Automatic analysis device
View Patent ↗There is provided a high-accuracy automatic analysis device achieving both of measurement in a wide concentration range and high sensitivity at a low concentration. The signals of a plurality of wavelengths λ 1 to λ 12 where the sensitivity of light absorption caused by fine particles is high from a light source 40 are converted to absorbances by a spectroscopic optical system (detector) 41 . The absorbances are converted to a secondary parameter from in which a noise component is cancelled by using a previously-defined conversion table 54 , so that a concentration of a measured material (predetermined component) is calculated by an operation unit (calculating means) 53 based on the secondary parameter. Thus, analysis being resistant to the noise even at the low concentration can be achieved in a range up to a high concentration.
1. An automatic analysis device for measuring a component of a sample based on light absorption caused by latex agglutination or immunonephelometry, comprising:
at least one reaction container;
a sample probe discharging a sample into the reaction container;
a reagent probe discharging a reagent into the reaction container;
a light source irradiating light through the reaction container;
a detector detecting light transmitted from the light source through the reaction container, for separating the light into a plurality of wavelengths, and for outputting a plurality of photocurrents, each photocurrent associated with a respective wavelength; and
a signal processing circuit, coupled to the detector, configured to calculate a concentration of a predetermined component in the sample, including:
logarithm amplifiers configured to convert the plurality of photocurrents to a plurality of absorbance values,
analog-to-digital converters, coupled to the logarithm amplifiers, configured to digitize the plurality of absorbance values,
a conversion table configured to store data corresponding to coefficient k representing a gradient of the wavelength dependency of the absorption caused by the aggregation, which is set to a different value for each predetermined component, the conversion table further configured to store data corresponding to A and B coefficients obtained by the least square method,
a calibration table configured to store calibration data obtained by previously examining a relationship between a concentration of a predetermined component and a value, a change amount, or a change gradient of the secondary parameter at a specific timing in the reaction process,
a variable conversion unit, coupled to the analog-to-digital converters and conversation table, configured to convert the digitized absorbance values to a secondary parameter, h(λ), using a linear combination of a signal function f(λ)=exp(−kλ) and a noise function g(λ)=a constant value caused by air bubbles in the sample,
the secondary parameter governed by the equation:
h (λ)= A·f (λ)+ B·g (λ), and
an operation unit, coupled to the variable conversion unit, for determining the concentration of the predetermined component based on the secondary parameter by using the stored calibration data in the calibration table.
2. The automatic analysis device according to claim 1 , wherein the negative coefficient is set to a different value depending on a type of measurement.
3. The automatic analysis device according to claim 1 , wherein an absorbance value at a wavelength where the absorbance value is higher than a previously-determined absorbance value is not used for calculating the concentration of the predetermined component.
4. The automatic analysis device according to claim 1 , wherein a plurality of times of measurement are performed in a process of reaction progress in the reaction container to previously examine a relationship between the concentration and a value, a changed amount, or a change gradient of the secondary parameter obtained in each time of the measurement, so that the concentration of the predetermined component in the sample is calculated based on the relationship.