Abstract:
An improved method and apparatus are disclosed for processing spectral data to remove undesired variations in such data and to remove interfering information present in the data. The method land apparatus corrects multiplicative effects present in the spectral data. Additive and interferent contributions can be corrected as well. In one aspect of the method, coefficients for a selected appropriate model are applied to the input spectral data based on first and second reference spectra. The spectral data are then corrected based on the estimated coefficients at least as to multiplicative errors for producing a linear additive structure for use in calibration, validation and determination by linear multivariate analysis. The method and apparatus will improve the accuracy of spectral data structures derived from measurements Using spectroscopy, chromatography, thermal analysis, mechanical vibration and acoustic analysis, rheology, electrophoresis, image analysis and other analytical technologies producing data of similar multivariate nature.
Abstract:
A multichamber cuvette for maintaining in independent and separate condition at least two reactants until such time that it is desired to mix them for reaction with each other and a reactant liquid sample while in the cuvette for analysis in the cuvette, and a method of use of such cuvette. There is provided a cuvette body of a suitable plastic defining at least two chambers interconnected by a passageway of relatively small cross section having at least the end portion thereof of capillary size to prevent under many circumstances, as by surface tension, accidental mixture of liquid reactants in the chambers. If there is a substantial head of liquid in one chamber and/or a risk of impact of the cuvette with an external foreign object, sufficient to break such surface tension, an air lock in the passageway when the latter is below the liquid levels in the chambers prevents such accidental mixture. A baffle in the passageway enhances separation of liquids and/or solid substances in the chambers. The chambers are open-topped, and a unitary probe-wiping multi-ply laminated cover of a type puncturable by a probe extends over the chambers closing them from the external environment. The laminated cover tends to be self-closing with reference to such punctures. One ply is of metal foil to act as a vapor seal and has an undercoating of a heat sealable material compatible with the body material and sealed thereto. The top ply is of a moisture-absorbent material which is secured to the foil ply by an intermediate plastic ply.
Abstract:
A method and apparatus for the determination of spectral samples is disclosed wherein spectral measurements are taken, normalization of the spectral measurements takes place, and a bilinear modeling is performed to extract spectral data. Once this data is derived, the interference quantitization levels are determined using multiple linear regression analysis, and are then removed from the sample readings in order to determine a more precise level of analyte spectra, such as analyte levels of glucose in serum or whole blood.
Abstract:
An improved flat field grating spectrometer for increasing the spectral resolutiion and usable spectral range. The spectrometer comprises an entrance slit or port, a concave grating, a field flattening lens and detection means encompassing the desired spectral region and capable of providing separate measurements between different regions of the spectral image plane. A second embodiment provides a beam splitter (dichroic or neutral density) placed between the grating and the detector to divert a portion of the energy at selected wavelengths through a second field flattening lens to a second detection means.
Abstract:
A method of and apparatus for determining stable and labile glycated compound levels in blood. Electromagnetic energy covering a multiplicity of wavelength bands within a wavelength range from 380 nm to 2500 nm is directed into a sample volume containing blood. Portions of the energy representative of both the source energy and energy after interacting with material within the sample volume are collected. The energy portions carry information relating to the source energy and the levels of labile and stable compounds within the sample volume, respectively. The portions are converted into electrical signals representative of the intensities of the respective portions in each of the multiplicity of wavelength bands. The electrical signals are pretreated in accordance with known information to remove deviations from established reference conditions to form data signals that are a function of the fractional portion of the energy in each of the wavelength bands absorbed and scattered by the material in the measurement volume. Selected groups of the data signals are processed in accordance with chemometric models developed from analysis of such data signals together with known values of the analytes derived from measurements on a calibration set of samples larger in number than the number of wavelength bands included in the set of the selected groups of data signals to develop analyte signals representative of the amounts of glycated compounds for which chemometric models have been developed and utilized. The analyte signals may be stored and displayed in a form suitable for medical use.
Abstract:
A multichamber cuvette for maintaining in independent and separate condition at least two reactants until such time that it is desired to mix them for reaction with each other and a reactant liquid sample while in the cuvette for analysis in the cuvette, and a method of use of such cuvette. There is provided a cuvette body of a suitable plastic defining at least two chambers interconnected by a passageway of relatively small cross section having at least the end portions thereof of capillary size to prevent under many circumstances, as by surface tension, accidental mixture of liquid reactants in the chambers. If there is a substantial head of liquid in one chamber and/or a risk of impact of the cuvette with an external foreign object, sufficient to break such surface tension, an air lock in the passageway when the latter is below the liquid levels in the chambers prevents such accidental mixture. A baffle in the passageway enhances separation of liquids and/or solid substances in the chambers. The chambers are open-topped, and a unitary probe-wiping multi-ply laminated cover of a type puncturable by a probe extends over the chambers closing them from the external environment. The laminated cover tends to be self-closing with reference to such punctures. One ply is of metal foil to act as a vapor seal and has an undercoating of a heat sealable material compatible with the body material and sealed thereto. The top ply is of a moisture-absorbent material which is secured to the foil ply by an intermediate plastic ply.
Abstract:
Apparatus and method for photometrically analyzing a constituent of interest in body or other fluids and well suited for kinetic determinations which are temperature-and-time dependent. There is provided a sample holder holding a cuvette supporting a liquid sample and other reactants among which is a trigger reactant to initiate the reaction which is analyzed. The trigger and the other reactants are initially isolated in the cuvette. The holder, one of a series, is moved periodically to move the cuvette, one of a series handled sequentially, to a temperature-sensing and preheating station, to a station where the contents of the cuvette are mixed to enable the reaction to proceed, to an optical station where the reaction is viewed for an optical density determination over a period of time under temperature conditions regulated within limits, and to a station for sensing the temperature of the mixture, by immersion of a temperature sensor therein, and supplying data for estimation of the real temperature during the optical determination for inclusion in the determination of the concentration of the constituent of interest, all in a relatively short period of time.
Abstract:
A method, system and apparatus for improving at least one of a) optical interactance measurements, b) optical transmittance measurements and c) optical reflectance measurements. The apparatus has a probe having a body portion and an tip portion. The body portion has a central tubular element having an opening therethrough. The tip portion has a central aperture and a number that is a plurality of ring openings therein. At least some of the plurality of rings are angled with respect to a longitudinal axis of the probe. A plurality of fiber optic bundles corresponds in number at least to the number of ring openings, and at least one fiber optic bundle is arranged at one end of the longitudinal axis for receiving specimen information and at another end of the longitudinal axis connected to a detector for receiving a signal.
Abstract:
Apparatus and a method are disclosed for the simultaneous or rapid sequential use of two or more different separations between the source and detector of the measuring apparatus to obtain spectral measurement data in diffuse transmission or “interaction” modes of collecting optical information from a specimen. The method and apparatus subsequently combine separate data taken from two or more different pathlengths to provide discrimination against undesired information while preserving or enhancing desired information. Additional reference information to normalize the optical signal is also provided. The optical and mechanical design of the optical probe also provides for transmittance, reflectance and interactance measurements on small amounts of specimen.
Abstract:
A lens for utilization in the radiation energy exit port of a radiation energy integrating sphere is provided, and functions to prevent instrumental specular radiation energy reflections from striking the interior wall surfaces of the sphere and being collected thereby. The instrumental specular radiation energy reflections include those from the lens, per se, and those from instrumentation disposed without the integrating sphere.