Method for carrying out an electrochemical measurement on a liquid measuring sample in a measuring chamber that can be accessed by lines, and corresponding arrangement
Especially in order to carry out the so-called enzyme-coupled DNA hybridization test in a closed cartridge including a microfluid system, using stored dry reagents, the reagents must be dissolved in the microfluid system and transported into the measuring chamber directly before the measurement. During the dissolution of the reagents in water, air cushions that cannot reach the measuring chamber must absolutely be prevented from forming upstream of the reagent liquid. According to an embodiment of the invention, the liquid measuring sample and the liquid reagents are transported in such a way that the air cushion is directed into the waste line and the measuring sample and the reagents are then introduced into the measuring chamber without any air bubbles. In this way, measuring errors can be avoided.
1. A method for bringing at least one reagent, in liquid form and supplied for an electrochemical measurement on a measuring sample in a measuring chamber accessible via lines, for interaction with the measuring sample, the method comprising:
pumping the measuring sample through an access point into the measuring chamber and bringing an excess of the measuring sample into a first waste line located on an opposite side of the measuring chamber from the access point;
delivering the at least one reagent from a line, initially without flowing through the measuring chamber, into a second waste line on a same side of the measuring chamber as the access point;
bringing the at least one reagent, free from air bubbles, to the measuring chamber for interaction with the measuring sample; and
performing electrochemical measurement.
2. The method as claimed in claim 1 , wherein the measuring sample and the at least one reagent are supplied to the measuring chamber through different access points.
3. The method as claimed in claim 1 , wherein the measuring sample and an air cushion in front of at least one reagent are delivered into different waste channels.
4. The method as claimed in claim 1 , wherein there is no air in the measuring chamber after the measuring sample and the reagents have been delivered to the measuring chamber.
5. The method as claimed in claim 1 , wherein the at least one reagent includes two reagents.
6. The method as claimed in claim 1 , wherein the liquid of the at least one reagent is produced “in situ” by dissolving at least one solid pre-dosed and pre-portioned dry reagent by supplying a solvent.
7. The method as claimed in claim 6 , wherein water is used as the solvent.
8. The method as claimed in claim 1 , further comprising providing a cartridge with a PCR chamber and at least one of label-enzyme- and enzyme-substrate reagent lines, wherein the electrochemical measuring includes performing an application for enzyme-linked DNA hybridization detection with prior PCR.
9. The method as claimed in claim 8 , wherein reagent lines are filled with water during the PCR.
10. The method as claimed in claim 8 , wherein air is discharged from the at least one of label-enzyme- and enzyme-substrate reagent lines after hybridization, so that the measuring chamber is subsequently flushed initially with a first reagent without an air cushion and subsequently with a second reagent without an air cushion, and wherein the electrochemical measurement is subsequently carried out.
11. The method as claimed in claim 2 , wherein the measuring sample and an air cushion in front of the at least one reagent are delivered into different waste channels.
12. The method as claimed in claim 2 , wherein there is no air in the measuring chamber after the measuring sample and the reagents have been delivered through the measuring chamber.
13. The method as claimed in claim 2 , wherein the at least one reagent includes two reagents.
14. The method as claimed in claim 5 , wherein liquids of the two reagents are produced “in situ” by dissolving solid pre-dosed and pre-portioned dry reagents by supplying a solvent.
15. The method as claimed in claim 14 , wherein water is used as the solvent.