Optics: measuring and testing – By particle light scattering – With photocell detection
Reexamination Certificate
2000-10-16
2003-09-09
Font, Frank G. (Department: 2877)
Optics: measuring and testing
By particle light scattering
With photocell detection
C356S336000, C356S337000
Reexamination Certificate
active
06618144
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
REFERENCE TO A “MICROFICHE APPENDIX”
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention involves the simultaneous measurement of light scattering from multiple, independent samples, comprising solutions containing polymers and/or colloids.
2. General Background of the Invention
The following patents are incorporated herein by reference:
U.S. Pat. Nos.: 3,809,912; 4,541,719; 5,011,286; 5,185,641; 5,255,072; 5,427,920; 5,907,399; 6,118,531; and 6,118,532.
U.S. Pat. No. 5,427,920 discloses multiple fluid compartments, each with its own light source and light detector.
U.S. Pat. No. 5,011,286 discloses a multisensor particle counter using a single beam to measure several fluid sample portions simultaneously.
U.S. Pat. No. 5,255,072 discloses using a single sensor to measure several fluids simultaneously.
SUMMARY OF THE INVENTION
The present invention comprises Simultaneous Multi-Sample Light Scattering, or SMSLS, for absolute and relative characterization of dilute macromolecular/colloidal solutions. Dilute here means that for a light beam incident on the solution the majority of scattering events are single scattering events. (Herein, ‘single scattering’ will refer to the case of light scattering in a solution wherein the majority of detected, scattered photons have scattered only once.) In prior art, light scattering devices have been made to measure only one sample at a time. This is in large part due to the fact that great care and expense has been taken to produce high quality optical cells for single samples, and it has not been obvious to practitioners that multiple independent measurements might be economically or technically feasible. Current art has also not taken account of the fact that significant advantages exist for being able to simultaneously measure the light scattered from multiple, independent samples. For convenience, the invention will be referred to herein as Simultaneous Multi-Sample Light Scattering, or SMSLS.
Emerging needs in new fields of polymer/colloid science and application now make such a multi-sampling capability extremely desirable. The following is a non-exhaustive list of fields in which multi-sampling will be of great utility:
1) Light scattering art has reached the phase where processes occurring in polymer/colloid solutions can be followed online.
1
At the industrial level, where large reactors are to be monitored, there is often considerable inhomogeneity within the reactor, so that samples withdrawn from different locations in the reactor can have different characteristics. Continuous and multi-stage reactors are other examples where SMSLS may be advantageous. The SMSLS invention will allow multiple samples withdrawn from different reactor locations to be characterized simultaneously, with a single device and computer. In prior art, the expense involved in using multiple, single sample instruments, each requiring a separate computer, with the attendant complication of trying to integrate all their signals, makes such multi-sampling economically and technically unattractive.
‘Computer’ used throughout the description of this invention refers to any device capable of receiving signals from light detectors, and performing the required data reduction and analysis on these signals. Hence, ‘computer’ can refer to any commercially available computer (e.g. such as those sold by IBM, Dell, Apple, etc.), including workstations (e.g. Sun Microsystems), as well as any microprocessor-based device whether commercially available or designed specifically for the data acquisition and analysis functions described herein.
2) In the emerging field of combinatorial chemistry applied to new polymer synthesis, research and development is focused on running dozens of reactions (‘reaction’ as used herein refers to both chemical reactions involving the making and breaking of covalent bonds, as well as any reaction that a polymer or colloid can have in response to time, interactions with itself or other agents, etc. that do not involve making or breaking covalent bonds; such reactions can include aggregations of polymers, changes in dimensions, hydrodynamic properties, excluded volume interactions, etc.) in parallel in microliter quantities. No light scattering technology currently exists which can make simultaneous, multiple measurements. In its simplest version, SMSLS will be useful in providing immediate information on whether polymer reactions are occurring at all, and what the relative rate constants are for each sample. In the more refined version, where absolute calibration would be made and exact sample concentration known or measured, the device would give absolute molecular weight characterization in real-time of the polymers as they polymerize. Again, such analyses can be made with a single device and a single computer. The analyses might be carried out on samples flowing through the SMSLS device, pipetted into and at rest in the SMSLS device, or samples in cuvettes which can be inserted into the SMSLS device. Hence, the SMSLS invention is expected to have favorable implications for this emerging field, which is being pursued by academic scientists, multi-national corporations, and small, emerging companies.
3) In university, pharmaceutical, industrial and other laboratories, time-dependent processes can be followed, using SMSLS, on many independent samples of varying composition, in order to determine the evolution and stability of solutions; e.g. determination of the shelf-life of a pharmaceutical product, the stability of an organic polymer in different solvents, the enzymatic degradation rates for polymers, or the interaction of small molecules with larger ones, etc. Users can have direct, real-time, graphical and numerical representations on their computer screens of the simultaneous evolution of many samples. Under current art, such measurements require monopolizing an expensive light scattering device and computer for each sample being tested. With an SMSLS device with, say, 250 sub-chambers (‘Sub-chamber’ as used herein refers to any sort of receptacle which can receive a liquid sample, and has means for introducing light to be scattered, and a means for detecting the scattered light. The sample can be introduced into the chamber by any means, such as flow, pipetting, being held in a separate sample cell which is inserted into the sub-chamber, etc.), all monitored by a single computer, measurements that might take a year of monitoring might be performed in a single day.
4) In Size Exclusion Chromatography (SEC) applications, and other separation/fractionation analyses, the SMSLS invention can be used as a detector for multiple SEC or other separation/fractionation devices. Currently, a costly light scattering detector is needed for each separation device. With this invention only a single SMSLS device would be needed for multiple separation devices. In this case, a separate computer would most likely be used to analyze the detected light from each sub-chamber, since, normally, there is a dedicated computer for each SEC instrument and the other detectors associated with each (e.g. refractive index detector, viscometric detector, ultraviolet/visible detector, etc.).
5) In a setting where high sample characterization throughput of unfractionated polymer batches is desired, the SMSLS invention could be readily adapted to robotic automation, wherein the samples could be automatically and simultaneously prepared, then simultaneously measured by SMSLS.
In summary SMSLS can be of decisive utility in academic and industrial laboratories that deal with, but are not limited to, polymers, resins, adhesives, foodstuffs, pharmaceuticals, water purification agents, pulp, paper and fiber products, coatings, etc.
The present invention involves making a single device with multiple sub-chambers, each of which is equipped with its own independent scattered light detection means (e.g. one or more optical fibers, window(s), etc.). Each sub-chamber ca
Font Frank G.
Garvey, Smith, Nehrbass & Doody, L.L.C.
Nehrbass Seth M.
Nguyen Sang H.
The Administrators of the Tulane Educational Fund
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