flow problems continue to cause inaccurate and imprecise sample analysis data. When sample quantities are extremely small, such as in radioactive quantitation of isotopes any cross-contamination is unacceptable.

It is therefore advantageous to have a method and apspreading of the samples because of such flow. Solid, liquid, or gaseous substances can be transported in the suitable gels.

paratus for reducing such cross-contamination and conical flowproblem, which can be used in an efficiently mechanized system for processing the analysis of a wide variety of samples.

SUMMARY OF THE INVENTION In the apparatus described herein, samples are spaced by a gel that provides good separation of discrete samples and is effective in cleaning the walls of the conducting tubing. This results from the greater cohesion forces of the gel and lack of adhesion to the wall. Particular gels are used that are compatible with the particular samples. Thus the samples and gel are such that the sample may not interact, they may be absorbed by the gel or they may react with the gel and become chemically incorporated into the gel. The gel has a relatively high coherence than the liquid carriers and with its absorbing capabilities relative to the sample, clean the tube wall and no sample film is left on the wall to cross-contaminate the samples. Also, the gel substantially eliminates the conical flow and thus the Fragmented aqueous gels of polyacrylamide. agar or agarose, aqueous gels of silicates and similar gels can be used.

Gels of acidic or alkaline content, used at elevated pressure, will absorb gaseous oxides of carbon, nitrogen, phosphorous, sulfur, arsenic and other such combustion products. They will also absorb hydrogen compounds of sulfur, nitrogen, selenium, chlorine, fluorine, bromine, iodine and the like and acidic and basic fluids such as organic acids and amines, vapors of alcohol, aldehydes, ketones, halogenated hydrocarbons and other volatile compounds. Gels can also be formulated to absorb substances selectively, as for example, amines but not carbon dioxide or the reverse.

In apparatus particularly adaptedto the gel technique, suitable chemicals are selected from reservoirs containing either the gel forming reagents, preformed gels, solubilizers, carrier fluids, and the like, and combined to form a carrier gel compatible with the substance to be carried. The samples are loaded into cartridges' which are to be placed sequentially into the path of thegel advancing or transported to the analytical or detector apparatus. To make the apparatus adaptable to a wide range of analytical processing, access points are provided for connection of various sample sources to introduce samples into the gel flow. Typical sample sources are liquid or gas chromatographic columns, fractionators, oxidizers, automatic sequential feed devices delivering prepared samples sequentially from storage containers and other such means.

An important feature of this invention is the provision of a new and improved method and apparatus for discretely transporting samples of substances to be analyzed with substantially no cross-contamination or conical center flow.

Another feature of this invention to provide a new and improved method and apparatus for transporting discrete samples, in spaced succession in a gel flow, to various types of analytical means without contamina tion between samples.

Another feature of this invention to provide a new and improved method and apparatus in which samples in gel filled cartridges are analyzed sequentially and in spaced intervals in a continuous gel flow.

Another feature of this invention .to provide a new and improved apparatus having access points at which samples can be injected into the gel flow from a variety of sources, either manually, semi-automatically, or fully automatically.

Other objects and many advantages of this invention will become more apparent upon a reading of the following detailed description together with an examination of the drawings, wherein like reference numerals refer to like parts throughout and in which:

FIG. 1 illustrates a plurality of sample cartridges on a holder, with sample injection being applied to one cartridge.

FIG. 2 is an enlarged sectional view taken on line 22 of FIG. 1.

FIG. 3 is a diagram of the basic form of the complete apparatus.

FIG. 4 is a diagram of the apparatus with multiple sample input sources.

FIG. 5 is a sectional view withparts broken away of a conduit with spaced fragmented gel and a sample.

FIG. 6 is a sectional view with parts broken away of a conduit with fragmented gel and a sample.

FIG. 7 is a sectional view with parts broken away of a conduit with fragmented 'gel in larger particle sizes.

FIG. 8 is a sectional view with parts broken away of aconduit with continuous gel flow therein.

FIG. 9 is a sectional view with parts broken away of a junction conduit for inserting fragmented gel into a liquid flow stream. I

FIG. 10 is a sectional schematic view of a conduit arrangement for inserting larger particle size gel into the liquid flow in the conduit.

FIG. 11 is a sectional schematic view ofa conduit arrangement for introducing fragmented gel into a continuous gel stream.

FIG. I2-is a diagrammatic illustration of the problems in analysis results that occur in prior art devices.

FIG. 13 is a diagrammatic illustration of the analysis results obtainable with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the basic form of the apparatus as shown in FIG. 1, samples are deposited in cartridges 10 which are mounted on a holder 12, illustrated as a simple tray on which the cartridges are held by clamps I4. Holder 12 may be of any suitable type, such as a tray, rack, belt or carousel type conveyor, or any other means by which cartridges can be positioned sequentially at a handling station.

As shown in FIG. 2, each sample holder may, for example, comprise a known cartridge 10 having a cylindrical casing 16 of stainless steel or the like, with a small diameter inlet tube 18 supporting a sample tube 20.'()ne end of the cartridge is detailed in FIG. 2, the other end being similar in construction. The structure of the cartridge can be varied to suit the handling equipment, and the internal sample tube can be rigid or in the form of a coiled capillary.

For preparation of a sample, each cartridge is held between an injection cap 22 and a relief cap 24, which relief cap 24 may be applied by any suitable manually or automatically actuated means. The injection cap 22 has a body 26 with a socket 28 which fits closely over the end of cartridge 10. Depending on the material of the body, a gasket 30 may be used in the socket to prevent leakage. In the body 26 is a septum 32, held in place by a threaded plug 34 which has an axial bore 36, the body having a small bore 38 coaxial with bore 36 and positioned for alignment with the inlet tube 18. Septum 32 is of self-sealing rubber, or the like, and will withstand repeated penetration by the needle 40 of a syringe 42 used to inject the sample.

Relief cap 24 seats on the cartridge in a similar manner to the injection cap, but does not contain a septum. A drainage tube 44 connects the relief cap 24 to a waste receptacle 46, to accept the slight overflow of gel displaced by the injection of a sample into the cartridge.

In the basic apparatus illustrated in FIG. 3, the holder 12 is held by any suitable mechanism that will advance the cartridges successively to a handling station. At the handling station each cartridge is held in sealed relation between an inlet cap 48 and an outlet cap 50. Gel is obtained from reservoirs, illustrated as a first group of five 4 marked A-E and a second group of five marked F-K. Reservoirs A-E are connected to a selector valve '52, which is connected through a'pump 54 to a mixing valve 56. Reservoirs F-K are similarly connected.

through a selector valve 58 and pump 60 to the mixing valve 56, the output of which is connected to inlet cap 48. Thus the contents of any reservoir or combination of reservoirs from the two groups can be delivered by mixing valve 56 to produce the required gel. As one example, reservoirs A-E could contain solubilizers for radioactive samples, gas absorbers, preformed gels or gel forming agents, while reservoirs F-.-I( could contain scintillation solutions and the reagents necessary to form gels. The selector valves, pumps capable of delivering precisely metered'amounts of material, and the mixing valve are all available components. It should be understood that the quantities involved are very small, a typical cartridge having a capacity on the order of 300 microliters.

From outlet cap 50, a delivery tube 62 leads to a reactor 64 in which any necessary preparation of the sample for analysis, such as by thermal treatment or the like, can be accomplished. If no such treatment is necessary the reactor stage may be omitted. The sample carrying gel in the cartridge is forced through the delivery tube 62 into the analyzer 66, which may contain a wide variety of analytical means. Typical functions include spectrophotometric analysis, UV analysis, radioactive quantitation and the like, the instrumentation being well known. The analyzer is connected to suitable data presentation means 68, for display and recording of results. After analysis the gel and sample is carried to a waste receptacle 70.

The transporting flow of gel keeps the cartridges filled during the operation and has a self-cleaning action, so that each refilled cartridge is ready for injection of another sample. Initial filling of the cartridge is also conveniently accomplished in the apparatus, with the required formulation of gel;

In the more comprehensive apparatus illustrated in FIG. 4, the basic system of reservoirs, pumps, valves and the analytical means is similar to that described above and the parts are correspondingly numbered. Between pump 54 and mixing valve 56, there is a two way selector valve 72 for directing material from reservoirs A-E to the mixing valve 56 or to a chromatography column 74.- Effluent from column 74 is conveyed through a tube 76 to a mixing valve 78 inserted in the delivery tube ahead of reactor 64, so that the effluent can be injected into the gel as it is produced. A polyacrylamide or agarose gel fractionator 80 is connected to valve selector 84 through a valve 82. This apparatus allows analysis of the profile obtained by the electrophoretic processes.

In the delivery tube 62, a selector valve 84 is installed to receive inputs from various sample sources. Typical sources indicated include a gas analyzer 86 coupled to selector valve 84 through a valve 88, a sample oxidizer 90 coupled to the selector valve 92, and an automatic sample injector 94. Gas analyzer 86 may be a gas chromatography column or similar fractionator. The automatic sample injector is a well known type of apparatus that extracts samples successively from containers on an indexed carousel 96 or similar type rack.

Also installed in delivery tube 62 is an injection port 98, which is an available unit containing a septum 100 through which a sample can be injected by syringe into the gel flow. The apparatus can thus be installed in a complete system for analysis of a variety of samples from different sources, in addition to samples deposited in the cartridges.

In moving the gel and sample through the conduits mented gel 106 dispersed in a carrier fluid 104 and a.

sample 108 of a chemical compound to be analyzed is dissolved in a carrier fluid 104 moving in conduit 102. The fragmented gel 106 may comprise, for example, gels of polyacrylamide, agar, agarose, or a gelatin such a suitable animal gel or any suitable non-crystalline, colloidal gel which due to its chemical composition and cohesion forces retains its physical form or shape and is compatible with the carrying fluid which means it rethe sample which may be caused by conical flow. While in many instances the carrying fluid may be water, an aromatic hydrocarbon carrier including fluids such as benzene, toluene, or xylene can be used because they are fluids that wont dehydrate a water based gel. As previously described, the gel is fragmented to transport the sampleand the sample and gel are not macerated to be analyzed.

The gel can also take the form of large gel particles that are transported in a carrier fluid in the conduit. Referring to FIG. 7, a conduit 12 has gel particles 126 moving in fluid 124 and providing separation for sample 128 in the diffusion zone of 129. These particles 126 of gel are formedin the conduit 122 in the manner illustrated in FIG. 10. A conduit 122 has water 124 therein. Conduit 122 has an intersecting transparent conduit 136 that has a mixing junction 146. Materials tains its physical and chemical properties when exposed to the carrying fluid. Such gels as polyacrylamide, agar, agarose or a gelatin may contain as much as 98% water providing an aqueous gel. However, it should be recognized that non-aqueous polymeric gels can also be macerated and injected into the small conduits, that generally have a diameter of less than 0.05 inch.

The gels can be inserted into the conduit 102 by either a continuous or pulsating supply of fragmented gel being fed into the carrier fluid 104. Conduit 102 may, for example, be a conduit such as conduit 20 in FIG. 2. One method of inserting fragmented gel into a test conduit is illustrated in FIG. 9. A pair of mixing-

tubes

156 and 158 carry gel and water into a test conduit 167. The gel formed in enlarged tubing 160 is passed through a suitable screen 164 that fragments the gel into gel particles 166 that are mixed with the water in conduit 167. The pressure applied to the gel in tubing 160 determines the spacing of the fragmented gel as well as its compactness in conduit 167. The particular gel particle size is not critical so long as it can squeeze into the conduit 167. So even though the gel particle sizes can vary widely, the gel particles can be smaller than the diameter of the conduit and still sufficiently wipe the inner surface ofthe conduit to prevent smearing of the sample spaced by the gel in the conduit from other samples.

The sample is injected into the tube and gel downstream of the injection of the gel into the conduit, such as occurs in selector 84 of FIG. 4 in injecting samples from automatic sample injector 94. Larger amounts of the fragmented gel injected in the tube increases the compaction or amount of the gel in the tube and reduces the spread ofthe sample transported therein. Referring to FIG. 5, the expected diffusion zones of the sample 108 would be limited generally to the zone defined by the dashed

lines

110 and 112. In the continuous fragmented gel stream 116 is a carrier fluid 118 in conduit 114, see FIG. 6. The sample zone where the sample is injected in the compacted gel stream is limited to the zone between dotted lines 120. The gel again having a greater cohesion force not only wipes the tubing clean of the samples but also restricts spreading of such as an acrylamide solution is supplied through line 142 and a suitable catalyst 140, such as ammonium persulfate or riboflavin, is supplied through line 140. These materials are mixed at 146 andare illuminated by an ultra-violet lamp 138 through the transparent conduit 136. The material then passes through an extension of the conduit 136, where the mixed materials that were exposed to the ultraviolet light form a gel that is moved by the fluid pressure to project 148 through opening 150 into the conduit 122. The pressure of the water flow in tubing 122 causes portions ofthe gel 148 to break off into gel particles 126 that continue to flow through the conduit 122. The broken off gel particles 126 are replaced by new gel 148 projecting into the conduit 124 that are in turn broken off. The acrylamide is in water solution and can be of any suitable percentage, but generally is a percentage of about 10% This process produces fragmented gel in tubes of very small diameter and is what can occur in the mixer 56, FIGS. 3 and 4, to make gel particles from selected solutions from reservoirs A through E and F through K.

The sample in the embodiment of FIG. 10 is normally injected at 139 into the conduit 122 downstream of conduit 136. However the sample can be introduced in conduit 136 at, for example 137, so that the sample is in the material before. it is formed into gel. The sample is then incorporated into the .gel particles 126.

In using gels to transport samples in the circuits, it is normally difficult to insert a formed solid gel into the small-in-diameter conduit that normally is less than 0.05 inch in diameter. However, it is possible to form gel in the conduit by mixing solutions in the conduit to form a gel of great cohesion. Such gels provide chemical acceptance of samples that provide significant nondiffusion of sample zones, thus maintaining increased separation of the sample zones. Referring to'FIG. l1, appropriate solutions such as A, B and C are injected into mixer through

conduits

173, 174 and 175. Upon mixing, these solutions form a gel that is moved under fluid pressure into conduit 172. A sample is then injected through injector downstream of the mixer 170 to provide a sample zone 182. Other appropriate solutions can be injected into conduits 176 to mixer 170 as appropriate. A fragmented gel 166 such as was previously described relative to FIG. 9 is inserted into the continuous gel 182 from mixer 170. This fragmented gel in the non-fragmented gel will provide greater cohesion to the total stream that will, in effect, sweep the wall surfaces of the conduit 172 clean.

Samples may be introduced in many different solvents or solubilizers as a great number of them are compatible or miscible with water or aromatic hydrocarbons. Further, samples can bevintroduced into the gel stream in liquids which could interact in the gel and form chemical reactions in the sample zone. For example, gel can have an acid or base content. Then thegel can accept samples that have acids or bases with which they enter into chemical reactions. An example is gel with an acetic acid in H O receiving an introduced sample of ammonia that forms ammonium acetate, which is a stable zone in the gel and does not crystallize. The sample carried thereby is held in the separated and non-diffused zone and does not migrate, and the gel wipes the sides of the tubing restricting the diffusion of sample zones. Further, when introduced into the gel, vapor samples precipitate to a liquid upon cooling, or gas samples chemically interacting with, for example, a gel containing ammonia and this is converted to different chemical compounds which is now part of the gel and is preserved in the gel. Examples of this are SO: plus 2NH plus H O gives (NH SO and N plus NH plus H O gives NH,NO,-,, which form stable, chemically incorporated samples.

As previously stated, the most important considerations or problems in moving samples through a conduit, are cross contamination between samples and the interference in reading and detecting sample information resulting from the smearing of samples on the walls of the conduit causing cross contamination, and the excessive spreading of the samples that occurs because of the so called conical effect. Referring to FIG. 12, there is illustrated an example of the prior problem in movement of a sample 204 in a conduit 200 in a carrier liquid 202. Because of wall friction, the flow of the fluid is slower at the wall surfaces than at the center of the conduit along arrow 208. Thus, the sample assumes a conical shape. which because of faster center flow, becomes more pronounced the greater the distance of movement of the samples through conduit 200. So the sample can become very elongated if moved any reasonable distance through the conduit 200. Further, the sample adheres to the wall of the conduit 200 at 210, maintaining thin film on the wall. Thus the quantitative analysis curve 212 will take the general shape as illustated with the greatest portion of the sample being at 214, and the amount of the sample declining along curve 216 to a point 218 where the sample film adhered to the wall gives a continuous reading. It may be understood that in normal test situations, samples are moved through the conduit 200 at successive intervals. Thus the wall contamination plus the conical effect can and does cause portions of the sample 204 to communiintroducing fluid samples into the stream at spaced intervals, and wiping films of the liquid carrier and sample from the inner wall surfaces of said conduit with said gel spacers. 2. In a method for transporting samples of material through a conduit of an automatic transfer apparatus as a flowing stream of such samples separated by spacers. the improvement wherein the spacer consists essentially of a gel which is characterized by cohesive forces which cause the gel to retain its physical form and shape and having a size to be squeezed into the conduit which carries the sample stream thereby to wipe the inner surface of the conduit to prevent smearing of said material along the conduit, to reduce conical flow and cause discrete zonal flow of the samples which are spaced by the gel spacer.

3. The method as claimed in claim 2 including the following steps for introducing the gel into the conduit,

mixing an acrylamide solution with a catalyst in a tube,

exposing said mixed solution in said tube to ultraviolet light to form a gel,

moving the end of said gel from said tubing into said conduit at an angle to said conduit, and

moving a carrier fluid in said conduit with sufficient flow force to break off fragments of said gel projecting at the angle into said conduit, repeating the sequence of moving the end of said gel and said carrier fluid into said conduit.

4. The method as claimed in claim 3 including the step of.

introducing a sample solution into said conduit downstream of said gel projecting into said conduit.

5. The method as claimed in claim 3 including the step of,

introducing a sample solution into said mixed acrylamide solution and catalyst prior to said solution being formed into the gel entrapping said sample solution in the formed gel portions.

6. The method defined in claim 2 wherein the gel consists essentially of a non-crystalline, colloidal gel of water and a material selected from the group consisting of polyacrylamide, agar, agarose and gelatin.

7. The method definedin claim 6 wherein the gel consists essentially of water and polyacrylamide.

8. The method defined in claim 2 wherein the gel spacer consists essentially of at least one gel fragment squeezed into the conduit.

9. The method defined in claim 8 wherein the gel consists essentially of a non-crystalline, colloidal gel of water and a material selected from the group consisting of polyaccylamide, agar, agarose and gelatin.

10. The method defined in claim 9 wherein the gel consists essentially of water and polyacrylamide.

11. The method defined in claim 10 wherein the samples are transported through an analytical device for analysis thereof.

12. The method defined in claim 8 wherein the samples are transported through an analytical device for analysis thereof.

13. The method defined in claim 2 wherein the gel spacer consists of a multiplicity of fragments of gel squeezed together in the conduit to travel together as a block.

3 ,8 7 l ,8 26 v 9 10 l 14. The method defined in claim 13 wherein the sam- 16. The method defined in claim 15 wherein the gel P are transported through an analytical device for consists essentially of water and polyacrylamide.

analysis thereof- 17. The method defined in claim 16 wherein the sam- 15. The method defined in claim 13 wherein the gel 1 I d h h I l d consists essentially ofa non-crystalline, colloidal gel of 5 p es are trmsporte t.roug an ana ytlcl tor water and a material selected from the group consisting analysis thereofi of polyacrylamide, agar, agarose and gelatin.

Claims

1. IN THE METHOD FOR TRANSPORTING SAMPLES TO AN ANALYZER THE IMPROVEMENT COMPRISING THE STEPS OF: FORMING A STREAM BY INTRODUCING A LIQUID CARRIER INTO A CONDUIT AND BY INTRODUCING GEL SPACERS INTO SAID CONDUIT, INTRODUCING FLUID SAMPLES INTO THE STREAM AT SPACED INTERVALS, AND WIPING FILMS OF THE LIQUID CARRIER AND SAMPLE FROM THE INNER WALL SURFACES OF SAID CONDUIT WITH SAID GEL SPACERS.

2. IN A METHOD FOR TRANSPORTING SAMPLES OF MATERIAL THROUGH A CONDUIT OF AN AUTOMATIC TRANSFER APPARATUS AS A FLOWING STREAM OF SUCH SAMPLES SEPARATED BY SPACERS, THE IMPROVEMENT WHEREIN THE SPACER CONSISTS ESSENTIALLY OF A GEL WHICH IS CHARACTERIZED BY COHESIVE FORCES WHICH CAUSE THE GEL TO RETAIN ITS PHYSICAL FORM AND SHAPE AND HAVING A SIZE TO BE SQUEEZED INTO THE CONDUIT WHICH CARRIES THE SAMPLE STREAM THEREBY TO WIPE THE INNER SURFACE OF THE CODUIT TO PREVENT SMEARING OF SAID MATERIAL ALONG THE CONDUIT, TO REDUCE CONICAL FLOW AND CAUSE DISCRETE ZONAL FLOW OF THE SAMPLES WHICH ARE SPACED BY THE GEL SPACER.

3. The method as claimed in claim 2 including the following steps for introducing the gel into the conduit, mixing an acrylamide solution with a catalyst in a tube, exposing said mixed solution in said tube to ultraviolet light to form a gel, moving the end of said gel from said tubing into said conduit at an angle to said conduit, and moving a carrier fluid in said conduit with sufficient flow force to break off fragments of said gel projecting at the angle into said conduit, repeating the sequence of moving the end of said gel and said carrier fluid into said conduit.

4. The method as claimed in claim 3 including the step of, introducing a sample solution into said conduit downstream of said gel projecting into said conduit.

5. The method as claimed in claim 3 including the step of, introducing a sample solution into said mixed acrylamide solution and catalyst prior to said solution being formed into the gel entrapping said sample solution in the formed gel portions.

7. The method defined in claim 6 wherein the gel consists essentially of water and polyacrylamide.

14. The method defined in claim 13 wherein the samples are transported through an analytical device for analysis thereof.

15. The method defined in claim 13 wherein the gel consists essentially of a non-crystalline, colloidal gel of water and a material selected from the group consisting of polyacrylamide, agar, agarose and gelatin.

16. The method defined in claim 15 wherein the gel consists essentially of water and polyacrylamide.

17. The method defined in claim 16 wherein the samples are transported through an analytical device for analysis thereof.