US3784310A - System and method for improved operation of a colorimeter or like optical analysis apparatus - Google Patents

Abstract

New and improved system and method for improved operation of a colorimeter or like device are provided and comprise the processing of the colorimeter output data in such manner that a separating fluid-segmented fluid sample stream may be passed through the colorimeter flow cell without adverse effect on said output data. This is accomplished by sampling said output data at periodic intervals and selecting for retention only that of the thusly sampled data which is known to have occurred when the flow cell sight path was filled with a fluid sample segment to the exclusion of the separating fluid segments.

Description

United States Patent [191 Barton et al.

[ SYSTEM AND METHOD FOR IMPROVED OPERATION OF A COLORIMETER OR LIKE OPTICAL ANALYSIS APPARATUS [75] Inventors: Stephen P. Barton, New Milford,

Conn.; Herman G. Diebler, North Haledon, NJ.

{73] Assignee: Technicon Instruments Corporation,

Tarrytown, N.Y.

[22] Filed: June 7, 1972 [21] Appl. No.: 260,552

[52] U.S. Cl 356/181, 356/226, 356/246,

, 73/432 A, 23/253, 23/259, 23/230 [51] Int. CL, G0lj 3/46, G06g 7/00 [58] Field of Search 235/616 E; 356/179,

[56] References Cited 1 UNITED STATES PATENTS 3,539,777 1/1967 Rohland 235/6l.1l 3,715,601 2/1973 Tucker 356/39 OTHER PUBLICATIONS Habig et a1., Advances in Automated Analysis- Technicon International Congress, 1969, Vol. 1, pp.

S'TREAM OF'SEPARAT/A/G FLUID-SEGMEA/TED FZU/D SAMPLES 5] Jan. 8,1974

1 Primary Examiner-John K. Corbin were!!! iwmiasrzR-lLII eater Attorney-S. P. Tedesco and S. E. Rockwell 57 ABSTRACT New and improved system and method for improved operation of a colorimeter or like device are provided and comprise the processing of the colorimeter output data in such manner that .a separating fluid-segmented fluid sample stream may be passed through the color-- imeter flow cell without adverse effect on said output data. This is accomplished by sampling said output data at periodic intervals and selecting for retention only that of the thusly sampled data which is known to have occurred when the flow cell sight path was filled with a fluid sample segment to the exclusion of the separating fluid segments.

14 Claims, 2 Drawing Figures 1 SYSTEM AND METHOD FOR IMPROVED OPERATION OF A COLORIMETER OR LIKE OPTICAL ANALYSIS APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention.

This invention relates to a new and improved system, and method, for enabling the advantageous passage of a separating fluid-segmented fluid sample stream through a colorimeter flow cell without requiring the removal of the separating fluid segments while nonetheless extracting colorimeter output data readings which are indicative only of the light absorbence characteristics of said fluid sample.

2. Description of the Prior Art.

Although automated colorimetric fluid sample analysis apparatus are known which utilize a separating fluid to segment a fluid sample stream which consists ofa series of different fluid samples, it may be understood that the same do, in general, include means to remove the separating fluid segments from the sample stream prior to the passage of the latter through the colorimeter flow cell, with the attendant disadvantages that the cleansing action of said separating fluid segments on the flow cell is lost, sample carryover is increased since the delimiting action of the separating fluid segments is lost upon the removal thereof, the required separating fluid removal means add to the complexity and cost of the colorimeter and are not always operable in satisfactory manner, and the removal of the separating fluid segments will, of necessity, entail the loss of some portion of the fluid samples of interest. The latter two of these disadvantages are of particular significance with regard to the most advanced versions of said automated fluid sample analysis apparatus which are operable with very small fluid sample quantities and at substantially reduced flow rates. Further, although analog systems have been implemented to enable satisfactory colorimeter function with separating fluid segment passage through the colorimeter flow cell, it may be understood that such systems are particularly complex and expensive in that the same generally require level detector and slope detector components.

OBJECTS OF THE INVENTION It is, accordingly, an object of this invention to provide a new and improved system, and method, for colorimetric or like analysis which enable the advantageous passage of separating fluid segments through the colorimeter flow cell without adverse effecton the colorimeter output data readings.

Another object of this invention is the provision of a system and method as above which may be implemented through the use of readily available, relatively inexpensive components of proven dependability, and which are operable in relatively simple and very highly reliable manner.

A further object of the invention is the provision of a system and method as above which are particularly adaptable for use in conjunction with automated blood sample treatment and analysis means.

SUMMARY OF THE DISCLOSURE New and improved system and method for colorimetric or like analysis which enable the advantageous passage of a separating fluid-segmented fluid sample stream through the colorimeter flow cell without adverse effect on the colorimeter output data readings, are provided, and comprise the periodic sampling of the colorimeter output data in such manner that at least one of a series of n of such samplings will occur when the flow cell sight path is filled with a fluid sample segment to the exclusion of the separating fluid segments. This output data sampling will be the largest of said series, and the same is selected by the consecutive comparison of the n output data samplings in the order that the same occur with attendant retention of the largest, only, of said data samplings in each instance. As a result, the output data sampling retained at the completion of the occurrence of the series ofn data samplings will be the largest of said series, and will be indicative of the optical characteristics of a fluid sample segment, only.

DESCRIPTION OF THE DRAWINGS The above and other objects and advantages of the invention are believed made clear by the following detailed description taken in conjunction with the accompanying drawings wherein:

FIGS. 1A and 1B are respectively schematic diagrams illustrating an application of the system and method-of the invention to automated fluid analysis means.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIGS. 1A and 18, a colorimetric flow cell is indicated at 10 and comprises a sight path having a length L. A stream of appropriately treated fluid sample segments S as separated by segments SF of an appropriate separating fluid in the nature of air is flowed as shown through the flow cell 10 and therefrom to waste. A light source is indicated at 12, an aperture at 14, and a suitable optical filter at 16; while a detector which may, for example, take the form of a photomultiplier tube is indicated at 18. The concomitant flow of the appropriately treated sample segments S through the flow cell sight path and passage therethrough of the light energy from light source 12 is effective in accordance with Beers Law, in manner well understood by those skilled in this art, to provide for a detector output consisting of data which is indicative of the concentration of a sample constituent of interest in said sample segments.

The output data from detector 18, which takes the form of a relatively weak analog signal, is applied as indicated toa log amplifier 20 to improve the signal to noise ratio and provide the log of the signal. Since Beers Law is logarithmic, this latter function of amplifier 20 will, of course, simplify subsequent calculations. The signal is then applied as indicated to integrator 22 to further improve the signal to noise ratio and provide for an average signal.

The integrated'or averaged signal is then applied as indicated to sample and hold means 24 for obvious purpose, and therefrom to A/D converter means 26 for conversion to digital form. The operational timing of the integrator 22 and sample and hold means 24 are controlled as indicated from timing circuit means 25 which are in turn operable in accordance with the sampling rate of the colorimeter in a manner described in greater detail hereinbelow.

Considering now for example an application of the system of the invention wherein the sample segments S are constituted by liquids in the form of a stream of successive, appropriately reacted and treated blood samples, and the separating fluid segments SF are constituted by a suitable gas in the nature of air, all in a manner made clear, for example, in US. Pat. No. 3,241,432, it may be understood that any output data reading taken when all or a part of a segment SF is in the flow cell sight path will, of necessity, be of relatively small magnitude due to the reflection and/or scattering of the light energy from light source 12 by the miniscus or interface between such segment SF and the adjacent liquid segment S with attendant substantial reduction in the amount of such light energy which reaches detector 18. Conversely, the output data readings taken when the flow cell sight path is filled completely with a liquid sample segment will be of relatively large magnitude since the attenuation thereof is due primarily only to the amount of said light energy absorbed by said liquid sample segment S in accordance, for example, with the concentration of a solute therein, at the wavelength of filter 16. As a result, it may be understood that discrimination between such output data readings of substantially different magnitudes to select those of the same which were generated during the flow of a liquid sample segment S, only, through the sight path of the flow cell will make possible the operation of the colorimeter with the flow of the separating fluid segments SF through the flow cell to significant advantage as discussed hereinabove.

For utilization of the system and method of the invention in an automated blood sample analysis application as discussed directly hereinabove, and to provide for the absolutely reliable discrimination between output data readings taken while a segment S fills the flow cell sight path, and those taken while some or all of a segment'SF is present therein, it may be understood that the operational parameters of the colorimeter, and the sample and hold means, as would include the respective volumes of the sample segments S and separating fluid segments SF, the volume of the sight path portion of the flow cell 10, the fluid flow rate through the flow cell, and the duration of an interval between the periods during which the detector output data is sampled, are respectively chosen to ensure that at least one of a predetermined consecutive number n of detector output data samplings will occur in its entirety when the volume of the flow cell sight path L is filled as illustrated in FIG. 1 with a sample segment S to the complete exclusion of the separating fluid segments SF, and to insure that the flow cell sight path is never fully occupied by a separating fluid segment SF. Thus, and considering for example a system and method application wherein the segments SF are provided in the stream of interest at a rate of approximately 90 per minute or one every 2/3 seconds, the respective sample segments S are of substantially equal volume, the respective separating fluid segments SF are of substantially equal volume, the flow rate through the flow cell is substantially constant and sufficient to insure that only liquid be present in the flow cell sight path after a segment SF leaves the same, the flow rate is predetermined in accordance with liquid segment S volume to insure that each liquid segment S takes longer than approximately 0.255 seconds to traverse the flow cell sight path, and the detector output data is sampled and held once every approximately 0.240 seconds, respectively, it becomes clear that at least one output data sampling for each liquid segment S is obtained and that a choice of n equal to 3 will insure that at least one of each consecutive series of three such output data samplings will occur in its entirety with a liquid segment S, only, in the flow cell sight path.

If the description of system operation is commenced at the beginning of a series of three consecutive output data samplings, it may be seen that at the end of the first data sample and hold period, and following the required very short A/D conversion time, a conversion complete strobe pulse will be applied from A/D converter 26 on line 27 to latch or register 28 causing the latter to acquire the digital information of interest from said'A/D converter in the form of levels on the indicated N bit lines (N may, for example, equal 15) and apply the same to the digital comparator 30 on input A. This being the first of the series of three consecutive detector output data samplings of interest, it may be understood that the input now applied at input B of comparator 30 (from latch 40 as explained in detail hereinbelow) will be zero, whereby a true level or pulse will be applied as indicated on line 32 from comparator 30 as one input to and gate 34. The simultaneous application of the strobe pulse, as delayed by delay means 36, on line 38 as a true level to the other input of said gate will result in the opening thereof with resultant application of the strobe pulse to latch 40 on line 42, and attendant application of the data from latch 28 to latch 40 on the indicated lines for temporary storage in the latter, and application therefrom on input B of comparator 30 on the indicated lines.

The delayed strobe pulse is also applied on lines 44 and 46 to counter 48 (which has also been reset to zero) to bring the count therein to one. This count is applied on the indicated lines to decoder 50 which, in the given example wherein n equals 3, is set to provide an output on line 52 to and gate 54 only when said count is three. As a result, the application of the further delayed, as by delay means 56, strobe pulse on lines 57 and 58 to gate 54 will be ineffective to open the same. Thus, notching further occurs at this point in time.

At the completion of the second output data sampling and conversion period, a new strobe pulse is applied to latch 28 with resultant acquisition thereby of the new data acquired during said second period. This data is immediately applied as indicated on input A of comparator 30 and compared therein with the data from the first data sampling period as is being concomitantly applied thereto from latch 40 on input B. If it is assumed that this data from the second data sampling period is less than or equal to the data from the first data sampling period, it may be understood that the same is simply discarded as indicated on line 60 or 62 as the case may be, and that nothing further occurs at this point in time with the exception that the application of the delayed strobe pulse to counter 48 will raise the count therein to two.

At the completion of the third output data sampling and conversion period, the resultant strobe pulse will effect the acquisition of the relevant data by latch 28 and application thereof to comparator 30 on input A, it being understood that the data from the first data sampling period still remains in latch 40 and is being concomitantly applied to comparator 30 on input B. If it is assumed that the data now on input A is greater than the data now on input B, it may be understood that a pulse will again be applied from comparator 30 on line 32 to and gate 34, and that the simultaneous application of the delayed third strobe pulse to said gate will be effective to open the same with resultant application of the strobe pulse to latch 40. This strobing of latch 40 is effective to causethe same to acquire the data from the third data sampling period from latch 28 on the indicated lines in replacement of the data from the first sampling period as had till now been stored therein. v

The simultaneous application of the delayed strobe pulse to counter 48 will raise the count therein to three with the result that decoder means 50 will apply a true level or pulse on line 52 as one input to and gate 54. As this occurs, the strobe pulse, which has been further delayed by delay means 56, will arrive at the other input of gate 54 with resultant opening thereof and application of the strobe pulse therefrom on lines 64, 66 i and 68 to strobe the latch 70 and effect the acquisition thereby on the indicated lines of the data from the third data sampling period from latch 40.

Following this, the strobe pulse as further delayed by delay means 72, will be applied as indicated on lines 74 and 76 to respectively reset counter 48 and latch 40 to zero for commencement of the succeeding three data sampling periods.

Although described for purposes of illustration in accordance with three consecutive data sampling periods wherein the data from the third such period is the largest, it is believed apparent that the end result at the conclusion of such periods, namely the presence in mg ister 70 of the largest of such data, will be the same if such data is acquired during the first or second of the three data sampling periods. Operation is, of course, continuous in the manner described until all of the liquid samples of interest have been flowed in the described, separating fluid-segmented manner through the flow cell 10.

Since the data in latch 70 is of the largest magnitude, or is at least equal in magnitude to the largest data magnitude obtained during the three data sampling periods of the series of interest, it is believed clear that such data is indicative, as described in detail hereinabove, of a reading taken when a liquid sample segment S, only, is flowing through the flow cell sight path, and is thus indicative in the given system application of the concentration of the constituent of interest in said liquid sample segment. The display of this data in readily interpretable and reproducible manner may be effected as illustrated by the additional application of the delayed strobe pulse from line 66 to D/A conversion means 78 on line 80 to trigger the former for acquisition and conversion of the digital data from latch 70 on the indicated lines and subsequent application of the resultant analog data on line 82 to drive a strip chart recorder 84 in mannerwell known to those skilled in this art. Alternatively, and in instances wherein further processing of the data in latch 70 is desired, the delayed strobe pulse on line 80 may simply be utilized to identify said data as the largest of that obtained during a series of three consecutive data sampling periods.

Resetting of latch 70 to zero following data acquisition by D/A converter 78 may then be effected by the application of the further delayed strobe pulse thereto as indicated through delay means 90 on lines 86 and 88.

Although disclosed hereinabove by way of illustration as operable in accordance with n equal to three, it is believed clear that the system and method of the invention would be operable with n equal to any number greater than one within practicable limits. Too, although disclosed hereinabove by way of illustration as applicable to the automated colorimetric analysis of a series of appropriately treated and ainsegmented blood samples, it is believed clear that the system and method of the invention would be equally applicable to the colorimetric analysis of any multi-fluid segmented stream wherein a suitably light reflective or light scattering interface is formed between adjacent fluid segments. F urther, although disclosed by way of illustration as operable through use of primarily digital components, it is believed clear that the system and method of operation of the invention could alternatively be effected by equivalent analog components, albeit at the expense of increased complexity and cost, or through use of an appropriately programmed general purpose computer. In addition, it is believed clear that the system and method of the invention are not limited to use with a colorimeter, but rather, would be applicable for use with a wide variety of like optical analysis apparatus which comprise a flow cell.

While we have shown and described the preferred embodiment of our invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

What is claimed is:

l. A system for processing the output data from a colorimeter or like optical analysis apparatus wherein a liquid sample stream is segmented at substantially regu' lar intervals with separating fluid segments of substantially equal volume and flowed through the sight path of a colorimeter flow cell at a substantially constant flow rate, the volume of the resulting segments of said sample liquids being, at least, equal to the volume of said sight path, and means to direct light energy through said sight path, photodetector means to detect light energy passed through said sight path and to generate a signal having an amplitude. indicative of the intensity of said passed light energy, comprising means to periodically sample said signal at a rate to effect a se' ries of a number n of consecutive samplings, said number n being sufficiently high to ensure that at least one of the samplings of said signal corresponds to the sight path being filled in its entirety with sample liquid, means to compare said samplings on an amplitude basis and to select those samplings which occurred when the sight path was filled with sample liquid to the exclusion of any separating fluid segment.

2. The system as in claim 1 wherein said selection and comparison means include means to select that sampling in said series of samplings having the greatest magnitude.

3. A system as in claim 1 wherein, n is two.

4. A system as in claim 1 wherein, n is equal to three.

5. The system as in claim 1 wherein said comparison and selection means comprise sample and hold means to receive said series of samplings corresponding to each of said fluid segments.

greater than 6. A system as in claim 1 wherein, said separating fluid-segmented sample fluid stream is an airsegmented stream of treated blood samples.

7. A method for processing the output data from a colorimeter-like optical analysis apparatus wherein a liquid sample stream is segmented at substantially regular intervals with separating fluid segments of substantially equal volume and flowed through the sight path of colorimeter flow cell at a substantially constant flow rate, the volume of the resulting segments of said sam ple liquid being, at least, equal to the volume of the sight path, comprising the steps of, detecting light energy passed through said sight path and generating a signal having a magnitude indicative of said passed light intensity, sampling said signal at a rate to effect a number n of consecutive samplings, said number n being sufficiently high to ensure that at least one of the samplings of said signal corresponds to the sight path being filled in its entirety with sample liquid, comparing the samplings in each of said series on an amplitude basis and selecting that sampling corresponding to the sight path being filled with a fluid segment to the exclusion of any separating fluid segment.

8. The method as in claim 7 including the further step of selecting that sampling in said series of samplings having the greatest magnitude.

9. A method as in claim 7 wherein, n is greater than two.

10. A method as in claim 7 wherein, n is equal to three.

11. The method in claim 7 including the further step of retaining the selected sampling corresponding to each fluid segment.

12. A method as in claim 7 wherein, said separating fluid-segmented sample fluid stream is an airsegmented stream of treated blood samples.

13. The system as in claim 3 wherein said selection and comparison means further includes A/D converter means, and means responsive to said selection and comparison means to retain the selected samplings corresponding to each fluid segment.

14. The system as in claim 3 further including means to strobe said sampling means, said comparison and selection means, and said retainer means.

Claims (14)

1. A system for processing the output data from a colorimeter or like optical analysis apparatus wherein a liquid sample stream is segmented at substantially regular intervals with separating fluid segments of substantially equal volume and flowed through the sight path of a colorimeter flow cell at a substantially constant flow rate, the volume of the resulting segments of said sample liquids being, at least, equal to the volume of said sight path, and means to direct light energy through said sight path, photodetector means to detect light energy passed through said sight path and to generate a signal having an amplitude indicative of the intensity of said passed light energy, comprising means to periodically sample said signal at a rate to effect a series of a number n of consecutive samplings, said number n being sufficiently high to ensure that at least one of the samplings of said signal corresponds to the sight path being filled in its entirety with sample liquid, means to compare said samplings on an amplitude basis and to select those samplings which occurred when the sight path was filled with sample liquid to the exclusion of any separating fluid segment.

2. The system as in claim 1 wherein said selection and comparison means include means to select that sampling in said series of samplings having the greatest magnitude.

3. A system as in claim 1 wherein, n is greater than two.

4. A system as in claim 1 wherein, n is equal to three.

5. The system as in claim 1 wherein said comparison and selection means comprise sample and hold means to receive said series of samplings corresponding to each of said fluid segments.

6. A system as in claim 1 wherein, said separating fluid-segmented sample fluid stream is an air-segmented stream of treated blood samples.

7. A method for processing the output data from a colorimeter-like optical analysis apparatus wherein a liquid sample stream is segmented at substantially regular intervals with separating fluid segments of substantially equal volume and flowed through the sight path of colorimeter flow cell at a substantially constant flow rate, the volume of the resulting segments of said sample liquid being, at least, equal to the volume of the sight path, comprising the steps of, detecting light energy passed through said sight path and generating a signal having a magnitude indicative of said passed light intensity, sampling said signal at a rate to effect a number n of consecutive samplings, said number n being sufficiently high to ensure that at least one of the samplings of said signal corresponds to the sight path being filled in its entirety with sample liquid, comparing the samplings in each of said series on an amplitude basis and selecting that sampling corresponding to the sight path being filled with a fluid segment to the exclusion of any separating fluid segment.

8. The method as in claim 7 including the further step of selecting that sampling in said series of samplings having the greatest magnitude.

9. A method as in claim 7 wherein, n is greater than two.

10. A method as in claim 7 wherein, n is equal to three.

11. The method in claim 7 including the further step of retaining the selected sampling corresponding to each fluid segment.

12. A method as in claim 7 wherein, sAid separating fluid-segmented sample fluid stream is an air-segmented stream of treated blood samples.

13. The system as in claim 3 wherein said selection and comparison means further includes A/D converter means, and means responsive to said selection and comparison means to retain the selected samplings corresponding to each fluid segment.

14. The system as in claim 3 further including means to strobe said sampling means, said comparison and selection means, and said retainer means.

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