400 results about "Tetramethyl benzidine" patented technology

The invention relates to a method for simulating peroxidase by manganese dioxide nanosheet for detection of reductive biological molecules. The peroxidase simulated by manganese dioxide nanosheet can perform catalytic oxidation on substrates of 3,3',5,5'-tetramethyl benzidine TMB, 2,2-azino-di(3-ethyl-benzothiazoles-6-sulfonic acid) diammonium salt ABTS and o-phenylenediamine OPD, and changes the color from colorless to blue, green and orange respectively, at the same time, the manganese dioxide nanosheet can sensitively and selectively perform an oxidation reduction reaction with reductive biological molecules such as glutathione and ascorbic acid, oxidation product concentration of the substrates such as TMB, ABTS and OPD is changed, and then, the reductive biological molecules such as glutathione and ascorbic acid are subjected to quantitative determination through a colorimetric analysis method. The method has the characteristics of simple operation, high sensitivity, good reappearance and high selectivity; a detection linear scope of glutathione is 1-15 [mu]M, the detection limit is 0.3 [mu]M; the detection linear scope of ascorbic acid is 3-100 [mu]M, the detection limit is 0.8 [mu]M; and the method can be used for detecting various phenolic compounds.

The invention discloses bovine serum albumin-platinum composite nanomaterial mimetic peroxidase as well as a preparation method thereof and application. Bovine serum albumin is used as a template, and the bovine serum albumin-platinum composite nanomaterial mimetic peroxidase is prepared through biomineralization. Bovine serum albumin-platinum composite nanomaterials are prepared through the following method that chloroplatinic acid aqueous solutions are added to bovine serum albumin aqueous solutions and are mixed, sodium hydroxide aqueous solutions are added to obtain mixed solutions, and water bath heating is carried out; ultrafiltration is carried out on the solutions, then the solutions are washed, and bovine serum albumin-platinum composite nanomaterial aqueous solutions are obtained. The bovine serum albumin-platinum composite nanomaterials have excellent peroxidase activity, and can catalyze hydrogen peroxide oxidation 3, 3', 5, 5'-tetramethyl benzidine hydrochloride to be in color development. Meanwhile, the mimetic peroxidase resists acid and base, high temperature and high salinity, and has excellent short-term indoor temperature stability and long-term indoor temperature stability.

The invention discloses a mercury-ion detection method simulating peroxidase based on nano platinum and a kit. After the specificity interaction of the nano platinum and mercury ions, the inhibition variation of the activity of the perioxidase is simulated, hydrogen peroxide is catalyzed by the nano platinum to oxidize 3, 3', 5, 5'-TMB HCL to achieve color developing. The invention provides a novel rapid, simple and ultrasensitive mercury ion detection method. The nano platinum used in the detection method is simple to prepare and easy to obtain, and visualized and convenient analysis on the mercury ions can be realized. The detection method has the advantages of simplicity in operation, short detection time, high sensitivity, high specificity and the like and is easy to popularize and use.

The invention relates to a method for detecting trivalent arsenic in water body through a colourimetry by using protoheme peroxidase catalytic activity, chlorhematin has horseradish peroxidase activity, under the existence of hydrogen peroxide, a chromogenic substrate 3,3', 5,5'-tetramethyl benzidine (TMB) can be catalyzed to generate an oxidation reduction reaction, the solution have variable color change by naked eyes, the addition of a nucleic acid aptamer can inhibit catalytic activity, after adding the trivalent arsenic in the solution, the catalytic activity obtains recovery, so that the color of a whole system enables substantial change, the absorbance and trivalent arsenic concentration at 442nm present a direct proportion relation, thereby the method can be used for detecting the trivalent arsenic of the water body. The detection method provided by the invention has the advantages of high sensitivity and good selectivity, the lowest detection limit is 1ppb, the operation is simple, and a large-scale apparatus is not required, and the method can be used for detecting the trivalent arsenic in drinking water.

The invention relates to a color developing agent and a preparation method and an application thereof. The color developing agent is prepared by mixing a CoOOH nano sheet suspension with 3, 3', 5,5'-tetramethyl benzidine water solution according to the molar ratio CoOOH nano sheets to 3, 3', 5,5'-tetramethyl benzidine of 2:1. The color developing agent is used for detecting ascorbic acid, and has high sensitivity and low detection limit.

The invention discloses a method for detecting a surviving gene based on a graphene-gold composite material electrochemical DNA (Deoxyribose Nucleic Acid) biosensor. The method comprises the following steps: a specific probe is designed according to a gene segment to be detected; a capture probe is self-assembled on the surface of G-3DAu / GCE through a gold-sulfur bond; the capture probe and a signal probe with the tail end marked by biotin are respectively combined with a target DNA to form a 'sandwich' model in the presence of the target DNA; a horse radish peroxidase marked by avidin can be combined with the biotin marked by the signal probe, so that the HRP (Horse Radish Peroxidase) can be fixed on the surface of an electrode; the electrode is placed in a base solution of 3, 3', 5, 5'-tetramethyl benzidine (TMB) and H2O2, and the H2O2 can oxidize TMB to generate a bidiazotizedbenzidine material under the catalyzing of the HRP, so that an electrochemical signal is generated. The method has the advantages of being simple, quick and green in preparation process, and high in selectivity and sensitivity.

The invention discloses a colorimetric analysis method for detecting kanamycin based on aptamer-modified magnetic beads and gold nanoparticles to simulate enzyme activity, and belongs to the technical field of analytical chemistry. In the present invention, the gold nanoparticles synthesized by tyrosine reduction of chloroauric acid simulate the peroxidase-like activity inherent in the enzyme AuNPs, and the gold nanoparticles modified by kanamycin-specific aptamers modify their complementary single-stranded cDNA The capture of nanoparticles, and the displacement of gold nanoparticles by the combination of kanamycin and aptamer, the peroxidation-like peroxidation of gold nanoparticles AuNPs contained in the supernatant after magnetic separation is related to the concentration of kanamycin The enzyme activity catalyzes the color reaction between the substrate tetramethylbenzidine (TMB) and H2O2, realizes the visual detection of kanamycin, and uses the linear relationship between the absorption value at 450 nm and the concentration of kanamycin to realize the detection of kanamycin. Colorimetric quantitative analysis of kanamycin. This method has the advantages of high sensitivity and good specificity, and is suitable for the quantitative analysis of kanamycin residues in food samples such as honey.

The invention relates to detection on hydrogen peroxide, and specifically discloses mimic enzyme test paper for detecting hydrogen peroxide, and preparation and application thereof. The mimic enzyme test paper is a surface modified cellulosic material loaded with an iron-based compound and a color developing agent, wherein the load amount of the iron-based compound is 1%-30% of the mass of the surface modified cellulosic material; the load amount of the color developing agent is 0.1%-20% of the mass of the surface modified cellulosic material; the color developing agent is 3, 3', 5, 5'-tetramethyl benzidine (TMB). According to the test paper provided by the invention, the color developing agent and the iron-based compound are loaded on the cellulosic material (such as filter paper, cotton and cotton cloth), the test paper simulates enzymatic decomposition of hydrogen peroxide and detects hydrogen peroxide, the mimic enzyme test paper is used in chemical industry, spinning, environment protection, medical treatment and food processing, and the application belongs to detection on hydrogen peroxide in the range of food safety, medical treatment, public health and environmental technology.

The invention discloses a folic acid-porous platinum-graphene oxide composite nano material as well as an application thereof in detecting tumor cells. The folic acid-porous platinum-graphene oxide composite nano material is prepared by the following steps: by taking graphene oxide as a substrate, carrying out amidation to crosslinked folic acid molecules; and carrying out in-situ synthesizing on platinum nano particles with porous structures. The folic acid-porous platinum-graphene oxide composite nano material can specifically identify a folate receptor on the surface of the cell, and meanwhile has a characteristic of simulating peroxidase and can catalyze hydrogen peroxide oxidized 3, 3', 5, 5'-tetramethyl benzidine hydrochloride to develop color. The number of the tumor cells can be quickly and agilely detected by means of chromogenic reaction, and 30 MCF-7 (Michigan Cancer Foundation-7) cells can be detected to the minimum extent. The material further can catalyze diaminobenzidine to generate a reddish brown precipitate on the surface of the cell so as to realize targeted positioning detection.

The invention belongs to the technical field of in-vitro immunodetection and in particular relates to a kit for detecting myeloperoxidase (MPO) concentration in a sample and a preparation method of the kit. The kit comprises a porous plate coated with an anti-MPO monoclonal antibody, an MPO series standard substance and a quality control material, a horse radish peroxidase-labeled anti-MPO monoclonal antibody, a sample buffer solution, a citrate buffer solution of hydrogen peroxide, a citrate buffer solution of tetramethyl benzidine, a 1-2M sulfuric acid solution, and a phosphate buffer solution containing surfactants. Because the used detection instruments are simple and are universal instruments, the kit is low in detection cost and contributes to popularization; the kit is easy to operate and can be realized without professionals. Meanwhile, according to the unique standard diluent and sample buffer solution formula in the kit, the reliability and the accuracy of the detection result are greatly improved.

The invention belongs to the field of detecting a trace amount of ions in the water environment, and particularly relates to a visualization method for rapidly detecting a trace amount of uranyl ions in the water environment. The method mainly includes the steps that DNAzyme with the specific recognition function on UO2 <2+> is fixed to the surfaces of magnetic beads, and horse radish peroxidase is preassembled on the surface of nano-gold; then the magnetic beads are connected with the nano-gold through the cutting effect of the UO2<2+> on the DNAzyme and the hybridization reaction of DNA, after separation and collection are carried out through an external magnetic field, H2O2 oxidation tetramethyl benzidine is efficiently catalyzed through the horse radish peroxidase to enable a solution to be changed from the blank to the blue, and therefore sensitive and specific visualization rapid detection of the UO2<2+> ions is achieved. As the method has the advantages of being high in sensitivity, high in specificity, high in matrix interference resistance, simple, rapid, low in cost and the like, the method can be used for site rapid visualization detection of the trace amount of UO2<2+> ions in various water samples.

The invention discloses a paper-based dual-mode detection method of lead ions. A hydrophobic area and a hydrophilic area are prepared on paper with wax printing and laser cutting technologies, and three electrodes are printed with a silk-screen printing technology. Different areas of a paper chip are functionalized with multiple methods, and visual judgement of the lead ions can be realized through the developing function of 3,3',5,5'-tetramethyl benzidine. Super-sensitive detection of to-be-detected articles can be realized by means of an electrochemical work station through the specific recognition function of the lead ions and DNA enzyme and specific catalysis of glucose oxidase for glucose.

The invention discloses a kit capable of quantitatively detecting soluble B7-H1, which comprises a horseradish peroxidase label, tetramethylbenzidine serving as a reaction substrate, bovine serum albumin, an elisa plate, washing liquor, stop solution, a coating antibody, a standard protein and a detection antibody, wherein the coating antibody is a mouse anti-human B7-H1 monoclonal antibody and the nucleotide sequence of the heavy chain of the coating antibody is represented by a nucleotide sequence SEQ ID No.3 in the sequence list, and the nucleotide sequence of the light chain of the coating antibody is represented by a nucleotide sequence SEQ ID No.4 in the sequence table. The kit capable of quantitatively detecting soluble B7-H1 has high specificity and can be used for accurately quantitative analysis on soluble B7-H1 protein factor concentration in liquid for human cell culture supernate, serum, plasma, hydrothorax and the like.

The invention discloses a preparation method for a sensor based on hydrophilic up-conversion nano-particles and application of the sensor to detection of hydrogen peroxide and glucose. Monodisperse up-conversion nano-particles which are good in water solubility, stable and uniform in size are prepared under an amphiphilic system by adopting an ultrasonic micro emulsion process, utilizing hydrophobic-hydrophobic effects between oleylamine-modified polysuccinimide high polymers and oleic acid on the surfaces of the up-conversion nano-particles and hydrolyzing part of chain elements of the polysuccinimide high polymers under an alkaline condition to form a hydrophilic group; the up-conversion nano-particles are mixed with tetramethyl benzidine and horse radish peroxidase to obtain the hydrogen peroxide and glucose sensor. Compared with a conventional detecting method, the method is small in background interference, strong in signal and low in cost, and has the characteristics of being quick, accurate, high in flexibility and high in selectivity. The hydrogen peroxide and glucose sensor can be used for providing a novel opportunity for monitoring hydrogen peroxide and glucose in real time in a living microenvironment in future.

The invention provides a visualization reagent architecture that is used for peroxydase measurement and a preparation method thereof. The visualization reagent architecture comprises urea peroxide, a heavy metal ion complexing agent and a compound of 4-tert-butyl-4'-methoxy-dibenzoylmethane, 3.3' 5.5'-tetramethylbenzidine and sodium hyposulfite, the preparation method of the architecture comprises the following steps: (1) a storage liquid I is prepared and ready for use, and a storage liquid II is prepared and ready for use; and (2) the storage liquid I and the storage liquid II are mixed, pH value of a buffering liquid is adjusted and volume is limited. Peroxides and chromophoric substrates in the visualization reagent architecture that is provided by the invention can coexist stably without reaction for a long time, thus leading the solution architecture to be easily stored and have consistent sensitivity during measurement.

The invention discloses rapid hydrogen peroxide test paper and a preparation method thereof. The test paper comprises a base plate and a test paper piece; one end of the base plate serves as a handheld end, the other end of the base plate serves as a test paper piece paste end, the test paper piece is pasted at the test paper piece paste end, and the test paper piece is soaked in a test paper soaking solution and then dried to obtain the test paper; the test paper soaking solution is prepared by mixing an antioxidant system, an enzyme protection system and a color developing agent, the antioxidant system is prepared by dissolving tea polyphenol, vitamin c and sodium thiosulfate into water, and the enzyme protection system is prepared by dissolving sucrose, polyethylene glycol and bovine serum albumin into water. Accordingly, groups, prone to oxidization, of tetramethyl benzidine are protected by the antioxidant system, so that the rapid hydrogen peroxide test paper can be preserved for 1 year at normal temperature.

The invention discloses a manganese dioxide sheet mimic enzyme sensor and a preparation method thereof as well as a T4PNK detection method. The preparation method comprises the following steps: (1) mixing a MnO2 nanosheet solution with a TMB (3,3',5,5'-tetramethyl benzidine) solution to obtain a MnO2-TMB mixed solution; (2) dissolving hairpin DNA in a Tris-HCl buffer solution, and adding ATP (adenosine triphosphate) and lambda EXO (lambda exonuclease) for mixing to obtain a DNA solution; and (3) mixing the MnO2-TMB mixed solution and the DNA solution to obtain the manganese dioxide sheet mimic enzyme sensor. The preparation method is simple in operation, and the sensor has the characteristics of high sensitivity, low detection limit and simple operation when used for detecting T4PNK.

The present invention relates to a urine iodine determination kit. It includes urine purification device, diluent liquor, color-developing liquor, composite oxidant and standard colorimetric plate. Said kit can quickly remove interference substance from the urine, and can be used for accurately determining iodine concentration in the urine. The above-mentioned urine purification device is a titration type container in which a selective specific adsorbent for specifically adsorbing interference substance in the urine is held. Said selective specific adsorbent is made up by using purification active carbon and iodine adsorption agonist NaCl, MgCl2 or NaBr through baking activation process, the above-mentioned color-developing liquor is a mixed reagent formed from tetramethylbenzidine aqueous solution and polyethylene glycol. Besides, said invention also provides the composition of the composite oxidant.

The invention discloses an ultra-sensitive aflatoxin B1 enzyme-linked immunosorbent assay kit. The kit comprises an aflatoxin B1 standard solution, a solid phase carrier, an enzyme labeling object, a substrate developing solution, a sample dilute solution, a termination solution and a concentration washing solution, wherein the solid phase carrier is a micropore plate; and the enzyme labeling object is an aflatoxin B1 protein coupling object labeled by horseradish peroxide and is coated by an aflatoxin B1 monoclonal antibody, and the substrate developing solution is tetramethyl benzidine (TMB). The invention also discloses a preparation method of the ultra-sensitive aflatoxin B1 enzyme-linked immunosorbent assay kit and a method for detecting aspergillus flavus B1. By using the kit according to the invention to detect aflatoxin B1 the kit has the characteristics of simple operation, high sensitivity, good specificity, good linearity and the like.

The invention discloses a platinum-sulfonated graphene composite nano material with characteristics of simulated peroxidase. Sulfonated graphene is taken as the substrate, platinum nano particles are synthesized by a sodium borohydride reduction method, and sulfonated graphene and platinum nano particles are used to prepare the platinum-sulfonated graphene composite nano material. The platinum-sulfonated graphene composite nano material has an excellent activity of peroxidase and can catalyze the oxidation reactions between 3,3',5,5'-tetramethylbenzidine hydrochloride to trigger color development. The composite nano material has good affinity on the substrate namely 3,3',5,5'-tetramethylbenzidine hydrochloride. The composite nano material can be used to detect hydrogen peroxide with a low concentration. The absorbance of catalytic product and the concentration (0.01-0.1 mmol / L) of hydrogen peroxide are in a linear relationship, and the detection limit is 0.0025 mmol / L.

The invention discloses a method for measuring nano-gold mimetic peroxidase based urease and an inhibitor thereof. The method is characterized by comprising the following steps: coupling a urease catalysis urea reaction system with a nano-gold mimetic peroxidase-hydrogen peroxide-3,3',5,5'-tetramethylbenzidine dihydrochloride catalytic chromogenic reaction system, and combining with the changes of solution colors and ultraviolet absorption spectrum characteristics to directly measure the content of urease and the inhibitor thereof, wherein in a range of 1.8-90U / L, A450 and the urease concentration have a linear relationship, and the limit of detection is 1.8U / L; and by virtue of software fitting, IC50 of obtained acetohydroxamic acid of the urease inhibitor is 0.05mmoL / L. The method disclosed by the invention is simple and convenient to operate and high in sensitivity, and can be applied to the measurement of the content of urease and the inhibitor thereof in environment and life science systems as an analysis method.

The invention provides a CsxWO3 type peroxide mimic enzyme, and a preparation method and application thereof. The CsxWO3 type peroxide mimic enzyme has the activity similar to that of peroxidase, and can be used for catalyzing H2O2 to generate a great quantity of hydroxyl free radicals and effectively oxidizing a substrate, 3,3',5,5'-tetramethyl benzidine to generate a color developing reaction. The CsxWO3 type peroxide mimic enzyme is combined with glucose oxidase for use, the content of glucose in a solution can be indirectly detected by measuring an ultraviolet absorption value of the oxidized 3,3',5,5'-tetramethyl benzidine and the detection limit is 0.1 micro milliliter. Compared with horse radish peroxidase (HRP), the CsxWO3 nano material has the advantages of simple preparation process, low cost, stable chemical activity and the like; the catalytic effect and the applicability of the CsxWO3 nano material are higher than those of natural peroxidase, and thus the CsxWO3 nano material can be used as a substitute of natural peroxidase.

The invention discloses a boron-doped graphene quantum dot and a preparation method thereof. The boron element-doped graphene quantum dot is prepared by one-step hydrothermal synthesis in a mixed aqueous solution of 1,3,6-trinitropyrene and borax, and the prepared boron-doped graphene quantum dot can emit yellow fluorescence and has good fluorescence stability, and the fluorescence intensity afterthe boron-doped graphene quantum dot is placed for 3 months still keeps 99% of initial fluorescence intensity. The high-stability boron-doped graphene quantum dot provided by the invention has peroxidase-like reaction activity, and can catalyze a color reaction that hydrogen peroxide oxidizes 3,5,3',5'-tetramethylbenzidine. The boron-doped graphene quantum dot has obvious selective recognition ability on iron ions, and the iron ions can quench fluorescent signals of the boron-doped graphene quantum dot, and corresponding stability is achieved within 3 minutes.

The invention discloses a novel method for detecting lead ions based on the sensitivity of a DNA-MOF material. The method comprises the following steps: preparing a gold-paper chip working electrode Au-PWE; synthesizing Au-MOF from 5,10,15,20-tetra(4-methoxy phenyl)porphyrin, ferric chloride and nanogold; carrying out functionalization by virtue of GR DNA, so as to synthesize a GR-Au-MOF material; modifying the prepared Au-PWE with HP DNA, and dropwise adding a GR-Au-MOF solution mixed with 3,3',5,5'-tetramethyl benzidine, hydrogen peroxide and a sample solution to HP modified Au-PWE; and connecting the modified chip to an electrochemical working station by virtue of a three-electrode system, and detecting the concentration of lead ions by virtue of a differential pulse voltammetry. The novel method for detecting the lead ions is high in sensitivity and good in selectivity, and the real-time monitoring of samples can be realized.

The invention relates to a human anti-rabies virus IgG antibody ELISA test kit. An ELISA plate is firstly coated with an anti-rabies virus monoclonal antibody, wherein the coating buffer solution is a 0.05M carbonate buffer solution of which the pH value is 9.6, and the coating amount is 0.1-1ug per hole; a blocking solution is a BSA or skimmed milk of which the mass concentration is 1-10%; the ELISA plate is coated with a rabies virus purified antigen after being blocked, wherein the coating amount is 0.1-1ug per hole; a sample diluent is a 0.01mol / L phosphate buffer solution (PBS) which contains bovine serum albumin (BSA) with a mass concentration of 0.1-10% and NaN3 with a mass concentration of 0.01-0.05 and has a pH value of 7.2-7.4; an enzyme conjugate is a horse radish peroxidase-mouse anti-human IgG enzyme conjugate; a concentrated cleaning solution is a 0.01mol / L PBS which contains tween-20 with a volume concentration of 0.05% and has a pH value of 7.2-7.4; a zymolyte A solution is a 3,3'-5,5'-tetramethyl benzidine solution, and a zymolyte B solution is an oxydol solution; and a stop solution is a 1mol / L H2SO4 solution, and a positive control and a negative control are arranged in the kit. The specificity of the kit is up to 100%, and the sensitivity is 1:640. The kit is used for evaluating the immunity effect of humans inoculated with rabies vaccines.

An enzyme-linked detection kit for detecting VEGF. A kit body contains an enzyme-linked reaction plate coated by a VEGF acceptor and a monoclonal antibody, an enzyme conjugate labelled by HRP and configured by antibody and a protective agent, a freeze-drying powder of the VEGF protein as a positive contrast, a protein freeze-drying powder as a negative contrast, a sample diluent, a PBST concentrated lotion, a chromogenic substrate configured by 3,3',5,5'-tetramethyl benzidine, 2MH2SO4 as a stopping solution and a seal plate gummed paper. The kit can be used in diagnosis and prognosis of cancer, angiopathy, diabetes, retinopathy and rheumatoid arthritis, and has advantages of accuracy, specificity, sensitivity, stability and convenience, etc.

The invention discloses an agent tape and kit for testing alcohol content in spit. The content of alcohol in spit would be semi-quantification tested according to the color of agent tape after ethanol oxidase and peroxidase oxygenating N, N, N', N'-tetramethyl benzidine.

The invention discloses a premature rupture of membrane (PROM) detection kit using an intercellular adhesion molecular (ICAM)-1 as an examination index. The kit comprises a perforated plate coated with an ICAM-1 monoclonal antibody, biotin-labeled ICAM-1 monoclonal antibody (biotin-ICAM-1Ab) examination fluid, aidin-horseradish peroxidase combined with the biotin-labeled ICAM-1 monoclonal antibody, chromogenic substrate 3',3',5,5'-tetramethylbenzidine and ICAM-1 protein standard. A preparation method of the kit comprises the following steps of: (1) preparing the perforated plate coated with the ICAM-1 monoclonal antibody; (2) preparing the biotin-labeled ICAM-1 monoclonal antibody examination fluid; and (3) preparing the aidin-horseradish peroxidase, the chromogenic substrate 3',3',5,5'-tetramethylbenzidine and the ICAM-1 protein standard.

The invention relates to a monodispersive bimetal Au / Pt nano-particle modified electrode for detecting mercury in water and a preparation method thereof. The preparation method of the electrode comprises the following steps of: adding chloroplatinic acid to 3,3',5,5'-tetramethylbenzidine to obtain a purple precipitate, i.e. a Pt(II) doped organic nano fiber material; modifying the organic nano fiber material containing Pt(II) onto the surface of a glassy carbon electrode and then putting the modified glassy carbon electrode in a chloroauric acid solution; and carrying out electrochemical reduction by adopting cyclic voltammetry, wherein in the reduction process, the chloroauric acid is reduced into simple substance Au, and partial Pt(II) doped in the organic nano fiber material is also reduced into simple substance Pt, thereby forming a glassy carbon electrode which is adhered with Au-Pt bimetal nano particles on the surface and modified by a three-dimensional porous composite membrane with a network-shaped structure by using organic fibrous nano material as a supporting skeleton. The electrode can be used for detecting the content of mercury by adopting anodic stripping voltammetry, and has low detection limit to 0.008ppb, high sensitivity, strong selectivity and convenient and quick operation.

A method for amperometric detection of proteins, especially haemoglobin in faeces, using an electrochemical sensor. The electrochemical sensor includes: a working electrode having an electrically conductive matrix holding a first reagent and / or a second reagent, the second reagent being an oxidising agent, or a precursor thereof, for the first reagent; a counter electrode and optionally a reference electrode; wherein a reaction between the first reagent and the oxidising agent is catalysed by the protein to provide a detectable signal at the working electrode. The electrically conductive matrix is an electrically conductive carbon- or graphite-containing matrix or an electrically conductive porous matrix.