DD294569A5

DD294569A5 - ARRANGEMENT FOR DETERMINING ANALYTES IN LIQUID MEDIA

Info

Publication number: DD294569A5
Application number: DD33993090A
Authority: DD
Inventors: Bernd Gruendig; Christa Krabisch; Beate Strehlitz; Holm Kopinke
Original assignee: Adw,Institut Fuer Biotechnologie,De
Priority date: 1990-04-20
Filing date: 1990-04-20
Publication date: 1991-10-02
Also published as: DD294569B5

Abstract

Die Erfindung betrifft eine Anordnung zur Bestimmung von Analyten in flüssigen Medien, die unter Anwendung der FIA-Technik als flexibel anpassbares analytisches System eines Prozessmessgerätes zur quasikontinuierlichen Prozesskontrolle einsetzbar ist. Die Anordnung weist anstelle der zwischen Injektionsventil und Detektionssystem befindlichen Mischstrecke eine variabel einstellbare Kolbendosier-Mischeinrichtung unmittelbar vor der Probeschleife des Injektionsventils auf, so dass in einem großen Bereich beliebig wählbare Verdünnungsverhältnisse bei sehr geringen Totzeiten zwischen der Entnahme der Probe und deren Ausmessung realisierbar sind. Die Erfindung ist in der Biotechnologie, Wasserwirtschaft, Abwasserbehandlung und chemischen Industrie einsetzbar. Fig. 1{FIA-Technik; Kolbendosiermischeinrichtung; Prozessmessgerät; Prozesskontrolle; Biotechnologie: Wasserwirtschaft; Abwasserbehandlung; chemische Industrie}The invention relates to an arrangement for the determination of analytes in liquid media, which can be used using the FIA technique as a flexibly adaptable analytical system of a process measuring device for quasi-continuous process control. Instead of the mixing section located between the injection valve and the detection system, the arrangement has a variably adjustable piston metering mixing device immediately before the test loop of the injection valve, so that arbitrarily selectable dilution ratios can be achieved with very small dead times between the removal of the sample and its measurement over a large range. The invention can be used in biotechnology, water management, wastewater treatment and the chemical industry. Fig. 1 {FIA technique; Kolbendosiermischeinrichtung; Process measuring device; Process control; Biotechnology: water management; Wastewater treatment; chemical industry}

Description

Eine zweite Pumpe fördert kontinuierlich eine Trägerstrcmflüssigkeit. Durch eine 60°-Drehung des Injektionsventils, das unmittelbar vor dem Detektionssystem angeordnet iii, wird der Analyt in den Trägerstrom injiziert und unmittelbar darauf erfolgt die Indikation über den Detektor als Strom- bzw. Spannungspeak. Währenddessen kann nach entsprechender Spülung der Kolbendosierpumpe eine neue Probe vorbereitet werden.A second pump continuously pumps a carrier fluid. By a 60 ° rotation of the injection valve, which is arranged immediately in front of the detection system iii, the analyte is injected into the carrier stream and immediately thereafter the indication is made via the detector as a current or voltage peak. Meanwhile, after appropriate flushing of the piston metering pump, a new sample can be prepared.

Bei hohen erforderlichen Meßfrequenzen können zwei zeitlich versetzt arbeitende Kolbendosierpumpen verwendet werden. Da nur ein kleiner Teil der im Zylinder der Pumpe aufbereiteten Probe für die Mossung verwendet wird, sind prinzipiell mit einer Probenahme mehrere aufeinanderfolgende Messungen durchführbar, die die Sicherheit des Meßergebnisses erhöhen. Wesentlichste Vorteile dieser Anordnung sind jedoch, daß nur eine sehr geringe Totzeit zwischen der Entnahme der Probe und deren Ausmessung besteht und in einem vergleichsweise großen Bereich beliebige Verdünnungsverhältnisse einstellbar sind. Das heißt, neben der selbstständigen Erstellung von Kalibrierkurven aus nur einer Stammlösung, kann während der Prozeßmessung eine Nachkalibrierung durchgeführt werden, die sich am letzten aktuellen Meßwert orientiert, und die Verdünnung der Probe so eingestellt werden, daß der optimale dynamische Meßbereich eines Detektionssystems bzw. eines Sensors stets eingehalten wird. Insofern ermöglicht diese Lösungsvariante eine größere Flexibilität gegenüber bisher praktizierten FIA-Systemen, insbesondere unter dem Aspekt der Prozeßkontrolle.At high required measuring frequencies, two piston pumps operating at different times can be used. Since only a small part of the sample processed in the cylinder of the pump is used for the removal, several successive measurements can be carried out in principle with one sampling, which increase the reliability of the measurement result. The most important advantages of this arrangement, however, are that only a very small dead time between the removal of the sample and its measurement and in a relatively large range arbitrary dilution ratios are adjustable. That is, in addition to the independent creation of calibration curves from only one stock solution, a recalibration can be performed during the process measurement, which is based on the last current measurement, and the dilution of the sample are set so that the optimal dynamic range of a detection system or a Sensor is always adhered to. In this respect, this solution variant allows greater flexibility compared to previously practiced FIA systems, especially in terms of process control.

embodiment The invention will be explained in more detail below by way of example. The drawing shows Fig. 1: analysis part of a process analyzer for glucose determination.

Das Analysenteil eines Prozeßanalysators zur Glucosebestimmung besteht aus einer Kolbendosierpumpe 1 mit 2 ml Zylindervolumen, die über ein Zweiwegeventil 2 zum einen direkt mit der Probeschleife 3 eines e-Port/S-Kanal-Schaltventils, das als Injektionsventil 4 dient, und zum anderen mit dem Zen'ralport eines 6-Port-Schaltventils 5 verbunden ist. Unmittelbar nach dem Injektionsventil 4 ist eine Durchflußmeßzelle 6 angeordnet, die eine amperometrische Enzymelektrode 7 als analytisches Element enthält. Weiterhin führt eine thermostatierte Zuleitung 8 zum Injektionsventil 4, die mit einer Schlauchpumpe 9 verbunden ist. Das 6-Port-Schaltventil 5 enthält um den Zentralport fünf anwählbare Einzelports, die Anschlüsse jeweils für Pufferlösung, eine Kalibrierlösung, destilliertes Wasser, einen Abfluß und einen Probebypaß aufweisen. Die Steuerung der Funktionselemente bzw. die Erfassung und Auswertung der Meßsignale erfolgt über eine separate Elektronikeinheit. Durch Ansteuerung der Kolbendosierpumpe 1 und entsprechender Ports des 6-Port-Schaltventils 5 werden in definierter Weise nacheinander Phosphatpufferlösung, eine glucosehaltige Probe und nochmals Phosphatpufferlösung 10 in den Zylinder der Kolbendoslerpumpe 1 gesaugt und aufgrund der starken Turbulenzen, die durch die schnellen Ansaugvorgänge erzeugt werden, sofort homogen im Zylinder gemischt. Dieses Probe-Puffergemisch wird über das Zweiwegeventil 2 in die Probeschleife 3 des Injektionsventils 4 ausgestoßen. Die Schlauchpumpe 9 fördert kontinuierlich als Trägerflüssigkeit Phosphatpufferlösung, die zunächst zum Erreichen einer definierten Temperatur von 30°C die thermostatierte Zuleitung 8 durchströmt und danach über das Injektionsventil 4 in die Durchflußmeßzelle gelangt. Durch eine 60°-Drehung des Injektionsventils 4 wird das in der Probeschleife3 befindliche Probe-Puffergemisch in den Trägerstrom injiziert und gelangt sofort in die Durchflußmeßzelle. Beim Vorbeiströmen der verdünnten Probe an der Elektrode diffundiert die Glucose durch eine semipermeable Membran, mit der die darunter befindliche immobilisierte Glucoseoxidase auf der Elektrodenoberfläche fixiert ist, und wird durch das Enzym oxidiert. Der aus dieser Redoxreaktion resultierende Elektronentransfer verursacht einen Strompeak, dessen Höhe proportional zur Glucosekonzentration ist.The analysis part of a process analyzer for glucose determination consists of a piston metering pump 1 with 2 ml cylinder volume, via a two-way valve 2 directly to the test loop 3 of an e-port / S-channel switching valve, which serves as an injection valve 4, and the other Zen'ralport a 6-port switching valve 5 is connected. Immediately after the injection valve 4, a flow measuring cell 6 is arranged, which contains an amperometric enzyme electrode 7 as an analytical element. Furthermore, a thermostatically controlled supply line 8 leads to the injection valve 4, which is connected to a peristaltic pump 9. The 6-port switching valve 5 contains five selectable ports around the central port, each having ports for buffer solution, a calibration solution, distilled water, a drain, and a sample bypass. The control of the functional elements or the detection and evaluation of the measured signals via a separate electronic unit. By controlling the piston metering pump 1 and corresponding ports of the 6-port switching valve 5 phosphate buffer solution, a glucose-containing sample and again phosphate buffer solution 10 are sucked in a defined manner in the cylinder of Kolbendoslerpumpe 1 and due to the strong turbulence generated by the rapid intake processes, immediately mixed homogeneously in the cylinder. This sample-buffer mixture is discharged via the two-way valve 2 into the test loop 3 of the injection valve 4. The peristaltic pump 9 promotes continuously as a carrier liquid phosphate buffer solution, which first flows through to reach a defined temperature of 30 ° C, the thermostatic feed line 8 and then passes through the injection valve 4 in the flow measuring cell. By a 60 ° rotation of the injection valve 4, the sample buffer mixture contained in the sample loop 3 is injected into the carrier stream and passes immediately into the flow measuring cell. As the diluted sample flows past the electrode, the glucose diffuses through a semipermeable membrane, which fixes the immobilized glucose oxidase underneath it on the electrode surface, and is oxidized by the enzyme. The electron transfer resulting from this redox reaction causes a current peak whose level is proportional to the glucose concentration.

Währenddessen wird die Kolbendosierpumpe 1 nacheinander mit Wasser und Pufferlösung bei entsprechender Ansteuerung der jeweiligen Ports des 6-Port-Schaltventils S gespült, und danach kann ein neuer Meßzyklus beginnen. Der erforderliche Verdünnungsfaktor wird bei der Erstellung einer Kalibrierkurve nach Programm geändert und richtet sich während der Prozeßkontrolle oder bei Nachkalibrierung nach der aktuellen Glucosekonzentration im Prozeßmedium.Meanwhile, the piston metering pump 1 is sequentially rinsed with water and buffer solution with appropriate driving of the respective ports of the 6-port switching valve S, and thereafter, a new measuring cycle can begin. The required dilution factor is changed when creating a calibration curve according to the program and depends on the actual glucose concentration in the process medium during process control or recalibration.

Claims

Arrangement for the determination of analytes in liquid media, consisting of a flow injection analysis device with carrier flow pump, injection valve, mixing section and detection system, characterized in that instead of between injection valve (4) and detection system (6,7) located Miochstrecke a variably adjustable piston meter Mixing device (1) immediately before the test loop (3) of the injection valve (4) is arranged.

For this 1 page drawing

Field of application of the invention

The invention relates to an arrangement for the determination of analytes in liquid media, which can be used in particular as part of a process analyzer in biotechnology, water management, wastewater treatment and the chemical industry.

Characteristic of the known state of the art

Flow Injection Analysis (FIA) was first described by Hansen and RuiiCka in 1977 (Anal. Chim. Acta 89 [1977], 241) and has since become increasingly prevalent, particularly in automatable fetal assays of liquid media requiring high analysis frequencies. , by.

This analysis system consists essentially of a continuous conveying carrier flow pump, an injection valve - as known from liquid chromatography - a subsequent mixing or reaction chamber and a detector system. About the injection valve, the sample to be examined is injected with a defined volume in the carrier stream and diluted in the mixing section or subjected to a reaction and fed to the detection system. The resulting measurement signal has a peak shape. On this basis work a number of commercially available analyzers (eg FIAstar 5010 system, Tecator, K-1000, Hitachi). For the interests of process measuring technology, the FIA is of interest insofar as a quasi-continuous measurement can be realized due to the possible high measuring frequency. However, such an application is counteracted by the large dead time between the removal of the sample and its measurement, since a comparatively long period of time for mixing the sample with the carrier or reaction liquid is required, especially for applications on complex composition media a reduction in the Strömungsqueischnittes the mixing section limited is possible. Another problem is the lack of variability for creating arbitrary calibration curves and "real-time dilutions" during process control, which can not be achieved without additional effort (tube replacement, provision of a variety of calibration solutions) New approaches to this were provided by the methods developed by Clark and co-workers (Anal. Chem. 61 [1989], 1773), which allows variably adjustable dilutions up to a factor of 1: 15000 with minimal reagent consumption, provided, however, that there are no changes or fluctuations in the tube geometry and the delivery rate of the tube used Müller and Kramer (Fresenius, Z. Anal. Chem., 335 [1989], 205) see an alternative in the calibration of FIA systems in the course of the indicated signal peak after injection of the discrete sample volume, with the desired infinite dilution series itself, depending on the current situation Such a dilution curve is t can be described by the Gaussian gamma function. However, this requires - in addition to a high temporal reproducibility - an approximately same physicochemical nature of sample media and calibration, which is necessary for measurements z. As in media whose viscosity changes during the course of the process is not expected.

The goal of the Erflndun

The aim of the invention is an arrangement for the determination of analytes in liquid media, which requires little effort for calibrations, and allows minimal dead times between sampling and measurement, eino high accuracy and the use as flexibly adaptable analytical system in a process device for quasi-continuous process control.

Explanation of the essence of the invention

The object of the invention is an arrangement that allows arbitrary mixing ratios without changing the apparatus design.

According to the invention, the object was achieved by using a FIA arrangement with carrier flow pump, injection valve, mixing section and detection system so that instead of the injection valve and detection system located 'mixing section a variably adjustable piston dosing Micheinrichtung is arranged immediately before the test loop of the injection valve. As variably settable metering and mixing device is a microcomputer controlled Kolbendosierpumpe with stepper drive, which is combined with a vortex chamber or a baffled supply line. By three successive fast suction of dilution or reaction liquid, sample and again Verdünnuigsflüssigkeit takes place an immediate homogeneous mixing in the cylinder of Kolbendosierpumpe, the mixing ratio can be variably specified in a very large range. A portion of this sample thus processed is then expelled via a two-way valve to fill the sample loop of the injection valve.