|Publication number||US3904373 A|
|Publication date||9 Sep 1975|
|Filing date||26 Oct 1973|
|Priority date||26 Oct 1973|
|Publication number||US 3904373 A, US 3904373A, US-A-3904373, US3904373 A, US3904373A|
|Inventors||Gerald Bruce Harper|
|Original Assignee||Gerald Bruce Harper|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (74), Classifications (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent  Harper Sept. 9, 1975 INDICATORS COVALENTLY BOUND TO INSOLUBLE CARRIERS  Appl. No.: 409,876
 US. Cl 23/253 TP; 252/408; 260/448.2 B;
 Int. Cl. GOln 29/02; GOln 31/00;
GOln 33/00  Field of Search 252/408; 23/253 TP; 424/7  References Cited UNITED STATES PATENTS 2,626,855 1/1953 Hand 23/253 TP 2,929,829 3/1960 Morehouse 252/408 X 3,350,175 10/1967 McConnaughey ct al...... 23/253 TP OTHER PUBLlCATlONS New Method Makes Possible Nonbleeding Indicator Paper, Chem. and Engin. News, Vol. 48, No. 10, p. 38 (Mar. 9, 1970).
Surface-Produced Alignment of Liquid Crystals, Kahn, F. J., et al., Proc. of The IEEE, Vol. 61, No. 7, pp. 823-828 (July 1973).
Primary ExaminerBenjamin R. Padgett Assistant ExaminerT. S. Gron Attorney, Agent, or FirmF." Campbell Rutherford [5 7 ABSTRACT Indicators insolubilized by covalent bonding to inorganic carriers for indicating the hydrogen ion concentration, oxidation-reduction state or specific ion concentration in liquid media. Since the indicators are insoluble they do not contaminate the solution tested, and they may be used repeatedly in different media. They replace the well known indicator test papers which consists of a substrate 'dyed with an indicator. Methods of making the indicators are also provided.
17 Claims, N0 Drawings INDICATORS COVALENTLY BOUND TO INSOLUBLE CARRIERS This invention consists of a new type of indicators, which are hereinafter referred to as bound indicators.
Indicators are organic compounds which absorb visible light, which absorption(s) change in wave length and/or intensity as the composition of a solution to which the indicator may be exposed changes. Indicators are widely used to determine such parameters in solutions as hydrogen ion concentration (pH), oxidation-reduction potential or specific ion concentrations.
The term indicator", as used herein, refers to organic molecules or ions which absorb visible light and whose absorption(s) change in wave length and/or intensity as solution conditions are varied, and includes precursors, organic species which are not indicators as free species, but which when bound to inorganic carriers via silane coupling agents give a bound indicator. The term bound indicator, as used herein, refers to any complex comprising an organic species covalently coupled via a silane coupling agent to a carrier having available hydroxyl or oxide groups, which absorb visible light and which ahsorption(s) change in wave length and/or intensity as solution conditions are varied.
Conventionally, indicators have been used by dissolving the indicator chemical entity in the liquid to be tested, or by coating a carrier, such as paper, with the chemical entity and then contacting the coated carrier with the liquid to be tested.
In whatever form indicators were previously used, a quantity of the indicator was required for each test. If a liquid was being monitored for changes in pH, ion concentration or oxidation-reduction potential with an indicator, samples of the liquid to be tested had to be contacted with the appropriate indicator and the sample then had to be discarded because it has been contaminated by the indicator or, in the case of a coated paper indicator, because the paper had absorbed a component of the test liquid. Thus the amount of previ ously known indicators consumed in an active chemical laboratory, or for control purposes in a plant, could be substantial. Such use could also be costly since a typical indicator species is expensive to prepare.
My invention consists of insoluble bound indicators which are able to fulfill the various functions of soluble indicators. Bound indicators have several advantages over soluble indicators:
1. they can, in most cases, be used repeatedly 2. they are largely unsusceptible to microbial attack 3. they are insoluble and hence do not contaminate systems 4. they may be made in a form which is especially convenient for laboratory operations, e.g. glass stirring rods Bound indicators are very useful in analytical procedures in laboratories and industry and may also be used in the preparation of many foodstuffs, chemicals and pharmaceuticals. I have observed continued and apparently constant activity, as indicated by the intensity of colour changes, over a period of months, upon expo sure to various organic and aqueous assay conditions. Because of their advantages, bound indicator sintered glass rods and the like are preferable to pH papers and soluble indicators for many uses. While bound indicators may be made with either inorganic or organic carriers, the former are normally preferable for use because they are more rigid and insoluble and more resistant to microbial attack.
Bound indicators must be substantially insoluble in a solution to be useful in it. Most indicators in widespread use change colour with pH and are, in fact, used to measure the pH of solutions. Other indicators have different functions, e.g. the measurement of the oxidation-reduction potential of a system, and the detection and measurement of various ions in solution.
The silane coupling agents are molecules which are characterized by two different kinds of reactivity. These are organofunctional, and silicon-functional, so characterized that the silicon portion of the molecule has an affinity for inorganic materials, such as glass and aluminum silicate, while the organic portion of the molecule is an indicator or precursor or is tailored to combine with indicators or precursors. One function of the coupling agent then, is to provide a bond between the indicator and the carrier. The variety of possible organofunctional silanes useful in this invention is limited only by the number of organofunctional groups which bind to silicon to give a stable coupling agent, by the stability of the bonds to the carrier and to the indicator and by the available sites in the organic species which yield an active bound indicator.
Many different silane coupling agents of the general formula X,,SiR can be used, wherein X is a substituent, which may be a substituted (or unsubstituted) aryl, alkyl or lower alkyl-aryl, nitro, nitroso, diazo, cyano, isocyano, isothiocyano, carboxy, carbonyl, keto, halocarbonyl, sulfoxy, sulfonyl halide, or more complex derivatives of any of these; R is a member selected from a group comprising lower alkoxy, phenoxy and halo; and n is an integer which is l, 2 or 3, usually I. The silane coupling agent may or may not itself be an indicator. This definition includes simple silane coupling agents wherein X is simply amino, carboxyl, carbonyl, sulfliydryl or halocarbonyl.
Coupling agents include gamma-aminopropyltriethoxysilane, 2,4,6-trimethoxybenzyltriethoxysilane, N- beta-aminoethyl-gamma-aminopropyltrimethoxysilane, and N-beta-aminoethyl-(alpha-methyl-gammaaminopropyl)-dimethoxymethylsilane. While some simple silane coupling agents are commercially avail able, many others, including more complex ones, may be made by known chemical methods. For example, I have added 2,4,6-trimethoxybenzoic acid to trichlorosilane in acetonitrile, then added tri-n-propylamine to form 2,4,6trimethoxybenzyltriethoxysilane. Ethanolysis yielded the useful coupling agent 2,4,6- trimethoxybenzyltriethoxysilane. As another example, gamma-aminopropyltriethoxysilane couples to inorganic carriers giving the aminoalkylsilane derivative, which can be reacted with alkoxybenzoyl chlorides to form another complex which binds diazotized indicators or precursors. Another reaction sequence involves reacting the aminoalkylsilane derivative with pnitrobenzoyl chloride, reducing the nitro group with sodium dithionite and diazotizing with sodium nitrite: this diazonium salt attacks activated aryl rings of indicators or indicator precursors. Alternatively, an aminoalkylsilane derivative may be reacted with thiophosgene to give an isothiocyanoalkyl derivative which binds amino groups. Where the indicator or precursor or derivative contains a suitable aromatic ketone. aldehyde, acyl chloride or carboxy group it is possible to prepare silane coupling agents which are also indicators or precursors.
The carriers used can be organic, but generally, inorganic materials with available hydroxyl or oxide groups are preferred. The quantity of indicator or precursor which can be bound, and hence the colour intensity of the bound indicator. increases with increasing surface area of the carrier. Hence, a carrier such as smooth, unetched glass is an unsatisfactory carrier, as it yields a bound indicator of weak colour. The carriers must have little or no solubility in various solutions and are either weak acids or weak bases. They may also be classified in terms of chemical composition as siliceous materials, non-siliceous metal oxides, or as mixtures of the two, such as Zirconia-clad glass. Of the siliceous materials, the preferred carriers are sintered, etched or porous glass. These may be used in such forms as rods or discs. or as fragments. Glass has the advantages of being dimensionally stable, of being transparent or white in colour thus allowing colour changes to be easily judged, and it can be thoroughly cleaned to remove contaminants as, for example, by sterilization. The corrosion rate of glass varies with glass composition and solution conditions, but corrosion has remained undetectable throughout this work. Other useful siliceous inorganic carriers are silica gel, eoloidal silica (commercially available under the trade mark Cab-O-Sil), wollastonite (a naturally-occuring calcium silicate) and beatenite. Representative non-siliceous metal oxides include alumina, hydroxy apatite and nickel oxide. These inorganic carriers may be classified as in Table I.
Bound indicators may be classified under three general headings:
1. pH indicators 2. redox indicators (i.e. oxidation-reduction indicators) 3. adsorption indicators (i.e. ion detectors) of which examples of each class are listed below. Bound pH indicators can be produced using many pH indicators or functionalized derivatives of those indicators. Suitable organic species include: phenolphthalein, fluorescein, phenol red, cresol red, pararosaniline, magenta red, xylenol blue, bromocresol purple, bromophenol blue, bromothymol blue, metacresol purple, thymol blue, bromophenol blue, tetrabromophenol blue, brom-chlorphenol blue, bromocresol green, chlorphenol red, o-cresolphthalein, thymolphthalein. metanil yellow, diphenylamine, N,Ndimethylaniline, indigo blue, alizarin, alizarin yellow GG, alizarin yellow R, Congo red, methyl red, methyl orange, orange l, orange II, nile blue A. ethyl bis( 2,4-dinitrophenyl) acetate, gamma-naphtholbenzein, methyl violet 68, 2,5- dinitrophenol, p-nitrophenol, and/or the various functionalized derivatives of the above species. Even when Bound adsorption indicators can be made from organic species which include fluorescein, diiodofluorescein, dichlorofluorescein, phenosafranin, rose bengal, eosin l bluish, eosin yellowish, magneson, tartrazine, eriochrome black T and others.
The following examples illustrate typical methods of preparation of the new indicators:
EXAMPLE I indicators in the form of a stirring rod, and in the form of a powder, were prepared, starting with a heavily etched silica glass stirring rod for the former, and 1 gram of fragments of 96% silica porous glass for the latter. Both carriers were cleaned by soaking in 0.2M nitric acid at 95 C for 1 hour, rinsing several times with distilled water and then heating overnight at 650 in air.
The two samples of glass were cooled, placed in flasks and to each was added 50 millilitres of a 10% solution of gamma-aminopropytriethoxysilane. Both mixtures were refluxed overnight, cooled and washed with acetone.
The two glass products, now in the form of aminoalkylsilane derivatives, were refluxed for one hour in solutions containing 10 ml of chloroform, 100 mg of pnitrobenzoyl chloride and 50 mg of triethylamine, washed with chloroform and air-dryed. The nitro groups were reduced by refluxing in 17! aqueous sodium dithionite, giving the arylamine derivative. The amino groups were diazotized by adding 10 ml of glacial acetic acid followed by an excess (0.3 g) of sodium nitrite. The mixtures were placed under vacuum until all air and gas bubbles were removed from the glass. after which 1 g of phenolphthalein was added to each followed by placing under vacuum for a further 30 minutes. The resulting products, which in each case was phenolphthalein coupled to the silane by an azo linkage with the silane bound to the glass, were washed with water, acetone and benzene until any phenolphthalein non-covalently adsorbed on the glass was not detectably eluted. The phenolphthalein glasses when exposed to liquids of different pH concentration underwent a colour change which I observed to occur in the pH range 8.59.0; at a pH of 8.5 the glasses were pale yellow and at a pH of 9.0 were deep red-brown. These indicators retained their colour and activity indefinitely, despite exposure to strong organic and aqueous acids and bases, to various solutions and reagents, and to air.
EXAMPLE II A l g sample of porous zirconia-clad silica glass amino alkylsilane derivative (e.g. Corning Glass Works product MAO-3930) was refluxed for 1 hour in a chloroform solution containing 100 mg p-nitrobenzoyl chloride and 50 mg triethylamine, as in example I. The nitro groups on this product were again reduced with dithionite. This was followed by diazotization by 0.3 g sodium nitrite in 10 ml glacial acetic acid, under a vacuum at 0. Excess (0.5 g) N,N-dimethylaniline was added. The product was a deep-burgundy colour in solutions of pH below 4.5. turning to a pale orange-red colour at pH 4.5 to 5.5 The bound indicator retained colour and activity, despite exposure to various conditions. Presumably. the bound indicator is of the following structure:
EXAMPLE 111 A g sample of 2.4.o-trimethoxybenzoic acid and 49 g trichlorosilane were dissolved in 200 ml acetonitrilc and refluxed for 1 hour. Two equivalents of tripropylamine were added at this point and the resulting mixture was refluxed at 80-90 for 8 hours. Treatment with dry ether caused the precipitation of tripropylamine hydrochloride (95% Distillation of the filtrate gave 1 l g of 2.4.6-trimethoxybenxyltrichlorosilane boiling at 8084 (6mm). This product was dissolved in 100 ml ethanol. Five equivalents of tripropylamine were added and the mixture refluxed for 1.5 hours at 7075. The mixture was distilled yielding 2.1 g of 2.4- ,t'w-trimethoxybenzyltriethoxysilane. l g of porous glass and ml of toluene were added to this and the mixture was refluxed overnight giving a trimethoxyarylsilane glass derivative.
Fifteen g of 3-nitro-N.N-dimethylaniline was mixed with 17 g of sodium thiosulphate in 200 ml water and refluxed for 1 hour to give 3-amino-N.N- dimethylaniline. This mixture was cooled to 10 and sodium nitrite (20 g) was added slowly. 3-diaZo-N,N- dimethylanilinium chloride was collected as a filtrate and added to the trimethoxyarylsilane glass derivative and 10 ml glacial acetic acid. in an ice bath. The mix ture was evacuated for minutes to remove air and gas bubbles from the glass. The reaction product, which was again N.N-dimethylaniline bound to glass by azo linkage to the silane. was washed extensively until molecules non-covalently adsorbed on the glass were not detectably eluted. The product was a bound indicator of the structure:
52 ocn N(CH3)2 O GLASS 0 831 N=N CH3 CH3 in acidic solutions of a pH below 4.0 it was burgundy in colour and underwent a colour change to pale orange-red between pH 4.05.5. The bound indicator retained colour and activity despite exposure to various organic and aqueous solvents and to strong acids and bases. Exposure to a sodium hypoehlorite solution caused irreversible colour change to pale yellow and hence its destruction as a useful bound indicator.
EXAMPLE IV The procedure of Example 11 was used to produce. from the reduced form of methylene blue. methylene blue bound by azo linkage to zirconia-clad glass. The glass is bright blue under most solution conditions. but turns reversibly pale yellow when exposed to strong reducing conditions such as Zinc dust in dilute sulfuric acid.
EXAMPLE V 2.4.6-trimeth0xybenzoic acid was dissolved in sulfonyl chloride and refluxed over a steam bath for 1 hour to give 2,4.6-trimethoxybenzoyl chloride. To 250 mg of this was added 10 ml of pyridine and l g of aminoalkylsilane porous glass (Corning GAO-3940). This mixture was stirred at room temperature. and then refluxed 30 minutes to give a glass complex with highly activated phenyl rings. presumably of the following structure:
This glass was decanted. washed in acetone and airdryed. The nitro group of Eriochrome Black T was reduced to an amino group. the product was recrystallized from ethanol. and: l g of this indicator derivative was added to 10 ml of glacial acetic acid over an icebath and diazotized with 0.5 g sodium nitrite. Then 1 g of the glass complex was added to this mixture. The resulting orange bound indicator was washed thoroughly with water. acetone and benzene until colour was no longer eluted. This orange bound indicator turned reversibly violet in the range pH 10.0 to 12.00.
EXAMPLE VI Nickel screen. of mesh and 0.1 mm thickness. was heated overnight in a furnace at 700 in an oxygen atmosphere to oxidize the surface. thus forming a NiO coating on the screen. The screen was then cut into strips 1 inch by 4 inches. which were rolled into cylinders of approximately 0.5 inch diameter and the ends soldered to prevent ravelling.
One of these NiO coated cylinders was refluxed overnight in a 10% solution of gamma-aminopropyltricthoxysilane in toluene. This aminoalkylsilane derivative was washed in toluene and air-dryed. The screen was refluxed in 10% thiophosgene in chloroform. The isothiocyanoalkylsilane derivative was washed with chloroform and coupled to ethoxazene. The bound indicator thus created underwent a colour change from red below pH 5 to yellow above pH 5.
EXAMPLE Vll 4-carboxy-alpha-hydroxy-alpha. alpha-bis (phydroxyphenol)-l-toluenesulfonic acid was prepared by condensing phenol with 3-carboxy-l-sulfobenzoic anhydride in the presence of zinc chloride. Equimolar quantities of this phenol red derivative and tri-npropylamine were combined with 3 molar equivalents of trichlorosilane in a vigorously exothermic reaction. After refluxing for 1 hour at 55-75 and treating the mixture with tri-n-propylamine hydrochloride in pentane, and ethanolysis, the product. an indicator silane. was isolated by low pressure distillation.
This silane coupling agent, 3-carboxyphenol red triethoxysilane was then bound to l g of porous 96V: silica glass in Example I. to give methylenephenol red glass which was red at pH 7.0 and below and changed to orange-yellow at pH 8.5.
EXAMPLE Vlll A bound indicator on a glass carrier was prepared by the procedure of Example I from fluorescein instead of phenolphthalein.
EXAMPLE lX A bound indicator on a glass carrier was prepared by the procedure of Example I from xylenol blue instead of phenolphthalein.
EXAMPLE X A bound indicator on a glass carrier was prepared by the procedure of Example I from cresol red instead of phenolphthalein.
While a number ofexamples of the bound indicators of this invention and methods of preparing them have been given. such disclosure is intended for illustration only and to impose no limitation on the scope of the invention beyond those included in the appended claims.
What is claimed is:
I. An insolubilized bound indicator useful in determining parameters such as hydrogen ion concentration (p"), oxidatiomreduction potential or specific ion concentrations in solutions consisting of an organic indicator covalently coupled by means of an organofunctional silane coupling agent to an inorganic carrier having available hydroxyl or oxide groups.
2. A bound indicator as claimed in claim 1 wherein said silane coupling agent is combined with said indicator by means of an alkyl linkage.
3. A bound indicator as claimed in claim 1 wherein said silane coupling agent is combined with said indicator by means of an azo linkage.
4. A bound indicator as claimed in claim I wherein said silane coupling agent is combined with said indicator by means of a sulfonamide linkage.
5. A bound indicator as claimed in claim 1 wherein said silane coupling agent is represented by the general formula in which X represents a substituted or unsubstituted aryl. alkyl or alkyl-aryl group, the substituent(s) being selected from groups which include hydroxy, lower alkoxy. amino, lower alkylamino, lower dialkylamino, alkyl. nitro, nitroso, diazo, cyano. isocyano, isothiocyano, carboxy, carbonyl, keto, halocarbonyl, sulfoxy and halosulfonyl; R represents a group which may be lower alkoxy, aryloxy or halogen; and n is one of the integers. l, 2 and 3.
6. A bound indicator as claimed in claim 1 wherein said carrier is a glass.
7. A bound indicator as claimed in claim 1 wherein said carrier is zirconia coated glass.
8. A bound indicator as claimed in claim 1 wherein said carrier is a metal oxide.
9. A bound indicator as claimed in claim 1 wherein said carrier is nickel oxide.
10. A bound indicator as claimed in claim 1 wherein said organic indicator is an N.N-dialkylaniline.
11. A bound indicator as claimed in claim I wherein said organic indicator is selected from the group consisting of diazo. amino. carboxy and alkylsilane derivatives of N,N-dimcthylaniline.
12. A bound indicator as claimed in claim 1 wherein said organic indicator is selected from the group consisting of B-naphthol and derivatives thereof.
13. A bound indicator as claimed in claim 1 wherein said organic indicator is selected from the group consisting of triarylmethyl compounds.
14. A bound indicator as claimed in claim 1 wherein said organic indicator is phenolphthalein.
15. A bound indicator as claimed in claim 1 wherein said indicator is methylene blue.
16. A bound indicator as claimed in claim 1 wherein said organic indicator is Eriochrome Black T.
l7. A process for the preparation of the bound indicator of claim 1 which includes the steps of providing a silane which has an organofunctional group, causing the silane to react with a carrier which has available hydroxyl or oxide groups. and causing the organofunctional group of the silane to react with an indicator.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2626855 *||26 Jun 1950||27 Jan 1953||Wilfred C Hand||Seafood spoilage indicating system|
|US2929829 *||12 Oct 1956||22 Mar 1960||Union Carbide Corp||Organosilicon acylamino compounds and process for producing the same|
|US3350175 *||2 Jul 1963||31 Oct 1967||Mine Safety Appliances Co||Colorimetric indicator device for the determination of gases|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3998591 *||26 Sep 1975||21 Dec 1976||Leeds & Northrup Company||Spectrochemical analyzer using surface-bound color reagents|
|US3999948 *||3 Nov 1975||28 Dec 1976||International Diagnostic Technology||Diagnostic reagent holder and method|
|US4034073 *||28 Mar 1975||5 Jul 1977||Corning Glass Works||Composite for biased solid phase radioimmunoassay of triiodothyronine and thyroxine|
|US4050895 *||17 Sep 1976||27 Sep 1977||Monsanto Research Corporation||Optical analytical device, waveguide and method|
|US4056609 *||28 Jan 1976||1 Nov 1977||Gunn, Kirchubel & Miller||Article for diagnosis of achlorhydria|
|US4142783 *||31 May 1977||6 Mar 1979||International Business Machines Corporation||Reversible electrochromic display device having memory|
|US4166804 *||14 Oct 1977||4 Sep 1979||Ceskoslovenska Akademie Ved||Polymeric color indicators and a method of their preparation|
|US4203952 *||8 Sep 1977||20 May 1980||The British Petroleum Company Limited||Process for the removal of heavy metals and transition metals other than platinum from solution|
|US4207075 *||8 Aug 1978||10 Jun 1980||Liburdy Robert P||Rabbit immunoglobulin-N-(3-pyrene)-maleimide conjugate for fluorescent immunoassay|
|US4207200 *||20 Mar 1978||10 Jun 1980||Hans Bunemann||Soluble complex former for the affinity specific separation of macromolecular substances, its preparation and its use|
|US4275300 *||23 Oct 1978||23 Jun 1981||Varian Associates, Inc.||Fluorescent composition, a process for synthesizing the fluorescent composition, and methods of use of the fluorescent composition|
|US4301027 *||3 Jul 1979||17 Nov 1981||Dynamit Nobel Ag||Silica gels incorporating insolubilized reagents|
|US4316041 *||19 Feb 1980||16 Feb 1982||Union Carbide Corporation||Liquid crystal silanes|
|US4377555 *||27 Jul 1977||22 Mar 1983||The British Petroleum Company Limited||Removal of metal from solution|
|US4396528 *||9 Jun 1981||2 Aug 1983||Varian Associates, Inc.||Fluorescent composition, a process for synthesizing the fluorescent composition|
|US4496482 *||22 Oct 1981||29 Jan 1985||Union Carbide Corporation||Liquid crystal silanes|
|US4530963 *||24 Feb 1983||23 Jul 1985||Devoe-Holbein International, N.V.||Insoluble chelating compositions|
|US4560248 *||9 Aug 1982||24 Dec 1985||Imperial Chemical Industries, Plc||Fibre optic sensor with bonded dye|
|US4568518 *||2 Dec 1983||4 Feb 1986||Avl Ag||Sensor element for fluorescence-optical measurement|
|US4585559 *||28 Jun 1984||29 Apr 1986||Devoe-Holbein International, N.V.||Insoluble chelating compositions|
|US4626416 *||22 Jun 1984||2 Dec 1986||Devoe-Holbein International, N.V.||Insoluble chelating compositions|
|US4626693 *||31 Mar 1983||2 Dec 1986||The Regents Of The University Of California||Remote multi-position information gathering system and method|
|US4654197 *||12 Oct 1984||31 Mar 1987||Aktiebolaget Leo||Cuvette for sampling and analysis|
|US4661338 *||19 Nov 1982||28 Apr 1987||Societe D'etudes Scientifiques Et Industrielles De L'ile De France||Process for determining hypoacidity|
|US4799756 *||1 Nov 1985||24 Jan 1989||The Regents Of The University Of California||Remote multi-position information gathering system and method|
|US4803049 *||12 Dec 1984||7 Feb 1989||The Regents Of The University Of California||pH-sensitive optrode|
|US4806311 *||28 Aug 1985||21 Feb 1989||Miles Inc.||Multizone analytical element having labeled reagent concentration zone|
|US4806312 *||28 Aug 1985||21 Feb 1989||Miles Inc.||Multizone analytical element having detectable signal concentrating zone|
|US4824789 *||10 Oct 1986||25 Apr 1989||Cardiovascular Devices, Inc.||Gas sensor|
|US4867919 *||26 Jan 1989||19 Sep 1989||Minnesota Mining And Manufacturing Company||Method of making a gas sensor|
|US4929561 *||8 Aug 1985||29 May 1990||Regents Of The University Of California||Absorption-emission optrode and methods of use thereof|
|US4965087 *||23 Mar 1988||23 Oct 1990||Avl Ag||Method of making a sensor element for fluorescence-optical measurements|
|US4999306 *||28 Apr 1988||12 Mar 1991||Minnesota Mining And Manufacturing Company||Composition, apparatus and method for sensing ionic components|
|US5006314 *||13 Jun 1988||9 Apr 1991||Minnesota Mining And Manufacturing Company||Sensor and method for sensing the concentration of a component in a medium|
|US5019350 *||13 Feb 1986||28 May 1991||Pfizer Hospital Products, Inc.||Fluorescent polymers|
|US5047208 *||23 Feb 1989||10 Sep 1991||Medtronic, Inc.||Blood gas monitoring sensors|
|US5057431 *||15 Sep 1988||15 Oct 1991||Max Planck Gesellschaft Zur Forderung Der Wissenschaften||Device for optical measuring of physical dimensions and material concentrations|
|US5071769 *||17 Dec 1987||10 Dec 1991||Abbott Laboratories||Method and device for ketone measurement|
|US5081041 *||3 Apr 1990||14 Jan 1992||Minnesota Mining And Manufacturing Company||Ionic component sensor and method for making and using same|
|US5081042 *||20 Mar 1990||14 Jan 1992||Minnesota Mining And Manufacturing Company||Ionic component sensor and method for making and using same|
|US5120510 *||6 Dec 1990||9 Jun 1992||Minnesota Mining And Manufacturing Company||Sensor and method for sensing the concentration of a component in a medium|
|US5175016 *||20 Mar 1990||29 Dec 1992||Minnesota Mining And Manufacturing Company||Method for making gas sensing element|
|US5182353 *||24 Jul 1990||26 Jan 1993||Puritan-Bennett Corporation||Method for bonding an analyte-sensitive dye compound to an addition-cure silicone|
|US5219527 *||28 Aug 1991||15 Jun 1993||Puritan-Bennett Corporation||Sensor element and method for making the same|
|US5266271 *||22 May 1992||30 Nov 1993||Puritan-Bennett Corporation||Microsensor copolymer and method of manufacture|
|US5284775 *||21 Sep 1992||8 Feb 1994||Minnesota Mining And Manufacturing Company||Gas sensing element and method for making same|
|US5326531 *||11 Dec 1992||5 Jul 1994||Puritan-Bennett Corporation||CO2 sensor using a hydrophilic polyurethane matrix and process for manufacturing|
|US5330718 *||14 Oct 1992||19 Jul 1994||Puritan-Bennett Corporation||Sensor element and method for making the same|
|US5335305 *||23 Oct 1992||2 Aug 1994||Optex Biomedical, Inc.||Optical sensor for fluid parameters|
|US5397536 *||8 Dec 1993||14 Mar 1995||Riken Keiko Co., Ltd.||Silane gas detecting tape|
|US5407829 *||29 Jun 1993||18 Apr 1995||Avl Medical Instruments Ag||Method for quality control of packaged organic substances and packaging material for use with this method|
|US5408999 *||2 Jun 1994||25 Apr 1995||Optex Biomedical, Inc.||Fiber-optic probe for the measurement of fluid parameters|
|US5462052 *||27 Apr 1993||31 Oct 1995||Minnesota Mining And Manufacturing Co.||Apparatus and method for use in measuring a compositional parameter of blood|
|US5541115 *||3 Jun 1991||30 Jul 1996||Abbott Laboratories||Method and device employing covalently immobilized colored dyes|
|US5830526 *||19 Feb 1997||3 Nov 1998||Fibermark, Inc.||Light-activated antimicrobial and antiviral materials|
|US5833882 *||2 Jun 1997||10 Nov 1998||Japan Pionics Co., Ltd.||Detecting agent|
|US6777243||11 Mar 2003||17 Aug 2004||Arkray Inc.||Method for measuring substance and testing piece|
|US7098038||11 Mar 2003||29 Aug 2006||Arkray Inc.||Method for measuring substance and testing piece|
|US7153696||11 Mar 2003||26 Dec 2006||Arkray Inc.||Method for measuring substance and testing piece|
|US7189576||11 Mar 2003||13 Mar 2007||Arkray Inc.||Method for measuring substance and testing piece|
|US7835003||1 Dec 2005||16 Nov 2010||Schlumberger Technology Corporation||Optical pH sensor|
|US20030175984 *||11 Mar 2003||18 Sep 2003||Takao Fukuoka||Method for measuring substance and testing piece|
|US20030175985 *||11 Mar 2003||18 Sep 2003||Takao Fukuoka||Method for measuring substance and testing piece|
|US20030180183 *||11 Mar 2003||25 Sep 2003||Takao Fukuoka||Method for measuring substance and testing piece|
|US20030203503 *||11 Mar 2003||30 Oct 2003||Takao Fukuoka||Method for measuring substance and testing piece|
|US20040062683 *||30 Sep 2002||1 Apr 2004||The University Of Hong Kong||Sensitive single-layer sensing device of covalently attached luminescent indicator on glass surface for measuring the concentration of analytes|
|US20080159912 *||15 Mar 2006||3 Jul 2008||Nathalie Dantan||Optochemical Sensor Membrane and Method for Producing the Same|
|US20090009768 *||1 Dec 2005||8 Jan 2009||Schlumberger Technology Corporation||Optical Ph Sensor|
|EP0039027A1 *||18 Apr 1981||4 Nov 1981||Gerhard Scharf||Chemical compounds, method for their preparation, means containing these compounds and their application|
|EP0072627A2 *||20 Jul 1982||23 Feb 1983||Imperial Chemical Industries Plc||Fibre optic sensor with bonded dye|
|EP0080411A1 *||18 Nov 1982||1 Jun 1983||Societe D'etudes Scientifiques Et Industrielles De L'ile-De-France||A colour indicator for the determination of hypoacidity in the gastric mucosa, utilizing gastroscopy|
|EP0211534A2 *||14 Jul 1986||25 Feb 1987||DeVoe-Holbein International N.V.||Insoluble composition for removing mercury from a liquid medium|
|WO2006059097A1 *||1 Dec 2005||8 Jun 2006||Schlumberger Holdings||Optical ph sensor|
|WO2006097481A1 *||15 Mar 2006||21 Sep 2006||Ng Bam Bundesanstalt Fuer Mate||Optochemical sensor membrane and method for producing the same|
|U.S. Classification||422/425, 436/169, 436/166|
|Cooperative Classification||G01N31/22, G01N31/221|
|European Classification||G01N31/22, G01N31/22B|