METHOD FOR MEASURING A CONCENTRATION OF A GAS

Abstract

A method of measuring a concentration of a gas in the headspace of a container is provided. The headspace contains particles and/or droplets and/or the container carries on an exterior section surrounding the headspace particles and/or droplets. The container is at least in parts transparent to electromagnetic radiation. The method comprises the steps: subjecting said headspace to input electromagnetic radiation; receiving from said headspace output electromagnetic radiation in form of transmitted and/or reflected and/or diffused input electromagnetic radiation; and generating from said received electromagnetic radiation a concentration indicative result; thereby diffusing outside the container and distant from the container said input electromagnetic radiation and/or diffusing outside the container and distant from the container said output electromagnetic radiation and/or moving said headspace with respect to said input electromagnetic radiation.

Claims

1. A method of measuring a concentration of a gas in the headspace of a container, wherein said headspace contains particles and/or droplets and/or said container carries on an exterior section surrounding said headspace particles and/or droplets and wherein the container is at least in parts transparent to electromagnetic radiation, the method comprising the steps: subjecting said headspace to input electromagnetic radiation; receiving from said headspace output electromagnetic radiation in form of transmitted and/or reflected and/or diffused input electromagnetic radiation; and generating from said received electromagnetic radiation a concentration indicative result; thereby a) diffusing outside the container and distant from the container said input electromagnetic radiation and/or b) diffusing outside the container and distant from the container said output electromagnetic radiation and/or c) moving said headspace with respect to said input electromagnetic radiation.

2. The method according to claim 1, wherein at least one of a) diffusing outside the container and distant from the container said input electromagnetic radiation; and b) diffusing outside the container and distant from the container said output electromagnetic radiation; is performed.

3. The method according to claim 1, wherein said particles and/or droplets are at least partially distributed in said headspace, in form of an aerosol and/or in form of particles and/or droplets on walls of said container.

4. The method according to claim 1, wherein the particles are particles of a lyophilisate.

5. The method according to claim 2, further comprising the step of additionally diffusing outside and distant of the container the input and/or output electromagnetic radiation.

6. The method according to claim 2, wherein the step of diffusing takes place on the surface and/or throughout the volume of a diffusor element.

7. The method according to claim 6, wherein at least one diffusor element is an etched or sandblasted surface.

8. The method according to claim 6, wherein at least one diffusor element is a plastic body.

9. The claim 6, wherein at least one diffusor element is moved.

10. The claim 1, wherein said input electromagnetic radiation is a narrow-band laser radiation, in the near-infrared range.

11. The method according to claim 1, wherein said concentration of a gas is the concentration of oxygen (O.sub.2); water vapor (H.sub.2O); hydrofluoric acid (HF); ammonia gas (NH.sub.3); acetylene (C.sub.2H.sub.2); carbon monoxide (CO); hydrogen sulfide (H.sub.2S); ethylene (C.sub.2H.sub.4); ethane (C.sub.2H.sub.6); methane (CH.sub.4); hydrochloric acid (HCl); formaldehyde (H.sub.2CO); carbon dioxide (CO.sub.2); ozone (O.sub.3); chloromethane (CH.sub.3Cl); sulfur dioxide (SO.sub.2); or nitrogen oxides (NO, N.sub.2O, NO.sub.2).

12. The method of producing a gas concentration tested container with a gas in the headspace, wherein said headspace contains particles and/or droplets and/or said container carries on an exterior section surrounding said headspace particles and/or droplets, wherein the container is at least in parts transparent to electromagnetic radiation, wherein the gas concentration lies in a predetermined concentration range and wherein the method comprises the steps of claim 1, and further comprises the step of either accepting said container as positively tested gas concentration container if the concentration determined is in said predetermined concentration range; or rejecting said container as negatively tested gas concentration container if the concentration determined is outside said predetermined concentration range.

13. The method according to claim 12, wherein the predetermined concentration range is 0%-21%.

14. An apparatus for performing the method according to claim 1, the apparatus comprising: a transmitter configured to direct input electromagnetic radiation towards a measuring zone, a holder configured to position said headspace of said container in said measuring zone, a receiver configured to receive output electromagnetic radiation emitted from said measuring zone, and an evaluation unit operably connected to said receiver and configured to generate a concentration indicative result based on the output electromagnetic radiation received by said receiver, wherein a diffusor element is arranged between said transmitter and said measuring zone; and/or a diffusor element is arranged between said measuring zone and said receiver; and/or said holder is movable with respect to said transmitter.

15. The apparatus according to claim 14, wherein a diffusor element is arranged between said transmitter and said measuring zone; or a diffusor element is arranged between said measuring zone and said receiver.

16. The apparatus according to claim 15, comprising a further diffusor element.

17. The apparatus according to claim 15, wherein at least one diffusor element diffuses electromagnetic radiation on its surface and/or throughout its volume.

18. The apparatus according to claim 15, wherein at least one diffusor element is an etched or sandblasted surface.

19. The apparatus according to claim 15, wherein at least one diffusor element is a plastic body.

20. The apparatus according to claim 15, wherein at least one diffusor element is mounted movable.

21. The apparatus according to claim 14, wherein said transmitter is a laser, emitting electromagnetic radiation in the near-infrared range.

22. An automatic headspace gas analyzer for measuring a concentration of a gas in the headspace of a container, wherein said headspace contains particles and/or droplets and wherein the container is at least in parts transparent to electromagnetic radiation, the automatic headspace gas analyzer comprising: an apparatus according to claim 14, a conveyor system configured to transport the headspace of containers to and from said measuring zone.

Description

[0058] The invention shall now be further exemplified with the help of figures. The figures show:

[0059] FIG. 1 a schematic view of the apparatus according to the invention for performing the method of measuring a concentration of a gas;

[0060] FIG. 2 a schematic view of an embodiment of the apparatus according to the invention for performing the method of measuring a concentration of a gas;

[0061] FIG. 3 a schematic view of a further embodiment of the apparatus according to the invention for performing the method of measuring a concentration of a gas;

[0062] FIG. 4a a schematic drawing illustrating the method of measuring a concentration of a gas according to the invention;

[0063] FIG. 4b a further schematic drawing illustrating the method of measuring a concentration of a gas according to the invention;

[0064] FIG. 5 an exemplary measurement from which a concentration indicative result may be derived, the measurement resulting as intermediate result in performing an embodiment of a method of measuring a concentration of a gas according to the invention;

[0065] FIG. 6 a flow chart of the method according to the invention of producing a gas concentration tested container with a gas in the headspace having a gas concentration lying in a predetermined concentration range.

[0066] FIG. 1 shows schematically and simplified, an apparatus according to the invention for performing the method of measuring a concentration of a gas.

[0067] The illustrated apparatus comprises a transmitter 1 configured to transmit electromagnetic radiation 4. Furthermore, the apparatus comprises a holder 5 by which a container 10 with a headspace 11 can be positioned such that the headspace 11 is arranged inside a measuring zone 6. Moreover, the apparatus comprises a receiver 2 configured to receive output electromagnetic radiation 4 in form of transmitted and/or reflected input electromagnetic radiation 4 the measuring zone 6 or rather the headspace 11 is subjected to. Even further, the apparatus comprises an evaluation unit 7 configured to generate based on the electromagnetic radiation received by the receiver 2 a concentration indicative result. In addition, the apparatus comprises at least one means of averaging over a multiplicity of various possible radiation paths of the electromagnetic radiation traversing the headspace of the container. On the one hand, such a means can be configured to diffuse 21 electromagnetic radiation 4 being transmitted by the transmitter 1 and provide thereby diffuse input electromagnetic radiation 4 the measuring zone 6 or rather the headspace 11 is subjected to. On the other hand, such a means can be configured to diffuse 22 output electromagnetic radiation 4 in form of transmitted and/or reflected input electromagnetic radiation 4 before the output electromagnetic radiation 4 is received by the receiver 2. Moreover, such a means can be configured to move 23 the headspace 11 with respect to the input electromagnetic radiation 4. The aforementioned means can be applied solely or in various combinations.

[0068] FIG. 2 shows schematically and simplified, an embodiment of an apparatus according to the invention for performing the method of measuring a concentration of a gas and a container in measuring position.

[0069] The illustrated apparatus comprises a transmitter 1 that transmits electromagnetic radiation 4. The electromagnetic radiation 4 is diffused by a diffusor element 3 being part of the apparatus. On a holder 5, also being part of the apparatus, a container 10 is placed. The exemplary container 10 contains a content 13, such as a lyophilized pharmaceutical, but is not fully filled with the content 13 such that above the content 13 a headspace 11 is formed. Particles and/or droplets 12 of the content 13 are attached to the wall of the container 10 in the region of the headspace 11. The headspace 11 is subjected to input electromagnetic radiation being diffused by the diffusor element 3 that is positioned between the transmitter 1 and the container 10 or rather the measuring zone where the headspace 11 is intended to be positioned. Output electromagnetic radiation 4 in form of transmitted and/or reflected input electromagnetic radiation is received by a receiver 2 being part of the apparatus. Based on the received output electromagnetic radiation 4 an evaluation unit 7 generates a concentration indicative result. The evaluation unit 7 is also part of the apparatus.

[0070] FIG. 3 shows schematically and simplified, a further embodiment of an apparatus according to the invention for performing the method of measuring a concentration of a gas and a container in measuring position.

[0071] This further embodiment differs from the embodiment shown in FIG. 2 both in terms of the amount and position of the diffusor element and in terms of the distribution of the particles/droplets 12 in the headspace 11. Instead of only one diffusor element, this embodiment comprises two diffusor elements 3, 3. The two diffusor elements 3, 3 are arranged in series, one 3 after the other 3. As a consequence, the electromagnetic radiation 4 transmitted by the transmitter 1 is diffused two-staged or in two steps. One step is performed by the first diffusor element 3, the second step is performed by the second diffusor element 3. Both diffusor elements 3, 3 are arranged outside the container 10, after the transmitter 1 and in front of the container 10, in the pathway of the electromagnetic radiation 4. As an example, which is not specific to the embodiment of the apparatus shown, the particles and/or droplets 12 are not attached to the wall of the container as shown in FIG. 2 but are finely distributed in the headspace 11 in the form of mist or dust.

[0072] FIG. 4a shows a schematic drawing that illustrates three variants of the method of measuring a concentration of a gas according to the invention. Vertical dashed lines separate the four variants marked as a+b, a and b.

[0073] What is common to all three variants shown are the steps of: [0074] Subjecting 201 of the headspace to input electromagnetic radiation, [0075] receiving 202 from the headspace output electromagnetic radiation in form of transmitted and/or reflected input electromagnetic radiation and [0076] generating 203 from the received electromagnetic radiation a concentration indicative result.

[0077] Furthermore, on the left hand side and indicated by the letters a+b, the steps of: [0078] diffusing 21 outside the container the input electromagnetic radiation and [0079] diffusing 22 outside the container the output electromagnetic radiation is shown.

[0080] Additionally, in the middle and indicated by the letter a, the step of: [0081] diffusing 21 outside the container the input electromagnetic radiation is shown.

[0082] Moreover, on the right hand side and indicated by the letter b, the step of: [0083] diffusing 22 outside the container the output electromagnetic radiation is shown.

[0084] FIG. 4b shows a further schematic drawing that illustrates four variants the method of measuring a concentration of a gas according to the invention. Vertical dashed lines separate the four variants marked as a+b+c, a+c, b+c and c.

[0085] What is common to all four variants shown are the steps of: [0086] subjecting 201 of the headspace to input electromagnetic radiation, [0087] receiving 202 from the headspace output electromagnetic radiation in form of transmitted and/or reflected input electromagnetic radiation and [0088] generating 203 from the received electromagnetic radiation a concentration indicative result.

[0089] Furthermore, on the left hand side and indicated by the letters a+b+c, the steps of: [0090] diffusing 21 outside the container the input electromagnetic radiation, [0091] diffusing 22 outside the container the output electromagnetic radiation and [0092] moving 23 the headspace with respect to the input electromagnetic radiation are shown.

[0093] Additionally, in the middle left and indicated by the letters a+c, the steps of: [0094] diffusing 21 outside the container the input electromagnetic radiation and [0095] moving 23 the headspace with respect to the input electromagnetic radiation are shown.

[0096] Moreover, in the middle right and indicated by the letters b+c, the steps of: [0097] diffusing 22 outside the container the output electromagnetic radiation and [0098] moving 23 the headspace with respect to the input electromagnetic radiation are shown.

[0099] The variant shown on the right hand side and indicated by the letter c is characterized by the step of: [0100] moving 23 the headspace with respect to the input electromagnetic radiation are shown.

[0101] FIG. 5 shows an exemplary measurement from which a concentration indicative result that can be derived, the measurement resulting as intermediate result in performing an embodiment of a method of measuring a concentration of a gas according to the invention.

[0102] The graph shows the intensity of electromagnetic radiation (y-axis) plotted against the wavelength of the electromagnetic radiation (x-axis). Furthermore, the intensity I.sub.0 of the electromagnetic radiation transmitted by the transmitter (upper dashed line) is indicated. The continuous line shows the wavelength-dependent intensity of the output electromagnetic radiation received by the receiver. The intensity of the output electromagnetic radiation comprises a minimum I.sub.min for the wavelength X (lower dashed line). This wavelength represents the absorption maximum of the gas in the headspace of the container. Such a graph provides several comparative values I.sub.1, I.sub.2 and I.sub.3 that can be used for determining the concentration indicative result being indicative for the gas in the headspace, e.g. as function of I.sub.2 and I.sub.0.

[0103] FIG. 6 shows a method 200 of producing a gas concentration tested container with a gas in the headspace, the headspace containing particles and/or droplets, the container being at least in parts transparent to electromagnetic radiation, the gas concentration lying in a predetermined concentration range, in particular a concentration range having its upper limit below 21%, in particular below 2.0%. The method may in particular be applied to oxygen concentration. The method comprises as first steps: [0104] subjecting 201 the headspace to input electromagnetic radiation; [0105] receiving 202 from the headspace output electromagnetic radiation in form of transmitted and/or reflected input electromagnetic radiation; [0106] generating 203 from the receiving electromagnetic radiation a concentration indicative result; [0107] thereby [0108] a) diffusing 21 outside the container said input electromagnetic radiation and/or [0109] b) diffusing 22 outside the container said output electromagnetic radiation and/or [0110] c) moving 23 said headspace with respect to said input electromagnetic radiation.

[0111] Then, depending on the determined concentration the decision 210 is made whether the determined gas concentration lies in the predetermined range or not.

[0112] If the concentration is in the predetermined concentration range (arrow yes), the step [0113] accepting 204 the container as positively tested gas concentration container is performed.

[0114] If the concentration is outside the predetermined concentration range (arrow no), then the step [0115] rejecting 205 the container as negatively tested gas concentration container is performed.

[0116] As result, a gas concentration tested container with a gas in the headspace having a gas concentration that lies in the predetermined concentration range is produced.

LIST OF REFERENCE SIGNS

[0117] 1 transmitter [0118] 2 receiver [0119] 3 diffusor element [0120] 3, 3 diffusor elements [0121] 4 electromagnetic radiation [0122] 4 input electromagnetic radiation [0123] 4 output electromagnetic radiation [0124] 5 holder [0125] 6 measuring zone [0126] 7 evaluation unit [0127] 10 container [0128] 11 headspace [0129] 12 particles and/or droplets [0130] 13 contents [0131] 21 diffusing input electromagnetic radiation [0132] 22 diffusing output electromagnetic radiation [0133] 23 moving [0134] 200 method of producing a gas concentration tested container with a gas in the headspace [0135] 201 subjecting the headspace to input electromagnetic radiation [0136] 202 receiving from the headspace output electromagnetic radiation [0137] 203 generating a concentration indicative result [0138] 204 accepting the container as positively tested [0139] 205 rejecting the container as negatively tested [0140] 210 decision