DE3822788C1 - Photometer to analyse liquid media - Google Patents

Abstract

A photometer to analyse liquid media having a cuvette for the admission of the medium to be examined, the cuvette being designed as a piston pump with a cylinder, cylinder head and pump piston, having a multiway valve for the connection of the cuvette designed as a piston pump with containers, a suction opening, a discharge opening and a mixing device with a mixing pump, having a control device for controlling the multiway valve, the pump piston and the mixing device and having a light source as well as a photoelectric receiver, which are arranged respectively axially with the cuvette on the cylinder head or on the pump piston. The said photometer is characterised in that the mixing device has a mixing container and in that the control device is designed for driving the multiway valve and the pump piston in such a way, that the cuvette designed as a piston pump can be connected to the mixing container and in that the pump piston, acting as a mixing pump, carries out at least one to and fro movement for the expulsion of the medium out of the cuvette designed as a piston pump into the mixing container and for sucking the medium out of the mixing container into the cuvette designed as a piston pump.

Description

The invention relates to a photometer in the preamble of claim 1 Art.

Such a photometer is known from EP 01 85 334 A2. It has the advantage of a very simple and straightforward Construction, especially because the cuvette and pump are too one unit are united. It is a mixer device provided, which after sucking in with each other to Re action liquids in the cuvette mixes to speed up the response time. As a mix is a device in the known construction Auxiliary pump provided that the cuvette contents in one Circuit mixed.

However, the disadvantage of this is the need for one separate auxiliary pump, which complicates the construction again Ornate, more prone to failure and more expensive and the war maintenance work, especially for cleaning makes.

The object of the present invention is therefore in a photometer of the type mentioned at the beginning create that with structurally simpler, cheaper and less maintenance-intensive construction a better one Trial mixing allowed.

This object is achieved with the features of the characterizing part of claim 1 solved.

This takes place in the construction according to the invention Mix by the fact that in the piston pump, ie the Cuvette-containing liquid to be mixed into one Mixing container pressed and from this back into the Pump is sucked. The liquid must rela tively narrow connection channels or hoses and that Multi-way valve pass and is from one room to another pumped over. This results in an excellent one Mixing. If necessary, this process can be repeated several times to make it difficult to mix Mix liquids well. There are none Additional devices, such as auxiliary pumps, required. Any mixing container can be used additional container can be used in addition to the existing containers is provided anyway. The  Construction is extremely simple and costly Cheap. Maintenance is also simplified because Cleaning problems of auxiliary pumps or the like are eliminated.

The features of claim 2 are advantageous here intended. The mixing tank is similar to that Piston pump, as a cylinder with a free-running piston educated. When pushing in liquid as well when the liquid is sucked off, the free-running follows Piston in its cylinder in a simple way defines a space of variable volume. Such Construction is extremely robust, easy to clean and long-term reliable.

Alternatively, a mixing container according to claim 3 before be seen. Flexible sacks are used as loading anyway container used, for example as a storage container for reagents. It is advantageous according to claim 4 the sack is made of elastic material, the collapse on the smallest surface when emptied pulls. This will cause problems with lagging Air bubbles and especially the cleaning problems Significantly reduced, since at the back after emptying permanent small surface of the elastic Sacks only little dirt get stuck.

The features of the claim are also advantageous 5 provided. The arrangement of the invention Mixing device can in particular also be used for mixing from ready-to-use reagents that only last for a short time longer lasting components are used, whereby this mixture takes place before the start of the measuring processes and then the finished reagent in the usual way for the Measurement procedures are withdrawn from the ready-to-use reagent container becomes.  

The features of the claim are also advantageous 6 provided. For securing evidence, for example briefly occurring impurities in the river water this can be determined by photometry be kept for preservation of evidence. Lots contaminants of interest decay, however longer storage time and must therefore be on preservation treated with a suitable fixative will. Even when inserting the fixative resulting mixing problems are solved with the invented device according to the invention solved in a favorable manner.

The features of the claim are also advantageous 7 provided. With a heater, the Ver mix the mixture to be heated, for example to accelerate the required chemical reactions nigen, which accelerates the entire measurement process becomes.

The features of the claim are also advantageous 8 provided. With a reaction column, for example wise chemically or catalytically reactive chemical reactions in turn accelerated their process or made it possible at all light or chemical reaction Implementations, such as reductions be to be found in a better substance detectable chemical state.

Finally, the features of the claim are advantageous ches 9 provided. With a filter device in the case of the chemical re running under mixing action failing solids are retained, that could otherwise interfere with photometry.

In the drawing, the invention is for example and shown schematically.

A piston pump 1 has a cylinder 2 with cylinder head 3 and a pump piston 4 , which is driven by a piston rod 5 via rack and pinion by a motor 6, which is connected to an electronic control device 8 for control via lines 7 .

The cylinder 2 of the piston pump 1 is designed as a cuvette of a single-beam photometer, with an axial beam path. The light beam 9 passes through the cylinder space between a light source 10 attached to the floor, which is connected via lines 11 to the control device 8 and an attached to the pump piston 4 photoelectric Emp catcher 12 , which is connected via lines 13 to the Steuerein device 8 .

The cylinder chamber of the piston pump 1 is connected via a hose 14 to a multi-way valve 15 , which is controlled by the control device 8 via lines 16 and can connect a larger number of outputs to one another if necessary. Such a multi-way valve can for example be equipped with a rotary slide valve, a rotary or sliding plug or the like.

At the multi-way valve 15 , an intake hose 17 is ruled out. Via this, the liquid to be examined is sucked in from the outside via a suction opening, for example from a water whose water quality is to be examined for impurities such as phosphate, cyanide or chlorinated hydrocarbons. After completion of the measurement, the waste water is discharged to the outside through a hose 31 through an outlet opening.

Via a hose 18 , a storage container 21 is connected, which is used to store reagents with which, after addition to the sucked-in water, a chemical reaction is triggered, which is evaluated photometrically with the light beam 9 . The storage container 21 is shown as a plastic bag commercially available.

The photometer described so far can be used for photo metric monitoring of liquids, e.g. B. be used for the monitoring of water on Ver impurities already mentioned. During a measuring process, the control device 8 first switches the multi-way valve 15 into a switching position in which the hoses 17 and 14 are connected. The motor 6 is driven in such a way that the pump piston 4 of the piston pump 1 sucks a certain amount of water into the piston pump via the suction hose 17 . It should now be examined for a specific water contamination for which the appropriate reagent is provided in the storage container 21 . The multi-way valve 15 is now switched to connect the hoses 18 and 14 , and by further retracting the pump piston 4 , a corresponding amount of reagent is drawn into the piston pump. Now a chemical reaction takes place, the result of which is a coloration of the water. The control device 8 now switches on the light source 10 and receiver 12 and evaluates or sends the data to an evaluation device, not shown, which can store or display the data received. To increase the measuring accuracy, a control measurement is carried out to determine the zero value before adding the reagent in the aspirated liquid.

The connection 14-31 is then established and expelled with the multi-way valve 15 . The photometer is now ready for a new measurement. Determinations of different substances in the water can be carried out one after the other for which different reagents are kept in stock. For this purpose, further storage containers can be provided for other necessary reagents, which can be designed in accordance with the storage container 21 shown and can be connected to additional connections of the multi-way valve 15 , for example the connections 33 to 35 shown . Between the individual measurement processes, the cuvette, that is, the interior of the piston pump 1, can be rinsed to remove the reaction products from the previous measurement by sucking in liquid one or more times and expelling it again.

At the multi-way valve 15 , a second cylinder 24 is connected via a hose 23 as a mixing container, which, similar to how the cylinder 2 of the piston pump 1 forms, is open at its upper end shown with a collar. In the cylinder 24 , a free-running piston 25 runs , which is mounted in the cylinder 24 so as to be freely displaceable in the axial direction without its own drive.

For mixing, the hoses 14 and 23 are connected by the multi-way valve 15 by appropriate control via the control device 8 . Now the layered water / reagent mixture can be pressed from the piston pump 1 into the second cylinder 24 , the piston 25 being advanced. The mixture is then sucked back into the piston pump 1 , the piston 25 withdrawing accordingly. This pumping from the piston pump into the second cylinder 24 can be carried out several times in order to mix particularly finely.

The pumped liquid flows through the relatively narrow hoses 14 and 23 as well as the internal connection paths in the multi-way valve 15 and is intensively mixed as well as during the inflow and outflow in the cylinders.

The mixing container can also be ausgebil det in other ways. For example, the storage container 21 can be used as a mixing container. The second cylinder 24 with its piston 25 could also be used as a storage container.

The mixing container ( 24, 21 ) used in each case must be rinsed after a mixing process in order to clean its inner surfaces, including the inner surfaces of the connecting tubes, of residues of reagents or reaction products before it is used for the next photometric determination, for example on a other pollutant with another reagent, can be used without problems. For this purpose, with appropriate switching of the multi-way valve 15 via the control device 8 with the piston pump 1, liquid is sucked in through the suction hose 17 , pressed into the mixing container, sucked in again and then expelled. This flushing can also be repeated several times.

The larger the inner surface of the mixing container, the more disturbing impurities can remain on it and may have to be removed with multiple rinses. In the case of the storage container 21 , which is designed as a plastic bag, the inner surface is relatively large. After emptying, larger drops remain which have to be rinsed out. Also in the second cylinder 24 with the piston 25 , relatively large areas have to be flushed.

It is therefore advantageous to use a mixing container which is a very small inner one when emptied Surface. Such a vessel is based on the Drawing described.

On a hose 26 , a container 28 is connected via a flange 27 , which consists of an elastic material. This can be inflated by pushing in liquid, as the dashed line shows. After the liquid has been sucked off, the inner surface of this container goes back almost to zero, so that, under certain circumstances, a single rinse is completely sufficient or rinsing can be dispensed with entirely.

The container 28 can be used in particular as a mixing container, but also as a storage container.

If particularly interesting pollutants are detected when using the photometer shown, for example for monitoring a water body for pollutants, it may be advantageous to keep them for evidence. These are connected to the multi-way valve 15 via hoses 31 to 34 storage containers, not shown, which can be designed according to one of the Darge presented container types 21, 24 or 28 .

To store a sample in one of the connected storage containers, with appropriate reversal of the multi-way valve 15, liquid is first sucked in via the suction hose 17 by the piston pump 1 and then pressed into the appropriately selected storage container. The liquid sample can later be taken from this and analyzed in a laboratory.

Some interesting ones that occur in the water Pollutants, such as cyanides, is one longer storage not possible because of these substances by itself, for example under oxygen effect, decompose and later no longer detectable would be. Therefore, it is necessary to store the Add a fixative to the sample that is of interest makes it durable for storage.

For this purpose, storage containers for fixing agents (not shown) are to be connected to the multi-way valve 15 . Before the sample sucked in from the outside by the piston pump 1 is pressed into the storage container, the piston pump draws in fixing agent from the fixing agent storage container to the sample, and only then is the fixed sample pressed into the storage container. Here too, thorough mixing of the sample with the fixative is advantageous. In an intervening mixing step, the fixative / sample mixture can then be pressed by the piston pump 1 into one of the mentioned mixing containers, sucked back again and then pressed into the storage container, with the mixing possibly being carried out several times.

For the described photometric examination of A reagent must be added to the liquid the one with the substance to be detected is photometric evaluable staining reaction results. Certain reagents cien is difficult to store for a long time hig. Under certain circumstances, it may be advantageous to do so Reagents are better just before they are used to produce storable components by mixing len. The photometer con structure can be used.

For example, components are kept in the storage container 21 and a further container, not shown, which are sucked in by the piston pump 1 before the start of a series of measurements and, after mixing, are pressed into a third container, for example the container 28 . The finished reagent resulting from the components after mixing is then stored in this and withdrawn in batches for use. Here, too, it is advantageous to pump the reagents one or more times for better mixing, for example by pumping between the piston pump 1 and the cylinder 24 with its piston 25 .

For certain chemical reactions, it may be beneficial to add heat to improve the reaction. In order to make this possible, a heating device is provided in the hose 23 leading to the cylinder 24 , which consists of an electrical heating element 32 with a flow around it, via lines 33 from the control device 8 which supplies the sample to be mixed and mixed with reagent before the measurement warmed up. Such or similar heating device can also be provided in other places.

To determine some impurities to be detected, it may be necessary to chemically change the substances to be detected before they are determined. This can be done in a reaction column 29 in the tube between the multi-way valve 15 and a further additionally provided Mischbe container 30 is arranged, which is formed corresponding to the mixing container 24 in a simple manner.

In the example shown, the reaction column 29 is filled with granules which, in the required manner, have surface or volume activity and, for example, have catalytic or ion-exchanging properties. It can trigger or accelerate chemical reactions when mixing.

For example, such an arrangement ( 29, 30 ) can be used for determining nitrate, the nitrate being reduced to nitrite in one or more passes through the reaction column 29 , which is then determined photometrically.

Filter devices can also be provided in an advantageous manner. For example, the water / reagent mixture can be pumped from the multi-way valve 15 through a freely continuous hose 20 into a mixing container 22 , which in turn corresponds to the cylinder 24 in its structure, but can also be of the type of the container 21 or 28 . When suctioning from the mixing container 22 , however, suction is not carried out through the freely continuous hose 20 , but rather through a hose with filter 19 parallel to it. During the mixing in the mixing container 22, failed solids are retained and no longer interfere with the subsequent photometric determination.

Such an arrangement can be used, for example, for sulfate determination to be used to precipitate barium filter sulfate.

Claims (9)

1. Photometer for analyzing liquid media, with a cuvette for receiving the medium to be examined, which is designed as a piston pump with cylinder, cylinder head and pump piston, with a multi-way valve for connecting the cuvette designed as a piston pump with containers, a suction opening, an outlet opening and a mixing device with a mixing pump, with a control device for controlling the multi-way valve, the pump piston and the mixing device and with a light source and a photoelectric receiver, which are each arranged cuvette-axially on the cylinder head or on the pump piston, characterized in that the mixing device has a mixing container (storage container 21 , mixing container 22 , cylinder 24 , container 28 , mixing container 30 ) and that the control device ( 8 ) is designed to actuate the multi-way valve ( 15 ) and the pump piston ( 4 ) such that the piston pump ( 1 ) trained cuvette with the mixing container is bindable and that the pump piston, as a mixing pump, carries out at least one reciprocating movement for ejecting the medium from the cuvette designed as a piston pump into the mixing container and for sucking the medium out of the mixing container into the cuvette designed as a piston pump. 2. Photometer according to claim 1, characterized in that the mixing container is designed as a cylinder ( 24 ) with a free-running piston ( 25 ). 3. Photometer according to claim 1, characterized in that the mixing container is designed as a flexible bag (storage container 21 , container 28 ). 4. Photometer according to claim 3, characterized in that the sack consists of stretch-elastic material (container 28 ), the surface of which is as small as possible in the depressurized state. 5. Photometer according to one of the preceding claims, characterized in that for mixing a finished reagent from components, the piston pump ( 1 ) sucks the components from component containers and presses them into a ready-made reagent container after mixing. 6. Photometer according to one of the preceding Ansprü surface, characterized in that for the storage of fixed liquid samples, the piston pump ( 1 ) sucks in liquid, mixes with fixative from a fixative reservoir and presses it into a storage container. 7. Photometer according to one of the preceding claims, characterized in that the mixing device (hose 23 , cylinder 24 ) is provided with a heating device (heating element 32 ). 8. Photometer according to one of the preceding claims, characterized in that the mixing container ( 30 ) is provided with a reaction column ( 29 ). 9. Photometer according to one of the preceding claims, characterized in that the mixing device (hose 20 , mixing container 22 ) is provided with a filter device ( 19 ).