Online mass spectrometer for real-time detection of volatile components from the gas and liquid phases for process analysis

Abstract

Device (1) for mass spectrometric analysis of substances present in liquid and gaseous samples, comprising aa) a mass spectrometer (29), bb) at least one inlet (2) for a liquid sample and cc) at least one additional inlet (4, 6) for a gaseous sample, wherein the at least one inlet (2) for a liquid sample has a hydrophobic at least partially porous membrane (13) with an average pore radius of 0.001 to 0.1 µm, by means of which volatile substances present in the liquid sample can be converted into the gaseous state.

Description

[0001] The present invention relates to a device for carrying out a method for mass spectrometric analysis of substances present in liquid and / or gaseous samples.

[0002] Process mass spectrometers for analyzing a gas phase are known from the prior art, for example from Thermo Scientific and Extrel CMS, LLC.

[0003] Furthermore, DE 41 33 300 A1 discloses an "online" mass spectrometer with a membrane inlet, which can detect volatile components of an aqueous solution with a sensitivity in the lower ppb range (ppb = "parts per billion"). According to the method disclosed in DE 41 33 300 A1, the liquid phase can be continuously fed via a capillary into a membrane inlet by means of a low-pulsation pump, passed over a PTFE membrane inside, and either returned to the starting point via another capillary or discarded. A forevacuum is present on the permeate side of the membrane inlet, causing the liquid to continuously evaporate at the membrane surface. When a rotary valve is opened, a portion of the gas flow located in the forevacuum, also referred to as a fine vacuum, enters a high vacuum and is measured there as an ion current in the mass spectrometer.

[0004] In GB 2392114 A, a device for preparing liquid and gaseous samples for mass spectrometry is disclosed, comprising a temperature-controlled semi-permeable membrane. By heating the membrane, substances previously absorbed in and on the semi-permeable membrane are released from a liquid or gaseous sample and conveyed to a mass spectrometer by means of a helium gas stream.

[0005] The ion source for a mass spectrometer described in US 2008 / 0048107 A1 has, in a preferred embodiment, two separate inlets to allow the simultaneous input of liquid and gaseous samples.

[0006] WO 2014 / 209474 A1 further discloses a method and a device for generating ions from liquids and solid samples for mass spectrometric analysis. Porous materials, such as filter paper or similar materials, are used to receive and transport liquid samples, and it is described that ions can be generated at the edges of the material by applying a high electrical voltage.

[0007] US 2005 / 0236565 A1 teaches a method and an instrument for the detection and determination of trace organic compounds from a continuously flowing sample system using mass spectrometry. Liquid samples are introduced into the system via a membrane inlet. Substances that do not pass through the membrane and thus remain in the liquid sample are introduced into the system via a capillary inlet.

[0008] US 2009 / 0294660 A1 discloses a mass spectrometer which has an inlet for examining gaseous samples from gas chromatography and an additional sample inlet, wherein a sample solution introduced into the sample inlet is atomized into a spray of liquid droplets and the spray is subsequently evaporated in an evaporator or with a heating element.

[0009] However, no mass spectrometer is known from the state of the art that can measure online, i.e. in real time, simultaneously from both a gas phase and a liquid, and that can also be operated reliably and automatically.

[0010] In summary, there is a high demand for a device for mass spectrometric analysis of substances that can automatically analyze both gaseous and liquid samples without modification of this device, especially for process monitoring.

[0011] It is therefore an object of the present invention to overcome the aforementioned disadvantages and, in particular, to provide a device for performing mass spectrometric analysis of substances present in liquid and / or gaseous samples, preferably in real time and fully automatically. In particular, the device is characterized by the fact that it is installed once in a reaction system and then, in real time with a utilization rate of preferably at least 90%, more preferably at least 95%, fully automatically analyzes the gaseous and / or liquid samples present in the reaction system and feedable to the device, determines the volatile substances therein, and, in the event of errors or problems, independently detects them, preferably by means of software or computer assistance, and, if necessary, takes appropriate safeguards against them.In particular, the invention is therefore based on the objective of creating a device for determining volatile substances or substances present in gaseous form, which also allows continuous determination of these substances, especially from flowing liquids, in real time, so that, for example in the chemical industry, control processes regarding the concentration of certain substances in a liquid and / or a gas mixture can be carried out.

[0012] The problem is solved by providing the subject matter of the independent claim. Advantageous embodiments arise from the dependent claims.

[0013] The present disclosure also includes a method for mass spectrometric analysis of substances present in liquid and gaseous samples, comprising the steps of: a) Selectively, preferably by valve control, introducing at least one or more substances of a liquid, preferably aqueous, sample into a first flow element of a device or at least one or more substances of a gaseous sample into a second flow element of the device, wherein the first flow element is different from the second flow element, such that the at least one or more substances are at least partially, preferably completely, gaseous, and b) mass spectrometric analysis of the at least one or several substances present in gaseous form in step a).

[0014] By introducing, preferably via valve control, the at least one substance of the liquid sample into a first flow element and, preferably at a later time, introducing the at least one substance of the gaseous sample into a second flow element, it is advantageously possible to analyze or determine at least one or more substances from both liquid and gaseous samples using mass spectrometry with a single device. By introducing the at least one substance of the gaseous and the liquid sample into one and the same device using two different flow elements, it is advantageously achieved that a modification of the device is no longer necessary if the samples to be measured have different states of matter. This allows substances from gaseous and liquid samples to be analyzed or determined "simultaneously" in a simple manner.In particular, these substances can be continuously analyzed or determined over a long period of time, albeit with a time delay, but without modification of the device for mass spectrometric analysis.

[0015] In a preferred embodiment of the method described herein, in a step a1) preceding step b), the at least one or more gaseous substances are introduced into a third flow element of the device, wherein a pressure of 0.01 to 0.5 mbar, preferably 0.15 to 0.2 mbar, is present in the third flow element. Preferably, the at least one or more gaseous substances from the gaseous sample are introduced into a first third flow element, and the at least one or more gaseous substances from the liquid sample are introduced into a second third flow element, wherein a pressure of 0.01 to 0.5 mbar, preferably 0.15 to 0.2 mbar, is present in the first and / or second third flow element. Alternatively, preferably, the at least one or more gaseous substances from the gaseous sample and the liquid sample are introduced into the same third flow element.

[0016] In a preferred embodiment of the method described herein, in a step a2) preceding step b), the at least one or more gaseous substances are introduced into a fourth flow element of the device, wherein a pressure of 10 is maintained in the fourth flow element. -5 mbar or less, preferably 10 -6 mbar or less, preferably 10 -7 mbar or less, preferably 10 -5 mbar up to 10 -10 mbar, is present.

[0017] Preferably, the at least one or more gaseous substances are first introduced into the third and then into the fourth flow element. Preferably, the at least one or more gaseous substances of the gaseous sample are first introduced into a first third flow element and then into a first fourth flow element. Preferably, the at least one or more gaseous substances of the liquid sample are first introduced into a second third flow element and then into a second fourth flow element. Alternatively, preferably, the at least one or more gaseous substances in the first and second third flow elements are introduced into the same fourth flow element. Preferably, a pressure of 10 is maintained in the first and / or second fourth flow element. -5 mbar or less, preferably 10 -6mbar or less, preferably 10 -7 mbar or less, preferably 10 -5 mbar up to 10 -10 mbar, before.

[0018] The present disclosure further comprises a method wherein the mass spectrometric analysis according to step b) comprises the following steps: i) Ionizing the at least one or more gaseous substances, ii) Accelerating the at least one or more substances ionized in step i), iii) Selecting the at least one or more substances accelerated in step ii), and iv) Detecting the at least one or more substances selected in step iii).

[0019] Preferably, the mass spectrometric analysis according to step b) comprises ionizing the at least one or more gaseous substances and subsequently detecting the at least one or more ionized substances.

[0020] In a preferred embodiment, the method described herein comprises the following steps: a) Selectively, preferably by valve control, introducing at least one or more substances of a liquid sample into a first flow element of a device, or at least one or more substances of a gaseous sample into a second flow element of the device, wherein the first flow element is different from the second flow element, such that the at least one or more substances are at least partially, preferably completely, gaseous. a1) at least partial, preferably partial or complete, introduction of the at least one or more substances present in gaseous form in the first and / or second flow element into a third flow element of the device, wherein a pressure of 0.01 to 0.5 mbar, preferably 0.15 to 0.20 mbar, is present in the third flow element, a2) at least partial, preferably partial or complete, introduction of the at least one or more substances present in gaseous form in the third flow element into a fourth flow element of the device, wherein a pressure of 10 in the fourth flow element -5 mbar or less, preferably 10 -6 mbar or less, preferably 10 -7 mbar or less, preferably 10 -5 mbar up to 10 -10 mbar, is present and b) at least partial, preferably partial or complete, mass spectrometric analysis of the at least one or more substances present in gaseous form in the fourth flow element, wherein the mass spectrometric analysis preferably comprises the following steps: i) at least partial, preferably partial or complete, ionization of the at least one or more substances present in gaseous form in the fourth flow element, ii) at least partial, preferably partial or complete, acceleration of the at least one or more substances ionized in step i), iii) at least partial, preferably partial or complete, selection of the at least one or more substances accelerated in step ii), and iv) at least partial, preferably partial or complete, detection of the at least one or more substances selected in step iii).

[0021] Preferably the first, second, third, preferably the first third and / or the second third, and / or the fourth, preferably the first fourth and / or the second fourth, flow element is a line, preferably a pipe or a hose, preferably a metal pipe or metal corrugated hose, preferably a stainless steel pipe or stainless steel corrugated hose.

[0022] In the context of the present invention, the term "and / or" means that the members of a group connected by the term "and / or" are disclosed alternatively, partially cumulatively, or fully cumulatively. For example, the expression "A, B, and / or C" means the following disclosure: A or B or C or (A and B) or (A and C) or (B and C) or (A and B and C).

[0023] Preferably, the first, second, and third flow elements are connected to each other by a first valve assembly, preferably directly. Preferably, the third flow element is connected to the fourth flow element via a second valve assembly, preferably directly. Preferably, the first valve assembly connects the first flow element to the third flow element in a first position. In a second position, the first valve assembly connects the second flow element to the third flow element. In a third position, there is no fluid contact between the first and second flow elements or the third flow element. Preferably, the second valve assembly connects the third flow element to the fourth flow element in a first position. In a second position, there is no fluid contact between the third flow element and the fourth flow element.

[0024] In an alternative embodiment of the method described herein, the first flow element is connected to the third flow element by a first valve assembly, preferably directly. Additionally, the second flow element is connected to the third flow element by a second valve assembly, preferably directly. Preferably, the third flow element is connected to the fourth flow element via a third valve assembly, preferably directly. Preferably, the first valve assembly connects the first flow element to the third flow element in a first position. In a second position, there is no fluid contact between the first and third flow elements. Preferably, the second valve assembly connects the second flow element to the third flow element in a first position.In a second position, there is no fluid contact between the second and third flow elements. Preferably, in a first position, the third valve assembly connects the third flow element to the fourth flow element. In a second position, there is no fluid contact between the third and fourth flow elements.

[0025] In an alternative embodiment of the method described herein, the first flow element is connected to the first third flow element by a first valve assembly, preferably directly. Additionally, the second flow element is connected to the second third flow element by a second valve assembly, preferably directly. Furthermore, the first third, the second third, and the fourth flow elements are connected to each other by a third valve assembly, preferably directly. Preferably, the first valve assembly connects the first flow element to the first third flow element in a first position. In a second position, there is no fluid contact between the first flow element and the first third flow element. Preferably, the second valve assembly connects the second flow element to the second third flow element in a first position.In a second position, there is no fluid contact between the second flow element and the second third flow element. Preferably, in a first position, the third valve assembly connects the first third flow element to the fourth flow element. Preferably, in a second position, the third valve assembly connects the second third flow element to the fourth flow element. In a third position, there is no fluid contact between the first third flow element, the second third flow element, and the fourth flow element.

[0026] In an alternative embodiment of the method described herein, the first flow element is connected to the first third flow element by a first valve assembly, preferably directly. Additionally, the second flow element is connected to the second third flow element by a second valve assembly, preferably directly. Additionally, the first third flow element is connected to the first fourth flow element by a third valve assembly, preferably directly. Additionally, the second third flow element is connected to the second fourth flow element by a fourth valve assembly, preferably directly. Preferably, the first valve assembly connects the first flow element to the first third flow element in a first position.In a second position, there is no fluid contact between the first flow element and the first third flow element. Preferably, the second valve assembly connects the second flow element to the second third flow element in a first position. In a second position, there is no fluid contact between the second flow element and the second third flow element. Preferably, the third valve assembly connects the first third flow element to the first fourth flow element in a first position. In a second position, there is no fluid contact between the first third flow element and the first fourth flow element. Preferably, the fourth valve assembly connects the second third flow element to the second fourth flow element in a first position. In a second position, there is no fluid contact between the second third flow element and the second fourth flow element.

[0027] In a preferred embodiment of the method described herein, each inlet for a gaseous sample or a liquid sample has a third and fourth flow element, wherein the different flow element strands are only combined via a valve device immediately before the mass spectrometer.

[0028] The first, second, third and / or fourth valve assembly makes it possible in particular to control the mass flow of gaseous substances into the third(s) and / or fourth(s) flow element(s) in a targeted manner.

[0029] Preferably, the first, second, third, and / or fourth valve assembly comprises at least one, preferably at least two, preferably exactly one, preferably exactly two valves. Preferably, the at least one valve is a switching valve, drum valve, or proportional valve. The at least one valve is preferably designed as an electric or pneumatic valve.

[0030] Preferably, the valves, preferably all valves, are controllable, preferably via a software-based control program or a programmable logic controller.

[0031] Preferably, a calibration solution is introduced into the second flow element for calibrating the mass spectrometer instead of a liquid sample. Preferably, a calibration gas or calibration mixture is introduced into the first flow element for calibrating the mass spectrometer instead of a gaseous sample, preferably via a valve.

[0032] In a preferred embodiment of the method described herein, the first, second, third, and / or fourth flow element is heated to a temperature of 60 to 80 °C, preferably 70 to 75 °C. The flow elements are preferably heated by a heating element. Preferably, each of the first, second, third, and / or fourth flow element is assigned its own heating element. Preferably, the first, second, third, and / or fourth flow element is at the same temperature.

[0033] The terms “the third flow element” or “the fourth flow element” encompass one or more flow elements of the same type. Accordingly, these terms also include the first third / first fourth and the second third / second fourth flow element, if present in the device.

[0034] Heating one or more flow elements prevents the deposition, preferably condensation, or adsorption of the at least one or more gaseous substances on the inside of the flow element, preferably the line, preferably the pipe or hose, preferably the metal pipe or metal corrugated hose, preferably the stainless steel pipe or stainless steel corrugated hose.

[0035] In particular, the first, second, third, and / or fourth valve assembly prevents an excessive amount of the gaseous or liquid sample and / or calibration medium from entering the flow elements, preferably the third and / or fourth flow element, or the mass spectrometer. This minimizes, and preferably prevents, damage, especially to the mass spectrometer.

[0036] In a preferred embodiment of the method described herein, the selective introduction of the at least one or more substances of the liquid or gaseous sample into the first or second flow element is controlled such that, in steps a1) and / or a2), equal quantities of the at least one or more gaseous substances are present in the third flow element. According to the invention, the term "equal quantities" means that, preferably via the control of the valve arrangement, the mass flow from the first flow element into the third flow element and the mass flow from the second flow element into the third flow element differ by a maximum of ±10%, preferably by a maximum of ±5%, and preferably by a maximum of ±1%. In the context of the present invention, the term "mass flow" means the mass of the at least one or more substances introduced into the third flow element over a specific period of time.This specific process, namely the introduction of equal quantities of the at least one or more gaseous substances into the third flow element, makes it particularly possible to switch fully automatically between the first and second flow elements, i.e., between introducing the at least one or more substances of a gaseous or a liquid sample. In particular, this makes it possible to calibrate the device according to the invention for mass spectrometric analysis with a single calibration medium and then introduce different samples via the first and second flow elements.

[0037] Preferably, at least one or more substances from at least two, preferably at least five, preferably at least ten different liquid samples are introduced via the first flow element through different inlets, preferably at staggered intervals.

[0038] Preferably, at least one, preferably at least two, preferably at least five, preferably at least ten, preferably a maximum of thirty, preferably a maximum of twenty different substances of a liquid sample are introduced via the first flow element.

[0039] Preferably, at least one or more substances from at least two, preferably at least five, preferably at least ten, different gaseous samples are introduced via the second flow element through different inlets, preferably at different times.

[0040] Preferably, at least one, preferably at least two, preferably at least five, preferably at least ten, preferably a maximum of thirty, preferably a maximum of twenty, different substances of a gaseous sample are introduced via the second flow element.

[0041] In a preferred embodiment of the method described herein, the pressure in the fourth flow element is detected. Preferably, the pressure is detected in the first, second, third, and / or fourth flow element. Preferably, the pressure is detected in both the third and fourth flow elements. This detection is preferably performed by a separate detection unit. This detection unit is preferably connected to a control unit. Preferably, the control unit comprises a software-based control program or a programmable logic controller (PLC).

[0042] In a preferred embodiment of the method described herein, upon a detected pressure increase in the fourth flow element, a controllable valve device arranged between the third and fourth flow elements is closed, so that there is no fluid contact between the third and fourth flow elements. Preferably, upon a detected pressure increase in the third flow element, a controllable valve device arranged between the third and fourth flow elements is closed, so that there is no fluid contact between the third and fourth flow elements.

[0043] Alternatively or additionally, upon detection of a pressure increase in the third flow element, a controllable valve device arranged upstream of the third flow element – ​​in the flow direction of the gaseous substances – is preferably closed. Preferably, upon detection of a pressure increase in the third and / or fourth flow element, all valve devices present in the apparatus are closed, so that there is no fluid contact between the flow elements connected, preferably directly, to these valve devices. Closing the at least one valve preferably prevents an excessive amount of gaseous substances, or an excessive amount of a gaseous or liquid sample, from entering the measuring device, i.e., the mass spectrometer used to analyze the at least one or more gaseous substances.

[0044] Preferably, the at least one or more gaseous substances flow from the fourth flow element, preferably directly, into the mass spectrometer, i.e., into the ionization device of the mass spectrometer designed and provided for carrying out step i).

[0045] Preferably, the process described herein consists of the aforementioned process steps. This means that preferably no further process steps are carried out beyond those mentioned above. Preferably, the process described herein consists of process steps a), a1), a2), b), i), ii), iii), and iv). Preferably, no fractionation of the at least one or more substances present in gaseous form in step a) takes place before they are analyzed by mass spectrometry in step b). Preferably, the process described herein is free of chromatographic, in particular gas chromatographic, fractionation, preferably of the at least one or more substances present in gaseous form.

[0046] Preferably, mass spectrometric analysis is performed on reactions taking place in gases or gas mixtures or liquids.

[0047] Preferably, the method described herein is used to measure ion currents of one or more gaseous substances, thereby enabling the calculation of the respective concentrations of these substances.

[0048] To generate the vacuum present in the third and / or fourth flow element, a pump is used in each case, which is designed to generate a corresponding pressure.

[0049] In a preferred embodiment of the method described herein, the liquid sample is passed by a liquid-impermeable but gas-permeable membrane, preferably located in a membrane device, also referred to as a membrane module, for introduction into the first flow element, such that under the conditions prevailing during the process, at least one or more substances can be volatilized, i.e., brought into the gas phase. The corresponding substances pass through the membrane and are thereby introduced into the second flow element. It is preferred that the liquid in the region of the membrane is maintained at a constant temperature, preferably at a temperature between 10 and 30 °C, more preferably 25 °C.

[0050] Preferably, the temperature can be varied for the specific application. Preferably, the temperature remains constant during the measurement period, preferably the entire measurement period. Preferably, calibration is performed at the same temperature.

[0051] Preferably, the introduction of the at least one or more substances of the liquid sample into the first flow element and / or the introduction of the at least one or more substances of the gaseous sample into the second flow element is carried out in such a way that the first flow element or the second flow element is fluidically, preferably directly, connected to the third flow element via the valve device, i.e., a certain suction effect, but also a vacuum in the first and / or second flow element, is created due to the negative pressure present in the third flow element.

[0052] In a preferred embodiment of the method described herein, the liquid sample passed by the membrane is routed to the liquid flow under investigation via a branch or bypass. In a preferred embodiment, the membrane device for introducing volatile substances from a liquid sample is configured to function as a bypass, with the liquid sample being drawn from a container or line using a low-pulsation pump and optionally returned.

[0053] The membrane is preferably supported by a porous disc. The membrane is sealed in a membrane housing by means of a polytetrafluoroethylene-encased sealing ring.

[0054] To maintain a constant vacuum in the third and / or fourth flow element, the vacuum detection devices assigned to the third and / or fourth flow element are connected to the vacuum pumps assigned to these flow elements via control loops, in particular controlled via a control unit.

[0055] The present invention relates to a device for mass spectrometric analysis of substances present in liquid and gaseous samples, comprising aa) a mass spectrometer, bb) at least one inlet for a liquid sample and cc) at least one additional inlet for a gaseous sample, wherein the at least one inlet (2) for a liquid sample has a hydrophobic at least partially porous membrane (13) with an average pore radius of 0.001 to 0.1 µm, by means of which volatile substances present in the liquid sample can be converted into the gaseous state of matter.

[0056] In a preferred embodiment of the present invention, the device is configured to carry out a method described herein.

[0057] Preferably, the method described herein is carried out using a device according to the invention.

[0058] In particular, the present device according to the invention is characterized by the fact that it is a very compact device with low dead volume.

[0059] In the device according to the invention, the at least one inlet for a liquid sample has a hydrophobic, at least partially porous membrane. This membrane is preferably located in a membrane assembly.

[0060] According to the invention, the membrane is a hydrophobic membrane. The membrane has a plurality of pores, the average pore radius preferably being 0.001 to 0.1 µm, more preferably 0.01 to 0.05 µm. The membrane preferably has a thickness of 1 to 100 µm, more preferably 10 to 80 µm, more preferably 40 to 60 µm. The membrane preferably has a porosity of 40 to 80%, more preferably 50 to 70%. The membrane is preferably a pervaporation membrane, more preferably a polytetrafluoroethylene (PTFE) membrane or a silicone membrane, more preferably a polydimethylsiloxane (PDMS) membrane. Alternatively, other specific membranes that are selective for certain substances can be used to obtain better measurement resolution, if required. Preferably, dense pervaporation membranes, preferably a silicone membrane, preferably a PDMS membrane are used as the membrane.

[0061] Preferably, a PTFE membrane is used as an inlet for at least one volatile substance from a liquid sample in a fermentation process or cell culture process, in particular as an integral part of a fermentation process or cell culture process vessel, preferably a corresponding disposable vessel.

[0062] In a preferred embodiment, the device according to the invention additionally has at least one inlet for a calibration medium.

[0063] In a preferred embodiment, the device according to the invention has at least one valve assembly which is arranged between the inlets and the mass spectrometer.

[0064] In a preferred embodiment of the device according to the invention, the at least one inlet for a liquid sample is designed as an in situ sensor.

[0065] The device according to the invention particularly preferably features a membrane assembly designed as an in-situ sensor. This in-situ sensor serves, in particular, to directly extract the volatile substances from a liquid reaction medium or a liquid medium, so that these substances can be introduced into the second flow element. This in-situ sensor can be used, in particular, in biotechnology, especially in the form of an Ingold fitting. It is considered a standard connection for installation in process vessels, especially in reactors, pipelines, and / or other plant components.

[0066] Preferably, the in-situ sensor comprises a cylindrical inner part with an external thread and a sleeve with an internal thread. More preferably, the cylindrical inner part is screwed into the sleeve, with the internal and external threads interacting. The inner part also has a longitudinally extending channel, preferably a bore, providing a fluid connection between the liquid medium or sample and the inlet of the device for the liquid samples. In particular, this channel is electropolished. This electropolishing advantageously prevents adsorption, i.e., the condensation of the gaseous substances supplied through the membrane on the surface of this channel. Preferably, the in-situ sensor has a heating element so that the entire sensor can be heated and is also heated during use in the method described herein.The membrane is clamped between the inner part and the sleeve using a suitable seal, preferably an O-ring seal, preferably by screwing the sleeve in place. The sleeve has an opening, preferably a bore, at this end so that a sufficient quantity of liquid sample can wet the membrane during intended use. Accordingly, the only intended path for the liquid, i.e., the liquid sample, into the second flow element is, as intended, solely via the membrane. This membrane is preferably installed in the in-situ sensor such that it forms a, preferably slight, outward bulge, i.e., in the direction of the liquid or sample.This preferred curvature increases the contact area of ​​the membrane with the liquid, preferably flowing past it, thereby improving the volatilization of volatile substances present in the medium and / or reducing biofilm formation on the membrane in a fermenter, particularly due to the improved surface area for the liquid to act upon. To prevent biofilm formation, a wiping element is preferably provided, either alternatively or additionally. This membrane is preferably supported by a disc, preferably a sintered disc, preferably against the curvature. The in-situ sensor can be preferably attached to a reaction vessel, preferably a fermenter, by means of a union nut, and preferably seals flush with the reactor interior, preferably the fermenter interior, via a ring seal on the outside of the sleeve, preferably in a liquid-tight manner.Preferably, the liquid flow and pressure at the membrane are taken into account in the method described herein. Alternatively, the in-situ sensor can also be designed as a flow sensor, which is preferably installed in a line, more preferably in a pipe.

[0067] The in-situ sensor can also be integrated into a stirrer, a baffle, or the reactor wall of a reaction vessel. The in-situ sensor is preferably used as an integral component of a fermentation or cell culture process vessel, preferably a suitable disposable vessel. The in-situ sensor, designed to hold the membrane, is made of plastic, preferably PTFE, or other materials. The membrane can be made of the same or a different material.

[0068] In a preferred embodiment of the device according to the invention, the at least one inlet for a gaseous sample is designed as a capillary inlet.

[0069] In a preferred embodiment of the device according to the invention, the capillary inlet has a quartz-coated and heatable capillary.

[0070] In a preferred embodiment of the device according to the invention, the mass spectrometer comprises an ion source, an analyzer and a detector.

[0071] In a preferred embodiment of the device according to the invention, the mass spectrometer is a quadrupole mass spectrometer.

[0072] In a preferred embodiment of the device according to the invention, the mass spectrometer is a process mass spectrometer.

[0073] In a preferred embodiment of the present invention, the device comprises a membrane assembly for volatilizing substances present in a liquid sample, a capillary for the inlet of a gaseous sample, and an in-situ sensor for the inlet of a liquid sample. Preferably, these components are connected via a cross-piece and switchable valves and can be controlled automatically. In a preferred embodiment, the device comprises at least two membrane assemblies for volatilizing substances present in a liquid sample and a capillary for the inlet of a gaseous sample, wherein at least one membrane assembly is configured as an in-situ sensor for the inlet of a liquid sample.

[0074] Preferably, the device according to the invention is designed as a transportable and self-contained module. The present device is preferably housed in a transportable enclosure. Accordingly, the device can be integrated into existing process flows.

[0075] The device according to the invention is in particular able to supply different samples, both gaseous and liquid samples and calibration media, preferably calibration solutions, to mass spectrometric analysis or determination of gaseous substances without modification of the device.

[0076] In a preferred embodiment, the device according to the invention also has an inlet for an acid or a base. The addition of an acid or base increases the sensitivity of the mass spectrometer to certain substances by improving the volatility of the substance to be measured through protonation or deprotonation, depending on the pKa value. In particular, the acid or base is first introduced into the liquid sample by means of a pump, especially if the membrane assembly is mounted in a bypass. In particular, the introduction of an acid or base in the bypass can be made possible by using two low-pulsation pumps.

[0077] The device according to the invention allows mass spectrometric analysis or determination of volatile substances to be carried out alternately from both liquid and gaseous samples without any modifications. One or more additional inlets for gaseous and / or liquid samples can be provided by means of at least one detachable flow element connection, also referred to as a flange, which includes a valve assembly.

[0078] The device according to the invention preferably has at least one heating element per flow element. These heating elements ensure a uniform temperature profile, thereby preventing the adsorption or condensation of gaseous substances on the inside of the flow elements, particularly the pipe.

[0079] Preferably, all flow elements and valve assemblies, in particular all surfaces with which the gaseous substances can come into contact, are electropolished. Electropolishing also prevents adsorption or condensation of the gaseous substances.

[0080] The device according to the invention preferably includes a control system. The control system enables communication with the mass spectrometer, the valve assemblies, in particular the valves, and the integrated pumps. This allows the device to be used autonomously in a wide range of applications.

[0081] The ion currents measured in the mass spectrometer are preferentially transmitted to the control system. This allows a pressure drop or increase to be detected and thus registered, and in case of suspected damage, such as liquid ingress, some or all valves in the device, especially the inlets, to be closed.

[0082] The control system preferably incorporates mathematical models that convert ion currents into concentrations based on automatic calibration. The user interface of the control system allows the user to query the necessary parameters for carrying out the process, such as the reactants used and the expected products. The control system preferably includes an automated calibration program. Specific process sequences can be programmed using the control system. In particular, the intervals between the measurement of a gaseous sample, a liquid sample, or a calibration medium can be defined, especially by controlling the various valves.

[0083] In particular, the device preferably integrates at least one interface through which the mass spectrometric values ​​measured here can be transmitted to higher-level control systems, especially reactor control systems. It is also possible, via corresponding interfaces, to transmit measured values ​​from other measuring devices, in particular the pH value, oxygen and carbon dioxide partial pressures, conductivity, amount of added substances, and optical density in a reaction medium. Preferably, further measured parameters, preferably the viable cell count of microorganisms, are estimated, preferably via a soft sensor.

[0084] The term "soft sensor" (a combination of the words "software" and "sensor"), also known as a virtual sensor or sensor fusion, does not refer to a physically existing sensor, but rather to a simulation of the relationship between proxy measurements and a target variable. Thus, the target variable is not measured directly, but calculated based on correlated measurements and a correlation model. For example, the concentration of non-volatile substances can be inferred from gaseous and / or volatile substances, particularly if the concentration of the non-volatile substance correlates with the concentration of the gaseous and / or volatile substances due to an ongoing reaction.

[0085] Advantageously, reactions can be analyzed and recorded in real time using the device according to the invention.

[0086] The term "in real time" means that at least one introduced substance can be analyzed within seconds, preferably within one second.

[0087] Furthermore, it is characterized by high robustness, high specificity and ease of use, low maintenance requirements, low operating costs and the possibility of integrating the measuring system into existing processes.

[0088] Furthermore, the device according to the invention makes it possible to measure substances even in very low concentrations from both liquid and gaseous samples with negligible time delay.

[0089] Particularly with regard to industrial biotechnology, further advantages become apparent. Specifically, the product concentration during fermentations can be determined precisely and easily in real time by measuring the products being formed. Accordingly, real-time measurement of the products and by-products allows for the optimization of fermentation with respect to maximum product formation rate and an increase in space-time yield. Furthermore, multiple reactors can be connected to the device according to the invention.

[0090] In exhaust gas analysis for bioprocesses, the partial pressures of CO2 and O2 are frequently measured to infer cell growth and product formation rates. The inventive setup, particularly the method and device described herein, allows for the measurement of the entire composition of the exhaust gas, including the products. Furthermore, the inlet for the liquid sample enables the measurement of the dissolved concentrations of CO2 and oxygen, as well as all other volatile substances from the fermentation broth.

[0091] The device according to the invention is suitable for measuring a wide variety of products and can therefore be used for different production processes that vary according to seasonal raw material availability and / or customer demand. Accordingly, the device according to the invention can be implemented as a customized analytical instrument integrated into production plants.

[0092] In addition to process monitoring, product quality control is also important. In biotechnology, various metabolic pathways lead to impurities in the product. For example, ethanol is contaminated by methanol, acetaldehyde, ethyl acetate, and diacetyl. The device according to the invention can detect these impurities. It can therefore be used as an analytical instrument for detecting contamination by volatile substances, i.e., for quality control. The device according to the invention is therefore particularly suitable for use in beer production.

[0093] The device according to the invention can be used in research and development, process monitoring of all types of process media with volatile components, and quality control, for example in the chemical, petrochemical, biotechnology, pharmaceutical, medical technology, and food industries. It can be used in laboratory and / or pilot plants and production facilities, particularly for optimizing the production process. It can also be used in modular and flexible production systems.

[0094] The device according to the invention is also suitable for quality assurance in sensitive production areas and for monitoring drinking water and / or wastewater, as it can detect trace substances. In particular, the device can measure all volatile components from liquid, preferably aqueous, as well as gaseous samples and record concentration changes over eight decades, from the lower ppb range to the high potency range. Furthermore, the device has short response times and the ability to measure up to 30, preferably 20, substances simultaneously.

[0095] In particular, the device according to the invention can be used in industrial biotechnology and bio-based production as a measuring instrument for process analysis. Specifically, the device can be used in enzymatic processes, for example in the production of butanediol, propanediol, succinic acid, ethanol from lignocellulose, butanol, polyols, butyl acrylate, thiols, esters, and lactic acid.

[0096] The device can also be used in medical technology to measure, for example, the gas composition of the breathing air, the gas emission from the skin and all volatile components directly from the blood.

[0097] The description of the method for mass spectrometric analysis, also referred to as the analytical method, and the description of the device for mass spectrometric analysis, also referred to as the analytical device, are to be understood as complementary to each other. Method steps of the analytical method that are explicitly or implicitly described in connection with the analytical device are preferably, individually or in combination, steps of a preferred embodiment of the analytical method described herein. Features of the analytical device that are explicitly or implicitly described in connection with the analytical method are preferably, individually or in combination, features of a preferred embodiment of the analytical device according to the invention. This preferably includes at least one feature that is caused by at least one step of a preferred embodiment of the analytical method.The analytical method described herein is preferably characterized by at least one method step which is determined by at least one feature of the analytical device.

[0098] The invention will be explained in more detail below with reference to the following five drawings. These show Fig. 1 a schematic representation of a device preferred according to the invention for mass spectrometric analysis of both liquid and gaseous samples, Fig. 2 an in situ sensor designed as an Ingold nozzle according to a preferred embodiment of the present invention, Fig. 3 Ion currents (IC) in [A] of different substances over time t in [min] during the ashing of a carbon fiber, Fig. 4 Ion currents (IC) in [A] of different gases present in a so-called reed switch over time t in [s], and Fig. 5 a measured enzyme kinetics and a mathematical model based on a hyperbolic rate equation.

[0099] In particular, it shows Fig. 1. A device 1 in which a liquid sample from a sampling chamber can be introduced via an inlet 2 having a line 3, and a gaseous sample can be introduced via inlets 4 and 6 having lines 5 and 7, respectively. Alternatively or additionally, a calibration solution stored in a container 9 can be introduced via an inlet 8 having a line 11. The liquid sample or the calibration solution is supplied to a diaphragm device M401 by means of a pump P401. The pump P401 is characterized by a flow rate of 0 to 50 milliliters per minute, preferably 10 milliliters per minute, and can thus generate a system pressure of 0 to 400 bar. Via a valve V401, preferably pneumatic, the liquid sample can be selectively supplied to the diaphragm device M401 in liquid form via line 3 or the calibration solution via line 11 by means of the pump P401.The liquid sample or calibration solution flows parallel to a membrane 13 located in the membrane assembly M401. According to the invention, the membrane 13 is a hydrophobic, at least partially porous membrane, by means of which volatile substances present in the calibration solution or the liquid sample can be converted into a gaseous state. The non-volatile liquid portion, or the portion used to wet the membrane 13, is either discharged via a line 15 into a container 17 or returned via a line 16 to the sample collection chamber. This can be controlled by a valve V402, preferably a pneumatic one. The volatile substances of the liquid sample or the calibration solution are present in gaseous form in a first flow element 19, preferably a line 19. The first flow element 19 is preferably heated by a heating element H401.Lines 5 and 7, intended for the gaseous samples, can also be heated via heating elements H301 and H302. The gaseous samples can be introduced into a second flow element 21, preferably a line 21, either via a valve V301 (preferably pneumatic) or a valve V302 (preferably pneumatic). A heating element is also preferably assigned to the second flow element 21. The gaseous substances can be introduced into a third flow element 23 via a valve V201 (preferably pneumatic) or via a valve V202 (preferably pneumatic) into a third flow element 23. This introduction is achieved both by switching and opening the valves V201 and V202 accordingly and additionally by the suction effect generated by a pump P101. The P101 pump generates, in particular, a pre-vacuum, i.e., a pressure of 0.01 to 0.5 mbar.Another flow element 22, which is in fluid contact with the third flow element, can be used either as ventilation or for connecting a [something] in [something]. Fig. The in-situ sensor shown in Figure 2 is used. A valve V203, preferably pneumatic, closes the flow element 22 in one switching position and establishes a fluid connection to the outside or to the in-situ sensor in another switching position. A PIRSA pressure gauge PIRSA101 (P = pressure; I = display; R = input; S = switchable; A = alarm) is also assigned to the third flow element 23. The gaseous substances pass from the third flow element 23 to a fourth flow element 25 via a manual valve VH101. The manual valve VH101 can also be designed as a control valve. A pump P102 is assigned to the fourth flow element 25, which is used in particular for generating a high vacuum, i.e., for generating a vacuum with a pressure of 10 -5mbar or less is suitable. A PIRSA pressure gauge PIRSA102 is also assigned to this flow element 25. The PIRSA pressure gauges PIRSA101 and PIRSA102 serve in particular to measure and record the pressure present in the third and fourth flow elements 23 and 25, and, if necessary, to trigger an alarm if the actual pressure differs from a preset target pressure. A heating element H101 is assigned to the manual valve VH101. All heating elements H101, H201, H301, H302, and H401 serve in particular to prevent fogging, i.e., condensation or adsorption of the gaseous substances present on the corresponding flow elements. The gaseous substances present in the fourth flow element 25 then pass to a filament F101 located in a mass spectrometer 29, which ionizes the gaseous substances.The generated ions are accelerated by a static electric field and pass through four centrally located, parallel electron beams. The points where these beams intersect a plane perpendicular to the cylinder axis form a square, the so-called quadrupole 27. In the alternating field between the quadrupole beams, m / e selection takes place, ensuring that only particles with a defined mass can pass through the field. The ions then enter a detector E101 with a measuring amplifier, which measures the ion current. This measurement is then converted by the software of the connected PC into the count rate or partial pressure. The detector E101 is a secondary electron multiplier E101_1 (abbreviated as SEM or SEV). It also features a Faraday trap E101_2. The mass spectrometer 29 also includes a QIR sensor QIR101 (Q = quantity, I = display, R = recording).Furthermore, the PIRSA101 pressure gauge and the P101 and P102 pumps are each connected to a drive electronics system via an RS485 interface.

[0100] The device elements marked with symbol A can be controlled by a digital or analog programmable logic controller (PLC). Elements marked with symbol B have an OPC connection. Elements marked with symbol C have an RS485 interface connection, and elements marked with symbol D have an external connection but no connection to the PLC.

[0101] Fig. Figure 2 shows an in-situ sensor 100 comprising a cylindrical inner part 101 with concealed external threads and a sleeve 102 with concealed internal threads, wherein the cylindrical inner part 101 is screwed into the sleeve 102, the internal and external threads interacting. The inner part 101 also has a longitudinally extending, concealed channel, preferably a bore, providing a fluid connection between the liquid medium or sample and the inlet of the device for the liquid samples. Preferably, the in-situ sensor 100 includes a heating element, allowing the entire sensor 100 to be heated. A diaphragm 109 is clamped between the inner part 101 and the sleeve 102 by means of a suitable seal, preferably an O-ring seal, preferably by tightening the sleeve 102.The sleeve 102 has an opening, preferably a bore, at this membrane end, so that the liquid sample can wet the membrane in sufficient quantity during intended use. This membrane 109 is preferably inserted in the in-situ sensor 100 such that it forms a, preferably slight, outward curvature, i.e., in the direction of the liquid or sample. This preferred curvature improves the volatilization of the volatile substances present in the medium and / or reduces biofilm formation on the membrane in a fermenter. To prevent biofilm formation, a wiping element is preferably provided alternatively or additionally. This membrane 109 is preferably supported by an invisible disc, preferably a sintered disc, preferably against the curvature.By means of a union nut 105, which also has a thread 107, the in situ sensor can preferably be attached to a reaction vessel, preferably to a fermenter, and preferably seals flush with the reactor interior, preferably the fermenter interior, via a ring seal 111 located on the outside of the sleeve 102, preferably in a liquid-tight manner. An external thread 103 is provided at the end of the sensor 100 opposite the membrane end, with which the in situ sensor 101 can be connected to the device 1, in particular to the flow element 19, preferably directly.

[0102] Fig. Figure 3 shows ion currents (IC) in [A] over time t in [min] during the ashing of a carbon fiber at 700 °C. Curve 200 shows the ion current of CO2, curve 201 the ion current of hydrogen, curve 202 of benzene, curve 203 of aliphatic hydrocarbons, and curve 204 of aromatic hydrocarbons.

[0103] Fig. Figure 4 shows the ion currents (IC in [A]) over time t in [s] of various gases present in a reed switch (nitrogen (curve 300), hydrogen (curve 301), oxygen (curve 302) and helium (curve 303)). For online measurement of the gas composition of the glass tube of the reed switch, it was broken in situ directly under vacuum with a magnet.

[0104] Fig. Figure 5 shows the methanol concentration during the enzymatic production of methanol and formic acid from formaldehyde. A prior calibration of the mass spectrometer allows for the conversion of ion currents to concentrations. The high data density of the kinetics enables mathematical modeling of the enzyme reaction. Accordingly, it shows Fig. 5 the methanol concentration c in g / l over the progressing time t in minutes.

Claims

[1] Device (1) for mass spectrometric analysis of substances present in liquid and gaseous samples, comprising aa) a mass spectrometer (29), bb) at least one inlet (2) for a liquid sample and cc) at least one additional inlet (4, 6) for a gaseous sample, wherein the at least one inlet (2) for a liquid sample has a hydrophobic at least partially porous membrane (13) with an average pore radius of 0.001 to 0.1 µm, by means of which volatile substances present in the liquid sample can be converted into the gaseous state. [2] Device according to claim 1, which additionally has at least one inlet (8) for a calibration medium. [3] Device according to claim 1 or 2, wherein the at least one inlet (4, 6) for a gaseous sample is designed as a capillary inlet. [4] Device according to claim 3, wherein the capillary inlet has a quartz-coated and heatable capillary. [5] Device according to any one of claims 1 to 4, wherein the mass spectrometer (29) comprises an ion source (F101), an analyzer (27) and a detector (E101). [6] Device according to any one of claims 1 to 5, wherein the mass spectrometer (29) is a quadrupole mass spectrometer (29). [7] Device according to any one of claims 1 to 6, wherein the mass spectrometer (29) is a process mass spectrometer (29).

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