Abstract: A method and apparatus for measuring and calibrating the measurement of small volumes of liquids. The small volumes of liquid are typically dispensed from liquid delivery devices, the delivery device often having multiple channels to analyze many samples at once. The liquid samples are delivered to one or more cells, typically in a multi-well plate, and positioned in a spectrophotometer for determining an absorbance of a chromophore in the liquid sample. Based upon an absorbance measurement and the concentration of the chromophore, a path length of the liquid sample is determined, from which a volume of the sample may be calculated. The method and apparatus provide various means for correcting for differences in the dimensions and/or other factors causing a non-linear deviation from the Beer-Lambert law. A system or kit may be provided including sets of sample solutions of varying dilution ranges for calibrating different liquid volumes.

Abstract: An apparatus and related method for optical calibration of spectrophotometers is described. The apparatus is a calibration plate including one or more cuvettes filled with solutions of interest. The cuvettes are sealed to prevent evaporation. The cuvettes also possess a compressible component to allow for expansion of the solution and a bubble control apparatus to ensure that the compressible component does not intersect the beam path. A piece of neutral density glass is optionally included in the apparatus to track optical changes of the solutions over time.

Abstract: A method and apparatus for measuring and calibrating the measurement of small volumes of liquids. The small volumes of liquid are typically dispensed from liquid delivery devices, the delivery device often having multiple channels to analyze many samples at once. The liquid samples are delivered to one or more cells, typically in a multi-well plate, and positioned in a spectrophotometer for determining an absorbance of a chromophore in the liquid sample. Based upon an absorbance measurement and the concentration of the chromophore, a path length of the liquid sample is determined, from which a volume of the sample may be calculated. The method and apparatus provide various means for correcting for differences in the dimensions and/or other factors causing a non-linear deviation from the Beer-Lambert law. A system or kit may be provided including sets of sample solutions of varying dilution ranges for calibrating different liquid volumes.

Abstract: A method and apparatus for measuring and calibrating the measurement of small volumes of liquids. The small volumes of liquid are typically dispensed from liquid delivery devices, the delivery device often having multiple channels to analyze many samples at once. The liquid samples are delivered to one or more cells, typically in a multi-well plate, and positioned in a spectrophotometer for determining an absorbance of a chromophore in the liquid sample. Based upon an absorbance measurement and the concentration of the chromophore, a path length of the liquid sample is determined, from which a volume of the sample may be calculated. The method and apparatus provide various means for correcting for differences in the dimensions and/or other factors causing a non-linear deviation from the Beer-Lambert law. A system or kit may be provided including sets of sample solutions of varying dilution ranges for calibrating different liquid volumes.

Abstract: A method and apparatus for measuring and calibrating the measurement of small volumes of liquids. The small volumes of liquid are typically dispensed from liquid delivery devices, the delivery device often having multiple channels to analyze many samples at once. The liquid samples are delivered to one or more cells, typically in a multi-well plate, and positioned in a spectrophotometer for determining an absorbance of a chromophore in the liquid sample. Based upon an absorbance measurement and the concentration of the chromophore, a path length of the liquid sample is determined, from which a volume of the sample may be calculated. The method and apparatus provide various means for correcting for differences in the dimensions and/or other factors causing a non-linear deviation from the Beer-Lambert law. A system or kit may be provided including sets of sample solutions of varying dilution ranges for calibrating different liquid volumes.

Abstract: A reagent system for accurately determining the volume of a pipette using a photometer is disclosed. The reagent system for use with the photometer includes a first container holding a reference solution and at least one second container holding a sample solution. A container holding the reference solution having maximum absorbance at a first wavelength is positioned in the photometer. The absorbances of the container at the first wavelength and at a second wavelength are measured. Then the optical pathlength of the container at the second wavelength is calculated from the measured absorbances at the first and second wavelengths. An aliquot of the sample solution is introduced into the container with a pipette to be calibrated. The sample solution has maximum absorbance at the second wavelength. The sample solution is mixed with the reference solution to form a mixture. Then the absorbance of the mixture in the container is measured at the second wavelength.

Abstract: Methods and apparatus for accurately determining the volume of a pipette using a photometer. A reagent system for use with the photometer includes a first container holding a reference solution and at least one second container holding a sample solution. A container holding the reference solution having maximum absorbance at a first wavelength is positioned in the photometer. The absorbances of the container at the first wavelength and at a second wavelength are measured. Then the optical pathlength of the container at the second wavelength is calculated from the measured absorbances at the first and second wavelengths. An aliquot of the sample solution is introduced into the container with a pipette to be calibrated. The sample solution has maximum absorbance at the second wavelength. The sample solution is mixed with the reference solution to form a mixture. Then the absorbance of the mixture in the container is measured at the second wavelength.

Abstract: An apparatus and method for making a photometric absorbance measurement of hemoglobin in a blood sample utilizing a reusable cuvette and an inexpensive photometer. The cuvette is a unitary plastic body having a flow-through slot of a predetermined height which allows an absorbance measurement to be made with an undiluted blood sample and which permits cleaning by inserting the body in a liquid cleaning solution. Two absorbance measurements are made, the first at a wavelength at which the absorbance of oxyhemoglobin and deoxyhemoglobin are approximately equal, near an isobestic point, and a second measurement at which these components absorb substantially no light. By making the first measurement near an absorbance minimum at about 510 nm, an absorbance measurement can be made with a relatively thick slot required for cleaning and with an undiluted blood sample and an inexpensive photometer.

Abstract: A comparitive colorimeter for use in the field which simultaneously compares the color densities of two liquid samples and designates the degree of difference. The apparatus includes two major subsystems, optical and electronic. The optical subsystem is designed to provide identical light beams through both the sample and standard solutions and to minimize the effect which imperfect sample tubes have on the output. The electronic subsystem includes a log conversion and differential amplifier circuit for generating a difference signal representative of the difference between the optical densities of the sample and standard solutions. The difference signal is evaluated by a comparative circuit consisting of a resistive chain having a plurality of node voltages and hex inverters connected to the node voltages. The hex inverters drive a series of LED indicator lights to designate the relative degree of difference between the optical densities of the sample and standard.

Abstract: A web dryer for use in the graphic arts industry or the like includes a dryer housing through which a printed web travels and which contains a plurality of nozzles, an air inlet, an air exhaust and a source of heat. The desired ventilation rate for purposes of maintaining the interior dryer environment at a required low percentage of the Lower Flammable Limit is designed to be dependent on the measured or calculated rate of ink application to the web. The ink application rate and information regarding the actual exhaust flow or ventilation rate is fed to a ventilation rate control and the exhaust flow or ventilation rate is then varied in response thereto, as by controlling a variable speed exhaust blower. At the same time, make-up air is provided to the dryer interior, preferably at a point remote from the exhaust discharge duct so that it thoroughly mixes with recirculating air within the dryer to reduce condensation problems.

Abstract: The gas sampling apparatus may be embodied as a hot sampler or a cold sampler, and basically comprises an insulated housing concentrically supporting an inlet tube which in turn supports a nozzle through which the gas sample is metered, passing to the detection cell. The gas sample is drawn past the cell by an aspirator. A controllable heater is disposed concentrically about the inlet tube and proximate to the aspirator for maintaining the sensing cell at its perferred operating temperature which in one case is 704.degree. C. The aspirator is preferably maintained above 430.degree. C. but below 590.degree. C. by the heater. By maintaining the sample gas in this elevated temperature range, accumulation of residuals of the process are avoided. Provision is made for periodic purging of the apparatus with fresh air to remove residuals from the sampler.