Fluorometric titrator
First Claim
1. A fluorometric titrator comprising a device operable to aspirate and subsequently discharge a sample, reversible means to transfer said device between first and second positions, sample control means to aspirate a precise sample volume into said device when in said first position and to discharge that volume in said second position, a fluorometer including a cuvette to receive the discharged volume and to hold a reagent that fluoresces when said sample volume is discharged therein, means to deliver chelating agent into said cuvette, a pulse generator controlled by the output of said fluorometer in response to resulting fluorescence to operate the delivery means for the chelating agent at a decreasing rate as the fluorescence is reduced and to produce an indication at the value of a chemical contained in the sample.
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Abstract
A fluorometric titrator has means to transfer a pipette between first and second positions and a buret for a chelating agent has a reversible drive powered either by a pulse generator or an oscillator. Valve controlled means are operable to place the buret in communication with the pipette or a reservoir. In the first position of the pipette, a precise sample volume is aspirated into it by the buret, then driven by the oscillator and in its second position and with the buret drive reversed but still powered by the oscillator, the sample volume is discharged from the pipette into a cuvette in the fluorometer. On the resulting fluorescence the fluorometer output drives the pulse generator to dispense chelating agent and to operate a counter until a selected end point is reached. The pipette is then returned to its second position with the buret drive again operated by the oscillator and during the return, the buret is refilled. Both before the sample volume is aspirated, and before that volume is discharged, backlash is removed from the buret drive. The effect of hysteresis on the photocell of the fluorometer is minimized by light control also enabling the response time of the titrator to be accelerated.
20 Citations
36 Claims
- 1. A fluorometric titrator comprising a device operable to aspirate and subsequently discharge a sample, reversible means to transfer said device between first and second positions, sample control means to aspirate a precise sample volume into said device when in said first position and to discharge that volume in said second position, a fluorometer including a cuvette to receive the discharged volume and to hold a reagent that fluoresces when said sample volume is discharged therein, means to deliver chelating agent into said cuvette, a pulse generator controlled by the output of said fluorometer in response to resulting fluorescence to operate the delivery means for the chelating agent at a decreasing rate as the fluorescence is reduced and to produce an indication at the value of a chemical contained in the sample.
- 22. A fluorometric titrator comprising a device operable to aspirate and subsequently discharge a sample transferrable between first and second positions, sample control means operable to aspirate a precise sample volume into said device when in said first position and to discharge that volume with the device in said second position, a fluorometer including a cuvette to receive the discharged volume and to hold a reagent that fluoresces when the sample volume is discharged therein, means to deliver chelating agent into said cuvette, a pulse generator controlled by the output of said fluorometer in response to resulting fluorescence to operate the delivery means for the chelating agent at a decreasing rate as the fluorescence is reduced and to produce an indication of the value of a chemical contained in the sample.
- 25. A fluorometric titrator comprising a device operable to aspirate and subsequently discharge a sample to contain a selected sample volume, reversible means to transfer said device between first and second positions, the first position the sample receiving position, sample control means to discharge that volume when the device is in said second position, a fluorometer including a cuvette to receive the discharged volume and to hold a reagent that fluoresces when said sample volume is discharged therein, means to deliver chelating agent into said cuvette, a pulse generator controlled by the output of said fluorometer in response to resulting fluorescence to operate the delivery means for the chelating agent at a decreasing rate as the fluorescence is reduced and to produce an indication of the value of a chemical contained in the sample.
- 28. A fluorometric titrator comprising a fluorometer which yields an output, a cuvette for a fluorometric indicator solution, pumping means for a chelating agent including a delivery conduit in communication with the cuvette and operable to deliver a chelating agent thereto after a sample has been introduced into the cuvette to cause fluorescence, and delivery means controlled by the output of the fluorometer in response to the resulting fluorescence to operate the pumping means at a decreasing rate as the fluorescence is reduced, said pump means including a cylinder having an outlet at one end, a slidable piston having an axial bore opening towards the other end of the cylinder and including a fixed nut located at the open end of said bore, and the delivery means includes a motor, a drive shaft rotated thereby and including a threaded portion threaded through said nut and extending into said bore, the nut and shaft threads being of the micrometer type.
- 30. A fluorometric titrator comprising a fluorometer which includes a sensor provided with an output circuit, a cuvette, a stirrer in the cuvette, the cuvette for a fluorescent indicator solution, pumping means for a chelating agent including a conduit in communication with the cuvette and operable to deliver the chelating agent thereto after a sample has been introduced into the cuvette that causes fluorescence, a drive for said pumping means including a stepper motor, the output circuit of the sensor of the fluorometer including a pulse generator operable to drive said motor and operating at a pulse-producing rate that decreases as the fluorescence is quenched and a detector opening said circuit when the fluorescence is reduced to a value selected as the end point of the test, said circuit also including means operable to adjust said end point to compensate for end point drift at least after the first of a series of titrations.
- 33. A fluorometric titrator comprising a fluorometer which yields an output and including a cell, a lamp and a cuvette between said cell and said lamp to receive a selected sample volume and adapted to hold a reagent that fluoresces when said sample volume is received therein, means to deliver chelating agent into said cuvette, a pulse generator controlled by the output of said fluorometer in response to resulting fluorescence to operate the delivery means for the chelating agent at a decreasing rate as the fluorescence is reduced, and means in control of said lamp and operable to maintain the cell luminosity at a constant level at least between the titrations.
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36. In combination, a fluorometer having a chamber that opens downwardly and includes a holder detachably attached to the chamber to close the chamber opening and formed with a flat-surfaced recess, and a cuvette molded from a transparent material and dimensioned to fit the chamber and within the recess and be held in a predetermined position therein by the holder.
Specification