Ovens for analytical systems, titration systems, and titration methods

Abstract

The present invention relates to an oven (1, 1') for an analytical system, in particular for a titration system, in particular for a Karl Fischer titration system. The oven (1, 1') comprises a housing, a blocking system (2a, 2a', 2b, 2b', 2c, 2c') and an insert (3, 3') for a sample container. The blocking system (2a, 2a', 2b, 2b', 2c, 2c') is arranged at least partially around the insert (3, 3'). At least one heating element is arranged between the blocking system (2a, 2a', 2b, 2b', 2c, 2c') and the insert (3, 3') and at least partially surrounds the insert (3, 3'). The present invention also relates to a titration system and a titration method having such an oven (1, 1').

Description

[Technical Field]

[0001] The present invention relates to an oven for an analysis system, in particular for a titration system, a titration system comprising such an oven, and a titration method. [Background Art]

[0002] The use of ovens is known in the prior art, particularly in connection with titration systems, especially Karl Fischer titration. Ovens enable thermal sample preparation for samples that cannot be directly titrated. This may be the case, for example, when a sample is poorly soluble, when water cannot be released unless at high temperature, or when the sample reacts with Karl Fischer (KF) reagent. In the oven method, the sample is heated, and the released water is transferred to a titration cell using a dry carrier gas. Since only water comes into contact with the KF reagent, contamination of the electrode and the titration cell is avoided, and carry-over and memory effects that may distort the measurement result are eliminated.

[0003] Common ovens currently commercially available have the drawback of a relatively long waiting time until the set temperature is reached. A solid metal block heated by a heating cartridge reacts very slowly to temperature changes due to its heat capacity. Furthermore, heating the ovens currently in use requires a large amount of energy. Additionally, conventional ovens lack compactness.

[0004] European Patent Application Publication No. 3441757 describes an oven configuration for a Karl Fischer titration system. The oven configuration has a ventilation system for cooling the housing. A shut-off system prevents heat loss during the heating phase. [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] The object of the present invention is to overcome the shortcomings of the prior art. In particular, the object of the present invention is to provide an oven for an analytical system that enables rapid and effective sample heating with low energy consumption. Providing a compact oven is also an object of the present invention. Furthermore, the object of the present invention is to provide a titration system and titration method having such an oven. [Means for solving the problem]

[0006] The problem is solved by the independent claim. Specific embodiments can be found in the dependent claims.

[0007] A first aspect of the present invention relates to an oven for analytical systems, particularly for titration systems, and more particularly for Karl Fischer titration systems. The oven comprises a housing, a shut-off system, and an insert for a sample container. The shut-off system is at least partially positioned around the insert. At least one heating element is positioned between the shut-off system and the insert, at least partially surrounding the insert.

[0008] Preferably, at least one heating element is clamped to the insert by internal tension. A notch in the wall of the insert is also conceivable, in which at least one heating element is positioned or can be positioned.

[0009] Such an oven is characterized by the fact that at least one heating element can be brought particularly close to the sample, thus enabling particularly fast and effective heating of the sample. This also allows for a reduction in the energy required compared to known ovens.

[0010] The housing can be formed by the shielding system, or the shielding system can be further enclosed in the form of an outer shell. The shielding system may comprise two side half-shells and a base shield. However, it is also possible to design the side shields as a single unit. Preferably, the shielding material has a thermal conductivity of less than 0.5 W / (m*K). Therefore, the shielding system is preferably an insulating system. For example, the shielding material can be made of mineral microporous shielding material made of inorganic silicate material, such as shielding material WDS Ultra (e.g., manufactured by Morgan Advanced Materials PLC). The shielding material can also be coated with aluminum, for example, aluminum adhesive tape. Pyrogel is also possible.

[0011] At least one heating element may be a tubular cartridge. The tubular cartridge may have a thermocouple. Optionally, the thermocouple may be a separate temperature sensor or a temperature sensor integrated into the tubular cartridge.

[0012] The tubular cartridge can be arranged spirally around the insert. Preferably, in the case of a spiral tubular cartridge, only one tubular cartridge is used. The tubular cartridge can be wrapped around the insert for sample containers with volumes of 6 mL and 8 mL in 7 to 8 turns.

[0013] Tubular cartridges have the advantage of being readily available as standard products and easy to handle. Various designs of tubular cartridges are available, and custom-made tubular cartridges can also be easily produced. The helical configuration allows for optimal heating of the insert and brings it as close as possible to the sample.

[0014] However, it is also possible to position several heating cartridges vertically around the insert and supply them via a common connector. A heating mat or mikanite surface heating element can also be used. The heating element used should, among other things, be able to generate the temperature required for sample preparation and / or analysis. For example, heating mats are not very suitable for high temperatures around 300°C.

[0015] The insert preferably has an inner diameter of 16 mm to 31 mm, and particularly preferably 22 mm to 24 mm. Typically, an insert for a 6 mL sample container may have an inner diameter of 22.45 mm. An insert for an 8 mL sample container may have an inner diameter of, for example, 23.25 mm.

[0016] The insert has the advantage of being either perfectly fitted to or able to be fitted to the sample container. This allows for particularly efficient and rapid heating. The space between the insert and the sample container is minimized.

[0017] The oven may have an outer diameter of 60-62 mm, preferably 61 mm. Typically, vials, usually sealed with a septum, are used as sample containers.

[0018] Regardless of the vial size, the outer diameter remains advantageously constant. Adjustment to different vial sizes can be done, for example, by changing the wall thickness of the barrier.

[0019] The oven may have an external height of 50-90 mm, preferably 51-88 mm, and particularly preferably 55-56 mm, and an internal insert height in the range of 28-60 mm, preferably 33 mm.

[0020] The oven is characterized by its particularly compact design. Its small installation space allows it to be placed almost anywhere, and it can even be retrofitted to existing systems. It is also possible to use two ovens per analytical instrument.

[0021] The size of the oven relative to the size of a standard vial can have, for example, the following oven dimensions.

[0022] [Table 1]

[0023] The insert can preferably be made of a thermally conductive material having a thermal conductivity higher than 10 W / (m·K).

[0024] The thermally conductive material can be, for example, brass, silver, aluminum (up to 250°C), stainless steel, carbon-filled PEEK or ceramic. Brass is particularly preferred. Stainless steel is particularly interesting in terms of its chemical resistance. This list is not exhaustive. In principle, all materials having a suitable thermal conductivity are conceivable.

[0025] A material with high thermal conductivity enables particularly efficient heating of the sample. The insert can be provided with a temperature sensor. Preferably, the temperature sensor is attached to or incorporated into the wall of the insert. The wall of the insert can be made very thin, and can have a wall thickness of 1 mm to 3 mm, preferably 2 mm to 2.5 mm, and most preferably 2.3 mm. Accordingly, the sensor fits straight into the wall, enabling the most accurate measurement possible, without being distorted by excessive wall thickness. However, as mentioned above, it is also possible for the temperature sensor to be an integral part of the tubular cartridge.

[0026] On the one hand, the thin wall thickness of the insert reduces the amount of material required, and on the other hand, the temperature inside the insert can be determined quickly and accurately.

[0027] Advantageously, the oven may comprise a temperature protection switch, which may preferably be arranged below the insert. However, other positions of the switch are also conceivable. Due to the available space, positioning below the insert is preferred.

[0028] The temperature protection switch prevents overheating of the sample and / or the system and thus ensures reliable long-term operation.

[0029] A further aspect of the present invention relates to a titration system, in particular a Karl Fischer titration system. The titration system comprises at least one oven as described above.

[0030] However, the titration system is not limited to Karl Fischer titration, and may be any volumetric or coulometric titration system.

[0031] For high sample throughput, it is also possible to equip the titration system with two ovens as described above.

[0032] Preferably, the titration system also has a sample exchanger and comprises at least one first transfer system for transferring samples from a sample rack to the at least one oven. The transfer system may for example be an automatic lift system, or a gripper arm or an arm of a sample robot.

[0033] The sample exchanger allows handling of several samples in one continuous operation. Advantageously, the titration system may further comprise at least a second transfer system for transferring samples from the oven to the titration cell.

[0034] For example, the at least second transfer system may comprise a double hollow needle having an inlet needle and an outlet needle, a carrier gas stream, and a heated transfer tube. The sample is preferably located in a sample container within the oven, for example in a vial sealed with a septum.

[0035] Such a transfer system allows only the gaseous components of the sample to be transferred to the titration cell, preventing side reactions between other components of the sample and the titration reagent.

[0036] The system can be automated at least partially, and preferably fully automated.

[0037] Systems that are at least partially automated feature a continuous, and therefore high-speed, operating mode. This allows for faster analysis of samples. Furthermore, the operating procedure can be better controlled, resulting in improved reproducibility and accuracy.

[0038] A third aspect of the present invention relates to a titration method, preferably the Karl Fischer titration method. This method is - To provide the titration system described above, - To provide samples, - Heating the sample in the oven described above, -Titration of the sample and Includes.

[0039] The water content of the sample is preferably determined using a titration method. In detail, this procedure can be carried out as follows: The sample or substance to be analyzed is weighed into a vial, sealed, and positioned in the oven in this manner. The sample can be heated in the oven so that, for example, water can be released. A needle, preferably a double-hollow needle, penetrates the septum of the vial or container, and a carrier gas stream, such as air or an inert gas, passes through the heated sample. The carrier gas carrying the released water flows through the exhaust needle into the titration cell via a heated transfer tube. In the titration cell, the concentration of water can be quantified by coulometric or volumetric titration.

[0040] This ensures that only water enters the titration cell, thus avoiding side reactions between other substances in the sample and the titration reagent. It is understood that this method is not limited to the quantitative determination of water, but can, in principle, be applied to any heatable sample.

[0041] The present invention is described in more detail below using exemplary embodiments. These exemplary embodiments should not be understood as limiting. They illustrate the following: [Brief explanation of the drawing]

[0042] [Figure 1] This figure shows an oven according to the present invention, which has a lateral barrier. [Figure 2] This figure shows the oven according to the present invention, which does not have lateral barriers. [Figure 3] This figure shows an alternative embodiment of the oven according to the present invention having two cable outlets. [Figure 4] This figure shows the oven according to the present invention, which does not have lateral barriers. [Modes for carrying out the invention]

[0043] Figure 1 shows a perspective view of an oven 1 according to the present invention. The oven 1 comprises a shutoff system consisting of two side half-shells 2a and 2b and a bottom shutoff 2c. In this embodiment, the shutoff system forms the housing of the oven 1. The shutoff half-shells 2a and 2b surround an insert 3. The insert 3 has an inspection opening 5 for checking the temperature. The insert is surrounded by a tubular cartridge (not shown). Connection lines 4 of the tubular cartridge extend to the sides of the shutoffs 2a and 2b. Connection lines 6 for a temperature sensor and two connection lines 7 for a temperature protection switch extend from the base shutoff 2c.

[0044] Figure 2 shows the oven 1 according to the present invention of Figure 1, without a shutoff system. In addition to the insert 3 and connecting lines 4, 6, and 7, a tubular cartridge 8 can also be seen here. The tubular cartridge 8 is spirally wound around the insert with 8 turns. The temperature protection switch 9 is located below the insert 3, and the temperature sensor 10 is located below the tubular cartridge 8.

[0045] Figure 3 shows an alternative embodiment of oven 1' according to the present invention. Oven 1' has two cable outlets A and B. Both cable outlet A and cable outlet B have connection lines 7' and 7'' for a temperature protection switch (9' in Figure 4). A connection line 6' for a temperature sensor is provided at cable outlet B. Other elements are essentially identical to those in Figure 1.

[0046] Figure 4 shows the oven 1' according to the present invention of Figure 3, without a barrier. The essential elements are identical to those of Figure 2. The main difference between Figure 4 and Figure 2 is that the two connection lines 7' and 7'' for the temperature protection sensor are physically separated from each other.

Claims

1. An oven (1, 1') for an analytical system for a titration system, comprising a housing, a shut-off system (2a, 2a', 2b, 2b', 2c, 2c'), and an insert (3, 3') for a sample container, wherein the shut-off system (2a, 2a', 2b, 2b', 2c, 2c') is at least partially positioned around the insert (3, 3'), wherein at least one heating element is positioned between the shut-off system (2a, 2a', 2b, 2b', 2c, 2c') and the wall of the insert (3, 3'), at least partially surrounding the insert (3, 3'), and the at least one heating element is a tubular cartridge (8, 8') positioned or can be positioned within a notch in the wall of the insert.

2. The oven (1, 1') according to claim 1, wherein the tubular cartridge (8, 8') is arranged spirally around the insert (3, 3').

3. The oven (1, 1') according to claim 1, wherein the insert (3, 3') has an inner diameter of 16 mm to 31 mm.

4. The oven (1, 1') according to claim 1, wherein the oven (1, 1') has an outer diameter of 60 to 62 mm.

5. The oven (1, 1') according to claim 1, wherein the oven (1, 1') has an external height of 50 to 90 mm and an internal height in the range of 28 to 66 mm.

6. The oven (1, 1') according to claim 1, wherein the insert (3, 3') is made of a thermally conductive material having a thermal conductivity higher than 10 W / (mK).

7. The oven (1, 1') according to claim 1, wherein the insert (3, 3') has a wall thickness of 1 to 3 mm.

8. The oven (1, 1') according to claim 1, wherein the insert (3, 3') is equipped with a temperature sensor (10, 10').

9. The oven (1, 1') according to claim 1, wherein the oven (1, 1') has a temperature protection switch (9, 9') which is located below the insert (3, 3').

10. A titration system comprising at least one oven (1, 1') according to any one of claims 1 to 9.

11. The titration system according to claim 10, further comprising a sample changer and at least a first transfer system for transferring a sample from a sample rack to the at least one oven (1, 1').

12. The titration system according to claim 10, wherein the titration system comprises at least a second transfer system for transferring a sample from the oven (1, 1') to the titration cell.

13. The titration system according to claim 10, wherein the titration system is at least partially automated.

14. Titration method, - To provide the titration system described in claim 10, - To provide samples, - Heating the sample in the oven (1, 1') described in claim 1, - Titration of the above sample and A titration method, including

15. A titration method according to claim 14 for quantifying the water content of a sample.

Images