WO2023061832A1 - Système d'introduction d'échantillons - Google Patents

Système d'introduction d'échantillons Download PDF

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Publication number
WO2023061832A1
WO2023061832A1 PCT/EP2022/077746 EP2022077746W WO2023061832A1 WO 2023061832 A1 WO2023061832 A1 WO 2023061832A1 EP 2022077746 W EP2022077746 W EP 2022077746W WO 2023061832 A1 WO2023061832 A1 WO 2023061832A1
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WO
WIPO (PCT)
Prior art keywords
sample
introduction system
sample introduction
nebulizer
ultrasonic
Prior art date
Application number
PCT/EP2022/077746
Other languages
English (en)
Inventor
Hans-Jürgen Schlüter
Ayrat MURTAZIN
Jan OSMERS
Original Assignee
Thermo Fisher Scientific (Bremen) Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB2114481.1A external-priority patent/GB2611576A/en
Priority claimed from GBGB2207593.1A external-priority patent/GB202207593D0/en
Application filed by Thermo Fisher Scientific (Bremen) Gmbh filed Critical Thermo Fisher Scientific (Bremen) Gmbh
Priority to DE212022000307.1U priority Critical patent/DE212022000307U1/de
Publication of WO2023061832A1 publication Critical patent/WO2023061832A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
    • H01J49/0431—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components for liquid samples
    • H01J49/0454—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components for liquid samples with means for vaporising using mechanical energy, e.g. by ultrasonic vibrations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G01N21/714—Sample nebulisers for flame burners or plasma burners

Definitions

  • the present invention relates to nebulization in spectroscopy, chemical analysis and physical analysis. More in particular, the present invention relates to a sample introduction system for an analytical apparatus, such as a spectrometer, and to a method of introducing a sample into an analytical apparatus, such as spectrometer.
  • a sample In spectrometry systems and many other types of analytical apparatus, a sample must be introduced into the analytical apparatus.
  • Various types of samples can be used, such as solid samples, liquid samples and gaseous samples. While many samples are liquid, several types of analytical apparatus require a gaseous input. That is, the sample must be contained in a gas stream which is introduced into the analytical apparatus.
  • Liquids may be introduced into an analytical apparatus by means of a gas stream if the liquid is nebulized, that is, if the liquid is provided as droplets which are small enough to be carried by the gas stream of a carrier gas.
  • nebulizers have been developed which serve to convert a flow of liquid into an aerosol, a stream of tiny droplets.
  • Such droplets may, for example, have a diameter between 1 and 100 pm.
  • nebulizer Several parameters of a nebulizer are important to determine its suitability for a particular application.
  • One of these parameters is the total amount of aerosol produced.
  • Another parameter is droplet size distribution (DSD), indicating how the droplet diameter is distributed around its mean value.
  • DSD droplet size distribution
  • Other important parameters are the stability of the total aerosol amount and droplet size distribution over time and the robustness of the target diameter and of the droplet size distribution when variations in the properties of the liquid sample occur.
  • robustness of the nebulizer that is, clogging of orifices should be rare or even non-existent.
  • the demand for small droplet sizes makes robustness difficult to achieve.
  • United States patent application US 2015/165466 Al discloses an example of an ultrasonic nebulizer including a piezoelectric element that vibrates responsive to a drive signal having an alternating voltage.
  • a nebulizing layer that may be a passive resonator is bonded to a first surface of the piezoelectric element and has an outer surface that transforms a liquid into a mist responsive to vibration of the piezoelectric element.
  • the surface of the passive resonator may be textured to guide the liquid flow.
  • sample introduction systems based upon ultrasonic nebulizers have several disadvantages, such as the need for a drained spray chamber, large dimensions, a high power consumption, the need for external cooling and a relatively high price.
  • alternative sample introduction systems have been proposed which have smaller dimensions and are more efficient and less expensive.
  • United States patent US 8 642 954 discloses a sample introduction system for an atomic spectrometer which utilizes a spray head including a vibrating mesh. Other techniques have also been proposed.
  • British patent GB 2 548 071 discloses a liquid sample introduction system for a plasma spectrometer.
  • the liquid sample introduction system comprises a sample container for a liquid sample, a surface acoustic wave (SAW) nebulizer, an electronic controller for supplying power to the SAW nebulizer so as to produce an acoustic wave on a surface of the nebulizer for generating an aerosol from the liquid, and an aerosol transport arrangement for receiving the aerosol and carrying it into a plasma or flame of a spectrometer.
  • the SAW nebulizer comprises a substrate with apertures and an electrode arrangement.
  • the invention seeks to overcome the above-mentioned and other disadvantages of sample introduction systems of the prior art. Accordingly, the invention provides a sample introduction system for an analytical apparatus, such as a spectrometer.
  • the sample introduction system may comprise: a sample inlet for receiving a sample to be nebulized, a nebulizer for nebulizing the sample, a gas inlet for receiving gas for transporting the nebulized sample, and a conduit for providing the nebulized sample to the spectrometer.
  • the nebulizer can comprise at least one transducer configured for providing an ultrasonic vibration and at least one ultrasonic horn for amplifying the ultrasonic vibration.
  • the nebulizer may be arranged for producing droplets having a diameter of less than approximately 20 pm.
  • the ultrasonic vibration may have a frequency of at least 60 kHz, preferably at least 100 kHz, more preferably at least 200 kHz.
  • a nebulizer arranged for providing an ultrasonic vibration By providing a nebulizer arranged for providing an ultrasonic vibration, the advantages of ultrasonic nebulizers are retained.
  • at least one ultrasonic horn configured for amplifying the ultrasonic vibration, further advantages are achieved.
  • the amplification due to the one or more ultrasonic horns allows a lower power consumption, a lower cost and an increased stability of the aerosol properties.
  • an ultrasonic horn allows to spatially separate the source or sources of the ultrasonic vibration and the nebulization zone or zones.
  • the sample introduction system of the invention may operate without ionization.
  • the invention allows a fine nebulization.
  • An even finer nebulization can be achieved using higher frequencies, for examples frequencies of at least 100 kHz, at least 200 kHz, at least 300 kHz, at least 400 kHz, at least 500 kHz, at least 600 kHz, at least 700 kHz or at least 800 kHz.
  • a frequency range of approximately 50 kHz of 60 kHz to approximately 5 MHz or even 10 MHz can be used, for example approximately 150 kHz to approximately 5 MHz, approximately 300 kHz to approximately 2 MHz, or approximately 800 kHz to approximately 2 MHz. This allows droplets to be formed having a diameter of less than approximately 10 pm, less than approximately 5 pm, less than approximately 3 pm, less than approximately 2 pm or even less than approximately 1 pm.
  • the nebulizer of the invention does not require a heater and does not use electrospray ionization.
  • the energy consumption of the nebulizer of the invention may be less than 5 W, even less than 1 W.
  • the nebulizer of the invention may comprise at least two ultrasonic horns. That is, the nebulizer may comprise two, three, four, five, six or more ultrasonic horns.
  • the at least two ultrasonic horns may be arranged in series. Additionally, or alternatively, the at least two ultrasonic horns may be arranged in parallel.
  • Providing two or more ultrasonic horns in series has the advantage of a greater amplification of the ultrasound.
  • Providing two or more ultrasonic horns in parallel has the advantage of spreading out the nebulization over multiple ultrasonic horns, which can result in a better control of the particle size.
  • the present invention also provides a nebulizer having ultrasonic horns both in series and in parallel.
  • An arrangement of four ultrasonic horns, for example, may consist of two parallel sets of each two ultrasonic horns in series.
  • United States patent US 6 669 103 discloses a device for atomizing a liquid for ultrasonic spray pyrolysis.
  • the prior art device includes cascaded ultrasonic horn stages.
  • ultrasonic spray pyrolysis is used for producing ultra-fine powders, for instance for thin film coating.
  • US 6 669 103 fails to disclose or suggest the use of ultrasonic horn stages in sample introduction systems for analytical apparatus.
  • each ultrasonic horn, or each series arrangement of ultrasonic horns could be provided with an individual transducer.
  • two or more parallel ultrasonic horns, or two or more parallel arrangements of ultrasonic horns may share a transducer.
  • at least two ultrasonic horns may have a single common transducer.
  • a single ultrasonic horn or each series arrangement of ultrasonic horns may be provided with more than one transducer, for example two, three, four, or more transducers.
  • At least some of the transducers may be piezo-electric transducers.
  • the ultrasonic vibration produced by at least some of the transducers may have a frequency between 50 kHz and 1 MHz, for example between 100 kHz and 500 kHz, although other frequencies are also possible, such as frequencies up to 1 MHz or above 1 MHz, for example 2 MHz, 5 MHz, 10 MHz or higher frequencies.
  • the frequency of the ultrasonic vibration may be between 50 kHz and 10 MHz, in particular between 100 kHz and 5 MHz, more in particular between 200 kHz and 5 MHz, still more in particular between 1 MHz and 5 MHz, although other ranges can also be envisaged.
  • the frequency may be fixed or variable.
  • the at least one ultrasonic horn may have a suitable cross-section, for example round, oval, square, hexagonal or octagonal. In some embodiments, the at least one ultrasonic horn may have a rectangular cross-section. The at least one ultrasonic horn may comprise a Fourier horn.
  • the at least one ultrasonic horn may comprise an end face or ultrasonic transfer surface for transferring the amplified ultrasonic vibration to the sample.
  • the sample introduction system may further comprise at least one feed tube for feeding the sample to the vicinity of at least one end face.
  • two or more feed tubes may be provided to feed the sample to one, two, three or more end faces of ultrasonic horns.
  • the at least one feed tube may extend at least partially through at least one ultrasonic horn of the nebulizer. Alternatively, or additionally, the at least one feed tube may extend around at least one ultrasonic horn of the nebulizer. An open end of the feed tube may be located adjacent the end face to allow direct transport of the sample from the open end of the feed tube to at least one end face of the ultrasonic horn.
  • an open end of a feed tube may be located spaced apart from the ultrasonic horn so as to allow surface transport of the sample from the open end of the feed tube to the end face of the corresponding ultrasonic horn over an exterior of the ultrasonic horn.
  • This surface transport can be made possible by capillary forces and/or other forces.
  • a channel and/or a pair of ridges may be provided to facilitate the surface transport of the sample from the open end to the end face over an exterior of the ultrasonic horn.
  • the nebulizer may for example be made using MEMS technology.
  • MEMS micro-electro-mechanical systems. This technology enables very small structures to be made to a high precision.
  • Suitable materials for making nebulizers using MEMS technology or another technology may for example be silicon, silicon nitrides, silicon carbides, other ceramics, silicon dioxides (quartz), aluminium oxides, polymers, metals (such as, but not limited to, aluminium and copper), PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxy alkanes).
  • the sample introduction system may be configured for receiving a liquid sample.
  • the sample introduction system may be configured for receiving a solid sample.
  • Solid samples may be dissolved in a liquid or suspended in a liquid.
  • Powders may also be dissolved in a liquid or suspended in a liquid. The size of solid particles suspended in a liquid is only limited by the internal diameter of the feed tube.
  • the conduit may comprise a spray chamber.
  • the conduit may be constituted by a pipe section or a similar tubular conduit.
  • the present invention also provides a nebulizer for use in a sample introduction system as described above, the nebulizer comprising at least one transducer configured for providing an ultrasonic vibration and at least one ultrasonic horn for amplifying the ultrasonic vibration.
  • the present invention further provides an analytical apparatus, such as a spectrometer or a gas chromatograph, comprising a sample introduction system as described above.
  • a spectrometer according to the present invention may further comprise at least one mass analyser, mass separation device or wavelength disperser and at least one detector unit.
  • a spectrometer according to the present invention may be an optical spectrometer or a mass spectrometer.
  • a spectrometer according to the present invention may further comprise a plasma source, such as a plasma torch.
  • the present invention further provides a sample introduction system for an analytical apparatus, comprising: a sample inlet for receiving a sample to be nebulized, a nebulizer for nebulizing the sample, a gas inlet for receiving gas for transporting the nebulized sample, and a conduit for providing the nebulized sample to the analytical apparatus.
  • the nebulizer can comprise at least one transducer configured for providing an ultrasonic vibration and at least one ultrasonic horn for amplifying the ultrasonic vibration.
  • the nebulizer may be arranged for producing droplets having a diameter of less than approximately 20 pm.
  • the ultrasonic vibration may have a frequency of at least 60 kHz.
  • Such a nebulizer may have small dimensions and may use a small amount of power, for example less than 5 W, or less than 3 W, or even less than 1 W.
  • the transducer may be a piezo-electric transducer, for example.
  • the present invention additionally provides a method of introducing a sample into an analytical apparatus, such as a spectrometer, the method comprising: receiving a sample to be nebulized, nebulizing the sample, receiving gas for transporting the nebulized sample, and providing the nebulized sample to the spectrometer, wherein nebulizing the sample comprises utilizing at least one transducer configured for providing an ultrasonic vibration and at least one ultrasonic horn for amplifying the ultrasonic vibration, wherein nebulizing the sample comprises producing droplets having a diameter of less than approximately 20 pm using an ultrasonic vibration having a frequency of at least 60 kHz.
  • nebulizing the sample may comprises utilizing at least two ultrasonic horns arranged in series.
  • nebulizing the sample may, in a method according to the present invention, comprise utilizing at least two ultrasonic horns arranged in parallel.
  • At least one ultrasonic horn may be a Fourier horn.
  • Fig. 1 schematically shows a first embodiment of an analytical apparatus in which a sample introduction system according to the present invention is used.
  • Fig. 2 schematically shows a second embodiment of an analytical apparatus in which a sample introduction system according to the present invention is used.
  • Fig. 3 schematically shows a third embodiment of an analytical apparatus comprising a sample introduction system according to the present invention.
  • Figs. 4A - 4C schematically shows a first, a second and a third embodiment of a nebulizer for a sample introduction system according to the present invention respectively.
  • Fig. 5 schematically shows a fourth embodiment of a nebulizer for a sample introduction system according to the present invention.
  • Fig. 6 schematically shows a fifth embodiment of a nebulizer for a sample introduction system according to the present invention.
  • Fig. 7 schematically shows a sixth embodiment of a nebulizer for a sample introduction system according to the present invention.
  • Fig. 8 schematically shows a seventh embodiment of a nebulizer for a sample introduction system according to the present invention.
  • Fig. 9 schematically shows an eighth embodiment of a nebulizer for a sample introduction system according to the present invention.
  • Fig. 10 schematically shows a nineth embodiment of a nebulizer for a sample introduction system according to the present invention.
  • Fig. 11 schematically shows a perspective view of the embodiment of Fig. 10.
  • Fig. 12 schematically shows various cross-sections of nebulizers for a sample introduction system according to the present invention.
  • Fig. 13 schematically shows the size of droplets as may be produced with a sample introduction system according to the present invention as a function of the frequency.
  • the present invention provides a sample introduction system for analytical apparatus, such as spectrometers.
  • a sample introduction system according to the invention may comprise a nebulizer having at least one transducer configured for providing an ultrasonic vibration.
  • a sample introduction system according to the invention may further comprise at least one ultrasonic horn for amplifying the ultrasonic vibration.
  • the invention allows nebulization droplets to be formed having a diameter of less than approximately 20 pm, less than approximately 10 pm, less than approximately 5 pm, less than approximately 2.5 pm or even less than approximately 1 pm. This will be further explained with reference to the drawings. Embodiments of the invention use no ionizing.
  • FIG. 1 An embodiment of an analytical apparatus comprising a sample introduction system according to the present invention is schematically shown in Fig. 1.
  • the analytical apparatus 100 of Fig. 1 comprises a sample introduction system 10 comprising a nebulizer unit 20 according to the invention, which will later be explained in more detail.
  • the sample introduction system of Fig. 1 is constituted by a sample introduction unit 10 configured for receiving a sample, such as a liquid sample, and converting this sample into an aerosol AS.
  • This aerosol may optionally be conditioned by desolvation, charging or atomization.
  • the aerosol is provided to a further unit, for example an analyzer unit 30, such as an analyzer unit of a mass spectrometer or of an elemental analyzer.
  • the analyzer unit 30 of this embodiment provides an analyte-specific physical output AO, such as light or ions, to the detector unit 50 of the analytical apparatus 100.
  • the detector unit 50 In response to the analyte-specific physical output AO of the analyzer unit 30, the detector unit 50 produces a detection signal DS which is supplied to the signal processing unit 60.
  • the processed detection signal DS results in an output signal OS, which may also be referred to as analytical signal and which describes the chemical and/or isotopic composition of the sample.
  • the analytical apparatus 100 of Fig. 2 also comprises a sample introduction system according to the invention.
  • the analytical apparatus 100 is an optical emission spectrometer.
  • the sample introduction system of Fig. 2 is constituted by a sample introduction unit 10 configured for receiving a sample, such as a liquid sample, and converting this sample into an aerosol AS.
  • This aerosol is provided to a plasma unit 40 for exciting the aerosol constituents.
  • the plasma unit 40 provides a physical output PO, such as light, to the analyzer unit 30.
  • the analyzed physical output AO is supplied to the detector unit 50 of the analytical apparatus 100.
  • the detector unit 50 In response to the physical output PO of the plasma unit 40, the detector unit 50 produces a detection signal DS which is supplied to the signal processing unit 60.
  • the processed detection signal DS results in an output signal OS which describes the chemical or isotopic composition of the sample.
  • the analyzer unit 30 may be absent.
  • the plasma unit 40 may be coupled to the detector unit 50 without an intermediate analyzer unit 30.
  • a desolvation unit may be used with an analytical apparatus comprising a plasma unit to decrease the solvent load of the plasma and thereby improve the sensibility and matrix robustness of the analysis.
  • Fig. 3 schematically shows an embodiment of an analytical apparatus in more detail.
  • the analytical apparatus 100 is shown to comprise a sample introduction unit 10 according to the invention.
  • the analytical apparatus 100 is shown to comprise a plasma unit or plasma chamber 40 and a detector unit 50.
  • a connection tube 15 connects the sample introduction system 10 to the plasma chamber 40, while an optical guide 49 connects the plasma chamber 40 to the detection unit 50.
  • the analytical apparatus 100 may comprise further components, such as a signal processing unit, which are not shown in Fig. 3 for the sake of clarity of the drawing.
  • An analyzer unit (30 in Figs. 1 & 2) may be arranged between the plasma chamber 40 and the detector unit 50.
  • the sample introduction system 10 of Fig. 3 is shown to comprise a sample introduction tube 11, a nebulizer 20 and a carrier gas introduction tube 12, as well as the connection tube 15 mentioned above.
  • the sample introduction tube 11 is, in the embodiment shown, configured for receiving a liquid sample to be nebulized and supplying the liquid sample to the nebulizer unit 20.
  • the carrier gas introduction tube 12 is configured for receiving a carrier gas CG, for example argon, for carrying the nebulized sample from the nebulizer unit 20 to the plasma chamber 40.
  • the introduction tube 12 is shown to be connected to the nebulizer unit 20 so as to feed carrier gas directly to the nebulizer. In this way, coaxial gas and liquid flows may be provided in some embodiments. In other embodiments, however, the carrier gas introduction tube 12 may be space apart from, and thus not be in contact with the nebulizer 20. Such embodiments may have a so- called cross flow geometry.
  • the nebulizer unit 20 comprises in accordance with the invention one or more transducers for producing ultrasound and one or more ultrasonic horns for amplifying the ultrasound, as will be further explained later with reference to Fig. 4.
  • the sample introduction unit 10 may additionally comprise a spray chamber arranged between the nebulizer unit 20 and the connection tube 15.
  • the plasma chamber 40 may be a plasma chamber according to the prior art.
  • An example of a suitable plasma chamber is disclosed in WO 2020/208085 (Thermo Fisher Scientific), the entire contents of which are herewith incorporated by reference in this document.
  • the plasma chamber 40 comprises a plasma torch 41, which in the embodiment of Fig. 3 is an inductively coupled plasma (ICP) torch.
  • This ICP torch comprises a coil 42 for inducing an alternating magnetic field to excite the gas and thus to generate a gas plasma 45.
  • the plasma may be generated using microwaves, at least one laser, DC electrical discharges, RF (radio frequency) electric discharges, and/or other techniques which may be known as such.
  • the connection tube 15 is arranged so as to direct the gas stream containing the aerosol to the plasma torch 41.
  • the aerosol that is, the nebulized sample contained in the gas stream entering the plasma chamber 40 is excited by the high temperature of the plasma 45 (in some applications approximately 8000 K) and will emit electromagnetic radiation, such as light.
  • At least part of the emitted light can be guided to the detector unit 50 by the optical guide 49, which may be constituted by a so-called periscope.
  • the optical guide 49 is shown here to be arranged along the axis of the plasma torch 42 (axial view), the optical guide 49 or a further optical guide (not shown) may alternatively, or additionally, be arranged perpendicularly to the plasma torch 41 (radial view).
  • the optical guide 49 transmits light from the plasma chamber 40 to the detector unit 50, which in this embodiment is an optical detector unit.
  • the detector unit 50 may comprise one or more detector arrays, for example CCD (charge coupled device) detector arrays, for detecting the emitted light and converting the detected light into one or more digital images.
  • CCD charge coupled device
  • the nebulizer unit 20 comprises at least one transducer for generating a high- frequency vibration of at least one surface of the nebulizer.
  • the nebulizer unit 20 further comprises, in accordance with the invention, at least one acoustic horn for amplifying the high-frequency vibration.
  • Such nebulizer units will further be explained with reference to Figs. 4 - 10.
  • FIG. 4A An exemplary embodiment of a nebulizer unit 20 for use in a sample introduction system of an analytical apparatus is schematically shown in the cross-sectional view of Fig. 4A.
  • the embodiment of Fig. 4A comprises a nebulizer housing 21 in which a horn section 24 is accommodated.
  • the horn section 24 is provided with an end face 25 having a reduced crosssection.
  • a transducer 22 is shown to be arranged in the housing 21, in the embodiment shown against a back wall of the horn section 24 of the nebulizer unit 20.
  • a feed tube 23 passes through the back wall of the nebulizer housing 21, through the transducer 22 and the horn section 24 so as to provide a liquid sample at the end face 25.
  • the open end 29 of the feed tube 23 is arranged axially with respect to the longitudinal axis of the horn section 24, and also with respect to the feed direction of the aerosol AS.
  • the open end 29 is shown in Fig. 4A to extend beyond the end face 25 and also beyond the nebulizer housing 21.
  • the sample S will be nebulized outside of the nebulizer unit 20.
  • the open end 29 of the feed tube 23 may be located in the same plane as the end face 25 of the horn section 24.
  • the feed tube 23 may be connected to the sample introduction tube 10 shown in Fig. 2.
  • the nebulizer housing 21 may be omitted.
  • the nebulizer is provided with at least one aperture in the back wall of the nebulizer housing 21 through which the feed tube 23 passes and may be provided with further apertures for feeding through electrical leads towards the transducer 22. However, these apertures are typically closed off by the parts they are provided for.
  • the horn section 24 may be made of silicon or a silicon dioxide compound, for example.
  • the electrical leads can be used to supply a suitable excitation signal to the transducer 22.
  • the frequency of the ultrasonic vibration produced by the transducer may be controllable by the excitation signal.
  • a transducer having a variable frequency may be used.
  • the voltage of the excitation signal may be controlled, for example, or its frequency, or both.
  • the nebulizer unit 20 comprises at least one ultrasonic horn.
  • the horn section 24 tapers towards its end face 25, having sides 26 which slope over at least part of their length, thus decreasing the diameter of the horn section 24 towards the end face 25.
  • the sloping sides thus define a tapered section 27, while the transducer is located at a base section 28 having substantially parallel side walls in the embodiment shown. This may also be the case in embodiments with a curved cross-section, where the transition from slanting side walls to parallel side walls, or from a conical cross-section to a cylindrical cross-section, is not defined by a clear transition.
  • An ultrasonic horn is also known as acoustic horn or acoustic waveguide and its shape serves to amplify the ultrasonic vibrations. Due to the amplification, the nebulizing process is more effective and more droplets may be obtained while requiring less energy to produce the droplets.
  • the ultrasonic horn is provided by the tapering of the side walls 26, resulting in a reduced crosssection towards the end face 25.
  • the horn section 24 need only be tapered in one dimension. That is, in a dimension perpendicular to the drawing, the cross-section may be constant over the length of the horn section 24. Alternatively, the cross-section of the horn section 24 may also be tapered in a second dimension.
  • a constant cross-section is preferably rectangular, for example square, but may also be round, oval, or polygonal (for example hexagonal or octagonal), as will later be explained with reference to Fig. 12.
  • a conical horn section 24 can be envisaged.
  • the feed tube 23 extends over the entire length of the nebulizer 20 and passes through its interior. In other embodiments, the feed tube 23 may pass around instead of through the horn section 24, as will later be explained with reference to Fig. 5.
  • the horn section 24 of Fig. 4A can be solid. If the horn section 24 is hollow, as illustrated in Fig. 4B, the feed tube 23 may extend over only part of the length of the nebulizer 20, for example almost exclusively through the transducer 22, as shown in Fig. 4B. Thus, the sample S may be transported through the interior of the horn section 24, in which case the end face 25 should be at least partially open.
  • the feed tube 23 passes around the horn section 24.
  • the opening 29 of the feed tube 23 is not located at the end face 25 but spaced apart from the end face 25.
  • the opening 29 is preferably spaced apart from the end face 25 both in the longitudinal direction of the horn section 24 and in its radial direction, thus providing a small gap G between the opening 29 and the outer surface of the horn section 24.
  • This gap G is small enough to allow the liquid sample S to be transported along the outer surface of the horn section 24 towards the end face 25.
  • a shallow groove 23' and/or low ridges may be provided on the horn section.
  • Figs. 4A, 4B and 4C may also be used in the embodiments of the remaining figures and are therefore not limited to embodiments having a single horn section.
  • the horn section 24 may have a specific length.
  • the horn section 24 may have a length of approximately half a wavelength of the ultrasound produced by the transducer 22.
  • the length of a horn section may thus be proportional to the wavelength and therefore inversely proportional to the frequency.
  • the wavelength is not only dependent on the frequency, but also on the material of the horn section 24.
  • the wavelength may be equal to approximately 10 mm, resulting in a half wavelength /2 of approximately 5 mm.
  • the nebulizer unit 20 shown in Fig. 4A may have an overall length of less than 10 mm.
  • An advantage of the ultrasonic nebulizer of the invention is the small amount of power that is required to achieve the desired nebulization. Due to the small dimensions of the nebulizer, it can suitably be produced using MEMS (Micro- Electro-Mechanical Systems) technology, which is well known to those skilled in the art. Suitable materials are, for example, silicon, glass, quartz, and silicon composites.
  • the nebulizer of the invention may be manufactured by injection molding, machining, grinding, polishing and/or 3D printing (additive manufacturing).
  • the transducer 22 may be a piezo-electric transducer, which is well known in the art. More than one transducer 22 per horn section 24 may be used, in which case the two or more transducers may be arranged against the same wall or against different walls of the horn section 24.
  • the nebulizer of the present invention may be configured for producing droplets having a diameter between 1 pm and 50 pm, preferably droplets having a diameter less than 20 pm, more preferably droplets having a diameter less than 10 pm, although other droplet sizes are also possible.
  • the droplet size may depend on the transducer frequency and other parameters, such as the flow of the sample S through the feed tube 23, the diameter of the feed tube 23 and/or the location of the open end 29 of the feed tube 23 relative to the horn section 24.
  • the embodiment of Fig. 5 comprises two ultrasonic horns arranged in series.
  • the nebulizer unit 20 of Fig. 5 comprises a double horn section, a first horn section 24A abutting the transducer 22 and a second horn section 24B having an end face 25.
  • the second horn section 24B is configured to receive ultrasound from the first horn section 24A and, due to its shape, further amplifies the ultrasound. Due to the double acoustic horn, a greater amplification of the ultrasound can be achieved.
  • Each tapered part of the acoustic horn sections has a horn length HL.
  • the horn section 24A is shown to comprise a tapered section 27 having sloping side walls 26 and a base section 28 which rests against the transducer 22.
  • the embodiment of Fig. 5 comprises two tapered sections 27 and a single base section 28.
  • the first horn section 24A and the second horn section 24B can both be solid.
  • the feed tube 23 is absent from the interior of the nebulizer unit 20. Instead, the feed tube 23 extends along the exterior of the nebulizer unit 20, the open end 29 of the feed tube 23 being located adjacent to the end face 25 of the nebulizer unit 20. It is noted that a small gap G' may be present between the end of the feed tube 23 and the horn sections, in particular but not exclusively between the end of the feed tube 23 and the end face 25 of the last horn section, so as to avoid any direct contact between the feed tube and the horn sections, which could influence the resonance characteristics of the horn sections.
  • the feed tube 23 is L-shaped, in contrast to the substantially straight feed tube 23 of Fig. 4. It is noted that the feed tube 23 may pass through the nebulizer housing 21 while passing around the horn sections.
  • the end face 25 may in some embodiments have a surface area between 0.1 mm 2 and 4 mm 2 , although both smaller and larger surface areas are feasible.
  • the end face 25 may have an outer surface which is structured.
  • a structured outer surface of the end face 25, on which the sample liquid may be supplied, allows the nebulization to have a more localized character, which can further improve both the efficiency of the aerosol generation and the properties of the generated aerosol.
  • the structured outer surface may comprise a single channel or a plurality of channels, and/or a single ridge or a plurality of ridges.
  • the channels and/or ridges may be straight or curved, parallel and/or crossing, and may have the same or different aspect ratios.
  • the end face 25 may be round, oval, rectangular (including square), polygonal (including hexagonal), or have another shape.
  • the diameter of the end face 25 may for example be between 0.1 mm and 10 mm, preferably between 0.5 mm and 2 mm, although other diameters may also be used.
  • the embodiment of Fig. 6 comprises a series arrangement of three ultrasonic horns having horn sections 24A, 24B and 24C respectively.
  • the feed tube 23 is shown to be arranged outside the nebulizer housing 21, near the end face 25.
  • the embodiment of Fig. 7 comprises a series arrangement of four ultrasonic horns having horn sections 24A, 24B, 24C and 24D respectively.
  • the nebulizer unit 20 of Fig. 7 is shown to comprise two transducers, of which a first transducer 22 is arranged against the back wall of the first horn section 24A, while a second transducer 22' are arranged against the bottom wall of the first horn section 24A. If required, a third transducer 22" could be arranged against the top wall and/or a fourth transducer 22"' could be arranged against a side wall.
  • Fig. 7 does not include a housing, although a suitable housing could be provided.
  • the embodiment of Fig. 8 comprises two parallel arrangements, each comprising three ultrasonic horns in series.
  • the nebulizer 20 of Fig. 8 is provided with an individual transducer 22 and an individual feed tube 23 for each arrangement.
  • the first series arrangement comprises horn sections 24A, 24B and 24C, while the second series arrangement comprises horn sections 24D, 24E and 24F.
  • Two feed tubes 23 are provided, each ending near a respective end face 25.
  • parallel arrangements of ultrasonic horns are also possible with one, two, four, five, six or more ultrasonic horns per arrangement.
  • three or more parallel arrangements of one, two, three, four, five, six or more ultrasonic horns each can be envisaged.
  • Fig. 9 comprises a tapering cross-section constituted by side walls 26 which are not straight but curved.
  • the side walls are concave.
  • the cross-section may be shaped differently and may for example have a stepped cross-section.
  • Bezier curves may be used to define the cross-section of the horn section 24.
  • a Bezier curve is a parametric curve used in computer graphics and other fields to provide smooth shapes.
  • Fig. 10 schematically shows another embodiment having a tapered section 26 which has a curved cross-section.
  • a feed tube 23 is configured for delivering a sample S near the end face 25.
  • the horn section 24, which may be solid, is provided with a flange 241 which may be used for fastening the nebulizer unit 20.
  • the transducer 22 couples its mechanical energy into the horn section 24 via a gel layer 29.
  • the horn section 24 is shown in a perspective view in Fig. 11.
  • Fig. 12 schematically shows various cross-sections of a nebulizer according to the invention, taken along the line C-C in Fig. 9.
  • the first cross-section CS1 is rectangular, which the second cross-section CS2 is oval.
  • the third cross-section CS3 is square and the fourth cross-section CS4 is substantially circular.
  • the fifth cross-section SC5 is polygonal, the present example shows a hexagon.
  • ultrasonic horn sections may be hollow, they are preferably partially or entirely solid.
  • Fig. 13 schematically shows the droplet size as may be produced with a nebulizer and/or sample introduction system of the present disclosure versus the frequency of the ultrasonic vibration.
  • a first graph 201 shows simulation results, while a second graph 202 shows the results of actual measurements.
  • the simulation is a good approximation of the measurement results.
  • Droplets having a diameter of 20 pm may be generated at a frequency of approximately 60 kHz. Droplets of about 5 pm would require a frequency of approximately 800 kHz.
  • the particular frequency used to produce a desired droplet size can depend on the dimensions of the nebulizer.
  • the sample introduction system of the invention is primarily designed to produce droplets smaller than approximately 20 pm, frequencies of at least about 50 kHz or 60 kHz are typically used.
  • frequencies of at least 240 kHz may be used, while to produce droplets of approximately 8.5 pm, a frequency of about 300 kHz may be used.
  • frequencies of at least 50 kHz can be used, although frequencies of at least 100 kHz are generally preferred.
  • Frequencies of at least 200 kHz may be used if droplets smaller than approximately 11.5 pm are desired.
  • the invention may be utilized in, for example, optical spectrometry and mass spectrometry but is not limited to those fields. Although the invention has been mainly explained with reference to spectrometry systems, the invention is not so limited and may be utilized in other technical fields, for example chemical analysis in general and/or physical analysis in general.
  • Examples of chemical analysis in which the teachings of the present invention may be utilized include elemental analysis, isotope ratio analysis, and other analysis applications.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Biochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Plasma & Fusion (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)

Abstract

Système d'introduction d'échantillons (10) pour un spectromètre, comprenant : - une entrée d'échantillon (11) destinée à recevoir un échantillon à nébuliser, - un nébuliseur (20) destiné à nébuliser l'échantillon, - une entrée de gaz (12) destinée à recevoir du gaz pour transporter l'échantillon nébulisé et - un conduit (15) destiné à fournir l'échantillon nébulisé au spectromètre. Le nébuliseur (20) comprend au moins un transducteur configuré pour fournir une vibration ultrasonore et au moins un avertisseur ultrasonore destiné à amplifier la vibration ultrasonore. Le nébuliseur (20) est conçu pour produire des gouttelettes présentant un diamètre inférieur à environ 20 µm. La vibration ultrasonore peut présenter une fréquence d'au moins 60 kHz.
PCT/EP2022/077746 2021-10-11 2022-10-05 Système d'introduction d'échantillons WO2023061832A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE212022000307.1U DE212022000307U1 (de) 2021-10-11 2022-10-05 Probenzuführungssystem

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB2114481.1A GB2611576A (en) 2021-10-11 2021-10-11 Sample introduction system
GB2114481.1 2021-10-11
GBGB2207593.1A GB202207593D0 (en) 2022-05-24 2022-05-24 Sample introduction system
GB2207593.1 2022-05-24

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WO2023061832A1 true WO2023061832A1 (fr) 2023-04-20

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4570068A (en) 1982-11-17 1986-02-11 Hitachi, Ltd. Interface for liquid chromatograph and mass spectrometer
WO1992021138A1 (fr) 1991-05-21 1992-11-26 Analytica Of Brandford, Inc. Procede et appareil permettant d'ameliorer l'ionisation par electrovaporisation d'especes de solutes
US6669103B2 (en) 2001-08-30 2003-12-30 Shirley Cheng Tsai Multiple horn atomizer with high frequency capability
US20050054208A1 (en) 2003-01-14 2005-03-10 Fedorov Andrei G. Electrospray systems and methods
US8642954B2 (en) 2011-04-20 2014-02-04 Perkinelmer Health Sciences, Inc. Sample introduction method and system for atomic spectrometry
US20150165466A1 (en) 2013-12-18 2015-06-18 Agilent Technologies, Inc. Ultrasonic nebulizer with controlled mist output
GB2548071A (en) 2015-12-18 2017-09-13 Thermo Fisher Scient (Bremen) Gmbh Liquid sample introduction system and method, for analytical plasma spectrometer
WO2020208085A1 (fr) 2019-04-10 2020-10-15 Thermo Fisher Scientific (Bremen) Gmbh Chambre de source de plasma destinée à un spectromètre

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4570068A (en) 1982-11-17 1986-02-11 Hitachi, Ltd. Interface for liquid chromatograph and mass spectrometer
WO1992021138A1 (fr) 1991-05-21 1992-11-26 Analytica Of Brandford, Inc. Procede et appareil permettant d'ameliorer l'ionisation par electrovaporisation d'especes de solutes
EP0588952A1 (fr) * 1991-05-21 1994-03-30 Analytica Of Branford, Inc. Procede et appareil permettant d'ameliorer l'ionisation par electrovaporisation d'especes de solutes
US6669103B2 (en) 2001-08-30 2003-12-30 Shirley Cheng Tsai Multiple horn atomizer with high frequency capability
US20050054208A1 (en) 2003-01-14 2005-03-10 Fedorov Andrei G. Electrospray systems and methods
US8642954B2 (en) 2011-04-20 2014-02-04 Perkinelmer Health Sciences, Inc. Sample introduction method and system for atomic spectrometry
US20150165466A1 (en) 2013-12-18 2015-06-18 Agilent Technologies, Inc. Ultrasonic nebulizer with controlled mist output
GB2548071A (en) 2015-12-18 2017-09-13 Thermo Fisher Scient (Bremen) Gmbh Liquid sample introduction system and method, for analytical plasma spectrometer
WO2020208085A1 (fr) 2019-04-10 2020-10-15 Thermo Fisher Scientific (Bremen) Gmbh Chambre de source de plasma destinée à un spectromètre

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