IL35418A - Optical system for a rotary photometric analyser - Google Patents

Description

IMPROVED OPTICAL SYSTEM FOR A ROTARY PHOTOMETRIC ANALYSER This invention relates, in general, to an improved optical system for rotary photometric analyzers. In one nspect this invention relates to improved analyzers wherein the absorption path length is doubled. In a further aspect, this invention relates to an improved optical system which permits simpler design and ease of operation.

In recent years the need for rapid, automatic, analytical devices has increased markedly due to the numerous microana lytica 1 studies in biochemical research, routine clinical testing for physicians and hospitals, enzymatic studies and the like. In addition to the increased demand for analyses, in certain fields it is often critical that a series of reactions be started at exactly the same time if reliable results are to be obtained.

This is particularly important for enzymatic studies wherein detectab e 'najipps nff n f;«ke olsce Si iter the reaction ss cc^^ds*? for only a few seconds or minutes. However, few devices are available which can analyze rapidly and accurately to handle the increasing number and varied test desired by clinicians and research workers Recently, multistation analytical photometers which utilize a centrifugal field have become available for the rapid microanalysis of a wide variety of liquids such as body fluids, e.g., blood serum, food products, and the like. Since numerous analyses can be performed rapidly and simultaneously these devices are of particular interest wherein a large number of samples is involved or a variety of tests on one sample is desired. Moreover, since these devices allow the use of relatively small volumes of reagents, i.e., in the microliter range, the use of expensive reagents can e 28, 545-562 (1969) . This device employes the principle of double-beam spectrophotometry wherein absorbencies of a liquid sample and a reference solution are intercompared . The system is basically a series of cuvets arranged around the periphery of a rotor so that when it is spun, centrifugal force simultaneously mixes and transfers reagents and samples to the cuvets where the concentration is measured spectrophotometrica lly . A sample loading disk is provided which consists of rows of cavities arranged concentrically.

Reagents are placed in the inner-most cavity and serum samples in the center cavity of the sample loading disk which is then indexed and positioned in the rotor with each reagent and serum sample having its respective cuvet. As the rotor is accelerated, centrifugal force moves the reagent and sample to the outer-most cavity where they are mixed and then transferred through a small channel to the cuvet.

The filled cuvets rapidly spin past the fixed light beam and the transmission of light is measured.

However, as indicated in the aforementioned article, the light source is placed below the cuvet holder and light is projected from below the centrifuge head through the samples under test in the head and the resultant light output is detected by photomultiplier tube mounted above the centrifuge head. This arrangement results in one optical pass through the sample under test and in the requirement that the photocell and its mounting and optics must be mounted so that it can be pivoted out of the way when loading samples or replacing the centrifuge head, (See Figure 1 on page 549 of the above article). This construction also requires that there be high quality windows both above and below the sample under test to allow . industry practices while many chemistries result in such small change in absorbence that the useful differential signal obtainable through a 1 centimeter sample is very small.

It is therefore an object of this invention to provide an improved optical system for rotary photometric analysers. A further object of this invention is to provide an improved system wherein the measured absorption path length is doubled over that currently employed in known analyzers. Another object of this invention is to provide an improved system wherein the cuvets require only one window through which the passage of light is transmitted. A further object of this invention is to provide an improved system wherein the light source and th photomultiplier tube are both located below the horizontal plane in which the disk rotates. A still further object is to provide an improved system which does not. necessitate any movement of t photometric detector when samples and/or reagents are added. These and other objects will readily become apparent to those skilled in the art in the light of the teaching herein set forth.

In its broad aspect, the invention relates to an improved optical system for rotary photometric analyzers. The improvement comprises providing a reflective mirror on the inner top surface and a transparent window on the bottom surface of each cuvet, a light source which projects a beam of light through the bottom windov; of each cuvet as it is rotated past the light source, the beam passing through the liquid sample, reflecting from the mirror back through the sample and out the window, and a photometric detector to measure the absorbence of said sample.

The improved optical system of this invention provides doubling the absorption path length and increasing the useful differential signal obtainable. Second, the construction of the disk containing the cuvets iy be s mplified b the elimination of the upper side window system. Third, the optical system is positioned below the horizontal plane in which the disk containing the cuvets rotates. Hence, the device can be constructed so that the rotating disk is built flush into the top of a table and the optical system contained below. This eliminates physical interference and obstruction above the tsble and providing a rigid relationship between light source and detector to further decrease noise caused by vibration of the optical path.

In general, the light source can be positioned below the rotor disk in such a manner that the beam emitted passes directl into the bottom of the cuvet. The source should be arranged so ; = i' 1-s - ^ · ■ — ti>.i - ■ . * r :-. "? t . r . ^ . *°- ^ < : : ' window. This allows proper positioning of the detector. Alternatively, the light source can be positioned in a manner wherein the beam is reflected into the window. For instance, the light beam can be projected perpendicular to the cuvet and reflected into the window by means of a prism or mirror at a 45 degree angle. The exiting beam can also be reflected so that the photometric detecto: can be positioned in most any convenient place.

In practice, the optical system of this invention csn be employed with a wide variety of light sources and detectors. For instance, any of the light sources currently in use in spectrophotometers or in the ana1v¾er escribed in h « foruamitleaned article cs be employed. Similarly, the detector can be chosen article, and having a six- inch di-imeter rotor with 15 cuvets was constructed so that both the light source and photomulti-plier tube were positioned below the table top which contained the rotor. A 1000 hour quartz iodide light source was situated so that the light beam passed perpendicular to the cuvet to a pair of 45 degree angle mirrors located below the rotor. The mirrors were tilted slightly so that the beam after being deflected by the first mirror and entering the cuvet exited at a different point on the cuvet window and deflected by the second mirror through a light culmina tor to the photomultiplier tube. A variety of analyses were conducted using the rotary analyzer and optical system functioned as well as the system wherein the light beam was passed through the cuvet.

Although the invention has been illustrated by the preceeding disclosure it is not to be construed as being limited to the particular embodiments or materials disclosed therein.

Rather, the invention encompasses the generic area as hereinbefore disclosed. Various modifications and embodiments thereof can be made without departing from the spirit and scope thereof.

Claims (4)

35418/2 · Claims :

1. . device for the automatic and essential ly simultaneous photometric analysis of a plural ity of l iquid samples wherein said samples to be analyzed are contained 1n cuvets arranged vertically and concentrically around a horizontally disposed rotatable disk, and wherein a ight source posi tioned below the horizontal plane in which said rotatable disk is disposed projects a l ight beam into each cuvet as it 1s rotated past said source, said l ight passing through said l iquid sample and the absorbence thereof is detected photometrically from below the horizontal plane in which said rotatable disk Is disposed and 1s recorded , the Improvement which comprises providing, in combination, a reflective mirror on the inner top surface and a transparent window on the bottom surface of each of said cuvet, a l ight source which projects a beam of l ight at an angle to said cuvet through the bottom window of each cuvet as it 1s rotated past said source , said beam passing through said liquid sample , reflecting from said mirror back through said sample and out said window, and a photometric detector to measure the absorbence of said sampte.

2. The device of claim 1 wherein said light source 1s disposed so as to project said l ight beam at a right angle to slid cuvet and reflecting means for reflecting said light beam from said angle Into said cuvet.

3. The device of claim 2 wherein said reflecting means Is disposed so that the beam enters and leaves said cuvet at different points on said window.

4. A device for the automatic and essential ly simultaneous photometric analysis of a plurality of liquid sample substantia ly as described hereinbefore and with reference to Fig. 2 of the drawings . Attorne for A licants