DE19839705A1 - Assay for an analyte is based on peripheral capillary flow of sample into test device comprises indicator-impregnated porous support between liquid-impermeable films - Google Patents

Abstract

Assay for an analyte in a sample comprises impregnating a porous support with an indicator solution, drying the support, laminating the impregnated support between liquid-impermeable films, immersing the resulting test device in the sample to allow capillary flow of the sample into the impregnated support from the periphery of the device, and measuring the extent to which the analyte-indicator reaction has penetrated into the device. Method for performing a rapid chemical test on liquid samples by micro-titration, micro-chromatography or other methods of dry chemistry and methods for production is effected in that the relevant chemical analysis processes become more accurate by having partial sampling take place according to the principal of vectorial capillary flow addition, which is achieved by at least two opposed flow directions in a capillary-active device with at least two inlet openings for the sample, where the whole test device is bathed in the sample and accurate quantitative evaluation is performed by means of an analyte-concentration-proportional area or distance measurement and where several analytes can be determined simultaneously with a test device having several differently prepared capillary zones. An Independent claim is also included for production of the test device by dissolving the relevant analytical reagents in a vaporizable solvent, impregnating a porous support with the solution, drying the support, laminating the support between two liquid-impermeable adhesive films, and punching out disks from the laminate.

Description

As is well known, there is a great need for simple, fast chemical Test methods that contain a specific analyte (substance to be determined) without can determine great effort "on site" with sufficient accuracy. The modern information society constantly demands further information about the material composition of certain matter samples. Another Improve medical diagnostics or environmental protection for example, only by increasing the chemical information (= Analysis data) possible. Traditional chemical analyzes usually require on well-established laboratory and qualified specialists. Classic Analysis methods usually work with larger sample volumes (milli liter range) and correspondingly greater use of chemicals. This leads to everyone a further increase in the frequency of analysis automatically to one corresponding increase in hazardous chemical waste, with each traditional analysis. There is therefore a need for chemical Analytical methods that do not have these disadvantages, no laboratory and / or need more qualified personnel or expensive analysis equipment.

According to this great need for simple analytical devices some systems have been on the market for a long time. You will be under the designation "test stick", "test strips" or something like that. The associated chemical field is called "dry chemistry" (Oswald Sonntag; Dry chemistry: analysis with carrier-bound reagents, Thieme Verlag, Stuttgart 1988). With these products you try a classic chemical Analysis (e.g. photometry using selective color reagents) on an inert, more or less porous supports made of paper, ceramic or the like minimal use of chemicals. The evaluation takes place at  these quick test products usually by color or intensity comparison using a supplied color comparison scale. The sample concentration of the The analyte in question is then the one with the same color. The different test sticks or test strips are similar to the known one pH indicator paper strips.

The disadvantage of all test sticks currently on the market is that limited analysis accuracy, which is why some manufacturers also clear of talk about "semi-quantitative" methods. A big problem with all devices The objective is without an automated and standardized evaluation device Color matching with the naked eye under the most varied lighting conditions or for colored samples. But also the duration of immersion of these Test stick is important for accuracy and must be carefully checked. In In some cases, chemicals from the test strips are also added to the sample washed out. Some rapid test devices are used to increase the Measuring accuracy is automatically absorbed by capillary micropipettes used, but because of their complexity, the production cheaper Prevent test sticks. Especially for the blood analysis were integrated Sample preparation stages for the separation of e.g. B. the disruptive components (e.g. red blood cells). All of this made it more and more complicated built up test sticks, for example, not for a few pfennigs too are preserved.

A few years ago an attempt was made to use the somewhat uncertain color comparison to deal with lightfast and therefore expensive color scales to be supplied in that one has to measure the extent of a colored zone instead of a color, to get the analysis result (SALTESMO, Machery & Nagel, Düren). According to the inventors (F.J. Förg and M. Staub Chem. Rdsch. (Solothurn, Switzerland) 17, (1964) No. 19) for a "titration on the Paper ". The classic methods of dimensional analysis are based on the principle of chemical equivalence at the recognized end point, which is often indicated by a sharp visible color change of suitable, added indicators made visible becomes. According to these authors, "semi-quantitative titrations on paper" preferably suitable for the rapid control of certain limit concentrations.  

According to the analyte to be determined and its concentration in addition one soaked with a suitable original titer substance and indicator Filter paper made. On a usually round test stain this prepared filter on a suitable carrier is then placed centrally in the middle carefully apply the sample using an accurate micropipette (1-10 µL). The duration must also be taken into account. Then a second Micropipette with dist. Washed to remove the sample over the water to distribute the entire test area. Due to the isotropic capillary forces of the Filter paper results in concentric staining or staining zones around the Sample application location. The size of these spots is the concentration of the analyte proportional. Usually this semi-quantitative test only determines whether the entire test area is changed in color, which is to be checked Limit concentration corresponds. Such microtitration devices are commercially available directions for halide anions available. They are based on the implementation the halide ions with a colored silver salt (here silver chromate), which at the reaction is decolorized.

From Japan (US Pat .: 4744952) is an improvement on this halide method of determination known as the so-called Urtiter on paper berberine sulfate mixed with pigments, using Patent Blue V as an indicator. Another Japanese invention (U.S. Pat .: 4211532) describes the manufacture of the above-mentioned halide test stick using a colloidal Silver chromate solution, a surfactant and a buffer rea genzes. A similar device is known from the USA (US Pat .: 4444193) Skin plaque known to make a diagnosis of cystic fibrosis can be. To do this, a certain amount of skin sweat gets into the Brought reaction zone. After the local discoloration is exceeded via a certain dimension, a surrounding differently indexed second ring is discolored. If this happens, there is an increased chloride content and within the range Accuracy of measurement a positive diagnosis on cystic fibrosis.

One is from a German patent application (AZ: P 1 95 45 130.9-52) Device known that also determines the concentration via a Distance or number measurement of microtitrations carried out in parallel  carried out and therefore resembles the above developments, only that here with the Microsystem technology a much greater effort in the manufacture of Containments for the analytical reagents must be operated. The Problem of exact simultaneous sampling for each microtitration reactor can not be solved inexpensively with this patent, or is open has been left, which considerably limits its applicability.

There is therefore a great need for simple and inexpensive rapid test fixtures, most of all an automatic and highly accurate sampling integrate to the analysis accuracy from the semi-quantitative side to quantitative side (accuracies better than +/- 10%). A large The disadvantage of all the above-mentioned devices for rapid on-site analyzes is however, the fact that sampling and dosing the sample aliquot not done automatically and some manual effort and a large one Care is necessary. Also the controlled that is sometimes required Wash out with dist. Water in prescribed periods is not very practical and can lead to major errors in the event of non-compliance or neglect. In the SALTESMO device mentioned above, the test plates have to be first be pierced in the middle with a needle so that the sample is there can penetrate. The liquid sample then penetrates centrally and migrates through the capillary action of the soaked filter paper to the edge of the circular Platelets. The solvent front spreads unevenly in the paper from, these irregularities increasing towards the edge. The biggest problem here is to recognize when the test tile is complete has soaked and thus when the sampling or analysis is finished. When the sample liquid has reached the edge of the test plate, this should be done Test plates are taken from the analytical solution and you have to Estimate the size of the discolored zone using a comparison scale. Since the However, the solvent front spreads very unevenly Removal of the test plate from the sample solution is relatively unsafe as well Shape of the discolored surface naturally also uneven, so that a It is very difficult to estimate or measure the discolored area more precisely is. Because of these inaccuracies, the manufacturer only calls this test as semi-quantitative.  

Furthermore, many test strips or test sticks are known, which the Capillary suction effect of porous carrier material or narrow gaps without to use porous carrier material (so-called capillary fill devices) Transfer sample aliquot to the actual analysis device. For this purpose, in In the first case, capillary-active carrier materials that are not covered regularly (Blotter function) used. You can do so, almost from all sides accessible, soak up with the gaseous or liquid sample medium. The The amount soaked up represents the analyzed sample aliquot however, some problems arise that are the cause of the semi-quantitative Make character: One is the inflow direction of the sample in the porous absorbent carrier does not exactly define what a dependence on the Relative movement of the test strip to the measurement solution entails. On the other hand but it happens because of the large contact zone between the capillary force active zone and the solution to undesirable bleeding or undesirable Diffusion phenomena when sampling is too long, which is why the immersion time as factor to be precisely controlled. In contrast, the strapless So-called capillary filling devices are very popular in clinical analysis. she are usually with only one open side in contact with the sample brought and then suck themselves through the capillary forces and only through this one sample port full, with a vent hole at the other end of the Micropipette-like device marked the conclusion. Depending on the However, wettability can result in unfilled areas at the end of the Capillary pipette cannot be ruled out entirely, making the accuracy strong restricted.

A disadvantage of all known rapid test devices based on the so-called. Dry chemistry is the relative inaccuracy of aliquotization or cumbersome handling, the device only for a certain, measured Time to get in touch with the sample to fill it with after filling pull this opening out of the sample. The known inaccuracies along with the washout problems have so far made the development more accurate measuring test strips or sticks prevented. This also applies to the Application of absolutely measuring (no calibration required) procedures  Basis of the measurement analysis using immobilized primary titer substances (microtitration) and suitable indicators.

The present invention avoids all of the above disadvantages of the prior art the sampling technique through an ingenious and simple innovation that is best characterized by an exactly access control Capillary suction with vectorial liquid flow compensation an abrupt end of all capillary sample liquid flows. Characterizing restricted access control (minimized Contact zone between test stick and sample) is the diffusion limitation of the capillary suction zone, which is due to narrow, planar capillary filling zones with dense Interfaces and peripherally open narrow contact zones (inflow opening for Sample) is accomplished. The central point of the invention is further that the In contrast to all known techniques, sample liquid is not only available on one Penetrates into the test device. It is important that the sample is in a contiguous capillary flow path (capillary channel) always accurate opposite ends flows in, when the Capillary currents due to the vectorial addition of forces (see forces parallelogram) the capillary suction effect is abrupt overall (= accurate and reliable volume dosing) is stopped. Because of the small contact zone and the rest Limitation with dense barrier layers occurs when the reagents are washed out and / or a disturbing back diffusion practically no longer occurs.

The device according to the invention can also by means of a very simple manufacturing process. The present Invention - as already explained above - therefore solves in particular the problems of reproducible, automatic and simple sampling and dosing an exact sample aliquot. In contrast to the next most occasional Prior Art (SALTESMO) according to the invention not the analysis sample centro-symmetrical (or, as is generally the case with the prior art, only on one single spot) with or without a micropipette on the center of the test plate given, but the sample is left radially symmetrical (peripheral) from one penetrate the open edge on all sides into the test device. The Liquid transport through the capillary suction of a suitable  Carrier material or through the correspondingly closely opposed, liquid-tight interfaces.

In the sampling technique according to the invention, the process of sample opening occurs suction by capillary forces automatically stops when there is a round device (e.g. in the form of a coin) the radial transport flows meet in the center and block each other. In addition surprisingly found that you can go faster and too far more reproducible sampling aliquots than with any other Capillary filling devices with a single inflow opening. Obviously The differences in capillary sample transport level the closer the front comes to the center of the test plate, which allows a more precise evaluation and ensures that with the same dimensions and design of the Test platelets are always sucked in equal amounts of sample solution. Because of the nevertheless relatively large opening at which the liquid in the test badge can penetrate (entire extent of the badge), the duration is also reduced the analysis significantly and it can be compared to the ones described above dry chemical test strips larger sample aliquots with high accuracy be taken. Since the sample amount can be many times higher, there are corresponding increases in the detection limits, what as a another advantage is to count. The principle of the invention is lacking familiar terms here: vectorial flow addition to all-round standstill (= all-round balancing of forces) of liquid flows.

The invention also extends to micro-chromatography in which a selective detection reagent with or without other auxiliary substances is used. Precondition for this rapid chromatography with automatic Sample dosing is that the analyte is impregnated with the detection reagent Carrier material is strongly adsorbed or absorbed and a concentration proportional surface area then covered because of the detection reagent is clearly visible. In a further preferred application form a titrant between the interfaces with or without a carrier material Form of an original titer substance and a suitable indicator or others Auxiliary chemicals immobilized. If the area titer or total titer of the  Platelets is known, you can at the recolored zone or in this case, the indicator fully turned over without any Infer calibration to the analyte concentration. In principle, everyone can be known measurement analysis processes (neutralization, redox, precipitation, Complex formation) on a micro scale in the form of the device according to the invention carry out.

In the rapid test device according to the invention, the test plate (see Fig. 1) is simply thrown completely into the sample solution, the latter by the capillary suction of the support material soaked with the original titer and indicator or only soaked with a selective detection reagent and limited by dense interfaces (Filter paper or similar capillary-active carrier material) penetrates radially into the test plate. Due to the capillary forces of the material of the titrator (and indicator) support, the sample penetrates to the center, where the liquid absorption automatically stops due to the oncoming capillary liquid flows. Of course, the capillary suction effect also works without a capillary-active carrier if the two boundary surfaces are correspondingly closely opposed, which is easy to achieve by means of a spacer perforated on the circumference (spacer made of an inert material). With a radial arrangement of the capillary channels formed by the spacer (see Fig. 2), even multi-analyte test platelets can be produced. In this case, the detection reagents or titrants (+ indicator) are immobilized on the relevant channel surfaces on the inside of the interfaces.

If the test platelets are produced in a controlled and reproducible manner, the same amount of sample is automatically taken with the same dimensions. Extensive series investigations using gravimetric control measurements showed that the sample volumes recorded in this way are in the micro to milliliter range, depending on size, thickness (with or without spacer) and type of support, and surprisingly have excellent reproducibility of 1% (rel.). This solves the major problems of all the test devices explained above with regard to simple, automatic and, above all, highly precise sampling and sample dosing. The point in time at which the liquid zones in the center of the test plate converge at a point is easily visible to the naked eye and is a sign that the test plate has been removed from the sample and the differently colored (or recolored) zone has been measured (see Fig. 3 ). In order to make this point of time easier to recognize, an additional indicator can also be applied in the center of the test plate, which changes the color in the presence of the solvent in which the analyte to be examined is located. In the event that an aqueous solution is to be examined, an anhydrous blue cobalt (II) salt can be impregnated into the center of the plate, for example, which turns pink in the presence of water (moisture indicator). However, due to the automatic stopping of the capillary suction at this point in time, the time at which the test plate is removed from the sample is not nearly as critical as with all the devices listed above, in which the sample liquid is more or less radial from a center or from a single one middle drop point flows outwards. Here, the transport of the sample liquid does not automatically come to a standstill, so that manual accurate and exact monitoring (flow front reaches the edge of the test plate) is required for more precise sample volumes, which is too unwieldy for practice.

The present invention also includes a particularly advantageous and rational production method for these test slices or platelets. For this purpose, in the case of the micro-titration method, the capillary-active carrier material (filter paper, glass fiber paper, membrane filter or the like) soaked in a large format between two liquid-tight hot-melt adhesive films is laminated with a suitable primary titer substance + indicator + auxiliary reagents, in the case of micro-chromatography the capillary-active carrier material (filter paper, glass fiber paper, membrane filter or similar) and then punch out circular segments (for example with a cork drill), which are automatically open on the outer circumference and can pick up the sample there along the thin cutting surface. In the case of parallel, multiple punching out using a suitable punching template (e.g. on a roller), a large number of absolutely identical test plates are obtained at the same time, which can be batch-wise with the help of a template to be placed or printed on (see Fig . 4) can be calibrated (see Fig. 5). This method is very simple and inexpensive due to the presence of inexpensive hot laminating apparatus, so that the manufacturing costs of the test discs are in the Pfennig range.

This can be done accordingly in a further advantageous production method prepared carrier material with suitable (waterproof) adhesives, which the Do not influence the capillary effect in an unreproducible manner, even at lower ones Limit temperatures in a liquid-tight manner, which is the case with a biosensor-analog test stripes may be necessary due to their heat sensitivity. Here too for large-scale approaches (<DIN A3) a simple and extremely inexpensive Realize mass production. Similarly, the porous, capillary force active carrier material for microchromatographic or micromeasure analytical methods, also by spraying, immersion or different application of liquid-solidifying later Solutions with the necessary boundary layers. Here can use all known impermeable film materials (lacquers or polymers or the like, dissolved in an evaporable solvent) can be used.

Also pulling the dried, impregnated support through a dip bad can be used for this. The thickness of the boundary layers does not matter Role.

In another advantageous embodiment, a capillary-active carrier between the liquid-tight boundaries can also be dispensed with entirely. Then the relatively dimensionally stable, thin boundaries are separated by appropriate spacers, the latter determining the thickness of the suction capillary. According to Fig. 2, this arrangement is particularly suitable for multi-analyte test platelets. Instead of the spacer, however, it is also possible to use a correspondingly provided interface which is glued onto the other.

The principle of measurement of the rapid test device according to the invention is basically only comparable to the principle of test tubes for gases (K. Leichnitz; Test tubes paperback: Air investigations and technical gas analysis with Dräger-Röhrchen, Drägerwerk AG, Lübeck) but with the essential Difference that this is a liquid sample matrix and that in the  In contrast to the gas test tube, the present dosimeter is the analytical solution automatically itself and above all controlled from at least two sides without sucks up external pumps or the like, doing three analysis steps: samples Aliquot dosing and separation of the analyte from the matrix elegantly united. The separation from a possibly disruptive matrix (Stör components, solids, color etc.) happens here in a certain Arrangement through the filtering and chromatographic effect of the support materials (similar to paper chromatography).

The means of the present method and the present device Quantifiable substances are diverse and in the case of Micro-titration generally the underlying analytical titrations, i. H. all Substances covered by volumetric titration using a titrator The use of indicators can also be determined using the Test platelets can be determined in wide concentration ranges. The one on the porous carrier immobilized amount of original titer substance (corresponding to the Dimensional solution) as well as the radius or the distance in multi-analyte versions and the thickness of the test plate determines the concentration that can be detected in each case range corresponding to a stoichiometric consumption of standard solution). in the In the case of micro-chromatography, all analytes can be analyzed using this method determine that also photometrically in the visible range using a suitable detection reagent can be determined selectively if the Carrier material surface is selected so that the colored analyte rea genz complex on the support surface by ad- or absorption processes is held. In the event that the indication by light absorption or -emission (fluorescence) displayed in the UV range can be visual Can also be viewed under a UV lamp.

According to the invention, however, is in the interest of a sharp edge the color change zone (reading accuracy) to ensure that in the case of Micro-titration of the original titer substance or the color-changed indicator on the porous carrier not by the inward flowing by capillary forces Sample solution is also transported. For precipitation titrations or strong ones This is automatically guaranteed by adsorption forces. For titration types where  the titrator or indicator moves with the sample solution, this must be done by a suitable immobilization of titrator and indicator (e.g. covalent upper surface connection on the capillary active carrier or on the surface of the limit layers) can be prevented. Suitable methods for surfaces However, connections are available (compare immobilization of biomolecules on the surface of suitable transducers) and are the expert known.

It is also a matter of course for a person skilled in the art, in addition to immobilization of titrator (corresponds to the set titer solution in the dimensional analysis) and Indicator also additional auxiliary reagents on the porous support material fix. This can be, for example, buffer substances for setting a certain optimal pH value; but it can also be about Act reagents that have a known disorder caused by another substance for example precipitation or masking (by complex formation from the Prevent balance). Also known are substances that reinforce the point of transition of the indicator and thereby more clearly recognizable do. Catalysts, enzymes and Oxidizing agents and reducing agents into consideration.

It is also a matter of course for a specialist in the case of Micro-chromatography gives the microporous support a suitable surface function (Polarity) that optimally binds the analyte-color reagent complex. So For example, strongly polar analyte-reagent adducts can be fix the correspondingly polar surface at the point of origin. Conversely, highly lipophilic adducts can be caused by non-polar surfaces (e.g. analogous to the RP-18 material known from chromatography) at the location of your Education. In the case of electrically charged adducts, the Carrier material surface have the corresponding counter-charge. Polycations bind particularly strongly to polyanions. According to the invention but it is also sufficient if the indicated reaction product or the Reacting partner of the analyte during adduct formation on the carrier surface remains stationary.  

According to the invention, the microporous capillary suction effect of the Carrier material or the closely opposite, by a spacer separate, boundary surfaces from the chemical surface functionality separated, which is a new way of looking at things. When choosing a suitable one Backing material (paper, glass fiber mat, cellulose membrane, ceramic or Similar) is primarily interested in the suction speed of the capillary channels of the microporous material for the sample solution, hence the privilege of the patent, the automatic and volume controlled precise sampling without additional aids come into play. Which depending on the lipophilicity or Charge of the analyte optimized surface treatment of the microporous Backing material can be before or after impregnation or immobilization suitable reagents and auxiliaries or simultaneously. Nice with little basic knowledge in chromatography, the expert can optimized surface functionality (polarity) for the case in question take appropriate measures. If necessary, the carrier can material can also be brought to a higher polarity by plasma discharge.

In addition to the round shape, other design options (e.g. planar polyhedra or tubes packed with a porous carrier or unpacked, narrow capillary tubes (see Fig. 6) also come into consideration for the outer shape of the present rapid test device. Of central importance here is only the fact that the amount of sample sucked up in each rapid test is controlled very precisely and automatically by capillary flow currents that run towards each other and thereby slow down on contact Then the process of sample aspiration (blotting paper effect) comes to a standstill and surprisingly, extremely well reproducible sample aliquots are obtained, which distinguishes this device from all known capillary filling devices with only one sample inlet opening the white difference from traditional capillary pipettes, which are only immersed in the sample solution with one open end; In the present case, the entire capillary test tube has to be sunk into the sample so that it can absorb water from both ends and the effect of vectorial flow current compensation can take place. You do not have to hold the device in your hand until the end of sampling. To reinforce the stopping effect of the capillary flows, the zone in which the two oppositely flowing liquids meet can also be designed to be tapered. As in a volumetric flask with its thin neck with the graduation, the volume measurement accuracy is increased again.

However, the round, open form of the test strip (test badge, Fig. 1) has several serious advantages. On the one hand, the shape and large total opening significantly reduce the analysis time (since more sample can flow in due to the size) and, on the other hand, there are no edge effects that produce an uneven solvent front. Thirdly, circular color zones can be quantified very easily and precisely using a target scale made of concentric circles.

In addition to the round, externally open shape, a .: a) round disc and one or both of the foils have a liquid impervious in the middle Hydrophobized hole (<1 mm) for the escape of air through the Flow currents are displaced; b) rectangular shape in which the entire outer Border (i.e. all four edges) are open: c) rectangular shape, two themselves opposite sides of the edge are open; d) polygonal structures that the Show effect of automatic stop of suction flows; e) rectangular shape, only one edge of the edge is open. In the latter variant, however, lie there are no convergent capillary currents. This variant has the advantage that a discolored distance can then be measured better than circular radii, but this variant always has annoying edge effects that are not uniform Allow the solvent front.

In order to determine more than one analyte with the aid of a dosimeter in the sense of this invention, further design options come into consideration. For the simultaneous determination of two analytes, one can arrange two dosimeters one above the other (see Fig. 7). The following layers are thus obtained: outer interface / impregnated porous carrier (for analyte A) / separation surface / impregnated porous carrier (for analyte B) / outer interface. Hot-melt films with a double-sided polyethylene coating are commercially available, for example. The analyte A can thus be determined on the top side of the dosimeter, and analyte B can be determined simultaneously on the bottom side of the dosimeter. The middle boundary layer does not have to be transparent.

In the design of the round disks, in a further advantageous embodiment, the disks can be divided into wedge-shaped segments, each of which is impregnated differently - corresponding to the determination of different analytes (see Fig. 8). This allows the number of analytes to be determined to be multiplied. In order to counter the problem of different suction speeds caused by differently impregnated sub-segments, cationic surfactants (fabric softeners) can be impregnated. As a result, the different influences of the various impregnation substances can be overcompensated and the suction speed set uniformly everywhere. This multi-analyte arrangement can also be produced technologically easily in the carrier-free variant if, for example, the distance-controlling spacer is produced by the thick-film technology on one interface, while the reagents and the further auxiliaries are used on the other interface with the same technology be immobilized.

There can also be a reaction zone at the outer edge of the dosimeter be connected upstream, in the pretreatment of the analyte or interfering components can take place (e.g. oxidation / reduction of the determining analyte or interfering substance or precipitation or masking the latter).

Another variant of the present invention uses already finished Thin layer chromatography supports back then either either be laminated between two hot adhesive films or in which using a so-called spacers with inflow openings for the sample solution Capillary active flat cavity (thickness: <1 mm) is generated by the spacer has a double adhesive function and with a transparent cover any material, but preferably labile plastic film, closed  becomes. The titrator and / or the color reagent can either be on the thin layer chromatography plate or on the transparent cover be immobilized.

Particularly advantageous rapid test discs can be used with Make filter paper or paper for paper chromatography. Comprehensive Tests have shown that in the interest of a quick display the Suction speed (corresponds to the suction height in paper chromatography - usually specified in [mm / 30 min]) should be greater than 50 mm / 30 min. Good results have been obtained with papers that are related Had a speed of approx. 200 mm / 30 min. The optimal paper thickness should <0.05 mm, preferably <0.2 mm. Of course you can also other carrier materials with capillary active properties (glass fiber mats, Use felts made of different materials, porous ceramics etc.).

For impregnation, it has proven itself to be the titrator (original titer substance) and / or Indicator (s) and / or other auxiliary substances in an easily evaporable solution medium (mixture) to dissolve (impregnation solution) and then the capillary soak the active carrier with this impregnating solution so that the carrier evenly soaked. The solvent (mixture) is then left evaporate completely. An even one is of central importance here Assignment with the titrator (titer per area) and / or indicator (s) and / or other auxiliary substances.

Laminating the dried one has become the preferred welding technique impregnated carrier in known hot-melt films by means of the associated Apparatus particularly proven. Extensive preliminary tests have shown that for reasons of stability, the thickness of the films used for this is greater than 10 µm, preferably 60-125 microns should be. Of course, it can also be cold adhesive interfaces made of any materials can be used.

According to the invention, the principle of vectorial Capillary flow stop technology with at least two penetration openings too measure gaseous samples with increased accuracy. Here, the  analyte-selective reagent layer by hygroscopic means such. B. Lithium salts or magnesium perchlorate, polyvinyl alcohol or the like are kept moist, with in in this case a diffusion process is stopped. Alternatively, the gaseous sample but also by distribution (Henry's law) between Gas phase and a measured liquid volume (acceptor phase) over Place the liquid phase in the test plate. The distribution and the recording can also be done simultaneously.

In addition to the optical indication (color change or change in fluorescence), other types are of course also possible. For example, an electrochemical display can be achieved by concentrically mounted ring electrodes (vapor-deposited or printed on the inside of the boundary film), which likewise allow the size of the reaction zone to be determined. Electrochemical here means the methods of conductometry, amperometry and potentiometry. The planar electrodes can also automatically function as spacers. A possible embodiment variant for a three-electrode arrangement is shown in Fig. 9. The measuring or indicator electrodes (a _x ) are shown in the form of concentric circles on a circular test strip. These electrodes are as close together as possible for a small gradation of the concentration determination. For this purpose, up to x = 50 ring electrodes can be accommodated on a test strip. For reasons of clarity, only three measuring or indicator electrodes (x = 3) are shown in Fig. 9. Inside, another ring electrode is the counter electrode (b) and the central punctiform electrode is the reference electrode (c). To evaluate the fully soaked test strip, press the test strip onto a contact plate, with the wedge-shaped contacts (d) through the impermeable boundary layer (barrier layer ) of the test strip are pressed. This enables simultaneous tapping of the individual electrodes (a _x , b, c). The derivation can be done with the help of printed circuit boards on which conductor tracks (Aax, Ab, Ac) are applied. In order to enable precise positioning of the contacts (d) on the electrodes (a _x , b, c), the test strip is guided into the correct position by guide aids (e) before the impermeable boundary layer is pierced.

The following examples are intended to demonstrate the performance of the present invention underline:

example 1

Nickel dosimeter for determining the concentration of nickel ions (Ni ²⁺ ) in an aqueous sample matrix (e.g. in waste water).

Manufacturing

Dimethylglyoxime is dissolved in acetone and buffer pH = 7 is added. A white capillary-active paper is impregnated with this impregnation solution and the solvent mixture (acetone / water) is allowed to evaporate completely, the paper remaining pure white. After lamination between two commercially available hot-melt films, discs with a diameter of, for example, 3 cm are punched out (see Fig. 1).

execution

The nickel dosimeter is placed in the aqueous analysis solution to be examined. Due to capillary forces, the impregnated paper sucks the analysis solution into the test disk and displaces the air it contains. Since the dimethylglyoxime (DMG) is hardly soluble in water, the dye is not rinsed out by the incoming analytical solution. Incoming divalent nickel (Ni ²⁺ ) forms with the dye the well-known red water-insoluble nickel DMG precipitate, which is shown on the test plate in the form of a red ring (see Fig. 3).

The higher the concentration of the analyte, the larger the area that changes from white to red. The size of the red area and thus the concentration of the analyte can be determined visually with the naked eye. For more precise quantification, a transparent template with printed scale (concentric circles) can be used, on which the Ni ²⁺ content can be specified, for example in ppm (see Fig. 4). This scaling can also be printed directly on the hot-melt adhesive film (s).

Advantages over the state of the art

Traditional test strips for this analyte work on the principle of Indicator paper, in which a change in color and depth must be determined, which is difficult even for the experienced and color blind cannot. The coloring is strongly dependent on the immersion time and the pH of the solution. Therefore a further work step (pH control and adjustment) may be necessary.

Example 2

Sulphate dosimeter for determining the concentration of sulphate ions (SO ₄ ^2- ) in an aqueous sample matrix (e.g. for assessing the attack on concrete by water).

Reaction principle

BaRh _{(s, red)}

+ SO ₄ ^2- _{(aq., Colorless)}

→ BaSO _{4 (s, white)}

+ Rh ^2- _{(aq. White-yellowish)}

Rh = rhodizonate.

A particular difficulty in making a dosimeter after this The principle of reaction within the meaning of the patent is solid barium rhodizonate impregnate evenly on the carrier material, since it is neither in water still dissolves in organic solvents. That is why the barium rhodizonate precipitated directly on the carrier material.

Manufacturing

A white capillary-active paper is soaked in a dilute BaCl ₂ solution and the impregnated paper is dried in a drying cabinet. The dried paper is then impregnated with a freshly prepared aqueous disodium rhodizonate solution and the moist paper is rinsed with dilute hydrochloric acid. This results in a paper that is evenly colored red by barium rhodizonate. Then the impregnated paper is dried again. After drying, the impregnated paper is laminated between two commercially available hot-melt films and disks with a diameter of, for example, 4 cm are punched out.

execution

If you place the sulfate dosimeter in the analysis solution to be examined, the dosimeter sucks up the analysis solution again due to the capillary forces. Incoming sulfate ions form barely soluble barium sulfate, with the red barium rhodizonate dissolving stoichiometrically. The reaction on the dosimeter is shown by a color change from red to yellow. The higher the concentration of the analyte, the larger the area that changes from red to yellow. The size of the discolored area is then a measure of the concentration of sulfate ions. Fig. 10 shows an example of a calibration.

Advantages over the state of the art

The rapid tests for sulfate determination offered by Macherey-Nagel (visicolor® sulfate and nanocolor® sulfate 200) are based on the turbidity measurement of barium sulfate to be precipitated in aqueous solution. Kick in these quick tests two serious drawbacks, elegantly solved by the sulfate dosimeter become. On the one hand, it is much easier to measure a discolored area to quantify as a cloudiness and secondly does not apply to the Sulfate dosimeter the filtering of turbidity of the analytical solution itself, which the Would falsify the result. So with the sulfate dosimeter a whole There is no work step that is absolutely necessary for cloudy real samples.

The rapid sulfate test (Merckoquant® 10 019) offered by Merck consists of a test strip on which four test zones are applied, the different Contain amounts of a red barium-thorin complex. In the presence of a The corresponding amount of sulfate ions changes from red to yellow (free Thorin). To assess the sulfate concentration, dip the test stick briefly into the analytical solution and can be colored based on the number of yellow Test zones estimate the sulfate concentration. Since the test strip is only four Test zones, there are ultimately only three concentration ranges gradually assess. The sulfate dosimeter in the sense of this patent leaves in contrast, a continuous determination of the sulfate concentration.  

Example 3

Dosimeter for the determination of hydrogen peroxide in an aqueous sample matrix (e.g. in disinfectants).

principle

A water-insoluble leuco vat dye (e.g. indigo) is also reduced alkaline sodium dithionite solution, which turns the dye into a colorless and water-soluble form changes (see textile dyeing with vat dyes). Man impregnates a capillary-active carrier material (preferably cellulose fiber) with this Dye, let the solvent evaporate evenly under inert gas, laminated the impregnated carrier material and in turn punch out disks.

Put this dosimeter in a solution that like oxidants If the hydrogen peroxide is maintained, the dosimeter sucks the analysis solution again due to the capillary forces. Hydrogen peroxide oxidizes the reduced one Vat dye, which in turn intensifies the coloring of the vat dye arises. The size of the colored area is then a measure of the concentration of hydrogen peroxide (or other (strong) oxidizing agents).

Example 4

Surfactant dosimeter for the determination of cationic surfactants as well as lipophilic Amines in aqueous solution.

principle

The lipophilic anionic dye 3 ', 3' ', 5', 5 '' - tetrabromo-m-cresol sulfone In the mineral acid medium, phthalein sodium salt forms a green-blue complex cationic lipophilic surfactants (such as benzalkonium chloride) and lipophilic amines. The lipophilic anionic dye and is impregnated a citrate / hydrochloric acid buffer pH = 2-4 for example on a glass fiber paper or cellulose fiber paper, let the solvent evaporate, laminate the  impregnated carrier material and in turn punch out disks. Do you put that yellow dosimeter in a solution containing cationic surfactants or lipophilic amines contains, the dosimeter sucks the analysis solution again due to the Capillary forces. The size of the green-blue surfactant color The area forming the substance complex is then also a measure of the concentration of the Analytes.

Example 5

Gas dosimeter for the determination of aldehydes and ketones (e.g. formaldehyde in Indoor air).

principle

The aldehydes to be determined are set with the colorless N-methyl-benzo thiazolon- (2) -hydrazone to the corresponding blue tetra-aza-pentamethine cyanine compounds. This reagent is in the reagent layer of the test plate together with buffer and other auxiliary chemicals. For Analysis is the gaseous sample by a certain volume of one suitable acceptor solution (washing solution) passed. The test tile will during this process or after a certain time in the Given acceptor solution. After an appropriate calibration you can also penetrate the gaseous sample directly into a moist reagent layer to let.

Claims (15)

1. A method for a chemical rapid test of fluid samples by micro-titration, micro-chromatography or other methods of dry chemistry and method of manufacture, characterized in that the chemical analysis methods concerned are more precise in that the partial sampling according to the invention by the principle of Vectorial capillary flow addition takes place, which is achieved by at least two opposite directions of flow in a capillary force-active device with at least two inlet openings for the sample, the entire test device being washed around by the sample and the exact quantitative evaluation by means of an area proportional to the concentration of the analyte - or distance measurement takes place and in the case of several differently prepared capillary zones, several analytes can be determined simultaneously with one test device. 2. Device according to claim 1, characterized that a capillary-capable carrier (with blotting paper properties) together with all analytical reagents, indicators and auxiliary chemicals planar between two impermeable interfaces made of organic polymers or Glasses are laminated or glued and the sample of at least two opposite sides can flow peripherally, so that the Hit capillary liquid flows between the interfaces as centrally as possible and stop while doing so, at closely opposed interfaces, through a spacer allowing the sample to flow in are separated, even without additional liquid absorbent carrier can be accomplished and at several separate capillary suction zones with these properties and different chemistry, simultaneous multi-substance analyzes possible are.   3. Device according to claims 1 and 2, characterized, that the device is planar and polyhedral to round and a diameter in Centimeter range and a thickness between 1 micrometer and 5 millimeters has and the capillary force-active, with detection and determination chemicals impregnated carrier made of filter or flow paper on cellulose or Glass fiber base, made of porous solid or sintered materials (e.g. chalk, clay frits Glass or the like), absorbent powders, material for the thin layer chromatography etc. exists and is open at the edge to the side, so that the Sample fluid flows radially from the outer edge to the center and there at The meeting automatically comes to a standstill. 4. Device according to claims 1 and 2, characterized, that the device takes the form of a rod-shaped capillary micro pipette (Capillary made of glass or other transparent plastic, length in centimeter scale rich, inner diameter in the sub-millimeter range) with or without additional capillary force-active carrier filling (in addition to the detection and determination chemicals), but the sample liquid is unhindered from both ends must be able to penetrate. 5. Device according to claims 1-4, characterized, that at least one impervious interface from a transparent Material exists and a visual recognition of a colored area in the included partial sample zone with or without further aids (e.g. UV lamp, printed concentration ranges or similar) takes place or accordingly shaped planar ring electrodes with or without appropriate contact bushings for an electrochemical evaluation included.   6. Method of making the device according to claims 1-3 and 5, characterized, that the relevant reagents for analytical determination in one evaporable solvent and the porous carrier with it soaked and then dried so that a titer proportional to the area arises before it is between two liquid-tight adhesive films (hot or cold) is laminated or glued and from it the relevant test plate be punched out. 7. Method of making the device according to claims 1-5, characterized, that the necessary detection and determination reagents directly on the / the Surface (s) of the liquid-tight test room demarcation according to the known Chemical immobilization methods are given and instead of porous carrier material uses a separate or shape-integrated spacer that sets a distance of less than 1 mm between the interfaces. 8. Device according to claims 1-7, characterized, that the reaction space between the interfaces by means of surface-active Connections are modified so that sample-related differences in capillary flow and suction capacity can be leveled. 9. Device according to claims 1-8, characterized, that a suitable indicator substance in the middle of the test device indicates that the at least two capillary sample flows have met.   10. Device according to claims 1-9, characterized, that as a capillary force-active carrier material suitable for analysis Thin layer chromatography is used which separates the analyte from the Separates the sample matrix and the test plate an analyte-selective detection reagent contains immobilized for optical or electrochemical detection. 11. The device according to claims 1-10, characterized, that an additional sample treatment (chemical Reaction: precipitation, masking, redox reaction, immuno-reaction; or Filtration, dialysis, etc.) takes place. 12. The method according to claims 1-11, characterized, that the test device is based on the known biosensor types and the Analyte using extremely selective biomolecules (enzymes and antibodies, or bio-receptors, DNA-complementary DNA, etc.) is detected, with a reaction partner is measured in the enzymatic reactions and in the so-called binding assays the displacement of a labeled compound that is can be optically or electrochemically detected by the analyte for display is exploited. 13. Device according to claims 1-12, characterized, that several of the laminar individual test devices in a stack of two or more are joined together, making simultaneous analysis become possible. 14. Device according to claims 1-13, characterized, that the indication of the zone of the used original titer substance is electrochemical by spatially resolving methods of conductometry, potentiometry or  Amperometry is measured. 15. The method and device according to claims 1-10, characterized, that a quick and reliable determination of cationic surfactants and lipophilic amines is made possible by the fact that a lipophilic as an indicator anionically charged dye from the group of triarylmethane dyes such as the 3 ', 3 ", 5', 5" tetrabromo-m-cresolsulfonphthalein sodium salt and a buffer with pH = 2-6 is impregnated.