Apparatus for monitoring chemical reactions and employing moving photometer means

Abstract

Apparatus for measuring progressively the absorbance changes of a large number of aliquots from a plurality of different samples. The sample introduction, testing instructions, aliquot preparation, reagent dispensing, absorbance measuring and data recording all can be accomplished in a continuous mode of processing. Stat and batch operation also can be accomplished. The aliquots are in an array of cuvettes which is advanced slowly along a circular path. Photometer means, preferably having several photometric detectors, are mounted in fixed orientation on a common support that advances rapidly along a similar circular path, such that radiation passing through each of the cuvettes is monitored many times by a specific photometric detector by the time that that cuvette completes one circuit of its path. The photometric detectors can operate at several different wavelengths. Many different chemical reactions can be monitored at the same time. The radiant energy passing through each cuvette is received by the continuously moving photometer means, is converted electrically into a digitized value proportional to absorbance and is transmitted digitally from the moving assemblage of photometric detectors, cuvettes and electrical components to a stationary receiver. In one embodiment, the digital transmission is in the form of a pulsed train of light signals. In another embodiment, one or more slip rings transmit electric signals from the moving assemblage to the stationary portion. Suitable drive elements, sample and reagent storage and transfer mechanisms as well as cuvette laundry means may be provided as part of the complete apparatus.

Description

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation, of application Ser. No. 846,337, filed Oct. 8, 1977, coupled to the sleeve 64 to apply the rotational movement to the rotor 56 and its photometers, two of which are illustrated in FIG. 3. The photometer components and the short radiation paths 54 therebetween are thus held in fixed orientation with respect to each other and their radial orientation with respect to the axis 58. The journalled mounting of the support 56 provides a precision orientation of the radiation path 54 with respect to its distance from the axis 58, such distance remaining substantially constant as the rotor 56 is rotated.

The bearings 66 can be of any suitable conventional design and construction. The criteria for such bearings are accuracy, smoothness, reliability, in addition to providing the thrust support needed in view of the weight of the rotor 56 and its components. Radial support requirements in view of the weight and forces generated during rotation of the rotor 56 must also be taken into consideration in choosing the bearings 66.

The construction described together with a judicious choice of high quality bearings 66 will result in accurate tracking of the photometers during rotation of the rotor 56 thereby enable enabling accurate and repetitively identical photometric measurements to be taken during operation of the apparatus. Notwithstanding precautions taken to assure accurate tracking and elimination of any eccentricity during rotation, the nature of the invention is such that some eccentricity during this rotation will not adversely affect accuracy as it would in the case of the type of apparatus disclosed in Greaves et al, above-mentioned.

The annular array of cuvettes 32 is mounted on the turntable 74 as explained. These may be removable cuvettes or the turntable may be molded or otherwise formed with the cuvettes 32 permanently attached thereto. The turntable 74 is journalled for rotation on the same axis 58 as that of the rotor 56 and the disposition of the turntable is above the rotor 56 so that access may be had to the entrances to the cuvettes 32 from above, as will be explained. The array of cuvettes extend downwardly from the body of the turntable 74 which is somewhat disc-like or planar in character, defining an annular ring path through which all of the cuvettes travel during rotation of the turntable 74. This ring intersects all of the radiation paths 54 of the photometers mounted on the rotor 56. These paths 54 are radially arranged about the rotor 56 and in the case of the very short paths 54 of the embodiments of FIGS. 2 and 3 the spaces between the filters 60 and the lamps 50 also define a similar ring that coincides with that formed by the path of cuvettes 32.

The photometers 50-52 can be mounted on the upper surface of the rotor 56 in any suitable manner by clamps or brackets or the like or could be mounted on the interior of a thickened disc forming the rotor which could be accurately molded to receive the same. In such case, a groove or trough or annular configuration could be formed in the upper surface of the rotor 56 in annular configuration to receive and clear the depending array of cuvettes during their rotation. The radiation paths could then be arranged to pass through the groove in a radial direction which will enable them to pass unobstructed through the walls of the cuvette where the aliquot being measured is located. The cuvettes are obviously made out of some transparent or translucent material and should have properly oriented walls that do not refract or scatter the beam of radiation passing through the same.

The cuvette turntable 74 has a hub with depending collar 76, is centered on the axis 58 and is journalled for rotation by means of bearings 78 that are mounted between the collar 76 and the sleeve 64, thus permitting the cuvette turntable to be rotated independently of the rotation of the photometer rotor 56. Rotation of the turntable 74 in an indexing mode can be effected by conventional means not shown in FIG. 3, but illustrated in FIG. 4 and discussed with respect thereto. Since the turntable 74 and the photometer rotor 56 are coaxial on the same axis 58, and the collar 76 of the turntable 74 rotates within the sleeve 64 of the rotor 56, the path of the cuvettes and the area swept by the photometers are concentric and the cuvettes are caused to intercept the short radiation path 54 of each photometer with highly reproducible positional accuracy thereby promoting accurate photometric measurements without need for complex light guiding arrangements employed in the prior art.

To enhance the continuously smooth rotary motion of the photometer rotor 56 it can be designed with weighted circumferential volume to operate with a flywheel effect. In contrast the cuvette turntable 74 should be relatively lightweight if the indexing thereof is to be accomplished in steps with dwell periods between steps.

FIG. 4 illustrates primarily a slightly modified arrangement of the photometer means 50-52. Such modification and other differences between FIGS. 3 and 4 will be presented after the discussion of FIG. 5, which includes explanation of most of the operation of the structure shown in both FIGS. 3 and 4.

As shown in FIGS. 3-5, the electrical output from the radiation detectors 52 is coupled to electrical components for analog to digital conversion and transmission from the data generating component assembly 34 to the control console 10 (FIG. 1). Preferably, the electrical components would be secured to portions of the rotor 56 and its sleeve 64, by way of circuit components, circuit boards and connectors such as 80 and 82, so that the electrical components can move along with their associated photometers, during their rotation around the axis 58, without the need for slip rings, commutators or the like at the sensitive points of the circuit or more complex wiring arrangements. The transmission of a large quantity of discrete electrical measurements in the form of analog values from a plurality of radiation detectors 52 that is continuously moving presents problems, both mechanical and electrical, which will be recognized by those skilled in the art. It is believed that the need for greater throughput of precise data from many photometers, concerning numerous chemical tests being carried out on a high number of aliquots, is not practically satisfied by the prior technology. The arrangement in FIG. 5 provides an efficient, flexible, yet simple and precise mode of data transmission.

Commencing with the top left of FIG. 5, there is shown one of the assemblies mounted on the rotor 56 which will be termed a photometer module 84 with its radiation source 50 directing its radiation to pass through the walls of one of the cuvettes 32 and strike the sensitive surface of the detector 52, after passing through the filter 60. The detector could be a silicon diode, a photomultiplier, vacuum photodiode or other photoresponsive device. A few milliseconds of scanning time by one of the photometers moving past an effectively stationary cuvette will be sufficient to obtain the required analog measurement of the radiation incident on the detector 52 to enable eventual calculation of absorption and absorbance. The detector 52 responds to the amount of radiation transmitted through the aliquot in the cuvette and the cuvette walls by generating an electric signal proportional to such amount of radiation. An integrator 86 is connected to the detector and converts the generated signal to an output voltage signal which is proportional to the transmittance of the aliquot. A logarithmic analog to digital converter 88 is coupled to the output of the integrator and generates as its output on a line 90 a digital signal which is a function of the absorbance of the aliquot. One example of a log A/D converter usable herein is set forth in Dorman et al U.S. Pat. No. 3,566,133. For ease of illustration, only one of the eight photometer modules 84 is illustrated, but all eight of the photometer output lines 90 are shown.

Since at one instantaneous position of the continuously moving photometer rotor 56 all eight of the detectors 52 could be respectively receiving radiation which has traversed the samples in eight different cuvettes, a digital multiplexer 92 is connected to all of the photometer output lines 90. The multiplexer operates in typical switching manner under the control of a data control unit 94, by way of a control line 96, discretely to transfer the data from each of the log A/D converters 88 to the data control unit on a data line 98. Such data can be handled in the form of binary bits, with one binary word representing the absorbance reading from one cuvette. The correlation of each specific absorbance data word with its aliquot or cuvette identification can be accomplished by the data control unit. The means for such identification and coupling same to data control unit are not illustrated and are within the skill of the art. After the data word has been transferred to the data control unit 94, that unit will generate a rest reset command on a line 100 to the appropriate log A/D converter 88 to enable that converter to receive the next analog signal derived from the next cuvette to be scanned by that one photometer 84.

Each integrator 86 will be reset by its A/D converter when its digital word is fed into the multiplexer. A reset line 102 carries that command, usually prior to the resetting of the A/D converter by the data control unit 94. To ensure that the radiation through one cuvette does not include radiation from an adjacent cuvette as seen by its integrator 86 the integrator can be enabled by a start integrate command line 104 which can be triggered in response to one of various conditions, such as: a timing relationship with the rotor drive means 72, or a positioning of the cuvette relative to the radiation path 54, or the shape of the output signal waveform from the detector 52.

Depending upon the sophistication of the data control unit 94 and the size of its memory, if any, the manner of data input-output handling can be variable. For example, by employing a simple data control unit, each instance that a digital word is fed into the data control unit it can be transmitted to the master control unit 20 and be processed therein for receipt by the readout unit 22. The master control unit can have a data storage and correlation capacity as well as the earlier mentioned function control, instruction and command information. On the other hand, if the data control unit has sufficient storage capacity, at least all data words such as the 960 mentioned which are obtained during one or more rotations of the rotor 56 can be stored therein.

Assuming that each of the photometers 52 is operating at a different wavelength and that a specific cuvette 32 is to be monitored by only the one photometer 52 operating at that wavelength which optimizes the measurement of the specific reaction occurring in that cuvette, then of the 960 data words received by the multiplexer 92 during one cycle or revolution of the photometer rotor 56, only one hundred twenty of those words (for the example described) normally would be needed by the master control unit 20. The determination of which data words are to be employed for data processing is developed from the input information which associates specific samples with specific tests. The master control unit 20 then assigns each specific cuvette to a sample and a test and thereby a specific photometer; whereupon, the data word required from that cuvette for each revolution of the rotor 56 can be identified and related to the data words from the same cuvette 32 obtained from each of the next following rotor revolutions, which in the preferred embodiment totals one hundred twenty revolutions of the photometer rotor 56.

Depending upon the desirable extent of communications between the data control unit 94 and the master control unit 20, the sizes of their memories, the speed of operation of the apparatus, etc., all of which involve cost, throughput and other factors which influence engineering design, the engineering design can cause all ninety six thousand words to be transmitted to the master control unit for its selection of the needed twelve thousand data words; or, the two control units 20 and 94 can communicate such that only the desired twelve thousand words are transmitted from the data control unit to the master control unit.

The engineering design is influenced by the timing of the transmission of the data words from the data control unit to the master control unit. There may be a finite amount of unused time between the scanning of each cuvette, while the rotor 56 is moving into alignment with the next set of eight cuvettes, and also at the end of each revolution, when the cuvette array is indexed one step. Since the apparatus can operate in the continuous mode, as earlier described, one revolution can be followed by the next without any significant disruption, as contrasted to the batch mode of operation. Hence, data also can be transmitted in a continuous mode and not stored until some later time and then dumped into a processing unit. This continuous transmission of data from the data generating component assembly 34 to the control console 10 may be with some control by the data control unit 94, rather than exclusively by the master control unit 20, is above-mentioned.

In referring to unused time above, that is, time between the scanning of cuvettes or at the end of a revolution, no limitations on the invention are intended. Thus, it is feasible to measure dark current between cuvette scannings to set the photometer scales. The readings can readily be identified by the control unit and processed as desired and programmed.

Although a continuous operation mode has well known advantages over batch operation, there can be conditions which warrant batch handling. The apparatus of this invention can be used in batch processing. For example, the entire cuvette turntable 74 could be in the form of a removable disc to be replaced by one or more similar discs having the cuvettes already filled with aliquots and possibly even reagents, each replacement disc being a batch. If the batch would consist of only a few aliquots, the cuvette disc could be constructed in segments and then only a segment or portion of the disc be replaced with a prepared segment of cuvettes. Likewise, a stat or urgently needed test could be "inserted" into the apparatus.

Such a structure would have a turntable like that shown at 74 with a thin plastic disc, perhaps formed by vacuum molding a synthetic resin sheet with the depressions forming the cuvettes, capable of being clamped or snapped onto the upper surface of the turntable. The operation of the apparatus would not be too much different, being required only to enable proper orientation of the replaceable disc to provide sample identification and with some modification which starts and stops the apparatus so that the attendant may remove the used disc and replace it with a new one.

In normal operation such a disc or turntable would not be required to rotate and its cuvette would be scanned by the plurality of photometers during rotation of the disc on the turntable 74 could be of the rotor 56. Stepping of the disc or turntable 74 would be useful where the apparatus could be alternated between continuous and batch modes. The removability of advantage where stat testing is to be done and it is not desired to integrate such tests in with the routine ones being processed. Stepping could also be of advantage along with removability in a batch mode where the steps carry different sets of filters into the radiation paths.

In a batch method device where the rotor carries a plurality of photometers, such photometers could employ individual lamps 50 for each photodetector 62 or a single central source of radiation serving all photometers.

One variation of the invention could comprise a fixed or indexing turntable with cuvettes and a rotor having a single photometer, but differing from the structure of DeMendez et al patent mentioned above in that the rotor also carries a filter wheel arranged vertically and intercepting the beam of radiation from the photometer before it passes through the cuvettes. The rotor in such case is arranged to stop momentarily at each cuvette and automatically rotate the filter wheel to provide several measurements at different wavelength that are identified by suitable synchronizing means to be sent to the proper address of the storage or recording device through data control means. In this way, the effect of plural photometers is achieved without the need for any duplication of photometers.

It is pointed out that the refernece reference to the rotation or revolutions of the rotor 56 is not to be considered limited to movement in one direction since it is feasible for the rotor 56 to oscillate by rotating substantially one revolution and then reversing itself to rotate a revolution in the opposite direction, etc.

Next, with reference to FIG. 5, there will be disclosed both types of data flow and control; first, that which requires two-way communications between the control units 20 and 94; and second, one-way communications. The latter, although simpler than the former, would require more sophistication and also more storage capacity by the master control unit.

Two-way communication between the master control unit and the data control unit can be accomplished with the aid of a pair of communications logic units 106 and 108, a pair of transmitters 110 and 112, and a pair of receivers 114 and 116. The elements 106, 110 and 114 would be housed in the rotating portion of the data generating component assembly 34. The corresponding elements 108, 112 and 116 would be located in the control console 10 and/or a stationary portion of the assembly 34. A control bus 118 and a data bus 120 link and the data control unit 94 with its communications logic unit 106.

In like manner, control and data buses 122 and 124 link the master control unit 20 with the communications logic unit 108. Typical of the bidirectional control information on the buses 118 and 122 would be the availability of one or more data words to be written into or read from one or the other or both of the memories in the units 20 and 94 and the availability of the associated logic unit 106 and 108 to receive or transmit such data.

Since in the now being described embodiment of the electronics there is to be two-way communications between the data control unit in the reaction table and the master control unit in the control console, the control and data buses 118-124 will be bidirectional as indicated by the arrowheads in FIG. 5. Also, the communications logic units 106 and 108 will possess two-way capabilities. A commercial form of such communications unit is the IM 6402 Universal Asynchronous Receiver - Transmitter of Intersil Corporation, Cupertino, California. Such unit can be used in the other communications embodiment to be disclosed subsequently.

The bidirectional data buses 120 and 124 will carry each data word serially in parallel bit order, but the inputs from the receivers 114 and 116 and the outputs to the transmitters 110 and 112 will be serially by bit. The preferred embodiments of the transmitters and receivers, as illustrated in FIGS. 3 and 5, respectively are photoemissive and photosensitive. FIG. 4 employs a slip ring assembly 110-116; however, other forms of transmission and reception are possible, such as of the radio frequency type, and are encompassed within the general terms and are not to be considered limited by the illustration of the preferred embodiments.

Phototransmission, as by a photodiode, is both simple and well suited to the handling of binary serial bit data and is well known to those skilled in the art. Moreover, photoemission and reception are less subject to interference than radio transmission, especially when the elements 110-116 can be closely spaced.

As shown in FIG. 3, the transmitter 110 and receiver 114 can be housed within the sleeve 64 and rotate therewith close to the axis 58. The associated elements 116 and 112 could be stationary and lie close to the projection of the axis 58 and be wired into the logic unit 108 in the control console 10. Mounted in such a manner close to axis 58, the fact that the transmitter 110 and receiver 114 are rotating will not cause errors in the binary bit data transmission. On the other hand, if the magnitude of a signal, rather than presence or absence thereof, were the measure of the test data and the control commands, then relative movement of the transmitters and receivers could produce transmission errors.

From the foregoing it will be appreciated that for economical use of storage capacity in the master control unit 20 only the desired data words should be transmitted from the data control unit 94. To effect such economy the input information from the data input means 18 will enable the master control unit to establish a listing of the aliquots or their cuvettes from which data is desired. As new samples are added to the sample disc 30, associated input information fed into the master control unit and old samples complete their testing the "desired" listing will be updated continuously. As each data word is received by the data control unit 94 from the multiplexer 92 it will, by two-way communications, be checked with the desired data list and only be transmitted to the master control unit after an affirmative comparison. This communication will require the data control unit and its logic unit to have interchanges on the buses 118 and 120 regarding: the fact that a data word has been received from the multiplexer, identification of that word and that the logic units 106 and 108 are ready to communicate that identification information to the master control unit.

In like manner, the master control unit and its buses 122 and 124 with its logic unit 108 will: acknowledge availability to communicate, receive the identification data, provide a comparison reply and then either cause the data word to be discarded by the data control unit or cause it to be transmitted for storage by the master control unit. Each communication will require transmission and receipt by one or the other pair of components 110 and 116, or 112 and 114.

In the other embodied form of data communications, all data words are transmitted from the data control unit 94 to the master control unit 20 and the latter than itself will decide which data words to continue to store for ultimate readout purposes. Because of this simpler form of communications the data buses 120 and 124 need only feed in the direction toward the master control unit, the communications logic unit 106 will operate only as a sending unit, the communications logic unit 108 will operate only as a receiving unit and the transmitter-receiver pair of elements 112 and 114 will not be required. The bidirectional control buses 118 and 122 between the control units and their respective communications logic units are required for the purposes above-mentioned.

The differences between the embodiments of FIGS. 3 and 4 will now be described. First, concerning the photometer means, the radiation source 50 of FIG. 4 is located at the axis 58 and comprises a single element such as a General Electric type 58 tungsten lamp rather than a plurality of lamps positioned around the periphery of the photometer rotor 56 as in FIG. 3. The source 50 in FIG. 4 is connected to the rotor 56 for rotation therewith.

A plurality of lens-containing optical tubes 126 are mounted to the photometer rotor 56 of FIG. 4 such that one end of each tube is proximate to the radiation source 50 and the other end of each tube is close to the annular path or pattern traversed by the cuvettes and is aligned with a specific one of the radiation or photometric detectors 52. The photometric detectors 52 are also mounted on the rotor 56 substantially as in the FIG. 3 embodiment. The paths or patterns swept by the beams of radiation reaching each detector is in effect the same as in FIG. 3.

One advantage of employing a single source 50 is that it is easier to dissipate the heat generated thereby and thus easier to regulate the temperature of the cuvettes 32. Note that in the embodiment shown in FIG. 3 the individual lamps are located quite close to the annular ring defined by the cuvette path so that the heat of these lamps could be radiated or transmitted to the materials carried by the cuvettes. The nature of many of the reactions whose characteristics are being measured is such that temperature changes are critical. As a matter of fact, means will often be provided for incubation of the cuvettes during their scanning and the arrangement of FIG. 4 enables such structure to be easier achieved and more effective in operation because of the absence of heat sources.

Another advantage of a single source such as in FIG. 4 is that there is no problem with different intensities, colors or wavelengths which can be expected in a plurality of different lamps, even where matched. Whatever happens to the single source lamp 50 happens to all readings made so that the effect is not felt where relative measurements are made. The lamp 50 can be cooled very easily by air circulated in its vicinity in a manner which will not cool, for example, the cuvettes. The power supply for a single source 50 is simpler and more economical.

In the views described thus far shown there is a single beam 54 which passes through the cuvette 32 and thence impinges upon the photodetector 52 after passing through a filter 60 which is usually in close proximity if not incorporated into the photodetector. In the structure of FIG. 4 it is feasible to focus the light beam into a very fine pencil for passage through the lower portion of the cuvettes 32 but in addition it is feasible to incorporate beam splitting means into the focussing tube or outside thereof to provide two beams which may be directed in parallel paths through different levels of the cuvettes for investigating different strata of the analyte. Such a structure is shown in FIG. 4a to be described in detail below.

In FIG. 4a components equivalent to those of FIG. 4 carry the same reference numerals primed. The rotor 56' has a focussing tube 126' which directs a beam 54' derived from a source such as 50 (not shown in FIG. 4a) to a semisilvered or dichroic mirror 150 arranged at 45° in front of the tube 126'. A part of the beam passes through the mirror 150 and becomes a bottom beam 54'b and another is reflected at 90° upward and thence reflected from the 45° angled mirror 152 to become the upper beam 54'μ. These beams pass through different levels of the liquid 154 carried in the cuvette 32' mounted in the turntable 74' which is disposed to move in a path which carries it and its companion cuvettes through the groove 156 provided in the rotor 56.

There are two photodetectors at 52' and 52" mounted on the rotor 56 in suitable cavities aligned with the mirrors 150 and 152, respectively, and thus aligned to receive the beams 54'b and 54'μ against their sensitive surfaces. Each is provided with a filter 60' and 60", respectively. Openings 158 and 60 respectively enable the beams to pass.

It will be obvious that the beam 54' emerging from the focussing tube 126' splits, part going through a lower stratum of the liquid 154 and part going through an upper stratum of the same liquid. The photodetectors 52' and 52" are independent, each providing a different signal which can be transmitted through suitable connections to data processing equipment to provide additional information concerning the reaction which may be going on in the cuvette 32'.

FIG. 4 shows the drive means for the cuvette turntable 74, which was not illustrated in FIG. 3, because of drawing space limitations. A motor 128 has its drive shaft 130 coupled by a pinion gear 132 to a suitably mating configuration 134 on the periphery of the turntable 74. If the indexing of the cuvettes is to be in steps, the motor 128 could be a stepping motor, or there could be provided linkage, clutch means, etc., for providing appropriately timed stepping from a continuously driven motor.

As earlier mentioned briefly, a slip ring assembly 110-116 can provide the receiver and transmitter needs of the apparatus and couple data and other communications from and to the reaction table 34 and the master control unit 20. Such slip ring units are available commercially.

From the above, it now should be understood how the entire apparatus operates with its moving photometer means and preferably in a continuous mode to place into the master control unit 20 the digitized values of the readings related to absorbance from the data generating components assembly 34. Since reaction can be monitored at frequent intervals during a prolonged period of time rather than a small portion thereof, both rate and end point data are obtainable. Once into the master control unit, the raw data can be associated with each test and supplied to the readout unit 22 without any data reduction, conversion or analysis, such being left to the skill of a technician in interpreting the same. In a preferred mode of operation the master control unit would have the capability of associating the data for each test, obtaining mathematic rate and/or end point determination, then converting that information into a reading of the chemistry value in the desired concentration units for the test, thereafter feeding the results into the readout unit. Although some variations in structure and operation of this chemical reaction monitoring apparatus have been disclosed hereinabove, other variations are capable of being made by those skilled in the art without departing from the spirit or scope of the invention as defined in the appended claims. For example, the preferred embodiments teach continuous movement of the photometer rotor; however, a stepping device movement can be employed. Also, the photometer means are spaced around the circumference of their support, since such positioning enables a uniform weight distribution around the support; however, the photometer means could be mounted with variable spacing especially if the path of motion is other than circular. It may be desired to employ disposable cuvettes. If so, the laundry station 48 would be replaced by means for removing used cuvettes and for inserting clean cuvettes into the cuvette turntable 74. At least in such situation, the cuvettes need not move around a closed path. Reagents need not be liquid but may dispensed dry. Cuvettes may be used in a disposable mode with the reagent already in place, requiring only the addition of the aliquot and a diluent.

Claims

1. Apparatus for monitoring chemical reactions occurring in a plurality of liquid or the like sample substances carried in by a plurality of respective cuvettes whose walls are at least to some extent capable of transmitting radiant energy sample support members which comprises:

A. support means,

B. a rotor and a turntable mounted coaxially on the support means and capable of rotation relative to the support means and relative to one another, one of said rotor and turntable being journalled on the other, said other being journalled on said support means,

C. a plurality of radiant energy transmissive cuvettes sample support members mounted to the turntable and disposed in a circular arrangement about said axis and adapted to have sample substances producing chemical reactions carried in by at least some of said cuvettes sample support members,

D. first drive means for rotating the turntable on its axis in a first program of rotation whereby the cuvettes sample support members describe an annular path as the turntable rotates,

E. second drive means for rotating the rotor on said axis in a second program of rotation in which the number of total revolutions of the rotor for a given period of time is greater than the number of revolutions of the turntable for the same period of time,

F. photometer means mounted on the rotor and defining at least one beam path for radiant energy which extends at least through said annular path such that the beam path includes and traverses at least a portion of the sample substance which may be contained in carried by any of said cuvettes sample support members which intersects such beam path during rotation of the turntable or rotor,

G. the photometer means including means responsive to any radiant energy projected along said beam path to produce electrical signals as the cuvettes sample support members intersect the beam path, which signals are related to chemical conditions of the sample substances, if any, which may be contained in carried by said cuvettes sample support members,

H. means for generating usable data from any such signals and

I. means for coupling at most all of the electrical signals from said photometer means to said data generating means.

2. The apparatus as claimed in claim 1 in which the rotation of the turntable is unidirectional, the rotation of the rotor is unidirectional and both directions are the same.

3. The apparatus as claimed in claim 2 in which the beam path is arranged radially relative to said axis and at all times intersects said annular path described by said cuvettes sample support members.

4. The apparatus as claimed in claim 2 in which the first drive means rotate the turntable stepwise to provide a moving period and a dwell period for each cuvette sample support member relative to a fixed point of the support means.

5. The apparatus as claimed in claim 4 in which the dwell periods are respectively substantially longer than the moving periods and there are means provided for enabling the operation of said photometer means principally during said dwell periods and disabling the operation of said photometer means principally during said moving periods.

6. Apparatus as claimed in claim 3 in which the photometer means comprise source means of radiant energy and at least two radiant energy detectors spaced to provide two radial beam paths arranged to scan separated cuvettes sample support member, said radiant energy detectors being constructed to respond, respectively to incident radiant energy of different wavelengths.

7. Apparatus as claimed in claim 6 in which the radiant energy source means comprise a single source at said axis.

8. Apparatus as claimed in claim 6 in which the radiant energy source means comprise multiple sources, there being one of said sources aligned with each respective detector and defining the beam paths therebetween.

9. The apparatus as claimed in claim 2 in which said photometer means comprise a plurality of photometers mounted on said rotor and circumferentially spaced thereabout, each photometer having structure defining a beam path for radiant energy disposed radially relative to the axis of the rotor such that all beam paths will extend through said annular path and the cuvettes sample support member will intersect all of the beam paths as the rotor rotates, each photometer including independent means responsive to its radiant energy beam to produce electrical signals as the cuvettes sample support member pass through the beam, the means for generating data being arranged to generate data concerning the absorbance of the sample substances, if any, with regard to all of the beam paths, and the coupling means being arranged to couple all of the electrical signals to said data generating means.

10. The apparatus as claimed in claim 2 which includes means for mounting said turntable onto said rotor proximate to said axis such that said turntable is rotatable by said first drive means independent of rotation of said rotor by said second drive means.

11. Apparatus as claimed in claim 9 in which at least two of the photometers are constructed to be responsive to incident radiant energy at different wavelengths.

12. The apparatus as claimed in claim 1 in which an A/D converter is mounted on said rotor coupled between said means for producing electrical signals and said coupling means to convert said electrical signals to digital signals before said signals are coupled to said data generating means.

13. The apparatus as claimed in claim 1 including one motor drive means driving said first and second drive means.

14. The apparatus as claimed in claim 1, in which said turntable has a plurality of openings and said sample support members are removably engaged in said openings.

15. The apparatus as claimed in claim 1, in which at least one of said sample support members comprises at least one wall capable of transmission of said radiant energy for impingement of said sample substance and measurement of the resulting interaction by said responsive means.