JPH0752191B2 - Analysis device and analysis method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to methods and apparatus for analysis, in particular for assays involving the detection of substances in solution, such as direct analysis, reagent addition analysis, and known quantity addition analysis, titration, etc. Method and apparatus.

BACKGROUND ART Various methods have been known for a long time for automatically detecting and measuring substances in a solution, and they are generally classified into batch analysis and distribution analysis. To fully understand the advantages and novelty of the present invention, a brief description of the essential features and limitations of the prior art methods and means is provided. Review articles in the area of electrochemical analysis include Feher, Zs; Nagy, G; Toth, K; P.
Ungor, E. et al., CRC Crit. Rev. Anal. Chem. 1983.14,
There is 175-230 recording (hereinafter referred to as "Feher et al").
For more information on the prior art, see "Instrumental M
ethod of Analysis ", 6th edition, Willard, Merritt, Dean, S
It can also be found in reference books such as by Ettle, Wadworth Publishing Company, 1981.

1. Batch technology (a) Automatic batch direct analysis method This method is an analysis method that directly measures a sample without adding other substances.

(B) Automated batch reagent addition analysis method For the purposes of the present invention, the term "reagent addition analysis" refers to the addition of some solution to a fluid sample regardless of its purpose and includes the following:

(I) Simple reaction using one kind of reagent and sample.

(Ii) Complex multi-step reactions with several reagents that can be reacted simultaneously with the sample or sequentially.

(Iii) Does not react with the sample but enhances sensitivity, suppresses interference, pH
Addition of solutions that are added for various purposes such as fixing reaction variables such as ionic strength and ionic strength, and cleaning the detection system.

(Iv) Known addition in which a substance to be analyzed is added to a known amount and a known amount of a sample in a known amount.

(C) Automatic batch titration. Feher et al
Pp. 175-188.

Batch technology is generally superior in that it minimizes sample residue and provides high accuracy, but measures a fixed amount of sample, adds reagents or titration standards, mixes and / or transfers to detection systems, and completes analysis Since the detection system needs to be cleaned every time, it is mechanically complicated and not suitable for online measurement. The specific drawbacks of the automatic batch titration method are as follows.

(I) The accuracy of the volumetric analysis of the sample is detrimental to the overall accuracy. A relatively large amount of sample is usually required to avoid degrading accuracy. Generally, titration is not performed on samples of 1 milliliter or less, regardless of accuracy.

(Ii) This method is not suitable for online measurement and also not suitable for measurement of a minute portion of one kind of sample.

(Iii) It is necessary to determine the characteristics of the sensor, particularly the delay time, before titration, and it takes a sufficient time to stabilize the sensor after each addition of the titrant. This results in a reduction in the speed at which titration can be performed without sacrificing accuracy.

(Iv) The speed at which titration can be performed depends on the mixing speed of the titrant and the sample. Due to the relatively large amount of sample used, even a short mixing time results in a considerable reduction in the speed at which titration can be performed without loss of accuracy.

(V) Not suitable for slow reaction.

(Vi) Automatic sampling is a complicated procedure that requires cleaning of the sensor, stirrer titration container, and preparation of a new sample, so the frequency of sampling is reduced.

(Vii) Not very suitable for anaerobic measurement.

2. Flow method For the purpose of the present invention, a pump arranged in front of the detection point of the fluid flow path (that is, on the upstream side) is referred to as a “positive pump”,
A pump arranged after the detection point of the fluid flow path (that is, on the downstream side) is referred to as a “negative pump”.

(D) Automatic flow direct analysis For example, as described in US Pat. No. 3,556,950,
The sample is propelled along the fluid path by one positive pump or one negative pump with calibration means.

(E) Automatic flow type reagent addition analysis Several techniques using one or more positive pumps are well known as follows.

(I) Continuous flow analysis An example can be found in Feher et al., Page 216.

(Ii) Spatial partition analysis This method is described in Feher et al., Pp. 191-200.

(Iii) Flow injection analysis For this method and method, see Ruzica, J., “Flow Injection.
Analysis '' John Wiley and Sons, 1981, U.S. Patent No. 4002
2575, and Feher et al., Pp. 200-215.

(F) Automatic flow titration method As described in Feher et al., Pp. 219-227, several techniques using one or more negative pumps are well known as follows.

(I) Continuous flow titration method (ii) Gradient titration method of diluted sample or titrant.

(Iii) Gradient titration of an electrochemically generated titrant.

(Iv) Gradient flow injection analysis with diluted titrant.

See US Pat. Nos. 2,977,199 and 318 for continuous flow titration.
6800, 3192017, 4120657, West German Patent 203133
6, French Patent No. 2327543, European Patent Publication No. 159243
An example can be found in the issue.

Although the concept of performing analysis based on flow rate offers the prospect of overcoming the limitations of batch analysis methods, (d),
Prior art methods and means relating to the distribution methods of (e) and (f) have some common limitations as follows.

(I) The flow rate accuracy of the peristaltic pump commonly used in such a technique is low. This results in poor reproducibility, especially for techniques (e) and (f). Peristaltic pumps give rise to certain detector problems, such as static electricity being generated and affecting the potentiometric detector.

(Ii) Various types of flexible tubes used in peristaltic pumps are usually incompatible with organic solvents, and it is necessary to limit the type of solvent or the number of analyzes before piping.

(Iii) A sample containing undissolved solid may block the channel or impair the function of the detector. This is especially true for the techniques (e) and (iii) that use a small-diameter passage.

Further, the techniques (e) and (f) have the following specific drawbacks.

(Iv) The techniques of (e) (i) and (f) (i) are limited to on-line analysis and are not suitable for the analysis of small individual samples, as small samples are dispersed in the channel.

(V) The techniques of (e) (ii) cannot be used online against high pressure or variable pressure.
The technique i) requires a complicated injection system for online measurement.

(Vi) The time-based mixing method of the techniques of (e) (ii and iii) reduces the sampling frequency. Usually at least 10 seconds are required for one analysis.

(Vii) (e) (ii and iii) techniques carry carryover from one sample to the next due to exponentially remaining dross. This leads to lower accuracy and lower sampling frequency.

(Viii) The techniques of (e) (ii and iii) lack the quantitative relationship between the injection sample and the measured reaction product because of incomplete mixing. Therefore, a wide range of standard solution is required for calibration, and the sensitivity is lowered.

(Ix) There are some detectors that are not suitable for the techniques of (e) (ii and iii). For example, temperature detectors are not suitable due to heat loss in long pipes.

The techniques of (x), (e), and (ii) require a considerable amount of time to set up a particular analysis and are typically not suitable for short-term sample analysis.

(Xi) (f) (ii, iii and iv) is a relatively slow method that requires a titrant gradient before mixing the sample with the titrant and requires at least 1 minute for each titration and is reproduced. The rate is also about 1
Stay in%.

(Xii) (f) The technique of (iii) can use only a very limited titrant.

The techniques (xiii), (f) and (iv) also have the same drawbacks as the techniques (e) and (iii).

All prior art methods and means, except for the techniques of (f) (i), operate at a constant flow rate during the measurement.

Generally speaking, the prior art is configured to use separate pumps for sample delivery and titrant or reagent delivery, or to continuously aspirate both components using a dropper or similar device.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus that provides a flow analysis method that is not inferior to batch technology in terms of accuracy and that eliminates at least some of the drawbacks of the flow rate-based technologies listed above.

The main object of the present invention is the direct analysis of a sample without the need to measure the amount of sample and jet or inject the sample into the device,
It is to be able to perform reagent addition analysis or titration.

Another object of the present invention is to provide an analytical method applicable to the following uses.

(A) Continuous online analysis against high or variable pressure.

(B) Individual samples.

(C) Micro partial analysis of one sample.

In order to realize a substantial benefit in accordance with the above object, the present invention provides a novel analytical configuration, that is, a control fluid such as a reagent or a titrant by a plurality of pumps operating at different controllable flow rates. It is necessary to use a configuration in which the sample is positively delivered and aspirated to the detection position via the fluid junction and the sample is aspirated into the control fluid at the fluid junction.

Therefore, the analysis method provided by the present invention comprises the step of delivering the first fluid to the first joint (3) at a first flow rate, and at the same time the second fluid to be detected from the fluid joint.
And a sequence of functional steps each of which is defined by at least one of an individual flow rate ratio, a series of individual flow rate ratios, an individual gradient of flow rate ratios, or a series of individual gradients of flow rate ratios. According to the method, the method comprising controllably varying at least one of the flow rates to produce the first and second plurality of ratios, and detecting the state of the fluid at the detection location to perform the analysis. Wherein the first fluid is a reagent fluid and the step is such that the second flow velocity is greater than the first flow velocity and the sample fluid is aspirated at the fluid junction and pulled to the detection position. The sample fluid is mixed with a reagent fluid between the fluid junction and the detection location to form a mixed fluid detected at the detection location, the analysis of the sample fluid comprising: The state of the mixed fluid determined at the detection position with respect to the plurality of ratios of the first and second flow velocities and the state of the mixed fluid analyzed at the detection position is the ratio of the first and second fluids. Is determined by

In the simultaneous suction step, it is desirable to simultaneously suck the fluid to the detection position. Desirably, the larger flow rate is substantially constant and the first flow rate is controllably varied. It is advantageous to ensure that the first fluid and another fluid are mixed between the fluid junction and the fluid condition sensing location.

Advantageously, it also includes the step of flushing the conduit with the first fluid by confining the fluid within the conduit and maintaining the flow rate equal for a period of time prior to the delivering and aspirating steps.

In order to apply the titration method, a titrant is used as the first fluid, the first flow rate is continuously changed until the end point is detected at the detection point, and then the analysis is completed using the flow rate ratio. To do.

To apply the reagent addition method, a reagent is used as the first fluid, and the analysis is completed using the ratio between the flow rates and the detection result.

A liquid such as a solution can be used as the fluid.

The analyzer according to the invention comprises a first pump means (1) for delivering fluid at a first flow rate, comprising a pair of inlets and outlets (16, 17) and at least one inlet and outlet (18).
Second pump means (2) for sucking fluid at a flow velocity of, and the flow of fluid from the first inlet / outlet (17) of the first pump (1) to one inlet / outlet (18) of the second pump (2) At least one individual conduit means (4, 5) for communicating with said conduit means, and a sensor means (13) coupled to said conduit means (5) for detecting a fluid condition at a detection location within said conduit means (5). Flow rate ratio, a series of individual flow rate ratios, individual gradients of flow rate ratios, or a series of individual gradients of flow rate ratios to produce a plurality of ratios of said first and second flow rates according to a sequence of functional steps each of which is defined. A flow rate control means (100) operatively connected to at least one of said first and second pump means (1, 2) for controllably changing the flow rate of at least one pump means. An analyzer including: a first pump means ( The first entrance of) (17)
A fluid junction (3) in the conduit means (4, 5) for entering the sample fluid to be analyzed into the conduit means (5), between the first and the detection position and a first for adding to the sample fluid. Means (15) between the fluid junction (3) and the detection position for mixing the reagent fluid and sample fluid delivered by the pump means (1) to the conduit means (4) to form a mixed fluid. )
And the flow velocity control means (100) makes the second flow velocity larger than the first flow velocity so that the sample fluid is sucked at the fluid junction (3) and pulled to the detection position. To control at least one of the first and second pump means to analyze the sample fluid to determine the state of the mixed fluid at the detection position for a plurality of ratios of the first and second flow rates. The state of the mixed fluid determined by the relationship and analyzed at the detection position is determined by the ratio of the first and second flow velocities.

It will be appreciated that the first pump and the second pump constitute a positive pump and a negative pump, respectively, according to the nomenclature used herein.

Advantageously, the first pump is of piston-cylinder construction, comprising intermittently delivering a first fluid at said first flow rate and not delivering a first fluid into the conduit during filling of the first pump. Operates in a fluid motion cycle.

It is desirable to provide means for mixing the fluid in the conduit between the fluid junction in the conduit and the sensing location.

Preferably, the device of the present invention further comprises means operatively coupled to the first pump for varying at least the flow rate of the first pump according to a predetermined program. It is advantageous to provide each valve with control of its respective inlet and outlet and to provide means to cycle the operation of the two pumps and valves.

The fluid junction is preferably a T-junction, but if the conduit is partially submerged in the fluid, it is often an opening to allow fluid to be drawn from there. As used herein, the term "T-shape" does not necessarily refer to the actual shape of the fluid junction, but two or more fluid streams enter and merge together regardless of their shape or morphology. It includes all the fluid joints flowing out from the outlet.

Brief Description of the Drawings To facilitate an understanding and practice of the present invention, an example of a preferred embodiment and method of operation will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a combination block diagram showing the basic configuration of an analyzer for carrying out the method of the present invention when only one type of target solution requires analysis.

FIG. 2 schematically shows another constitution of the analyzer for carrying out the method of the present invention including the case where one or more kinds of target solutions need to be analyzed, and also possible variations in the positions and properties of individual parts. Show.

FIG. 3 is a somewhat schematic cross-sectional view of the device according to the invention, which is a detailed version of the block diagram of FIG.

Figures 4, 5 and 6 are graphs showing piston movement, flow velocity and sensor output for a particular analysis program.

Method of Carrying Out the Invention The analytical device shown diagrammatically in FIG. 1 comprises a positive pump 1 which is connected via a fluid line 7 to a container 9 of a solution 10. The negative pump 2 is connected to the drain port via the drain passage 8. A T-shaped fluid junction 3 is connected to the positive pump 1 by means of the positive fluid path 4, to the negative pump 2 by means of the negative fluid path 5 and to the container 12 of the sample 11 by means of the sample fluid path 6. The fluid paths 5 and 6 and the fluid joint 3 constitute a conduit means for communicating fluid between both pumps. The flow during normal analysis is from positive pump 1 to negative pump 2. When the flow rate (F _n ) of the negative pump 2 is higher than the flow rate (F _p ) of the positive pump 1, the sample 11 is led out along the test fluid path 6 toward the T-shaped fluid junction, and the flow rate F _x Is sucked from the joint 3 to the negative fluid path 5. Mixer 15
After uniformly mixing the solution 10 and the sample 11 in the fluid path 5, the sensor 13 detects the fluid state in the fluid path 5 and sends an output signal to the analysis circuit 14.

It will be apparent that a large number of analytical programs can be generated by varying the ratio of F _x : F _p . It should be noted that the following three methods can be used to obtain a desired F _x : F _p at a desired time.

(1) Changing the _{F n} while keeping the _{F p} constant, (2) changing the _{F p} while keeping the _{F n} constant, changing both (3) _{F p} and _{F n.}

However, the method (2) has the following advantages.

(I) The flow velocity passing through the sensor 13 becomes constant. This is desirable when the sensor response is flow dependent.

(Ii) Since the time required for the fluid to flow from the T-shaped fluid joint 3 becomes constant, the analysis becomes simple, especially in the case of titration.

(Iii) Various analysis programs can be created by changing the flow rate of one pump, that is, F _p , instead of the flow rate of both pumps.

According to the preferred method (2), the positive pump 1 needs to have the following characteristics.

(A) There is no pulse at least for the steps related to measurement.

(B) Instantaneous response to programmed changes in flow velocity (ie not damping).

(C) The flow rate recall rate is high when the analysis program is repeatedly executed.

The preferred embodiment of the positive pump 1 is a piston-cylinder pump with an inlet valve and an outlet valve, which completes one forward stroke and one reverse stroke in which the measurement is performed. If the negative pump 2 is also of this type, it is possible to perform highly accurate flow rate control and backwashing as will be described later, but a valve is required. A pump such as a peristaltic pump is desirable if the product solution is dirty or does not require high precision control or backwashing.

An embodiment as described above is shown in Figure 2a and in more detail in Figure 3. In FIG. 2a, the positive pump 1 and the negative pump 2 are piston-cylinder type pumps which operate together with the solution valve 16, the positive valve 17, the negative valve 18 and the drain valve 19. By opening and closing the four valves in synchronism with the forward movement or the backward movement of the piston, the following two states are produced in one operation cycle.

(I) A flow state in which the sample 11 and / or the sample solution 10 is caused to flow through the negative fluid path 5 for measurement.

(Ii) The sample 11 and / or the solution 10 are not allowed to flow in the positive fluid path 4 and the negative fluid path 5 and the positive pump 1 is filled with the solution, and at the same time, the reaction product, the unreacted sample 11 or the solution 10 is made negative. A state in which the flow discharged from the pump 2 to the discharge fluid passage 8 is stopped.

Therefore, it will be understood that the analyzer has an intermittent cycle of operation.

FIG. 3 is a sectional view showing the preferred embodiment of FIGS. 1 and 2a in more detail.

The positive pump 1 comprises a cylinder 46, an O-ring seal 47 and a piston 48. Positive valve 17 and solution valve 16 are connecting rods
It can be mechanically actuated by a cam 49 connected to 50. In addition, the valves 16 and 17 can be ball valves that operate with changes in fluid pressure, or switch-operated solenoid valves,
Alternatively, a motor-driven three-way tap may be used. Valve 16
And valve 17 is positive pump 1 is filling solution 10 or positive fluid path 4
Depending on whether or not the solution 10 is being discharged, the operation is performed at the opposite stages (opening stage and closing stage).

The negative pump 2 likewise comprises a cylinder 51, an O-ring seal 52 and a piston 53. Instead of providing an O-ring seal, a slightly flexible fluid seal such as a Teflon dropper may be provided at the end portions of the pistons 48 and 53. Negative valve 18
And the discharge valve 19 operates in synchronization with the valves 16 and 17. Cylinder 51
Has a larger capacity than cylinder 46. The piston 48 has an advancing step in which the piston 48 advances into the cylinder 46 to push the solution 10 in the cylinder 46 along the positive fluid path 4.
Piston 48 retracts from cylinder 46 and operates in two states, the retract stroke, in which solution 10 is introduced from vessel 9 along solution fluid path 7. Similarly to the piston 53, the piston 53 enters the cylinder 51 and pushes its contents into the fluid passage 8, and the piston 53 moves backward from the cylinder 51 to remove the fluid (sample 11, solution 10 or reaction product). ) Is introduced into the cylinder 51 through the negative fluid path 5 in the backward stroke. Piston 48 and piston 53 operate synchronously, but in reverse, in association with valves 16,17,18,19. Solution valve
When 16 is closed, positive valve 17 opens and piston 48 enters cylinder 46. At the same time, the negative valve 18 is opened, the discharge valve 19 is closed, and the piston 53 is pulled out from the cylinder 51. At this time, the amount of displacement of the piston 53 in the backward stroke is larger than the amount of displacement of the piston 48 in the forward stroke at the same time, and the difference becomes equal to the amount of the sample 11 sucked into the fluid path 5. . Conversely, when valve 16 is open, valve 17 is closed and piston 48 is withdrawn from cylinder 46. At the same time, the valve 18 is closed and the valve 19 is opened, and the piston 53 enters the cylinder 51.

The fluid passages 4, 5 and 6 are preferably constructed by tubes having an annular cross section. It is desirable to make the inner diameter as small as possible to optimize the sensitivity, but if it is made too small, there is a risk of clogging. The preferable range of the inner diameter is 0.5 to 2.0 mm, more preferably 1.0 to 1.5 mm. It is desirable to make the length of each fluid path as short as practically possible so as to reduce the flow resistance and minimize the detection delay.
The distance between the form junction 3 and the effective detection position must be sufficient to allow proper reaction for the required analysis (“reaction zone”). The length of this reaction zone is advantageously in the range of 10 to 30 mm for most applications.

The displacement of the piston 48 and the piston 53 can be achieved and controlled by the following means, for example.

(1) Individually programmed linear actuators, (2) Individually programmed speed control motors, (3) Cams contoured to a specific analysis program and connected to a common drive shaft.

The techniques (1) and (2) have the advantage of program flexibility, but are not suitable for very high-speed periodic operation because they do not synchronize when a load is applied. In contrast, technique (3) is precisely synchronized under load and can be easily adapted to variable or fast periods, but lacks flexibility and requires different cams each time the analysis program changes. . Nevertheless, this method is very desirable for fixed installations, for example.

FIG. 3 shows the technique (3), in which the shaft 56 is provided with a pair of cams 54, 55 for use. The cams 54, 55 are made of a material that is hard to wear and is resistant to corrosion, such as stainless steel. A device known as a "wire cutter" may be used to cut the contour of the cam into the desired mathematical curve with very high precision. This allows the piston displacement to be accurately reproduced from one operating cycle to the next. Cam 54,5
5 is connected to a motor 56 via a shaft 57. Motor 5
Reference numeral 6 is a relatively high speed motor, which is decelerated to a proper cycle speed by the transmission 58. An encoder 60 is attached to the shaft of the motor 56, and the encoder 60 generates a fixed number of pulses for each cycle regardless of the cycle speed and speed changes during the cycle. The pulses emitted by the encoder are synchronized with the output of the sensor 13 via the analysis circuit 14 and are recorded by the timer 59 and are used when it is desired to interrupt the cycle. Thus, the analysis circuit 14 always knows directly the cam position, and thus the flow velocity ratio, which can be related to the sample concentration as explained in the examples below.

Returning now to FIG. 2, another apparatus configuration for practicing the present invention is presented schematically. FIG. 2b shows a continuous flow type negative pump 2 which does not require valves 18 and 19 since it is not a piston and cylinder type. This pump 2 operates in association with a positive pump 1 of the piston-cylinder type and is stopped by a switch 20 during the filling of the positive pump 1.

FIG. 2c shows a negative pump 2 of the piston and cylinder type, but without the valves 18, 19 and the drainage passage 8. With this configuration, backflow cleaning can be performed when the positive pump 1 of the piston / cylinder type is filled with the solution 10. The content of the negative pump 2 is pushed back along the negative fluid path 5, passes through the sample fluid path 6, and the filter 21 provided at the end of the fluid path 6.
To pass into the sample 11. At this time, if particles are deposited on the filter 21 when the sample 11 is first introduced into the sample fluid path 6, it is removed. As a result, the sample 11 is contaminated, but this is not a problem when the measurement is performed only once for each static sample. If it is desired to make more than one measurement on a sample, the container 12 may be removed from the sample fluid path 6 during backwash to prevent contamination. This is not necessary if the sample is a stream. Further, when a precipitate is generated by the reaction between the solution 10 and the sample 11, the backwash cannot be performed.

Figure 2d shows a parallel positive pump configuration with positive valve
Positive pumps 1, 22 are connected to Y-shaped fluid junction 23 by positive fluid passages 4, 24 incorporating 17 and 29 respectively. The positive pump 22 includes a solution 27 via a solution fluid line 25 including a solution valve 26.
Connected to the container 28 of. In this configuration, the positive pump 1,22
Can be operated as a double-flow system that operates simultaneously, or as a "binary" system that operates either pump. The dual flow system is effective when the reagents or titrants are unstable and must be prepared from two components (solutions 10 and 27) before reacting with sample 11. The alternative system can be effectively used for multiple analysis and selection from two ranges when solution 10 and solution 27 differ in composition and concentration. It is also possible to connect two or more positive pumps in parallel.

FIG. 2d also shows an alternative configuration of the detection system which can be used in any of the configurations shown in detail. Sensor 13 is used in conjunction with a similar sensor 30 to form a differential sensor pair.
The sensor 30 may be located in the fluid path 4 as in FIG. 2d, or the sample fluid path 6 as in FIG. 2e, or 2f.
As shown in the figure, it may be arranged at a short distance to the sensor 13 on the negative fluid path 5. The last-mentioned arrangement produces an output close to the first derivative and is effective for potentiometric titration.
FIG. 2d also shows a method of flowing the sample 11 through the tube 12 instead of the measurement in the container 12.

Figure 2e shows the positive pump in series configuration. Positive pump 13 is connected to T-fluid junction 32 by positive fluid path 33, which includes positive valve 34, and is connected to container 35 of solution 36, via solution fluid path 37, which includes solution valve 38. Mixer 39 mix sample 11
The solution is mixed with the reaction product produced from the solution 10 and the solution 10.
With this configuration, continuous analysis using a plurality of solutions can be performed. Two or more positive pumps may be connected in series.

FIG. 2f is an example of the selection of FIG. 2e, in which a container 40 for the solution 36 is used instead of the positive pump 31 and is connected to the T-shaped fluid junction 32 by a positive fluid passage 33 including a positive valve 34. . The sample valve 41 operates synchronously with but opposite to the positive valve 34.

FIG. 2g shows a configuration in which the sample fluid passage 6 is removed. The positive fluid path 4 and the negative fluid path 5 are immersed in the sample 11,
It is noted that the shaped fluid joint 3 is configured as an opening provided in the fluid path and the sample 11 is introduced from there. The time required for the fluid to reach the sensor 13 from the mixer 15 is determined not only by the periodic velocity but also by the length of the fluid path between the mixer 15 and the sensor 13. This length should be very short when the reaction between sample 11 and solution 10 is fast.
If the reaction of 10 is slow, it can be changed to be relatively long. Fig. 2g shows the latter state in a schematic manner.

Fig. 2g shows the fluid passage without the sensor 13 in the negative fluid passage 5.
42, and therefore the analyte to the fluid path 5 without substantially affecting the amount of fluid introduced into the negative pump 2.
Also shown is a configuration in which the fluid is passed through the fluid passage 42 through the diffusion membrane or the dialysis membrane 43. The analyte entering the fluid passage 42 reacts with the reagent 44 propelled along the fluid passage 42 from the pump 45 at a constant speed.

A typical analysis cycle consists of several steps, the number, nature, duration and order of which can be varied to suit the particular analysis program. The duration of each stage can be characterized by a time interval, and the sum of the time intervals of all stages is the cycle time.

When the flow rates of a plurality of positive pumps are F _p ... F _z , the flow rate of one negative pump is F _n , and the flow rate of the sample is F _x , the basic equation relating to the flow rate is as follows.

_{F x} = F n _- is _(F p ...... ₊ F z) following ones as selective steps.

(A) Solution flushing F _n = F _p ...... + F _z ≠ O; F _x = 0 The sample 11 is not introduced into the negative fluid path 5, and if the sample 11 or reaction product is present, the negative fluid path 5 is used. Drain from and add solution 10 instead. The sensor 13 records a baseline after the sample 11 or reaction product has passed through the sensor 13.

(B) Sample Flushing _{F n> F p ...... + F} z O; as F _x> O F _x becomes high, and the sample to be measured in a short time a sample remaining in the sample fluid passage 6 Change. Therefore, the sample fluid path 6 is initialized with the sample 11. This step is not necessary for the configuration of Figure 2g.

(C) Measurement of sample _{F n = F x ≠ O;} F p ... + F z = not introduce the solution into O negative fluid passage 5. This step is used for direct analysis.

(D) Label _Fn > _Fp ... + _FzO ; _Fx > O When a relatively small amount of the sample 11 is introduced into the negative fluid path 5 in a very short time, the sensor 13 records a sharp spike waveform. , Which can be used as a marker for the starting point of the subsequent steps. This step is useful for titrations where the time from the label to the end point is the measured value of the sample concentration, regardless of the position of the sensor 13 in the negative fluid path 5.

(C) Single quantitative addition for reagent addition analysis _Fn > _Fp ... + _FzO ; _Fx >O; The value of K is chosen to suit the particular reaction and concentration range of the sample. The sensor 13 records the step change. At this time, the height (y) of the step is related to the concentration of the sample 11. It is desirable to allow y to be an average value, with sufficient time for the step duration sensor 13 to stabilize.

(F) Multiple quantitative addition That is, by changing K ₁ , K _2, ... K _n , it is possible to produce a series of step-like changes that rise or fall. The sensor records a series of step heights y ₁ , y ₂ , ... Y _n, which may or may not be equal. The quantitative addition step is used for known quantity reagent addition analysis.

(G) Single gradient formation for simple titration or reagent addition analysis When f (t) is an ascending or descending relationship with respect to step time, eg linear or non-linear function, F _n > F _p ...... + F _z O; F _x O; At this time the slope is equal to one of the following Start and end at.

(1) Infinity, that is, _Fp ... + _Fz = O (2) Zero, that is, _Fx = O (3) Ka (starting constant) and Kb (end constant) that can be changed according to the sample concentration in a specific range. ). Ratio of initial value to final value Determines the titration range.

(H) Multiple gradient format for more complex titrations One or more functions, Can be used to generate a series of gradients. For example,
f ₁ (t) = f ₂ (t) rises symmetrically with respect to the center point /
Produces a downward double titration. The gradient can be used not only for titration but also for reagent addition analysis.

(I) Stop _Fn = _Fp ... + _Fz = _Fx = O This step is effective for delaying the reaction time and completing or moving the sample fluid path 6.

(J) Change of valve The valves shown in FIGS. 2 and 3 are both open or closed, and can be changed in synchronization with other valves or independently.

(K) Filling With the valve closing the positive and negative fluid paths, the positive pump is filled with the solution from the solution container.

(L) Discharge While the positive and negative fluid paths are closed by the discharge valve, the content of the negative piston pump is discharged to the drain path. This is done at the same time as step (k).

(M) Transfer Transfer of the sample fluid path 6 to another sample in the positive fluid path 4 and the negative fluid path 5 in the state where the flow of the fluid does not occur as in the steps of (i), (k) and (l). can do.

(N) Reverse Washing With the positive fluid passage 4 closed and the negative fluid passage 5 open, the contents of the negative piston pump 2 are pushed back along the negative fluid passage 5 as described above.

The configuration of the analyzer according to the present invention described in the surroundings not only eliminates the need to perform a precise amount measurement as in the well-known flow method, but also causes the sample flow path to be a problem common to the conventional flow methods. It is far superior to the prior art in that it also eliminates the need to inject or inject. The jetting device is relatively complex and there is a risk of sample-to-sample contamination. As in the present invention, the structure for sucking the sample by using the double pump is relatively simple, and since flushing is easy, there is no problem of contamination and the accuracy is very high. Also, a simple piston pump can be used in place of the problematic peristaltic pump that was favored in the prior art.

The analysis method of the present invention can process a very small amount (1 ml or less) of a sample at a higher speed and with a higher reproducibility than conventional flow methods. Air-segmented an
analysis can be performed in 20 seconds once, and the flow injection analysis method can be performed in 10 to 20 seconds once, but in the method of the present invention, it is 1 second or less per time depending on the reaction time and the sensor response. Can be done at. Even when switching between analyzes, the device of the present invention can quickly exchange the sample and the reagent. Reproducibility is better than 0.1% for titration and 1 for reagent addition analysis.
% Better is illuminated.

When the method of the present invention includes an aggressive mixing action, it is believed that there is a reproducible and close quantitative relationship between the injected sample and the measured reaction product in the reagent addition analysis. This increases sensitivity and minimizes the need to use a wide range of calibration standards as opposed to air split or flow jet analyses. Usually, one or two standard solutions are sufficient.

The flexibility of the method of the present invention will also be apparent from the above description. The method of the present invention can be applied to continuous online applications, including those withstanding high pressures and variable pressures, individual samples and a small portion of a single sample.

Another important advantage of the present invention relates to the fact that a piston-cylinder pump can achieve highly accurate flow rate control. Therefore, titration can be performed within a very narrow flow velocity range around the expected end point value. This increases the sensitivity and the fineness of the range is smaller than in the case of the technology based on the well-known distribution method.

By operating the analyzer of the present invention intermittently and repeatedly, it is possible to incorporate a very simple structure for backwashing without causing any operational inconvenience, and to perform flushing of the sample flow path and washing of the associated filter. You can

A final point to note is the combination of several features into one technology, which has hitherto been achieved only using either distribution methods or batch technology. Among them, the features of interest are that there are no restrictions on solvents, detection systems can be selected from a wide range (possible by batch technology), anaerobic measurement, slow reaction, and differential detection or induction detection using two sensors. , And automatic compensation of sensor delays (all possible using one or more conventional distribution methods).

More specifically, the apparatus of the present invention can be constructed entirely of chemically inert materials such as stainless steel, glass, polypropylene, Teflon, etc., so that it can be used with chemically strong solutions. Furthermore, in the case of a high-speed reaction, the temperature type detector can be used because the mixing is complete and the residence time from the mixer 15 to the sensor 13 in the fluid path 5 is short. The absence of electrostatic activation means that the method and means of the invention are suitable for potentiometric sensors. Anaerobic analysis is also possible because the system is closed to the atmosphere and does not open.

Example 1 (j ₁ ), with infinite number of feasible analysis programs,
Analyze multiple quantitative reagent addition analysis including steps (b), (a ₁ ), (f), (a ₂ ), (j ₂ ) (k, l) in this order (using the symbols used above) The operation principle will be described by selecting the program as an example and examining it in detail. Other examples of direct analysis and titration will also be briefly discussed in relation to the steps already described.

For this example, path length of the FIG. 4a is a piston 48, FIG. 4b represents the stroke length of the piston 53, the 4c diagram F _n, the 4d diagram F _p, the 4e diagram plotting the F _x, respectively And 4f
The figure shows the output of the sensor 13. All the operation cycle times taken on the same horizontal time axis are plotted as a function,
The time from the point O (left side) to the point O (right side) represents one cycle. Figure 4f shows that the fluid is from the T-type fluid junction 3 to the sensor 13
Since it takes time to move to, it is deviated with respect to Figures 4a, b, c, d, and e. This delay is from time point O to time point O ^*
The interval is up to.

To clarify the relationship between FIGS. 4a and 4b, it is assumed that pistons 48 and 53 have equal cross-sectional areas, but this is by no means essential. Also,
Also for the purposes of this example, sensor 13 measures the reaction product organisms formed from reagent 10 and sample 11, and reagent 10 and sample 11 as well.
Suppose you don't respond to.

Next, each step will be described in detail.

In the time interval from stage (j ₁ ) 0 to t ₁ , valves 16 and 19 are closed and at the same time valves 17 and 18 are opened. Since neither the piston 48 nor the piston 53 moves during the time from 0 to t _1, it is possible to prevent the pressure surge from occurring in the fluid paths 4 and 5 when the valve is changed.

Step (b) In the time interval from t ₁ to t ₂ , valves 16 and 19 are closed and valves 17 and 18 are closed.
The piston 53 retracts from the cylinder 51 with the
To the 1 position, fluid is introduced along the fluid path 5 at a flow rate F _n . Again starting at time t ₁ , piston 48 does not move in the same time interval from t ₁ to t ₂ . First, the sample previously contained in the sample fluid path 6 is guided by the sample 11 to be measured to the T-shaped fluid joint 3 and further along the fluid path 6. Sensor 13 records the baseline because no reaction products are formed. F _p need not be zero, but it should be relatively small so that the flushing of the sample is finished in the shortest time.

During the time interval from stage t ₂ to stage t ₃ (a ₁ ) valves 16 and 19 close and valve 17
And 18 are opened, the piston 53 moves backward from the cylinder 51, moves from the position 1 to the position m, and the fluid flows at the flow velocity F _n to the fluid path 5.
Will be introduced along with. At the same time, the piston 48 starts from t _2.
By t ₃ it has entered the cylinder 46 and moved from position 0 to position g so that the solution 10 (reagent in this case) flows with F _p equal to F _n . The sample 11 does not flow along the fluid path 6, is contained in the fluid path 6 up to the T-shaped fluid joint 3, and is discharged from the fluid path 5 to replace the solution 10. Thus, the sample fluid path 6 is initialized with the sample 11 to be analyzed, but the fluid path 5 does not contain the sample 11. The analyzer 14 records the baseline.

Step (f) valves 16 and 19 are closed and valve 17 is closed during the time interval from T ₃ to t _4.
And 18 open and the piston 53 moves backward from the cylinder 51 and moves from the position m to the position n, so that the fluid is introduced into the fluid passage 5 at the flow velocity F _n . At the same time, the piston 48 further moves into the cylinder 46 in the time interval from t ₃ to t ₄ ,
The movement from the position g to the position h causes the reagent 10 to flow along the fluid path 4 at a flow rate of F _n or less. Sample 11 is T
It is sucked into the shaped fluid junction 3, where it merges with the reagent 10, is mixed by the mixer 15 and flows into the retracting pump 2 which has passed the sensor 13. By incremental change the ratio of F _{x /} F _p During this stage, stepped output of the height y1, y2, y3, y4 are obtained. This gives information about the response curve of the sensor, if this incremental difference (i.e. y4-y3, y3-y2,
If y2-y1) are not equal, profile matching between sample and standard improves accuracy. There may be any number of increments, but the number is initially determined by the time it takes to stabilize the sensor. When mixing is complete,
There will be a quantitative relationship between the sample concentration and the heights y1, y2, y3, y4.

During the time interval from step t ₄ to t _{5 of} stage (a ₂ ) valves 16 and 19 are closed and valve 17 is closed.
With the pistons 18 and 18 open, the piston 53 moves backward from the cylinder 51 and moves from the position n to the position p, so that the fluid is introduced along the fluid path 5 at the flow velocity F _n . At the same time, the piston 48 further enters the cylinder 46 and moves from the position h to the position i, so that the solution 10 flows at a flow rate equal to F _n . The sample 11 does not flow along the sample fluid path 6, but the reaction product is discharged from the fluid path 5 and replaced with the solution 10. Analyzer
14 records the baseline as before.

The time interval from t ₁ to t ₅ represents the total forward stroke of the piston 48 and the total backward stroke of the piston 53, while from t ₆
The time interval up to t ₀ is the total retract stroke of the piston 48 and the piston.
It represents the total forward travel of 53, and both pistons return to the initial starting position, ie the position of t ₀ .

In the time interval from stage (j ₂ ) t ₅ to t ₆ , valves 16 and 19 are opened and at the same time valves 17 and 18 are closed. Because during the period from t ₅ to t ₆ the piston 48 also the piston 53 does not move, the pressure surges in the fluid passage 4 and 5 is accompanied is prevented from occurring to make changes of the valve.

In the time interval from stage (k, l) t ₆ to 0, valves 16 and 19 open and
The piston 53 enters the cylinder 51 and moves from position p to position 0 with 17 and 18 closed, so that the contents are pushed out along the fluid path 8 to the drain port. At the same time, in the time interval from t ₆ to 0, the piston 48 moves backward from the cylinder 46 and moves from the position i to the position 0, so that the solution 10 flows into the cylinder 46 along the fluid path 7.
The solution 10 does not flow in the fluid paths 4 and 5, but the solution 10 exists in both fluid paths. During this time, the sample fluid path 6 can be transferred to another sample. In this way, the next operation cycle is restarted.

In order to prove the usefulness of the device of the present invention, the following analysis was conducted. Flows containing 500 and 1000 micrograms of iodide standard solution and low-fat milk separately per liter, respectively, into the device and including an iodide ion selective electrode and a single Ag / Ag Cl / 1M KCl reference electrode. Measured by adding a known amount of 0.01M potassium chloride (“reagent”) to 1000 micrograms of iodide standard solution per liter using a through cell (volume of 10 microliters) as a sensor, inside a conduit with an inner diameter of 1.6 mm. The mixture was mixed by a micro reed (20 mm x 0.7 mm) vibrating at 20 Hz. Judging from the characteristics of the pump and the displacement rate, the amount of solution aspirated and the amount of reagent consumed in one operation cycle are set to 15 seconds per operation cycle, and the two-step quantitative addition method is used. Then, when the ratio of the aspirated solution to the reagent was 60:40 and 40:60, respectively, it was 0.9 ml. As a result of repeating this measurement several times, the recall was within 1%. The amount of iodide in milk from the two standard solutions was calculated to be 760 micrograms per liter.

Example 2 FIG. 5 shows (j ₁ ), (b), (a ₁ ), (d), (g),
_{(A 2), (j 2} ), (l, m) is an illustration of the labeled single gradient program comprises the step of, convenience this example description particularly potentiometric titration, and more particularly a conventional bond It relates to acid-base titration using a pH electrode as a sensor.
Step (b) represents the step of discharging the previous sample and replacing it with the sample to be measured. Labeling step (d) shows a sharp spike defining the start of the titration. The gradient stage (g) in this case shows a controlled falling straight line at F _p , and F _x
Although a rising line is shown at, the slope need not be linear. The end point is at time point t _e , and the time interval from the label to t _e is the measured value of the sample concentration that compensates for the sensor delay. This is because if the sensor response is delayed, both the sign and the end point are changed by the same time interval. Titration range is F _x
/ F _p determined by the ratio of _(the end of step (g)) _(stage (start of g)) versus F _{x /} F _p, may be chosen to match the variations in the concentration of a particular sample group.

Titration analysis was performed as follows.

The sodium hypochlorite standard solution with chlorine of 2.0 ppm, 2.5 ppm, and 3.5 ppm and chlorinated tap water are separately sucked into the device, and the iodide ion selective electrode and the single Ag / AgCl / 1M KCl reference electrode are connected. Using a flow-through cell (volume: 10 microliters) as a sensor, titrate to 5 × 10 ^-5 M iodide in pH 4.7 buffer, and use 2 inside a 1.6 mm inner diameter conduit.
The mixture was mixed by a micro reed (20 mm x 0.7 mm) vibrating at 0 Hz. If the operating cycle time was 30 seconds and a single linear gradient was adopted and the titration range was 4, the amount of solution sucked and the amount of titrant consumed were again 0.9 ml each. The end point was measured from the first derivative, and the time taken from the start to the end point was measured personally. As a result of repeating each measurement several times, the recall was within 0.1%, and the total amount of chlorine remaining in tap water was calculated to be 2.8 ppm from the standard solution.

Example 3 FIG. 6 shows (j ₁ ), (b) (a ₁ ) (c), (a ₂ ),
(J ₂ ). 6 illustrates a direct analysis program including a backwash comprising step (n).

The solution 10 in this case is usually a standard solution containing a known concentration of the substance to be analyzed, which the sensor 13 records as a baseline in both stages (a). Since the solution 10 does not flow into the fluid path 5 in the step (c), the height y _x recorded by the sensor 13 in this step becomes the measured value of the concentration of the sample 11. In this case, the valve change (j ₂ ) is made only in relation to valves 16 and 17. In the backwash step (n), the mixture of the sample 11 and the solution 10 contained in the cylinder 51 is pushed back along the fluid path 5 and the sample fluid path 6. Since the contents of the cylinder 51 are not evenly distributed inside the cylinder 51, the sensor 13 records an irregular curve.

As a more detailed example, 0.9 ml of tap water was aspirated every 30 seconds through a flow-through cell (effective cell volume of 50 microliters) containing a microminiature pH electrode and a reference electrode, and a baseline of NBS6.88 phosphate buffer solution In comparison, the pH of tap water was measured. The measured pH value was 7.52, and the recall was better than 0.01 pH.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Peachay, Ruthsul Marsden Austrian Federation, In the State of Queensland, Deyurac, 4077, Freeman Road 36 (72) Inventor Sweetman, Dennis Ratsul, Australian Federation, In the State of Queensland, Corinda 4075, Oxkury Road 811 (56) Reference JP-A-52-128195 (JP, A) Kai 56-57954 (JP, A) JP 58-117458 (JP, A) JP 59-116550 (JP, A)

Claims (30)

[Claims] 1. At a second flow rate comprising a first pump means (1) for delivering fluid at a first flow rate, comprising a pair of inlets and outlets (16, 17) and at least one inlet (18). Second pump means (2) for sucking fluid and conduit means for communicating fluid flow from the first inlet / outlet (17) of the first pump (1) to one inlet / outlet (18) of the second pump (2) (4,5)
And a sensor means (1) coupled to the conduit means (5) for detecting the condition of the fluid at a detection position within said conduit means (5).
3) and at least one individual flow rate ratio, a series of individual flow rate ratios, a separate gradient of flow rate ratios, or a series of individual gradients of flow rate ratios, each according to the sequence of functional steps defined above Operatively connected to at least one of said first and second pump means (1, 2) for controllably varying the flow rate of at least one pump means to produce a plurality of ratios of flow rates. An analyzer including a flow rate control means (100), wherein a sample fluid to be analyzed is present between the first inlet / outlet port (17) of the first pump means (1) and a detection position by the conduit means. Fluid junction (3) in conduit means (4, 5) for entry into (5) and reagent delivered to said conduit means (4) by first pump means (1) for addition to sample fluid Mix fluid and sample fluid to form mixed fluid And a means (15) between the fluid junction (3) and the detection position is provided, and the flow velocity control means (100) sucks the sample fluid at the fluid junction (3), At least one of the first and second pump means is controlled to make the second flow rate higher than the first flow rate so as to be pulled to the detection position, and the analysis of the sample fluid is performed by the first and second pump means. The state of the mixed fluid is determined by the relationship of the state of the mixed fluid at the detection position with respect to a plurality of ratios of the second flow velocity, and the state of the mixed fluid analyzed at the detection position is determined by the ratio of the first and second flow velocity. An analyzer characterized by the above. 2. The step of delivering said sample fluid at said first flow rate and the step of not delivering sample fluid to said conduit means (4, 5) during refilling of said first pump means (1). The analysis device according to claim 1, which has a piston-cylinder configuration having a discontinuous flow cycle including. 3. The mixing means (3, 15) is a fluid joint (3).
And the mixing device (15) provided in the conduit means (5) between the detection positions. 4. The flow rate control means (100) is operatively connected to the first pump means (1) for controllably varying the flow rate of the first pump means (1). 1
4. The analyzer according to any one of 1 to 3. 5. A valve according to any one of claims 1 to 4, including respective valves for controlling said inlets and outlets (16,17,18), both pump means (1,2) and means for synchronizing the valves. The analyzer according to the item. 6. The analyzer according to claim 1, wherein the fluid junction (3) is a T-junction. 7. The fluid junction (3) comprises conduit means (4,
Analysis according to any one of claims 1 to 5, wherein 5) is a hole in the conduit means (4, 5) for aspiration of the sample fluid when it is partially immersed in the sample fluid. apparatus. 8. Sensor means (13) are provided for detecting the state of the fluid in the conduit means (4, 5) at two detection positions which are spaced close together and thereby obtaining a derivative output. The analyzer according to any one of claims 1 to 7. 9. The conduit means (4,5) for detecting the condition of the fluid in the conduit (4,5) towards either side of the fluid junction (3) by the sensor means (13). An analysis device according to any one of claims 1 to 8 which is coupled. 10. The step of the second pump (2) sucking fluid at the higher flow rate, and through the conduit means (5) during discharge of the second pump means (2). The analyzer according to any one of claims 1 to 9, which has a piston-cylinder configuration having a discontinuous flow operation cycle including a step of not sucking fluid. 11. A method according to claim 1, further comprising a container (9) for said reagent fluid, which is connected for delivering a fluid to a second port (16) of the first pump means (1).
10. The analyzer according to any one of 10. 12. Electronic means (14) connected to sensor means (13) and pump means (1, 2) for analyzing a mixture of reagent fluid and sample fluid as a function of fluid ratio and outputting an analytical value. ) The analyzer according to any one of claims 1 to 11, further comprising: 13. An outlet connected to said conduit means (4, 5) parallel to said first pump means for delivering respective additive fluid (27) to said conduit means (4, 5). (2
Analysis device according to any one of claims 1 to 12, further comprising at least one auxiliary pump means (22) having 9). 14. A filter (21) further coupled to said fluid junction (3), said filter being passed by the aspirated sample fluid and by reverse operation said second pump means. The analyzer according to any one of claims 1 to 13, which can be washed with the backflow fluid delivered in (2). 15. A flow control means (100) according to any one of the preceding claims, wherein the flow control means (100) produces a non-multiplicated, substantially pulse-free operation of the pump means (1,2). Analysis equipment. 16. The flow velocity control means (100) is a cam means (54,5) for controlling the operation of the pump means (1, 2).
The analyzer according to any one of claims 1 to 15, which comprises 5). 17. The analysis according to claim 1, wherein the flow velocity control means (100) has direct current or alternating current motor means for controlling the operation of the pump means (1, 2). apparatus. 18. The analyzer according to claim 1, wherein the flow velocity control means (100) is changed according to the dynamic control from the sensor means (13). 19. The analyzer according to claim 1, wherein the sensor means (13) is suitable for one or more of direct analysis, reagent addition analysis and titration. 20. The sensor means (13) further comprises an auxiliary conduit, an associated pump means and a sensor connected to the detection location for transferring the fluid or components thereof to another detection location. 20. The analyzer according to any one of the ranges 1 to 19. 21. The plurality of ratios comprises a plurality of individual ratios of the first and second flow rates at which the sample fluid is aspirated at the fluid junction (3) and delivered to a detection location. 2. The analysis according to claim 1 is determined by the relationship between the plurality of flow rate ratios and the state of the fluid at the detection position.
14. The analyzer according to any one of 14 above. 22. Delivering a first fluid to a first fluid junction (3) at a first flow rate, and simultaneously aspirating a fluid to be detected from the fluid junction at a second flow rate. Flow rate ratio, a series of discrete flow rate ratios, a discrete gradient of flow rate ratios, or a sequence of functional steps each defined by at least one of a series of discrete gradients of flow rate ratios.
And a controllable change of at least one of said flow rates to produce a second plurality of ratios, and the step of detecting the state of the fluid at the detection location to perform the analysis, One fluid is a reagent fluid, said step comprising at least one step in which the second flow rate is greater than the first flow rate and the sample fluid is aspirated at the fluid junction and pulled to the detection position. The sample fluid is mixed with a reagent fluid between the fluid junction and the detection position to form a mixed fluid that is detected at the detection position, and the analysis of the sample fluid is performed in the first and second An analysis method, which is determined by a relationship of a state of the mixed fluid at a detection position with respect to the plurality of ratios of flow rates, and a state of the mixed fluid analyzed at the detection position is determined by a ratio of the first and second flow rates. 23. The method of claim 22, wherein the first flow rate is controllably varied while the second flow rate is substantially constant. 24. Confining fluid to the conduit means (4, 5, 6), maintaining the flow rate equal for a period of time prior to the delivering and aspirating steps, the conduit means (4, 5, 6) with reagent fluid. 24. The method according to claim 22 or 23, further comprising flushing. 25. Flushing the conduit means (4, 5, 6) with the sample fluid by confining fluid to the conduit means (4, 5, 6) and holding the first velocity at zero for a period of time. 24. A method according to claim 22 or 23 including. 26. Using titration as the reagent fluid, continuously varying the flow rate until an endpoint is detected at the detection location, and using the ratio between the flow rates to complete the analysis. 25. The titration method according to any one of 25 to 25. 27. The reagent addition analysis method according to any one of claims 22 to 25, which comprises completing analysis using a ratio between flow rates and the detection result. 28. The method according to any one of claims 22 to 27, wherein the fluid is a liquid such as a solution. 29. The method according to any one of claims 22 to 28, wherein the analysis is direct analysis, reagent addition analysis or titration. 30. A plurality of ratios includes a plurality of individual ratios of first and second flow rates at which the sample fluid is aspirated at the fluid junction (3) and delivered to the detection location, the analysis of the sample fluid. 30. The method according to any one of claims 22 to 29, wherein is determined by the relationship of the state of the fluid at the detection position to the ratio of the plurality of flow rates.