Sample introduction system for nonsegmented continuous flow analysis

Claim 1

A sample injection system for nonsegmented continuous flow analysis (FIA), characterized in the use of a single confluence point (1) connecting three channels through which liquids may flow, wherein the first of said channels, the inlet channel (2), which alternately is contacting a liquid sample source (14) and a waste outlet (8), is operated in a countercurrent fashion by means of the intermittent action of two pumping devices (5,6,17), one of said pumping devices (6) capable of aspirating a stream of liquid through the inlet channel (2) and via said confluence point (1) into the second of said channels (3), in which said second channel, the analyzer channel (3), a detection device (7) for analyzing said flowing stream is situated, and the second one (5) of said pumping devices capable of forwarding a stream of liquid through the third of said channels, the carrier channel (4), towards and past said confluence point (1), the two pumping devices being operated in such a way that the flow rate in said carrier channel (4) is higher than the aspiration rate of said first pumping device (6) situated in said analyzer channel. 2. Sample injection system according to Claim 1, characterized in that said intermittent operation of flow of liquids is executed by first stopping the flow of liquid in said carrier channel (4) while the aspiration of sample fluid is effectuated through said inlet carrier channel when a desired volume of said sample fluid has flown past said confluence point (1) and into said analyzer channel (3). 3. Sample injection system according to Claims 1 and 2, characterized in that the length of the stop time of the flow of liquid in said carrier channel (4) can be selected in such a manner that it allows, together with the aspiration flow rate within said analyzer channel (3), the exact selection of the volumetric amount of said sample solution to be introduced into said analyzer channel in the form of a well-defined zone. 4. Sample injection system according to Claims 1 and 3, characterized in that the flow rate (x) of the stream of liquid in said carrier channel (4) is temporarily reduced or stopped below the flow rate of the aspiration flow rate (y) of liquid in said analyzer channel while a sample source is in contact with said inlet channel, and a higher rate of flow (x) in the carrier channel is resumed when a desired volume of the thus diluted sample fluid has flown past said confluence point (1) and into the analyzer channel. 5. Sample injection system according to anyone of the above claims, characterized in that said sample source (9) is a container or a continuously flowing stream, said sample sources being periodically manipulated so that the sample fluid comes into contact with the end of said inlet channel (2) only during the sample aspiration period and is removed from the end of said inlet channel during the sample inlet discharge period, which corresponds to the time sequence during which the pumping device (5) situated in said carrier channel (4) is operating at a volumetric pumping rate (x) exceeding that (y) of said pumping device (6) situated in said analyzer channel (3). 6. Sample injection system according to Claim 1, characterized in several analyzer channels (3) from the confluence point (1), each with a separate analyzer (7) to enable simultaneous determination of different substances. 7. Sample injection system according to anyone of Claims 1-5, characterized in that the second pump is in the form of a double channel pump (5,17), the first channel (5) being arranged to pump carrier solution through carrier channel (4) to the branch point (16) and the second channel to aspirate carrier solution and/or air through a channel (15) from a branch point (16) in the inlet channel (2), the pump rate for pumps (5,6,17) being x, y and z, respectively, where z x y, so that when the double channel pump (5,17) is stopped, sample (14) will be sucked in through the inlet channel (2) he confluence point (1), a filter (18) a coil (19), the analyzer channel (3) and the analyzer (7) by pump (6), which can be operating continually, and when the double channel pump (5, 17) is started, the part (5) is arranged to pump in carrier solution via the confluence point (1) out into the analyzer channel (3) and the inlet channel (2), while the pump (17) sucks from the inlet channel (2) carrier solution and sample solution and/or air depending on whether the sample container is removed or not. 8. Sample injection system according to anyone of Claims 1-5, characterized in that the second pump is in the form of a double channel pump (5,17) one part (5) of which being arranged to pump in carrier solution through carrier channel (4) to branch point (16) and the other part (17) to aspirate carrier solution and sample solution or air from branch point (16) in the analyzer channel (3) through the analyzer (7), the coil (19) and the filter (18), if any, to the confluence point (1), where additional sample solution and/or air is sucked in from the inlet channel (2), and further through the channel (15) to the drain, the pump rates for the pumps (5,6,17) being x, y and z, respectively, where z x y, so that when the double channel pump (5,17) is stopped, sample (14) will be sucked in through the inlet channel (2), the confluence point (1), the filter (18), the coil (19) and the analyzer (7) to the branch point (16) by pump (6), which can be operating continually, and when the double channel pump (5,17) is started, the sample will be led to the drain, the channels will be washed clean and filled with carrier solution. 9. Sample injection system according to anyone of Claims 1-8, characterized by a device for dozing reagent to the system for reaction with the sample. 10. Method for injecting a sample at nonsegmented continuous flow analysis, based on a confluence point (1) connecting three channels, an inlet channel (3) for the sample (14) with a movable source (9) for the sample, a carrier channel (4) with a pump (5) with the rate x and a source for the carrier solution (13), and an analyzer channel (3) with an aspirating pump (6) with a rate y and a detector (7) for determination of substances in the sample, characterized in that the pumping rate x > y and in STEP 1 prior to the injection, the carrier pump (5) pumps carrier solution to the confluence point (1), the analyzer pump (6) aspirates part of the carrier solution and the remainder goes to the waste through the inlet channel (2), in STEP 2 the sample source (9) is contacted with the inlet channel (2), the carrier pump (5) is stopped and the analyzer pump (6) aspirates sample (14) through the inlet channel (2) past the confluence point (1) and into the analyzer channel (3) in a predetermined amount, and in STEP 3 the carrier pump (5) is started again, and the sample amount in the analyzer channel (3) after the confluence point (1) is aspirated into the detector (7) and determined. 11. Method according to Claim 10, characterized in that the carrier pump (5) is made as a two-channel pump (5,17) and that an additional channel (15) is arranged from a branch point (16) in the inlet channel (2) to the pump (17) with capacity z, where z > x > y, and that in STEP 1 all the pumps are operating and the sample container can either be connected or disconnec ted, the carrier pump (5) pumping carrier solution into the system, the analyzer pump (6) sucking out carrier solution and the additional pump (17) pumping out a mixture of carrier solution and sample or air, in STEP 2 the sample container is connected, the two-channel pump is stopped and the analyzer pump (6) sucks sample into the inlet channel (2) and a certain predetermined amount past the confluence point (1) and into the analyzer channel (3), and in STEP 3 the two-channel pump (5,17) is started again and the carrier solution is forced past the confluence point (1) cutting off the measured sample amount which is sucked through the det and analyzed there. 12. Method according to Claim 10, characterized in that the carrier pump is made as a two-channel pump (5,15), that the carrier channel (4) extends from the pump (5) to the branch point (16) after the detector (7) in the analyzer channel (3) and that the channel (15) extends from the confluence point (1) to the additional pump (17), whereby in STEP 2 the sample passes through the detector (7) and is analyzed, and in STEP 3 the sample passes back through the detector to the confluence point (1) and from there out through the channel (15). 13. Method according to Claim 12, characterized in that a complete curve of the sample gradient is taken in the detector. 14. Method according to anyone of Claims 10-13, characterized in that reagent is dozed into the system for reaction with the sample.