Analysis device with a low-maintenance light source arrangement

Abstract

Analysis device (1) containing a chamber (2) containing an interior (3) which is filled with a liquid containing an analyte (4) to be measured, the chamber (2) having a liquid path (7) between the first (5) and the second wall (6), a light source arrangement (8) irradiating the interior of the chamber with UV light, a measuring detector (9) having at least one light source arrangement (8) observing the light across the liquid path (7), which is arranged opposite the second wall and is connected to a device (10) measuring and evaluating the light intensity, characterized in that the light source arrangement (8) comprises at least two light sources (11.1-11.2), preferably at least three light sources (11.1-11.3), each arranged at a distance of 1 mm to 1 m from the first wall (5) of the chamber, wherein the measuring and evaluating device (10) comprises a control which is designed to keep the UV radiation intensity of the at least two (11.1-11.2), preferably at least three, light sources (11.1-11.3) acting on the flowing liquid constant over the entire cross-section of the chamber (2), wherein preferably the at least two (11.1-11.2), preferably at least three light sources (11.1-11.3) are LEDs.

Description

The invention relates to an analysis device comprising a low-maintenance light source arrangement and to a method for analyzing analytes by means of the low-maintenance light source arrangement.Analytical devices based on absorption of an analyte in the infrared (IR) to UV range can be used to measure concentrations of analytes.Such analytes can be, for example, organic molecules such as proteins, nucleic acids, sugars, the sum of the dissolved organic constituents in an aqueous sample, and inorganic cations and anions, for example nitrates, or gases.Most analyzers for detecting analytes or substances that absorb in the ultraviolet (UV) range use a mercury lamp, deuterium lamp, or xenon flash lamp as a light source. Such instruments include cells or flow cells in which a solution containing one or more UV absorbing substances is passed between a UV light source (e.g., a mercury lamp) and a UV detector (e.g., a photomultiplier or photodiode), and changes in the intensity of the UV light reaching the detector are related to the concentration of the UV absorbing substances in the solution.LEDs are increasingly being used in analyzers because they are small compared to mercury lamps and allow a more compact installation. LEDs, however, also have disadvantages. In particular, UV LEDs have a decreasing intensity over a longer operating period. At the end of the lamp life period, a sudden complete failure often occurs. The decreasing intensity of the light source has negative effects on the measurement range, the accuracy and the detection limit of the measuring device. Due to the failure of the light sources, replacement of the light sources and thus maintenance is required.The object of the invention is therefore to provide a light source arrangement which significantly extends the maintenance intervals of the analysis device, i.e. by a multiple of the maintenance intervals from half to one year, and which makes it possible to maintain a stable light intensity of the analysis device over the entire product life and thus to achieve a constant measurement performance.The object is achieved by the analytical device (1) according to the invention, comprisinga chamber (2) containing an interior space (3) which contains a liquid containing an analyte (4) to be measured, wherein the chamber (2) has a liquid path (7) between the first (5) and the second wall (6),a light source arrangement (8) irradiating the interior of the chamber with UV light,a sensor (9) which views the light of the light source arrangement (8) via the liquid path (7) and is arranged opposite the second wall and is connected to a device (10) which measures and evaluates the light intensity, characterized in that the light source arrangement (8) comprises at least two light sources (11.1-11.2), preferably at least three light sources (11.1-11.3), which are each arranged at a distance of 1 mm to 1 m from the first wall (5) of the chamber, wherein the measuring and evaluating device (10) comprises a controller which is designed to keep the UV radiation intensity of the at least two, preferably at least three light sources, applied to the flowing liquid, constant over the entire cross section of the measuring chamber, wherein preferably the light sources are LEDs.The light source arrangement according to the invention provides an analysis device which has a plurality of light sources which can be operated simultaneously with reduced power or can be connected one after the other, as a result of which the maintenance outlay of the light source arrangement is significantly reduced.Compared to the prior art, the maintenance intervals are increased by at least a factor of 2, preferably by at least a factor of 3. Even more preferably, the maintenance intervals are increased by a factor of 3 to 10.In one embodiment of the analysis device, the path length of the at least two (11.1-11.2), preferably at least three light sources (11.1-11.3), is between 1 mm and 50 mm or 0.5 to 1.5 m.In one embodiment of the analysis device, the at least two light sources (11.1-11.2), preferably at least three light sources (11.1-11.3), are arranged on an arc (12), which runs concave with respect to the longitudinal axis (L) of the chamber (2), or on a line parallel to the longitudinal axis (L) of the chamber.In one embodiment of the analysis device, the arc ( 12) is preferably arranged on a plane perpendicular or parallel to the longitudinal axis of the chamber (L).In one embodiment of the analysis device, the chamber (2) is (a) a flow chamber containing an inflow and an outflow or (b) a cuvette.In one embodiment of the analysis device, a beam splitter (13), preferably a semi-transparent mirror (13), is situated in the beam path between the at least two (11.1-11.2), preferably at least three light sources (11.1-11.3), respectively, and the chamber (2), wherein the beam splitter, preferably semi-transparent mirror (13), is designed to (a) conduct a first part of the radiation of the respective light sources through the measurement sample to the measurement detector (9) and (b) conduct a second part of the radiation of the respective light sources to a reference detector (14), which is designed to measure the impinging radiation in order to determine the radiation intensity, wherein, if a predefined beam intensity falls below, the coupled-in power is adjusted to the LEDs via the controller.An adaptation of the power coupled in takes place from 0.5% underprint of the light intensity, preferably at 0.5-1% underprint of the light intensity.In one embodiment of the analysis device, at least two to all light sources, preferably at least three to all light sources, preferably 2-32, more preferably 3-32, even more preferably 2-16, most preferably 3-16, light sources are simultaneously turned on simultaneously.In one embodiment of the analysis device, 2 to 16, preferably 3 to 16, light sources, preferably LEDs, are simultaneously switched on.In one embodiment of the analysis device, the at least two light sources, preferably at least three light sources, preferably LEDs, lie in a wavelength range between 220 nm and 950 nm, wherein the at least two, preferably at least three, light sources have a uniform wavelength.In one embodiment of the analysis device, the at least two light sources, preferably at least three light sources, preferably LEDs, have a wavelength of 270 to 280 nm, preferably 275 nm.In one embodiment of the analysis device, the at least two light sources, preferably at least three light sources, preferably LEDs, have a wavelength of 463 nm, 527 nm, 590 nm, 621 nm, 840 nm, 850 nm, 875 nm, 880 nm, 885 nm, 890 nm, 940 nm or 950 nm.In one embodiment of the analysis device, the temperature of the liquid to be analyzed is between -20° C. and 150° C.In one embodiment of the analysis device, the temperature of the liquid to be analyzed is more than 0-8° C. or 100-150° C.Suitable liquids are aqueous liquids at temperatures of from 0 to 8° C. and up to 100° C. At higher temperatures, the liquids are oils, for example mineral oils or vegetable fats, for example palm oil.The invention also relates to a method for analyzing a measured variable in a measurement fluid, the method comprising:providing an analysis device according to the invention or an embodiment thereof containing at least two light sources (11.1-11.2), preferably at least three light sources (11.1-11.3)measuring the light intensity of the radiation impinging on the reference detector (14) and on the measurement detector (9), wherein the measurement electrode detects the radiation from a path length comprising the chamber (2) containing one or more reference solutions and subsequently the measurement solution or solutions, wherein the light intensity of the radiation is measured from:at least two light sources (11.1-11.2), for example of two to 16 light sources, preferably 3 to 16 light sources, orall light sources of the light source arrangement (8) are determined simultaneously, whereinthe light intensity is kept constant by continuously determining the radiation incident on the reference detector (14), transmitting it to the controller and, if a predefined beam intensity is undershot, adapting the coupled-in power to the LEDs by the controller.The light sources, which are designed as LEDs, typically comprise at least one electronic semiconductor component which emits light when current flows through. The light sources as described in this invention are embodied as multi-LED chips and thus consist of a multiplicity of individual semiconductor elements (LEDs).Both the measurement detector and the reference detector can be embodied as a diode or as a photomultiplier.It shows: FIG. 1 shows an embodiment of the analysis device according to the invention.FIG. 1 shows an embodiment of the analysis device according to the invention with seven light sources (11.1-11.7) and a chamber (2) which is designed as a cuvette. These light sources are either switched simultaneously or they are switched symmetrically one after the other. In addition to the measurement using the measurement detector (9), the light intensity is measured using a reference detector (14), which measures the light intensity independent of the analyte and passes it on to the controller of the evaluation device (10): a beam splitter (13.1-13.7), preferably a semi-transparent mirror (13.1-13.7), is arranged in the beam path between a respective light source and the chamber, as a result of which a first part of the radiation of the respective light sources is conducted through the measurement sample to the measurement detector (9) and a second part of the radiation of the respective light source is conducted to the reference detector (14). By controlling the evaluation device ( 10), the intensity of the radiation sources is adjusted via the power coupled to the LEDs in such a way that a constant light intensity impinges on the chamber ( 2) and the sample located therein.First, measurements are made with reference samples to calibrate the device. After the use of reference samples, these are removed from the cuvette (2) by a suction process. Before the subsequent measuring process, the cuvette is rinsed one or more times either with water or with a suitable cleaning solution. A flow cell is rinsed with a suitable cleaning solution, for example water, before measurement samples containing an analyte to be measured are conducted into the chamber.All the above-described embodiments of the analysis device can each be combined with one another and these can be combined with the analysis method, provided that this is technically possible.Reference numerals are not to be understood as limiting the scope of the subject matter protected by the claims. They are intended merely to make the claims more readily understood.List of reference characters1 Analysis device 2 chamber, cuvette, flow cell 3 interior space of chamber 4 analyte 5 first wall 6 second wall 7 liquid path 8 light source arrangement 9 measurement detector 10 evaluation device 11, 11.1-11.7 light sources 12 arc 13, 13.1-13.7 beam splitter, semi-transparent mirror 14 reference detector L longitudinal axis of the chamber

Claims

Analysis device (1) containing a chamber (2) containing an interior (3) which contains an analyte (4) to be measured with a liquid, wherein the chamber (2) has a liquid path (7) between the first (5) and the second wall (6), a light source arrangement (8) which irradiates the interior of the chamber with UV light, a measurement detector (9) which is arranged opposite the second wall and is connected to a device (10) which measures and evaluates the light intensity, with at least one measurement detector (9) which views the light of the light source arrangement (8) via the liquid path (7), characterized in that the light source arrangement (8) comprises at least two light sources (11.1-11.2), preferably at least three light sources (11.1-11.3), which are each arranged at a distance of 1 mm to 1 m from the first wall (5) of the chamber, wherein the measuring and evaluating device (10) comprises a controller which is designed to keep the UV radiation intensity of the at least two (11.1-11.2), preferably at least three light sources (11.1-11.3), which is applied to the flowing liquid, constant over the entire cross section of the chamber (2), wherein the at least two (11.1-11.2), preferably at least three light sources (11.1-11.3), are preferably LEDs.The analysis device according to claim 1, wherein the path length of each of the at least two (11.1-11.2), preferably at least three light sources (11.1-11.3), is between 1 and 50 mm or 0.5 to 1.5 m.The analysis device according to claim 1, wherein the at least two light sources (11.1-11.2), preferably at least three light sources (11.1-11.3), are arranged on an arc (12), which runs concave with respect to the longitudinal axis (L) of the chamber (2), or on a line parallel to the longitudinal axis of the chamber (L).Analysis device according to claim 3, wherein the arc (12) is preferably arranged on a plane perpendicular or parallel to the longitudinal axis of the chamber (L).Analysis device according to one of Claims 1-4, wherein the chamber (2) is (a) a throughflow chamber containing an inflow and an outflow or (b) a cuvette.Analysis device according to one of claims 1 - 5, wherein a beam splitter (13), preferably a semi-transparent mirror (13), is located in the beam path between the at least two (11.1-11.2), preferably at least three light sources (11.1-11.3) and the chamber (2), wherein the beam splitter, preferably semi-transparent mirror (13), is designed to (a) direct a first part of the radiation of the respective light sources through the measurement sample to the measurement detector (9) and (b) direct a second part of the radiation of the respective light source to a reference detector (14), which is designed to measure the incident radiation in order to determine the radiation intensity, wherein if a predefined radiation intensity falls short of it, the coupled-in power is adapted to the LEDs via the controller.The analysis device according to any one of claims 1-6, wherein at the same time at least two to all light sources, preferably at least three to all light sources, preferably 2-32, more preferably 3-32, even more preferably 2-16, most preferably 3-16 light sources are switched on.Analysis device according to one of Claims 1 - 7, wherein 2 to 16 light sources, preferably 3 to 16 light sources, preferably LEDs, are switched on simultaneously in each case.The analysis device according to any one of claims 1-8, wherein the at least two light sources, preferably at least three light sources, more preferably LEDs, lie in a wavelength range between 220 nm and 950 nm, wherein the at least two light sources, preferably at least three light sources have a uniform wavelength.The analysis device according to claim 9, wherein the at least two light sources, preferably at least three light sources, further preferably LEDs, have a wavelength of 270 to 280 nm, preferably 275 nm.The analysis device according to claim 9, wherein the at least two light sources, preferably LEDs, have a wavelength of 463 nm, 527 nm, 590 nm, 621 nm, 840 nm, 850 nm, 875 nm, 880 nm, 885 nm, 890 nm, 940 nm or 950 nm.The analysis device according to any one of claims 1-11, wherein the temperature of the liquid to be analyzed is between -20°C and 150°C.The analysis device of claim 11, wherein the temperature of the liquid to be analyzed is greater than 0-8°C or 100-150°C.Method for analyzing a measurement variable in a measurement fluid, the method comprising: providing an analysis device according to one of Claims 1-13 containing at least two light sources (11.1-11.2), preferably at least three light sources (11.1-11.3), measuring the light intensity of the radiation impinging on the reference detector (14) and on the measurement detector (9), wherein the measurement electrode detects the radiation from a path length which comprises the chamber (2) containing one or more reference solutions and subsequently the measurement solution or measurement solutions, wherein the light intensity of at least two light sources (11.1-11.2), for example of two to 10 light sources or all light sources of the light source arrangement (8) is determined simultaneously, wherein the light intensity is kept constant in which the radiation impinging on the reference detector (14) continuously determines, The power coupled to the LEDs is transmitted to the controller and, if a predefined beam intensity falls below, is adjusted by the controller.

Images