Procedure and apparatus for the quantitative determination of optic active substances.

p0001The invention relates to a method for the quantitative determination of the concentration of optically active substances, in particular of glucose in the body fluid of a patient by polarimetry to produce a comparison signal, in particular a difference or quotient signal, having two light sources, are generated with which linearly polarized light beams irradiate the analyte and pressurize via an analyzer a detector, as a fixed polarization direction of the second linearly polarized light bundle, a direction of polarization is chosen which deviates by a predetermined angle from the fixed polarization direction of the first linearly polarized light bundle, that the first and second light source in the alternately with a switching frequency switched on and off and that the associated measuring signals generated by the detector to the first and second linearly polarized light bundles are used to generate one or more comparison signals, in particular of difference or quotient signals, used, and also relates to an apparatus for performing the process.

p0002Such a method is known from DE-PS 39 08 114 C1, the apparatus described therein makes it possible to detect the concentration of optically active substances quantitatively and at the same time to reduce the influence of interference, for example due to aging of the constituent components. However, this device has the disadvantage that only the sum of the rotations of the optical light path located in the optically active substances can be detected with it. Therefore, it is not possible to determine the respective individual concentration components of interest in several optically rotating substances occur.

p0003Starting from this prior art, the invention aims to provide a device of the type mentioned, which makes it possible to detect the concentration of a predetermined optically rotating substance in the presence of other optically rotating substances quantitatively.

p0004This object is achieved for a method by the fact that indicative measurement signals are generated on a spectrally resolving multiple detector by a dispersing element in the beam path wavelength-dependent absorption, with their respective extinction in relation to a reference liquid to the concentration of each of a predetermined, optically rotating substance in can include the liquid, so that the said determined comparison signal of the optical rotation in the reference is corrected in this prior art optically rotating substances.

p0005This object is achieved according to a device achieved in that at least one dispersing element is provided in the beam path of the light beams that said or more detectors are designed as line detectors in the plane of the breaking or the diffraction angle of the dispersing element whose photo signal outputs latching to the measuring signals control and evaluation system is connected with the spectral signatures of the two liquids are respectively detected from which the concentrations of optically rotating interfering substances are determined that correspond to data stored in the control and evaluation, concentration-dependent optical rotation of predetermined substances, and with whose computing circuit a corrected control signal by the sum and / or difference formation from the said control signal having the thus calculated amounts of the optical rotation of one or more predetermined optically rotating substances is produced.

p0006Characterized in that the measurement and reference beam is spectrally dispersed, for example by means of a prism-like-structured cuvette, it is possible to determine the optical rotations for various contained in the fluids of optically rotating substances separately and so the example for an insulin pump to be used control signal in dependence from or to determine the desired substances. This results in the advantage that correction signals for previously known, probably, or definitely contained in the dialysate interfering substances are determined by the spectral decomposition of the measurement and reference light beams. These correction signals are added or subtracted, so that only remains generated from the material this optical rotation, from the corrected control signal can be derived for the comparison or control signal of the optical rotation of all substances contained in the liquid, depending on the direction of the optical rotation. Thus, the influence of also in the or the liquids existing, other optically rotating substances that could distort the measurement of the optical rotation, greatly reducing the on-utilizing measurement signal.

p0007Below exemplary embodiments of the invention are further illustrated by the drawings. Show it:<dl id="dl0001"><dt>Fig. 1</dt><dd>a schematic plan view of an apparatus for the quantitative determination of optically active substances according to an embodiment of the invention,</dd><dt>FIG. 2</dt><dd>a side view of the apparatus of Fig. 1, and</dd><dt>Fig. 3</dt><dd>a schematic plan view of an apparatus for the quantitative determination of optically active substances, according to another embodiment of the invention.</dd></dl>

p0008Fig. 1 shows a schematic representation of a plan view of an apparatus for the quantitative determination of optically refractive, optically absorbent, optical scattering and optically active substances according to a first embodiment. The apparatus comprises a first broadband light source 1 and the second wide-band light source 21 emit light at substantially the same wavelengths. These light sources 1 and 21 can be designed as light-emitting diodes, which operate in the same wavelength range of approximately 400 to 900 nanometers.

p0009Notwithstanding the use of FIG. 1 for illustrative representation of the simultaneous operation of the light sources 1 and 21, this work in measuring operation intermittently.

p0010The light sources 1 and 21 produce diverging light rays 2 and 22, which are deflected after passing through a polarizing beam splitter 31 by a collimator lens 32 into a parallel light beam. It could be with at least one lens for each beam path and each with a polarizer, for example in the form of a film, instead of the Strahteilerwürfels 31 with a collimator lens 32, a partially transparent mirror.

p0011The corresponding light beams 3 and 23 pass through holes 51 and 61 of a beam limiter 50 passes. Then they irradiate a cuvette 10 having a transparent to the wavelengths of the emitted light from the two light sources 1 and 21 front wall 12 and transparent back. 13 The cuvette has two chambers 14 and 15 which are separated by a partition wall 35 from each other. These chambers 14 and 15 extend parallel to the incident light beams 3 and 23 and extend from the front wall 12 to back wall 13. The first chamber 14 is filled with a dialysate 11, whereas the second chamber 15 is filled with a reference liquid 11 '. Preferably in the two chambers 14 and 15 are provided holes for the circulation of the liquids 11 and 11 'are not shown in the figures.

p0012The Doppelkammerküvette 10 has a front wall 12 advantageously has a beveled surface 33 which forms the cuvette a prism body. Advantageously, 38 can be introduced to the matched beam guiding and reinforcing spectral separation of the light beams 3 and 23 between the cell 10 and the beam limiter 50, an additional wedge.

p0013The wedge 38 by this additional spectral pre-separated light beams 3 and 23 then fall through the beveled prism surface 33 into the cuvette 10th

p0014The surface 33 is pivoted by an angle from the plane normal to the optical axis of the light beam 3 and 23, wherein this angle is the refractive angle 39 of the wedge 38 in one plane. The respective intermittently the two chambers 14 and 15 by radiating light beams 3 and 23 are thus spectrally further separated with simultaneous wavelength-dependent absorption, before they come out of the rear wall 13 of the cuvette 10th In FIG. 2, the rear wall 13 of the cuvette 10 is arranged substantially in the plane normal to the average optical axis of the various widening light beam 3 and 23. In another further development of the device, this rear wall 13 can be in accordance with the front wall 10 is also tapered so as to provide a larger refractive angle of the formed through the cuvette 10 prism.

p0015By the polarizing beam splitter 31, which can be formed for example by a beam splitter cube, the light beam 3 and 23 of the two light sources 1 and 21 are polarized perpendicularly to one another. Behind the rear wall 13 of the Doppelkammerküvette 10, a second polarizing beam splitter 36 is used as an analyzer, whose polarization plane is rotated with respect to the polarizing beam splitter 31 by 45 °. Thereby, the polarization directions of the beams 3 and 23 of the light beams from the light sources 1 and 21 are symmetrical, that is arranged with respect to an angle of 45 ° to the forward directions of the analyzer the two partial beams.

p0016The direct light passing through the polarizing beamsplitter 36 light passes through condenser lenses 53 and 63 on line detectors 54 and 64. The impinged with the reference liquid 11 'transmitted light line detector 64 forms the first reference detector. Next forms of the line detector 54 which is acted upon by the light passing through the dialysate light 11, a first measurement detector. The rows of detectors 54 and 64 are better seen in FIG. 2 wherein 'the individual measuring elements of the line detectors 54 and 64 are designated with 54. It is easy to recognize from Fig. 2 that the line detectors 54 and 64 lie in the plane of the refractive angle of the cuvette 10 and of the wedge 38th The measurement signals 54 and 64 received by the line detectors are the evaluation circuit 39, which may be provided with a measured value 40 fed. In this, due to the position of the respective, Spektralausschnitte representing part beams onto the line detectors 54 and 64, the optical refraction and the intensity ratios between the individual detectors 54 'of the detector lines 54 and 64, the Absorbtionsverhalten of the different components of the dialysate 11 or the reference liquid 11' are detected.

p0017To increase the spectral resolution a transparent optical grid 37 can be inserted between the polarizing beam splitter 36 and the condenser lenses 53 and 63rd There may also be provided only the optical grating 37 (without the wedge 38) and also having the cuvette 10 parallel walls 12 and 13. FIG. This may lead to a lower resolution to the detector rows 54 and 64, but avoids problems in the optical elements with respect to the no longer parallel beam guidance. It only needs at least a dispersing element in the optical path of the beams to be 3 and 23 are provided so that a spectral discrimination on detectors 54 'and 55 and 65 is possible.

p0018The drawn in FIG. 1 condenser lenses 53 and 63 are shown greatly oval to show the dispersion in the Doppelkammerküvette 10th In practice, however, the beam guide can be dimensioned so that circular collecting lenses can be used 53 and the 63rd

p0019Furthermore, the optical rotation of the individual components because of the different, corresponding to the signals intermits working light sources 1 and 21 on one and the same single detector 54 'of the line detector 54 can be detected. The measurement method corresponds to that of the Applicant in the DE 39 08 114 C1 in connection with the local Fig. 2 measurement method described in which on the latched signal photocurrents a difference or quotient signal is formed which in order to determine the concentration of the optically active substance 11 the dialysate can be used.

p0020Advantageously, from the spectrally resolved light beam by the intensity ratios between the individual detectors 54 'of the detector lines 54 and 64 the absorption properties of different components of the dialysate 11 or the reference liquid 11' is detected. Since the measurement signal of a specific wavelength range associated detector element 54 'a predetermined substance is assignable, it can be concluded directly on its concentration from the absorption of the light beams. This concentration of a previously known interfering substance, which are of course selected such that it is probable that they occur in the dialysate 11 is then in the evaluation circuit 39 corresponding to one of these substance and concentration optical rotation converted, determined in the specified below total optical rotation is included. The corresponding relation of the sign of the optical rotation determined with each other, whether it is in the optical rotation angle by the interfering substance to a rectified proportion and thus a subtraction or an opposite portion and therefore an addition to the measured total signal optical rotation.

p0021It is 54 'comprehensive line detector 54 and 64 so that a detection of the Störkonzentration possible by a variety of known, predetermined, probably, or definitely contained in the dialysate 11 substances with a, for example, hundreds of individual detectors, with the resulting additional optical rotations of the determined total rotation of the dialysate 11 is corrected, so that substantially only the optical rotation remains, for example, the self-non-absorbent and thus spectrally resolvable glucose.

p0022The deflected by the beamsplitter 36 light beams of the light sources 1 and 21 pressurize position sensitive detectors 55 and 65, which may comprise, for example (not shown in the drawing) two semicircular detector elements. Thus, by comparing the two signals to each other just by the smallest deviation respective dispersion determined. This result is more accurate than the determination on the line detectors 54 and 64 because there 'a large wavelength range, a plurality of detectors 54 sensitive, which eg can result in a patient differences in sensitivity at the long-term implantation of such a device which does not be compensated and falsify the measurement result. Through the determined dispersion the spectral measurement of the line detectors 54 and 64 can be calibrated.

p0023Next 65 is the total optical rotation of the dialysate 11 determined by comparing the total signal of the two halves of the second measurement detector 55 relative to the signal of the second reference detector. From this starting are then, as described above, the corresponding correction in accordance with the rotations determined by absorption measurements concentrations of interfering substances subtracted in the arithmetic circuit 39, so that finally results in the concentration of, for example, glucose. Such aforementioned highly optically rotating interfering substances may be particularly antibiotics, be turning in both directions and their signal strengths can make up 10 to 50 percent respectively of the total measured signal.

p0024Further laterally at the longitudinal sides of the chambers 14 and 15 of the cuvette 10 are scattered light detectors 56 and 66 are provided, with the aid of light scattering measurements can be made. This scattered light measurements follow a two-fold purpose. The entering into the cuvette dialysate also contains protein molecules. The larger of these molecules, in particular consisting of about 5000 atomic units, are usually kept in the preparation of the dialysate such as nets of entry into the cell. But the molecules under 5000 atomic units cause an optical rotation, which can account for 10 percent of the desired glucose-signal of the optical rotation. These molecules scatter the cuvette 10 passing light beam.

p0025Thus, the concentration of protein molecules can be detected by the intensity of the scattered light. The resultant, forming an interference effect, optical rotation of the protein molecules will be deducted in the calculation circuit 39 of the determined value of the optical rotation. Then remains in the obtained signal only the optical rotation of this substance, such as glucose, now that the interference of the optical rotation of spectrally not identifiable substances such as protein molecules by light scattering measurements, and the absorbent substances on the line detectors 54 and 64 of the detectors 55 and 65 determined total signal of the optical rotation have been eliminated.

p0026To improve the measurement sensitivity, advantageously, the process described in DE 39 08 114 C1 lock-in technique is used, with a maximum of a few kHz intermittently illuminating light sources 1 and 21 additionally modulated with a higher by at least an order of magnitude modulation frequency in the example.

p0027FIG. 3 shows a schematic plan view of an apparatus for the quantitative determination of optically active substances, according to another embodiment of the invention. Identical features bear the same, from FIGS. 1 and 2 acquired numerals.

p0028The deflection by a disposed directly behind the cuvette 10 further beam splitter cube 71 performs light beams 72 and 73 to the already described in connection with FIG. 1, the measuring arrangement with the line detectors 54 and 64 for spectral analysis and the detectors 55 and 65 to the dispersion determination and for determining the total signal of the optical rotation. The direct light passing through the beam splitter cube rays impinge further detectors 57 and 67, the detector 67 forms the reference detector. These are used for the direct measurement of the total optical rotation of the optically rotating substances contained in the dialysate eleventh Thus, the measurements are used at the respective two semicircular supplementary detectors 55 and 65 of the redundant determination of these signals and can be omitted for simplification of the evaluation circuit. 39 Then, it is measured with the aid of the detectors 55 and 65, only the refraction 'is used to match the spectrum to the rows of detector elements 54th However, the use of the four detectors arrays 54, 55, 56 and 57 (as well as 64, 65, 66 and 67 in the reference channel) for partially redundant determination of the measured values ​​with respect to the desired long-term stability during implantation in a human is desirable because such frequent operations for replacing the devices can be avoided.

p0029Finally, as light sources 1 and 21 and light bulbs are used, then called to generate the intermittent radiation beam chopper, chopper also be used.