JPS6257067B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for introducing a sample into an analytical device, particularly a mass spectrometer (MS), and the device thereof. By quickly vaporizing the liquid sample, effectively concentrating the vaporized substance, and continuously introducing it into an analysis device such as an MS, it is easy to introduce the liquid sample into the analysis device. The present invention relates to a method and apparatus that significantly expands the range of compounds that can be measured by mass spectrometry using MS, etc.

Analyzers, such as mass spectrometers (MS), collect ions onto one or more fixed ion-collecting electrodes and measure the ion current by continuously adjusting the accelerating voltage and magnetic field strength. This device is designed to obtain a mass spectrum using the obtained mass spectrum, and is widely used for the qualitative and quantitative determination of gases, as well as liquids and solid molecules that can be converted into gases. In recent years, such MS
Attempts have also been made to use them in combination with other separation and analysis instruments for effective analysis of mixtures.

For example, liquid chromatography (LC), particularly high-performance liquid chromatography (HLC), which has been attracting attention in recent years, is capable of separating fat-soluble and water-soluble substances into their respective components without modification by selecting the solvent and column. It has been recognized that this method is an excellent means for separating each component in a mixture and conducting its quantitative analysis. However, it takes
Although HLC is excellent in its ability to separate a mixture into its components, it has a problem in that it has a weak ability to identify the separated components. On the other hand, a mass spectrometer (MS) can identify a single component with extremely high sensitivity and high performance, but in the case of a mixture, the spectrum becomes complex, making identification difficult. Therefore, an LC-MS analysis system that combines LC and MS has been proposed in an attempt to effectively utilize the advantages of these two devices and compensate for their disadvantages.

On the other hand, analysis by MS is performed by ionizing a gaseous sample, which causes various problems when the sample is in a liquid or solution state with another solvent. In other words, in the case of a liquid sample in a liquid or solution state, it is necessary to vaporize it and guide it to the ionization section (ion source) of the MS. It is difficult to vaporize the sample and introduce it to the ionization part, and this is particularly difficult when the sample is a compound with high polarity or large molecular weight. In addition, the LC-MS analysis system described above has the same problem as above because the effluent from the LC separation column is a liquid (liquid sample), and it is continuously supplied. The practical application of this LC-MS analysis method is hampered by the fact that it is not easy to continuously remove the solvent (mobile phase) from the effluent, and therefore no effective means of concentrating the target components in the effluent has been found. This is a major hindrance.

Therefore, various studies have been conducted on methods for introducing such liquid samples into MS, and in particular, the so-called interface, the coupling mechanism between LC and MS in LC-MS analysis systems, is a key point in development. Although many studies have been conducted, there are still 2,
Only three research reports have been made.

Therefore, all of the interfaces proposed to date for coupling LC and MS have complicated mechanisms, require complicated operations, and are extremely expensive devices. There are many inherent problems, and the requirements for a practical device have not yet been fully satisfied. The fact that a practical device for such an interface has not been developed also means that a general method for introducing liquid samples into MS and its device have not yet been developed. Therefore, in order to establish the practical application of LC-MS analysis methods, it is an urgent issue to consider methods for introducing liquid samples into MS. There is a strong desire to develop a device that has high performance and is even cheaper.

Here, under such circumstances, the applicant of this application has previously filed Japanese Patent Application No. 52-108162 and Japanese Patent Application No. 53-
No. 111130 (Special Publication No. 58-3592), we proposed an effective method and device for introducing liquid samples into MS, but this method still cannot fully meet the conventional demands, especially when it comes to direct LC-MS connection. In order to achieve widespread use of the system, it is necessary to develop a method that can more effectively and quickly vaporize a liquid sample, concentrate the target components, and continuously introduce them into the MS. It became clear. Therefore, as a result of further studies following the previous application, the present inventors effectively atomized the liquid sample to be analyzed using a clever atomization method using ultrasonic waves. Immediately after heating, vaporizing, and concentrating by applying the gas jet method.
By introducing the liquid sample into the MS, it is possible to introduce the liquid sample into the MS more effectively.
The present invention was achieved based on the discovery that MS provides excellent advantages such as the ability to easily analyze compounds that have been considered difficult to analyze. In addition, the inventors have discovered that such a sample introduction method can be advantageously applied not only to MS but also to analytical instruments such as emission spectrometers and atomic absorption spectrometers.

That is, the main object of the present invention is to provide a novel method for introducing a liquid sample into an analytical device such as an MS, and a device for the same.

The purpose of the present invention is to easily vaporize many of the compounds that are difficult to vaporize and introduce into a specified analysis device due to their high polarity or large molecular weight, and to conduct a specified analysis. The object of the present invention is to provide a method and a device that enable continuous and stable introduction of a liquid sample into an analyzer.

Another object of the present invention is to combine LC, especially HLC.
The aim is to provide a completely new interface mechanism that directly connects MS, thereby making it possible to put LC-MS analysis into practical use.

Furthermore, another object of the present invention is to facilitate efficient vaporization of a liquid sample by effectively atomizing the liquid sample by employing an atomization method that skillfully utilizes ultrasonic vibrations; We have developed a high-performance sample introduction device that is simple in structure, easy to operate, and allows for the concentration of liquid samples, which was previously considered difficult, as well as continuous introduction into analysis equipment such as MS. This is what we provide.

Other objects of the present invention will become apparent from the following detailed description of the present invention and the drawings showing examples.

In order to achieve the above object, the present invention provides (a) introducing a liquid sample into a first nozzle section which is vibrated by ultrasonic waves, and atomizing the liquid sample by the ultrasonic vibrations; (b) jetting the at least partially gasified sample together with a separately introduced working gas; a step of spouting it from a second nozzle part into a concentration chamber maintained under reduced pressure;
(c) At least a part of the solvent component in the gasified sample is removed together with the working gas in the concentration chamber, and the concentrated sample gas is guided to a predetermined analysis device. This is a characteristic feature. In addition, for atomization by such ultrasonic vibration, it is particularly attached to the ultrasonic vibration means to amplify the vibration amplitude of the ultrasonic vibration means, and a first nozzle portion is provided at the tip thereof. The present invention is equipped with an atomizing means that atomizes the liquid sample guided by the amplified ultrasonic vibration, thereby stably and effectively atomizing the liquid sample. This was done so that it could be done quickly.

According to the present invention as described above, the liquid sample guided to the first nozzle part is heated by ultrasonic vibration.
Since the atmosphere is atomized into a fine mist at the opening at the tip of the nozzle, it is in a state where it can be vaporized extremely easily.Therefore, polar compounds and compounds with large molecular weight, etc. Even organic compounds that are difficult to analyze using mass spectroscopy can now be efficiently gasified and detected and identified using analytical equipment such as MS. In addition, at least a part of the fine atomized material formed by the atmosphere of the liquid sample is gasified by the applied heat, and then, together with a separately introduced working gas (dilution gas), it is removed under reduced pressure. By being ejected as a jet stream from the second nozzle part into the maintained concentrating chamber, light working gas components with small molecular weights and gasified solvent components move to the outside of the jet stream and are then released under reduced pressure. On the other hand, solute components with large molecular weights (sample components) are drawn into the jet jet without changing the jet direction much even when subjected to the evacuation action in the concentration chamber. Since the gaseous sample is present in the center of the jet stream, the gasified sample can be effectively introduced into the analyzer with an increased concentration of solute components from the introducing means into the analyzer such as MS that opens toward the jet stream. It is. In the present invention, the liquid sample only needs to be atomized by ultrasonic vibration or jetted out as a jet stream, so the operation is extremely easy and the structure is also extremely simple. As a result, the manufacturing cost of the device can be significantly reduced.

Hereinafter, the method and apparatus of the present invention will be explained in more detail based on the embodiments shown in the drawings.

FIG. 1 is a sectional view of a device (interface) according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of amplification of an ultrasonic vibration portion in the device. In these figures, 1 is a well-known ordinary cylindrical ultrasonic transducer with an oscillator in the center, which generates approximately 20KHz by electrical input through a connected electrical tangent 2. It is made to vibrate at a predetermined frequency within a range of approximately several MHz. At one end of this vibrator 1, a conical cone 3 consisting of a conical portion 3a and a cylindrical portion 3b having an annular flange 3c is attached to the cylindrical portion 3.
They are screwed together at the b end and are integrated. Then, this integrated vibrator 1 and conical cone 3
are provided with a through hole 4 passing through their axes, and a tube 6 for guiding the effluent E flowing out from the LC column 5 is inserted through the through hole 4.
The effluent E from the column 5 is guided to the conical part 3a of the conical cone 3 as a first nozzle, and is exposed to an ultrasonic atmosphere at the tip. It's starting to get foggy.

On the other hand, the cylinder body 8 having the conical part 8a with the second nozzle part 7 screwed onto its tip is connected to the inner cylinder 31 of the position adjustment mechanism 30 via the annular connecting member 9 at the cylinder body part 8b. By screwing and connecting them, the continuous hollow interior thereof becomes a passage 10 for a working gas to be introduced separately.
A working gas (helium gas; He is used here) is continuously supplied to the working gas passage 10 from a working gas source (not shown) through a needle 12 that passes through a plug 11 fitted to the end of the inner cylinder 31.
It is beginning to be introduced within the country.

In the working gas passage 10 space,
As shown in FIG. 2, the integrally coupled vibrator 1 and conical horn 3 are connected to the end of the annular connecting member 9 at only one location of the annular flange 3c provided at the vibration amplitude node. It is positioned by being supported via an O-ring 13 between the inner annular protrusion 8c of the main body portion 8b, and the ultrasonic vibrating vibrator 1 and the conical horn 3 are attached to a portion other than the flange 3c. The cylinder body 8 and the inner cylinder 31
It is designed not to come in contact with. Note that an appropriate number of working gas holes 3d are provided in the annular flange 3c of the conical horn 3.
The working gas passage 10 is not blocked by the attachment. Further, the tip of the conical portion 3a of the conical cone 3 faces the second nozzle portion 7 from inside at a predetermined distance, and the second nozzle portion 7 is located on the axis of the conical cone 3. Spout hole 7a
Further, an auxiliary heater 14 is provided outside the tip portion of the conical cone 3 to which the second nozzle portion 7 is screwed.

In addition, the space around the cylinder 8 and the cylinder 8
A cylindrical member 15 is arranged to surround the space in front of the second nozzle portion 7 at the tip, and a concentration chamber 16 is formed. This concentration chamber 16 is connected to a rotary pump (or oil diffusion pump) 17 that is a vacuum pump, and the inside of the concentration chamber 16 is maintained at a predetermined degree of reduced pressure (degree of vacuum) by the exhaust operation of the rotary pump 17. It is becoming possible to do so. Further, the tip of the cylindrical member 15 enters into the body 18 of the MS and is attached to a component 20 of the ionization chamber 19. A conical member 21 whose top is positioned opposite to the second nozzle section 7 is provided at the entrance of the ionization chamber 19, and a conical member 21 is provided at the entrance of the ionization chamber 19. Insert the sample into the sample inlet 21a at the top.
It is designed to be guided into the ionization chamber 19 through the ionization chamber 19. Moreover, the cylindrical member 1 around the second nozzle part 7
The main heater 22 is built into the 5 part, and it directly connects the concentration chamber 16 space and the second nozzle 7 part where the jet is ejected, and indirectly connects the first nozzle 3a part and the space in front of it. Then, the sample particles are heated to evaporate and gasify the atomized sample particles, so that effective concentration can be carried out in the concentration chamber 16.

On the other hand, the position adjustment mechanism 30 includes an inner cylinder 31 and an outer cylinder 33 externally inserted into the inner cylinder 31 via a spring 32.
The inner cylinder 31 and the outer cylinder 33 are screwed together to move the inner cylinder 31 and the outer cylinder 33 relatively.
1 and the concentration chamber 16
A suitable number of annular flanges 15a are provided at the rear end of the cylindrical member 15 forming the outer cylinder 33 with a predetermined phase difference.
It has an adjustment screw 35 that comes into contact with the inclined surface of a. Then, the appropriate number of adjusting screws 35 come into contact with each other,
By extrusion, the position adjustment mechanism 30
The conical horn 3 and the vibrator 1 are supported via the connecting member 9 and the cylinder 8 which are further screwed into the inner cylinder 31, and these are supported by adjustment using the adjustment screw 35. By moving the member around its axis, the second nozzle part 7 (spout hole 7a)
It is possible to match the sensor at the top of the conical member 21 (the inlet 21a). In addition, the adjustment ring 34
Depending on the degree of screwing, the inner cylinder 31 will move to the right against the biasing force of the spring 32 (in FIG.
This allows the distance between the second nozzle section 7 and the top of the conical section 21 to be adjusted.

Therefore, in such a configuration, column 5 of the LC
The effluent E flowing out from the tube 6 is guided to the tip of the conical portion 3a of the conical cone 3 through the vibrator 1 and the center of the conical cone 3 through the tube 6, which is the flow path, and is subjected to ultrasonic vibration there. The liquid is atomized into a fine atomization. That is, as shown in FIG. 2, the vibrations of the ultrasonic transducer 1 are amplified by the conical horn 3, and the opening is positioned where the amplitude is greatest. The energy of the ultrasonic vibration acts to the maximum extent on the liquid sample supplied to the opening to effectively and continuously atomize it.

At least a portion of the atomized liquid sample is gasified by the heat applied directly or indirectly by the heaters 14, 22, etc., while being introduced into the working gas passage 10 through the needle 12. Gas He is at flange 3 of conical horn 3
The conical horn 3 passes through the through hole 3d provided in c.
It reaches the tip of the conical portion 3a and is ejected from the second nozzle portion 7 together with the gasified sample into the concentration chamber 16 maintained under reduced pressure as a jet stream. What is unique about this process is that, unlike conventional methods, ultrasonic vibration energy is used to atomize the liquid sample, which involves a large endothermic reaction. However, the generated mist can be effectively used to vaporize, and the decomposition of thermally unstable sample components due to excessive heating can be prevented. In addition, in the jet stream ejected from the second nozzle part 7 into the concentration chamber 16, light working gas components and gasified solvent components with small molecular weights are removed by the rotary pump 17.
Due to the suction and exhaust action of the gas, the ejecting direction deviates outward (moves to the outside of the ejected flow), while heavy solute components (sample components) with large molecular weights move toward the ejected flow without changing their ejecting direction much. Since the solute component exists in the center of the jet stream, the solute component is continuously introduced into the high vacuum ionization chamber 19 of the MS from the inlet 21a of the conical member 21 that opens toward the jet stream with an increased concentration of solute components. , is ionized. Furthermore, since this jet stream is also heated by the main heater 22, etc., and the concentration chamber 16 is maintained under reduced pressure, if there is ungasified atomized material, it is heated there. Gasification can also proceed, and the gasified sample can be effectively supplied to the ionization chamber 19. In addition, the gasified sample (with a high concentration of solvent components) and working gas that are not introduced into the ionization chamber 19 through the sample introduction port 21a are removed from the rotary pump 17.
However, since the conical member 21 is used here as the sample introduction means, there is no rebound of the jet jet, and therefore disturbance of the jet jet due to head wind can be prevented. ,
While the concentrated gasified sample can be effectively introduced, the sample gas and working gas that have left the opening 21a of the conical member 21 are exhausted by the rotary pump 17.

Thus, according to the invention, the liquid sample
By continuously subjecting the LC effluent to an ultrasonic atmosphere and concentrating the gasified product using the jet separator principle before introducing it into the MS, thermally unstable substances such as polar compounds can be removed. We were also able to continuously and effectively introduce sample components into the MS, thereby significantly increasing the effectiveness of direct coupling between MS and LC.

Further, in this embodiment, all of the effluent E flowing out from the column 5 is guided to the first nozzle part 3a by the tube 6, but of course an appropriate splitter may be provided. Therefore, it goes without saying that a portion of the effluent can be guided to the first nozzle section 3a. However, the feature of the present invention is that, unlike conventional interfaces, MS and LC (particularly HLC) can be directly connected as in this embodiment. Also, L.C.
Not only when the effluent from the
In general, a solution or liquid prepared for mass spectrometry can also be introduced as a sample into the MS according to the present invention, and in this case, it can be introduced into the first nozzle part 3a by pressurizing the pump. becomes. Further, as the working gas, in addition to the above-mentioned helium gas (He), any gas can be used as long as it does not adversely affect the mass spectrum measurement in MS, such as nitrogen, argon, methane, Examples include isobutane and ammonia.

Furthermore, the jet stream ejected from the second nozzle part 7 can collect the concentrated gasified sample more effectively.
In order to lead to MS, it is desirable that the hole diameter of the inlet 21a of the conical member 21 facing the nozzle part 7 is larger than that of the ejection hole 7a of the nozzle part 7, and furthermore, The distance between the top of the conical member 21 and the top of the conical member 21 is determined by considering the suction force of the rotary pump 17, the amount of gasified material formed, the amount of gasified material drawn into the MS, etc. In the case of approx.
1 Torr). Ionization of the vaporized liquid sample (eluate) in the MS is performed according to a known method. For example, when a large amount of solvent vapor is introduced, chemical ionization (chemical ionization) in which the solvent acts as a reactive gas is performed. On the other hand, when the amount of solvent vapor is small, the ordinary electron impact ionization method can be suitably applied.
Ionization method or field ionization method
An ionization method such as a ionization method may be applied.

Note that the present invention is not limited to these embodiments in any way, and various changes and improvements can be made based on the knowledge of those skilled in the art without departing from the spirit of the present invention. For example, the third
Figures ac show another embodiment of the present invention, which is a modification of the ultrasonic atomization mechanism shown in Figure 1. The major difference between the mechanism shown in FIGS. 3a to 3c and that in FIG. 1 lies in the shape of the atomizing means and the method of introducing the liquid sample into the first nozzle portion formed therein. That is, in the mechanism shown in FIG. 1, a conical horn 3 is used as the atomizing means, but here a stepped horn consisting of a large-diameter cylindrical portion 3'b and a small-diameter cylindrical portion 3'a following it is used. 3' is used, and the ultrasonic transducer 1 is placed at the end of the large diameter cylindrical part 3'b.
It is screwed on. And the stepped horn 3'
A conical member 8' is provided with a second nozzle portion 7' at the tip which forms a working gas passage 10' at a flange 3'c formed on the other side of the large diameter cylindrical portion 3'b. a and the cylindrical member 8'b. Further, as shown in FIG. 3b, the stepped horn 3' has a continuous large-diameter hole 4b and a small-diameter hole 4a in its central portion, corresponding to portions 3'b and 3'a, respectively. In addition, it has a small-diameter inclined hole 4c extending from the small-diameter hole 4a to the outer surface of the 3'b portion, and a tube 6 that guides the effluent from the column 5 (not shown) passes through the vibrator 1. It is inserted into the small diameter hole 4a from the inclined hole 4c, and the small diameter hole 4
It reaches the opening of a. Therefore, the effluent from the column is guided through the tube 6 to the small-diameter cylindrical portion 3'a of the stepped horn 3', which serves as the first nozzle section. Third
The amplification effect as shown in FIG. c is performed, and the effluent discharged from the opening of the tube 6 located at the tip opening corresponding to the abdomen where the vibration is maximum is effectively atomized. The liquid sample to be atomized (in this case, the effluent) is sent to the first nozzle section 3'a by an appropriate method, and amplification in the atomization means is carried out as is well known. , varies depending on the shape and material of the means (horn), and therefore, an appropriate amplification mechanism will be adopted depending on the purpose. Furthermore, horn 3,
3', cylinder bodies 8, 8'a, 8'b, second nozzle parts 7, 7', etc., may be made of stainless steel, brass, pure alumina, ceramic, etc. as appropriate. .

In addition, although the above example describes MS, the sample introduction method according to the present invention can also be used as an efficient atomized sample introduction method for other inorganic solutions, such as emission spectrometers and atomic absorption spectrometers. This method can be widely used as a method for introducing samples into various analytical devices.

As detailed above, the present invention is applicable to liquid samples in a liquid or solution state, particularly LC, especially HLC.
The effluent from the column is taken out as it is, or a part of it is taken out with a simple ordinary splitter, and this is effectively atomized using a clever atomization method using ultrasonic vibration, making it easy to vaporize. At the same time, it is concentrated using the principle of a jet separator, and this is continuously subjected to MS.
By directing the effluent from the LC (HLC) to a predetermined analysis section of the analyzer, such as the ionization section of the analyzer, it is possible to direct the effluent from the LC (HLC) to a predetermined analysis section of the analyzer, such as the ionization section of the analyzer. It is possible to continuously and stably measure a liquid sample using an analysis device such as an MS, and by providing the method and device of the present invention, the LC-MS analysis operation is particularly facilitated. In addition, it is now possible to concentrate liquid samples such as effluent, which was previously considered difficult, and it is also possible to concentrate compounds with low vapor pressure that are relatively difficult to vaporize, compounds with high polarity or large molecular weight, etc. aromatic amines, pharmaceutical ingredients,
The present invention is extremely significant in that it includes steroids, amino acids, oligopeptides, polyethylene glycols, etc., and enables the detection and identification of these compounds by mass spectroscopy. Furthermore, the device of the present invention has the advantages of high performance and extremely practical use.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a device (interface) according to an embodiment of the present invention, FIG. 2 is a vibration explanatory diagram of an ultrasonic vibration part in the device of FIG. 1, and FIGS. 3 a and b , c are a main part explanatory view corresponding to FIG. 1 of an atomizing mechanism portion according to another embodiment of the present invention, an enlarged cross-sectional view of a stepped cone, and a graph showing the degree of amplitude amplification thereof. 1: Ultrasonic vibrator, 3: Conical horn, 3': Stepped horn, 5: Column, 6: Tube, 7: Second nozzle section, 8: Cylindrical body, 10: Working gas passage, 1
4: Auxiliary heater, 15: Cylindrical member, 16: Concentration chamber, 17: Rotary pump, 18: MS body,
19: Ionization chamber, 21: Cone member, 22: Main heater, 30: Position adjustment mechanism.

Claims (1)

[Scope of Claims] 1. A liquid sample is introduced into a first nozzle part that is vibrated by ultrasonic waves, and the ultrasonic vibrations atomize the atomized sample particles. heating the sample to gasify at least a portion of the sample; and transferring the at least partially gasified sample to a concentrating chamber maintained under reduced pressure from a second nozzle section together with a separately introduced working gas as a jet jet. and a step of guiding the concentrated sample gas, which has been concentrated by removing at least a part of the solvent component in the gasified sample together with the working gas in the concentration chamber, to a predetermined analysis device. A method for introducing a sample into an analytical device, comprising: 2 The liquid sample guided to the first nozzle part,
2. The method according to claim 1, wherein the effluent is part or all of the effluent flowing out from a column of a liquid chromatography device, and the analysis device is a mass spectrometer. 3 ultrasonic vibration means that performs ultrasonic vibration at a predetermined frequency by electrical input; an atomizing means configured to atomize a liquid sample guided thereto by the amplified ultrasonic vibration, and fine sample particles atomized by the atomizing means. a heating means for heating directly or indirectly to gasify the sample; and a second nozzle section located in front of the first nozzle section, and separately preparing an atomized sample in which at least a portion of the sample is gasified. a jet jetting mechanism that jets the working gas from the second nozzle part as a jet jet together with the working gas supplied to the second nozzle part; a concentration chamber for increasing the solute component concentration by removing at least a part of the solvent component in the sample gasified together with the working gas by a jet jet ejected from a second nozzle part; and a gas formed in the concentration chamber. 1. An apparatus for introducing a sample into an analyzer, comprising an introduction means for guiding a concentrated sample of the chemical sample to a predetermined analyzer. 4. The atomizing means is a stepped horn or a conical horn, and a liquid sample supply hole is provided in the center of at least the tip portion of the atomizing means to form a first nozzle portion. equipment. 5. The jet ejection mechanism is constituted by a tubular body having a second nozzle portion at a conical tip, through which working gas flows, and is located within the working gas passage space of the tubular body. The ultrasonic vibration means and atomization means, which are integrally attached, are supported by the tubular body at one point of the vibration node of the atomization means, while the first nozzle of the atomization means Claim 3 or 4, wherein the part faces the second nozzle part within the pipe of the tubular body.
Apparatus described in section. 6. The introducing means is a conical member having a top positioned opposite to the second nozzle part, and the concentrate of the gasified sample is introduced into a predetermined analysis through a sample introduction port provided at the top. 4. A device according to claim 3, which is directed to the device. 7. The apparatus according to claim 3, wherein the heating means is a heater provided on a wall portion of the concentration chamber at least near the second nozzle portion. 8. The device according to claim 3 or 7, wherein a heater is provided in the first nozzle section or in the atomizing section in the vicinity thereof, as the heating means or as an auxiliary thereof.