DE19909228A1 - Process for boiling liquid samples down to a residual volume comprises feeding the results from a sensor for determining the position of the liquid level in a vaporizing vessel to a controller - Google Patents

Abstract

Process for boiling liquid samples down to a residual volume comprises feeding the results from a sensor for determining the position of the liquid level in a vaporizing vessel to a controller so that the vaporizing parameters control the course of the vaporizing process. An Independent claim is also included for a device for carrying out the boiling down process comprising a control device to which the measured results from a sensor (10a) are fed to control the course of vaporization. Preferred Features: The vaporizing vessel is inserted into a tempering bath (2), the vessel and bath being heated by an infra-red radiation device. The sensor is an optical sensor.

Description

The invention relates to a method for evaporating Liquid samples to a determinable residual volume at which with at least one sensor the position of the liquid spike Gel is detected in an evaporation vessel and also before directions for performing this procedure.

Rotary evaporators are already known in the art to determine the remaining volume one of two inside each other dissolved substances can be used. The solution is  in a flask that rotates in a heating bath. While a heating phase, the solvent evaporates and becomes recovered via a downstream cold trap. The in Remaining amount of the dissolved substance in the evaporator vessel is determined by visual observation.

However, this way of working is not only time-consuming and expensive of course, but required because of the visual on Beo Great experience based decision. Yet the results remain relatively inaccurate.

Furthermore, it is already known to use a heated nitrogen flow through the solution in a flask send. This is done by optical or acoustic signals Reaching the desired residual volume of the solution is displayed.

Great experience is also required with this process to choose the right temperature individually and the Speed of the respective evaporation process put.

The inventor has set himself the task of a method specify with which an objective detection of the course of the Evaporation process and its control is possible and furthermore those suitable for carrying out the method To develop devices.  

This is achieved according to the invention in that the or the measurement results of the sensor or sensors to one Control device to be forwarded in accordance with that the evaporation parameters of the respective liquid level interdependently the evaporation process control process.

Because during the entire evaporation process by the or the sensors the respective liquid level in the ver steaming vessel is monitored and by the control device Signals is transmitted and the evaporation parameters, such as Pressure, temperature etc. interdependent Control evaporation process, it is possible that the Ver vaporization process runs optimally objectively.

In the subclaims there are some measuring techniques as examples techniques specified in which sensors are preferably used for loading the respective position of the liquid level during the evaporation process and to control the Control device can be used.

For a preferred implementation of the method for Narrowing the sample materials and determining the The remaining volume of one component is the ver steaming liquid sample into the evaporation vessel fills and placed in a heating bath. The liquid sample can be taken all at once or continuously Evaporation vessel are supplied. The temperature of the  Heating bath will be according to the signals of the rule direction set while the evaporation vessel around his Longitudinal central axis with a controllable rotation speed speed is rotated until it reaches the selected residual volume is indicated by a display device shows.

The evaporation flask is preferably vacuumed device connected to have the possibility of ver suck off steaming solvents and by changing the Pressure in the evaporation flask the boiling point of the solution by means of changing. Depending on this, the is also required Liche temperature of the heating bath determined and accordingly changed.

This changes the parameters, for example pressure, tempe temperature and speed of rotation are always carried out by Signals emitted by the control device, the in turn from the measurement data generated by the sensors is controlled.

This self-regulating residual volume determination is objek tiv, it leads to reproducibility with any repetition results and the evaporation process takes place optimized according to the respective test specifications.  

Preferred training for the implementation of the he Appropriate and preferred method according to the invention directions for determining the remaining volume result from the dependent claims and from the description of a number of experimental arrangements based on the drawing.

Show here

Figs. 1 to 6 in a schematic illustration of the method steps Ver humor in Restmengenbe using a light barrier as the sensor for the speed erforder union experimental parameters such as pressure, temperature and Rotationsgeschwin,

FIG. 6a is a block diagram for the control of the evaporation process,

Figure 7 is a schematic diagram of direction. An auxiliary device for filling up to a defined volume of liquid using another light beam sensor as a display and Regelein,

Fig. 8 to 12, a modification of the measuring apparatus according to Fig. 1 to 6 by using a plurality of light barriers,

FIG. 11a is a block diagram for the control by a plurality of light barriers,

Fig. 12 to 16, a measurement technique using a resistor as a sensor for the control of the evaporation process,

FIG. 16a is a block diagram for the control by means of a resistance sensor,

Fig. 17 to 21 a measurement technique using the conductivity of a non-electrolyte,

FIG. 21a is a block diagram for the control when using the conductivity technique for non-electrolyte,

Fig. 22 to 26 a measurement technique using gas ionization spark discharge measurement,

FIG. 26a is a block diagram for the control when using the Gasisonisations-Funkenent charge,

Fig. 27 to 30 a measuring technique using a balance,

FIG. 30a is a block diagram for the control using a scale as a sensor,

Fig. 31 to 34, a measurement technique using the induction voltage measurement,

FIG. 34a is a block diagram for the control with the use of induced currents, and

Fig. 35 to 37 a measurement technique for the control using a collecting vessel.

Corresponding components of the device are in the Figures marked with matching reference numerals.

A vessel 1 , the interior of which is filled with a heatable liquid speed 2 , is connected to a controllable heater (not shown). In the liquid bath 2 there is an evaporation flask 4 , which continues at its lower end in a cylindrical or pear-shaped taper in a continuation 3 . The piston 4 is rotatable about its vertically extending central axis, the rotation of the evaporation piston 4 being changed by a motor 102 controlled by a speed controller 102 a.

In the top sealable evaporation flask 4 protrudes a feed line 5 for the liquid sample 6 to be evaporated, also a pipe socket 7 for suctioning off the remaining amount in the extension 3 after completion of the Verdampfungsvor ganges and a rinsing line 8 (see Fig. 7) for the leadership a pure solvent used to completely rinse out the remaining amount. The air in the evaporating flask 4 as well as formed during the evaporation process solution are aspirated vapors through a vacuum hose 9 and the pressure regulated in the piston. The output of the pump 103 connected to the vacuum hose 9 can be regulated via a pressure regulator 103 a. A light barrier 10 a, b as a sensor is located outside the vessel 1 for the heating bath 2 , namely at the height of the pear-shaped extension 3 of the evaporation flask 4 , that is to say at a height which the liquid level of the remaining amount should take after the evaporation process has ended. The sensor in the form of a light barrier is formed by a light emitting diode 10 a and an opposing receiver diode 10 b.

The arrangement of the light barrier 10 a, b is fen getrof so that the receiver diode 10 b no light of the light emitting diode 10a receives when the liquid level in the Ver dampfungskolben 4 is located below the light barrier. As soon as the liquid level rises above the level of the light barrier 10 a, b, the beam emitted by the light emitting diode 10 a is deflected in the filling medium in such a way that it reaches the receiver diode 10 b. Further details of this measurement technology are explained in German patent application 198 51 158.2.

However, it is up to the subject's discretion whether they stick to conventional lighting technology and that Filling criterion with a different arrangement of the light barrier, e.g. B. with a central radiation of the evaporation flask wants to determine.

The following are those in the course of the evaporation process continuous process steps explained, with the Measurement technology according to German patent application 198 51 258.2 Reference is made.

Process stage 1

The evaporation flask 4 is empty or the volume of the liquid 6 to be evaporated is still below the light barrier 10 a, b. The receiver diode 10 b registers no light, so there are no signals to a speed controller 102 a, which in turn is connected to the control device 100 . This also does not send any signals to the thermoregulator 105 a of the heater 105 for the heating bath 2 .

During the inflow of the liquid from the reservoir 110 , controlled by the valve 110 a, that is to say during the filling process, there is 4 atmospheric pressure and room temperature in the evaporation flask. The piston stops (see Fig. 1).

Process stage 2

As soon as the liquid level in the evaporation flask exceeds the level of the light barrier 10 a, b, the receiver diode 10 registers light and signals the speed controller 102 a when the engine 102 starts to work. In the control device 100 , this causes the pressure to be reduced in accordance with the rotational speed. Furthermore, the control device 100 causes the heating to start, the temperature of the heating bath 2 is increased. Evaporation of the solvent begins at a now increased temperature and a reduced temperature.

Through the supply line 5, sample liquid continuously drips into the evaporation flask 4 . As a result of the force generated by the rotation of the centrifugal evaporation piston 4 to form a liquid layer 11 on the inner wall of the evaporation piston 4 and an air cone 12 (see Fig. 3).

Process stage 3

The filling process is complete. The light barrier 10 a, b continues to register light pulses that reach the speed controller 102 a. The speed is continuously increased and the other parameters are changed accordingly until finally the liquid film lying against the inner wall tears off the liquid 6 located in the pear-shaped extension 3 of the evaporation flask 4 and the light barrier 10 a, b no longer receives any light pulses. (State 0).

The evaporated solvent is still sucked off through line 9 . The concentration of the desired liquid component increases.

Process level 4

Now the speed is gradually reduced again until the liquid 11 which has risen on the inner wall of the evaporation flask 4 migrates downward and again combines with the amount of liquid 6 located in the pear-shaped extension 3 . The light barrier 10 a, b receives light pulses again (state 1 ) (see FIG. 5). This increases the speed again until state 0 of the light barrier is reached again (pendulum process). An increase in speed leads to an increase in temperature and a decrease in pressure. Lowering the speed causes the temperature to decrease and the pressure to increase.

Process stage 5

As a result, the above-described interplay is repeated until it is finally indicated by the light barrier 10 a, b that it can last for a long time, that is, despite the constant reduction in speed, e.g. B. continuously for at least 10 seconds, no light starts. For the test subject, this means that the evaporation process is complete. There is only a residual amount of liquid in the pear-shaped extension 3 , which takes up the predetermined volume (see FIG. 6).

As soon as the desired final volume of the solution is reached, the evaporation flask is vented, the heater 105 and the rotation of the flask 4 are switched off.

The control process described above is shown in FIG. 6a in the form of a block diagram. Signals from the light barrier 10 a, b are fed to the speed controller 102 , which in turn provides pulses to the motor 102 which causes the evaporation vessel 3 , 4 to rotate and sends it to the control device 100 . The control device 100 sends pulses depending on the speed to the pressure regulator 103 , which lowers the pressure in the evaporation vessel. Furthermore, depending on the speed, a temperature value is passed on to the thermoregulator 105 , which switches the heater 105 for the heating bath 2 in order to increase the temperature in the evaporation vessel 3 , 4 .

The residual amount 6 obtained is then, as shown in Fig. 7, sucked by means of the suction conduit 7 from the birnenför-shaped projection 3 of the evaporation piston 4, and transferred by means of a movable by a robot arm 14 needle with needle loop 15 a in a sample vial 16 . About the rinsing line 8 , the inside of the Verdampfungskol ben 4 is rinsed out with a pure solvent, which is passed together with the remaining concentrated components still in the flask into the sample bottle 16 .

The content of the sample bottle 16 is additionally filled with pure solvent to a desired final volume. Reaching this final volume is determined using the same light barrier technology using the light barrier 17 a, b.

In Figs. 8 to 11 show a further measuring device and the effect of the course is shown schematically during the evaporation process.

In the present example, the Verdampfungskol ben 3 , 4 is not in a heating bath, but is immediately z. B. heated with the aid of microwaves or the like. A dry air stream is introduced into the evaporation flask, which absorbs the evaporated solvent and carries it with it. The evaporation flask is rotated at a constant, relatively low speed to prevent delay in boiling.

On the outside of the evaporation flask 3 , 4 , a plurality of light barriers 18 a, b _{(1... N)} are arranged vertically one above the other at intervals. When the liquid level drops, the receiver diodes of the light barriers 18 a, b located above the liquid level receive light from the transmitter diode. They signal the control device 100 that the evaporation process should continue at a controlled, corresponding speed until finally the lowermost light barrier 18 a, b _n likewise sends out signals and thus indicates to the control device that the desired residual volume has been reached.

All light barriers 18 a, b _{(1... N) are} periodically, z. B. every 5 seconds. Depending on how many light barriers register light, the control device 100 controls a thermoregulator 105 a, which causes the heater 105 to increase or decrease the temperature by predefined degree steps and signals the compressed air reservoir 106 to increase or, if necessary, reduce the air supply .

When filling, the number of light barriers 18 a, b _{(1... N)} registering the light decreases. The temperature and air supply are increased according to this number. Maximum temperature and air supply is achieved when no more light barriers receive light. During evaporation, the number of light barriers 18 a, b ₍₁ ... _{N ')} receiving light increases again, the temperature and air supply are reduced in accordance with this number.

It can be seen from FIGS. 8 to 11 which of the light barriers 18 a, b ₍₁ ... _N) receive no light pulses due to the light passing through the solvent. Fig. 11 shows the final state of the evaporation process. The light from the transmitter diode 18 a passes through the solvent-free evaporation flask 3 , 4 and reaches the receiver diode 18 b. As soon as the control device 100 receives light pulses from the lowermost light barrier 18 a, b _{n for} longer than about 10 seconds, it switches off all test parameters. There is only the remaining amount in the Verdampfungskol ben 3 , 4th The trial is over.

A block diagram 11 a corresponding to FIG. 6 a shows the process of controlling the evaporation process when using several light barriers 18 a, b ₍₁ ... _N) and a directly heated evaporation flask 3 , 4 , the dry air from a compressed air reservoir 106 in a controlled manner Inflow (through flow controller 106 a) is supplied. The motor 102 rotates the evaporation vessel 3 , 4 at a constant low speed in order to avoid a delay in boiling.

The light barriers 18 a, b located above the liquid level in the evaporation vessel 3 , 4 signal the control device 100 to allow the air flow from the compressed air reservoir 106 to rise by predetermined steps. Furthermore, the control device 100 controls the thermo controller 105 a, which causes the temperature of the heating bath to increase. The control device 100 is programmed so that it continuously z. B. in 5 seconds the state of the light barriers 18 a, b ₍₁ ... _{N) is} queried. The signals sent by the control device 100 to the compressed air reservoir 106 and the thermal controller 105 a are dependent on the position or the number of light barriers 18 a, b emitting the light pulses ₍₁ ... _N) . This means that an individually controlled evaporation process is possible. Once the control device 100 is longer than 5 seconds, e.g. B. after 10 seconds, continuously supplied from all light barriers 18 a, b ₍₁ ... _N) pulses, it switches off the control parameters of the experiment and the experiment is ended.

For the determination of the passage of a liquid spittle gels by a measuring device with optical sensors also the difference in the material properties of air and solvents are used. When the Liquid level through the level of the measuring device the optical conditions such as refraction and Re change  inflections in the measurement plane. This also changes the Radiation intensity of ge from a transmitter to the receiver longing light. The signal level dependent on this controls the control device, which in turn controls the experimental pa parameters such as pressure, temperature, rotational speed etc. controls accordingly. The working principle is essentially correct Lichen with the working methods described above agree and can be according to the technique described above be performed.

The following are selected for meniscus determination suitable sensors are described.

In Figs. 12 to 16, the determination of the liquid level is shown schematically an adjustable in its height resistance sensor in use:
Designed as a resistor 19 end of a resistance sensor 19 a in a circuit 20 plunges into the evaporation piston 3 , 4 . Resistor 19 heats up in air at a predetermined current continuity indicated in ammeter 21 ( FIG. 13). As soon as the resistor 19 is immersed in the solution, it cools down, the resistance value drops, the display of the ammeter 21 increases ( FIG. 12a).

The current is first determined with a resistor 19 in air ( FIG. 12). The resistor 19 is initially in the air. As soon as the resistance is immersed in the liquid during the filling process, the display of the ammeter 21 rises and signals the adjusting device 108 to move upwards until the resistance sensor 19 a is no longer in contact with the solution. (Fig. 12a, Fig. 13) The adjusting device 108 is connected to the position sensor 108 a signal the control device to initiate the transition Verdampfungsvor and to regulate the pressure and temperature values, depending on its position. As soon as the liquid level drops below the end of the resistance sensor 19 a, its resistance value rises to the initial value, the display of the ammeter drops ( Fig. 13). During the process, the adjusting device 108 causes the resistance sensor 19 a to move up and down again in the region of the liquid level. The ammeter in turn controls the adjusting device 108 and this controls the course of the evaporation process. Finally, the resistance sensor 19 a drove down to an end point that corresponds to the liquid level of the desired residual volume. See Fig. 16. The resistance value increases to its initial value. The programming has been carried out in such a way that the control device 100 switches off the evaporation process, provided the resistance value does not change for 10 seconds.

From the block diagram 16 a, the control sequence of the evaporation process can be seen when using the resistance sensor 19 a.

The resistance sensor 19 a determines the current level (0.1) which can be determined in the ammeter 21 . The respective display 0 or 1 controls the actuating device 108 , which in turn changes the position of the resistance sensor 19 a. The position sensor 108 a of the actuating device 108 gives the control device 100 a position-dependent signal with which the pressure regulator 103 a and the thermal regulator 105 a are controlled.

The motor 102 also causes a constant low order of rotation of the evaporation vessel 3 , 4 to prevent a delay in boiling and thus any incorrect displays of the resistance sensor 19 a.

Alternatively, a resistance sensor with a negative Temperature coefficient can be used. With this contradiction level sensor, the resistance drops with increasing temperature decreases and increases with falling resistance temperature. The The control device is then controlled accordingly.

Thermal conductivity sensors in the form of smaller ones are also known sealed thermistors with negative temperature coefficient  efficient. These thermistors are at temperatures of heated to approx. 200 ° C. Due to the better heat conduction of the The thermistor cools down during the transition Air / liquid, causing its electrical resistance increases. The use of these thermistors to control the Evaporation process takes place according to the above in Relation to the resistance sensors with negative Temperature coefficient described procedure.

Can also be used as control signals for the actuating device Current signals are used to measure the conductivity of the An increased or show the decrease in conductivity. Advance The setting here is that the solution to be determined is electrically conductive and there is no elec suffers trolytic decomposition. In the latter case, that is You would have to deal with salts, acids and bases with small ones Electrodes in the respective measuring plane in the glass wall of the piston have melted in.

In Figs. 17 to 21, the measurement principle using the conductivity measuring technique is tert erläu case of non-electrolytes.

If the electrodes are immersed in the solution, they flow in the ampere meters of current, the electrodes are in the air,  that is, no current flows above the liquid level. To continuously control the evaporation process To be able to carry out is also an adjusting device provided, which serves to relative the height of the electrodes to be able to change to the liquid level.

In Fig. 17 there is a conductivity sensor 22 with the electrodes 22 a, b in contact with the solution in the evaporation flask 3 , 4 . An ammeter 21 detects the respective current level (0.1) and controls the adjusting device 108 for the evaporation process. In the state of FIG. 17, the electrodes 22 a, b are in contact with the solution. The ammeter 21 registers a high conductivity, a high current flows (state ( 1 )).

In Fig. 18 the liquid level has dropped so far that the electrodes are outside the solution. The contact between the electrodes 22 a, b is broken, no current flows. The actuating device 108 signals the electrodes 22 a, b to lower until the ammeter 21 again indicates current and thus signals contact with the liquid.

This process is repeated until the end point, namely the desired residual volume of the liquid, is finally reached. Here the contact between the electrodes 22 a, 22 b breaks off. The actuator 108 remains in its end position. The evaporation process is stopped.

The block diagram 21 a, which corresponds essentially to the diagram in FIG. 17 a, shows that the electrodes 22 a, b serving as conductivity sensors 22 alternatively supply current or no current to the measuring device 21 , which states (1,0) displays and thus controls the actuator 108 . The position sensor 108 a of the control device 108 controls the control device 100 and this in turn depending on the position of the control device 108, the pressure regulator 103 a and the thermal controller 105 a. The conductive speed sensor 22 is always oscillated via the adjusting device 108 in the region of the level of the liquid in the evaporation vessel 3 , 4 . If the ammeter 21 is longer than 5 seconds, e.g. B. does not display a current value for 10 seconds, this means that the adjusting device 108 has reached its lowest point. The control device 100 is shown the end of the evaporation process so that it switches off the test parameters.

As a further possibility for determining the liquid level, the person skilled in the art knows the measuring technique using the gas ionization spark discharge between two electrodes. (See Fig. 22-26).

The electrodes 23 a, b, which are adjustable in the height of the measuring plane, are connected to a high voltage generator 109 . As long as the two electrodes 23 a, b are immersed in the liquid in the evaporation flask 3 , 4 , no current flows because the solution acts as an insulator. As soon as the liquid level drops, the electrodes 23 a, b are free, there is a gas discharge in the gas space, provided the voltage of the generator 109 is selected high enough. The pulse to be determined on the measuring device 21 serves as a control signal for an actuating device 108 , which causes the electrodes 23 a, b to be lowered again until they are immersed in the solution. When the electrodes 23 a, b are immersed in the solution, the control device 100 controls the evaporation parameters, such as temperature and pressure. When a gas discharge occurs, the electrodes 23 a, b are sufficiently adjusted via the actuating device 108 until the gas discharge is interrupted again. According to the position of the adjusting device 108 , the evaporation parameters are changed via the control device 100 to the desired residual volume. When the state shown in Fig. 26 is reached, that is, the evaporation has progressed until the desired residual volume has been reached. The adjusting device 108 has moved the electrodes 23 a, b down to its lowest position, in which the electrodes 23 a, b are outside the solution. Your end position has been reached. The control device 100 switches off the parameters required for the evaporation and ends the activity of the actuating device 108 . The circuit required for this method can be seen in FIG. 26a.

Weighing technology serves as a further working principle for a continuous determination of the liquid level with the evaporation process controlled thereby via the control device. (See Figs. 27 through 30). The evaporation vessel 34 is located on a scale 24 . The continuous decrease in weight during the evaporation process, ie the display values of the scale 24 serve as a control for the control device 100 . When the weight corresponding to the residual volume is reached, the evaporation process ends. With this method, however, it is necessary that the specific weight of the residual liquid is known. The block diagram 30 a shows the required for the controllable evaporation process circuit.

The continuous determination of the liquid level in each case can also be carried out by means of an induction voltage measurement. See Figs. 31 through 34.

Around the evaporation vessel 3 , 4 , several mutually independent induction coils 26 a, b, c,. . . n arranged with corresponding voltmeters 28 a, b, c. . . n are connected.

A magnetized object floats on the surface of the liquid, e.g. B. a magnetic ball 27th If the liquid level drops, the magnetic lines of force of the magnetic table 27 sinking with the liquid level cut the conductor windings of the induction coils 26 a, b, c,. . . n and generate an induction current in the corresponding coil, the level of which by means of the voltmeter 28 a, b, c assigned to this coil. . . n is registered with the display states 0.1 and is used to control the control device 100 . According to the respective position of the liquid level shown in FIGS. 31 to 34, the various voltmeters 28 a or 28 b or 28 c or 28 d indicate the voltage state 0 or 1, which serves as a control signal for the control device 100 . This control is carried out until the liquid has reached the desired residual volume. FIG. 34a shows the measurement arrangement described in the form of a block diagram.

Ultrasonic sensors can also be used to determine the Liquid level can be used. It is namely knows that sound waves with frequencies <20 kHz are in gases and liquids spread differently and as a result of changing acoustic impedance (product of acoustic velocity density and density of the medium) are reflected at interfaces become.  

In the echo method, the reflection is caused by an in Located at the measuring level, serving as transmitter and receiver Transducer causes, the latter indicates whether there is in the Liquid or gas level is located.

The measuring techniques described above could also be carried out in connection with a collecting vessel for the distillate. As shown in FIGS. 35 to 37, a connecting line 29 for the vapors leads from the evaporation vessel 3 , 4 via a cooler 30 into a distillate collecting vessel 31 . The filling process in the collecting vessel 31 can be followed using the same measurement techniques as in the evaporation vessel. The liquid level in the collecting vessel 31 is determined and is used to control the evaporation process. A corresponding transfer of the techniques described above is within the skill of one of ordinary skill in the art.

Fig. 35 shows the start of evaporation. In Fig. 37, the end point of evaporation is reproduced. In the evaporation vessel 3 , 4 there is only the desired residual volume.

In the device shown in FIGS . 1 to 6, the evaporation vessel 3 , 4 was placed in a temperature-controlled bath. It is of course also possible to heat the evaporation vessel and / or the bath by means of controllable infrared radiation or using controllable microwave technology instead of the controllable temperature of the bath.

The Re suitable for controlling the evaporation process Gel devices can both electrical and elec tronic type and are any specialist in the field known in measurement technology.

According to what has been said, it should be possible for any specialist measurement techniques for limit values not mentioned here mood between liquid and gas to control a Control device through which the course of the evaporation pre ganges is determined to use. These equivalent means therefore also form the subject of this application.

Claims (43)

1. Method for evaporating liquid samples to a determinable residual volume, in which the position of the liquid level in a vaporization vessel is detected with at least one sensor, characterized in that the measurement result or measurements of the sensor or sensors are forwarded to a control device in such a way that control the evaporation parameters in dependence on the dependence of the respective liquid level on the course of the evaporation process. 2. The method according to claim 1, characterized indicates that an optical sensor- Technology is used. 3. The method according to claim 1 or 2, characterized ge indicates that one or more light barriers are used. 4. The method according to claim 1, characterized records that as a sensor resistance measurement technology is used.   5. The method according to claim 1, characterized records that as a sensor conductivity measurement technology is used. 6. The method according to claim 1, characterized records that used as a sensor weighing technology becomes. 7. The method according to claim 1, characterized records that as a sensor magnetically generated In production current is used. 8. The method according to claim 1, characterized records that the evaporation course with the help is controlled by ultrasonic measurement. 9. The method according to claim 2, characterized records gas ionization spark discharge tech nik is used. 10. The method according to claim 1, characterized records that to control the evaporation pre gangs thermal conductivity measurement is used.   11. The method according to any one of the preceding claims, since characterized by that for Control of the evaporation process the evaporation vessel is used in a temperature-controlled bath. 12. The method according to any one of the preceding claims, since characterized by that the ver the course of the vaporization is controlled by means of an infrared heater. 13. The method according to any one of the preceding claims, since characterized by that the ver control the vaporization with the help of microwave technology is heard. 14. The method according to any one of the preceding claims characterized by that for Control of the evaporation process the evaporation vessel is connected to a vacuum device. 15. The method according to any one of the preceding claims, since characterized by that for Control of the evaporation course of a gas, preferably a dried gas into the evaporation vessel is leading.   16. The method according to any one of the preceding claims characterized by that Gas is at a variably elevated temperature. 17. The method according to any one of the preceding claims characterized by that a Control device of electrical or electronic type is used. 18. The method according to any one of the preceding claims characterized by that the ver vaporizer rotates during the evaporation process becomes. 19. The method according to any one of the preceding claims characterized by that the Control of the evaporation process already during the Filling process begins. 20. The method according to any one of the preceding claims characterized by that after Er range of the selected residual volume in the evaporation vessel the remaining liquid and possibly one then rinsed into the evaporation vessel  aspirated liquid from the evaporation vessel and in a second sample container is transferred that the added as much pure solvent to the second sample container leads until a predeterminable volume of liquid is reached in the second sample container and that the Reaching the target volume in the second sample container is displayed by means of a second light barrier. 21. Device for carrying out the method according to one of the preceding claims 1 to 19 with a vaporization vessel in which the liquid to be evaporated is located, the liquid level of which can be determined by means of one or more sensors, characterized in that a control device ( 100 ) is provided is the measurement results of the sensor or sensors ( 10 a, b; 18 a,... n); 19 a; 22 a, b; 23 a, b; 24 ; 27 ; 26 a, b, c. . . n; 108 a are supplied to control the evaporation process. 22. The apparatus according to claim 21, characterized in that the control device ( 100 ) is of an electrical or electronic type. 23. The apparatus of claim 21 or 22, characterized in that the control device ( 100 ) is controllable as a function of the position of a Stellvor direction ( 108 ). 24. Device according to one of claims 21 to 23, as by in that the adjusting device (108) (a 108) to summarizes a position sensor, which supplies in dependence on the position of the liquid level signals to the control device. 25. The device according to claim 23 or 24, characterized in that as sensors one or more at a distance one above the other vaporization vessel ( 3 , 4 ) and / or a collecting vessel ( 31 ) for the vaporized liquid (distillate) arranged light barriers ( 10 a, b, 18 a, b _{(1... N) are} provided. 26. Device according to one of claims 23 to 24, characterized in that an electrical resistance ( 19 ) in the evaporation vessel ( 3 , 4 ) and / or in the collecting vessel ( 31 ) for the distillate is provided as a sensor for the liquid level. 27. Device according to one of claims 23 to 26, characterized in that two electrodes ( 22 a, b) in the evaporation vessel ( 3 , 4 ) and / or in the collecting vessel ( 31 ) are provided for the distillate as a sensor for the position of the liquid level are. 28. Device according to one of claims 23 to 27, characterized in that two electrodes ( 23 a, b) are provided in the evaporation vessel ( 3 , 4 ) and / or in the collecting vessel ( 31 ) for the distillate to determine the liquid level, connected to a high voltage generator ( 109 ). 29. The device according to any one of claims 23 to 28, characterized in that thermistors are used as sensors, the thermal conductivity signals of which an actuating device ( 108 ) for the thermistors and / or the control device ( 100 ) control. 30. Device according to one of claims 23 to 29, characterized in that the evaporation vessel ( 3 , 4 ) and / or the collecting vessel ( 32 ) for the distillate are on a balance ( 24 ) and are continuously weighed during the evaporation process, the measurement results being used to control the control device ( 100 ). 31. The device according to one of claims 23 to 30, characterized in that current loops ( 26 a, b, c... N) run around the evaporation and / or collecting vessel ( 3 , 4 , 31 ) to determine the liquid level and the induction currents are generated by a floating on the liquid magnetized object ( 27 ). 32. Device according to one of claims 23 to 31, characterized in that the evaporation vessel is inserted into a temperature-controlled bath ( 2 ). 33. Device according to claim 32, characterized in that a controllable infrared radiator is used to heat the bath ( 2 ) and / or the evaporation vessel ( 3 , 4 ). 34. Device according to claim 32, characterized in that a controllable microwave is used to heat the bath ( 2 ) and / or the evaporation vessel ( 3 , 4 ). 35. Apparatus according to claim 32, characterized in that a controllable resistance heater is provided for heating the bath ( 2 ). 36. Device according to one of claims 23 to 35, characterized in that the evaporation vessel is connected to a controllable vacuum device ( 9 ). 37. Device according to one of claims 23 to 35, there characterized by that the ver vaporization vessel during the evaporation process with controllable number of revolutions. 38. Device according to one of claims 23 to 35, characterized in that the axis of rotation of the evaporation vessel runs vertically and coincides with the longitudinal central axis of the evaporation vessel ( 3 , 4 ). 39. Device according to one of claims 23 to 38, characterized in that the interior of the evaporation vessel ( 4 ) tapers at its end opposite the filling opening in a cylindrical or pear-shaped extension ( 3 ). 40. Device according to one of claims 23 to 39, characterized in that at least one sensor ( 10 a, b) is arranged in the attachment area of the extension ( 3 ) of the evaporation vessel. 41. Device according to one of claims 23 to 40, characterized in that a suction line ( 7 ) extends into the extension ( 3 ) of the evaporation vessel ( 4 ), which leads to a collecting vessel ( 13 ), from which the Extension ( 3 ) aspirated concentrate and a rinsing solution, which may be subsequently filled into the flask and also aspirated, can be filled into a further sample container ( 16 ) which is located between a further light barrier ( 17 a, b) for determining the fill level. 42. Device according to one of claims 23 to 41, characterized in that a first feed line ( 5 ) is provided for the liquid to be evaporated ( 6 ). 43. Device according to one of claims 23 to 42, characterized in that the Ver vaporization vessel ( 4 ) with a second supply line ( 8 ) for the detergent can be connected.