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Colorimetry (chemical Method)
In physical and analytical chemistry, colorimetry or colourimetry is a technique used to determine the concentration of colored compounds in solution. A colorimeter is a device used to test the concentration of a solution by measuring its absorbance of a specific wavelength of light (not to be confused with the tristimulus colorimeter used to measure colors in general). To use the colorimeter, different solutions must be made, including a control or reference of known concentration. With a visual colorimeter, for example the Duboscq colorimeter illustrated, the length of the light path through the solutions can be varied while filtered light transmitted through them is compared for a visual match. The concentration times path length is taken to be equal when the colors match, so the concentration of the unknown can be determined by simple proportions. Nessler tubes work on the same principle. There are also electronic automated colorimeters; before these machines are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duboscq Colorimeter 1870
Duboscq is a French surname. People with the name include: * Genevieve Duboscq (1933–2018), author * Hugues Duboscq (born 1981), Olympic breaststroke swimmer * Jules Duboscq (18171886), instrument maker, inventor, and photographer * Lucien Duboscq (1893–1935, stage actor * Octave Duboscq Octave Joseph Duboscq (30 October 1868, Rouen – 18 February 1943, Nice) was a French zoologist, mycologist and parasitologist. He obtained doctorates in medicine (1894) and sciences (1899) at the University of Caen. From 1904 to 1923, he was c ... (1868–1943), zoologist, mycologist and parasitologist See also * Dubosc {{surname ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analyte
An analyte, component (in clinical chemistry), or chemical species is a substance or chemical constituent that is of interest in an analytical procedure. The purest substances are referred to as analytes, such as 24 karat gold, NaCl, water, etc. In reality, no substance has been found to be 100% pure in its quality, so a substance that is found to be most pure (for some metals, 99% after electrolysis) is called an analyte. See also *Analytical chemistry *Immunoassay *Magnetic immunoassay Magnetic immunoassay (MIA) is a type of diagnostic immunoassay using magnetic beads as labels in lieu of conventional enzymes (ELISA), radioisotopes (RIA) or fluorescent moieties ( fluorescent immunoassays) to detect a specified analyte. MIA involv ... References Analytical chemistry {{Analytical-chemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbidimetry
Turbidimetry (the name being derived from ''turbidity'') is the process of measuring the loss of intensity of transmitted light due to the scattering effect of particles suspended in it. Light is passed through a filter creating a light of known wavelength which is then passed through a cuvette containing a solution. A photoelectric cell collects the light which passes through the cuvette. A measurement is then given for the amount of absorbed light. Turbidimetry can be used in biology to find the number of cells in a suspension. Turbidity-is an expression of optical look of a suspension caused by radiation to the scattered and absorbed wavelength. Scattering of light is elastic so both incident and scattered radiation have same wavelength. A turbidometer measures the amount of radiation that passes through a fluid in forward direction, analogous to absorption spectrphotoometry. Standard for turbidimetry is prepared by dissolving 5g of hydrazinium (2+) sulfate(N2H4H2SO4) and 50g of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lovibond Comparator
The Lovibond comparator is an example of a colorimeter made in Britain by The Tintometer Ltd. It was invented in the 19th century by Joseph Williams Lovibond anupdated versionsare still available. Description The device is used to determine the color of liquids. A sample is put in a glass tube. The tube is inserted in the comparator and compared with a series of coloured glass discs until the nearest possible match is found. Among other things, the device is used to determine the concentration of certain chemicals in solution. In this use, some assumptions are made about what is in the sample. Given those assumptions, the concentration will be indicated by the disc which best matches the color of the solution. There are a number of standard tests in which a sample to be tested is mixed a colour reagent. In such tests, the resulting color indicates the concentration of the sample under test. Results can be approximate compared to other testing techniques, but the comparator i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permanganometry
Permanganometry is one of the techniques used in chemical quantitative analysis. It is a redox titration that involves the use of permanganates to measure the amount of analyte present in unknown chemical samples. It involves two steps, namely the titration of the analyte with potassium permanganate solution and then the standardization of potassium permanganate solution with standard sodium oxalate solution. The titration involves volumetric manipulations to prepare the analyte solutions. Permanganometry allows the detection and estimation of the quantitative presence of various chemical species, such as iron(II), manganese(II), oxalate, nitrite, and hydrogen peroxide. Reaction Depending on the conditions in which the titration is performed, the manganese is reduced from an oxidation of +7 to +2, +4, or +6. In most cases, permanganometry is performed in a very acidic solution in which the following electrochemical reaction occurs: : + 8 H+ + 5 e− → Mn2+ + 4 H2O; ''E''° = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3,3',5,5'-Tetramethylbenzidine
3,3′,5,5′-Tetramethylbenzidine or TMB is a chromogenic substrate used in staining procedures in immunohistochemistry as well as being a visualising reagent used in enzyme-linked immunosorbent assays (ELISA). TMB is a white solid that forms a pale blue-green liquid in solution with ethyl acetate. TMB is degraded by sunlight and by fluorescent lights. Enzymatic assay TMB can act as a hydrogen donor for the reduction of hydrogen peroxide to water by peroxidase enzymes such as horseradish peroxidase. The resulting one-electron oxidation product is a diimine-diamine complex, which causes the solution to take on a blue colour, and this colour change can be read on a spectrophotometer at the wavelengths of 370 and 650 nm. The reaction can be halted by addition of acid or another stop reagent. Using sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ELISA
The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence of a ligand (commonly a protein) in a liquid sample using antibodies directed against the protein to be measured. ELISA has been used as a diagnostic tool in medicine, plant pathology, and biotechnology, as well as a quality control check in various industries. In the most simple form of an ELISA, antigens from the sample to be tested are attached to a surface. Then, a matching antibody is applied over the surface so it can bind the antigen. This antibody is linked to an enzyme and then any unbound antibodies are removed. In the final step, a substance containing the enzyme's substrate is added. If there was binding, the subsequent reaction produces a detectable signal, most commonly a color change. Performing an ELISA involves at least ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicinchoninic Acid Assay
The bicinchoninic acid assay (BCA assay), also known as the Smith assay, after its inventor, Paul K. Smith at the Pierce Chemical Company, now part of Thermo Fisher Scientific, is a biochemical assay for determining the total concentration of protein in a solution (0.5 μg/mL to 1.5 mg/mL), similar to Lowry protein assay, Bradford protein assay or biuret reagent. The total protein concentration is exhibited by a color change of the sample solution from green to purple in proportion to protein concentration, which can then be measured using colorimetric techniques. Mechanism A stock BCA solution contains the following ingredients in a highly alkaline solution with a pH 11.25: bicinchoninic acid, sodium carbonate, sodium bicarbonate, sodium tartrate, and copper(II) sulfate pentahydrate. The BCA assay primarily relies on two reactions. First, the peptide bonds in protein reduce Cu2+ ions from the copper(II) sulfate to Cu1+ (a temperature dependent reaction). The amount of Cu2+ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coomassie Blue
Coomassie brilliant blue is the name of two similar triphenylmethane dyes that were developed for use in the textile industry but are now commonly used for staining proteins in analytical biochemistry. Coomassie brilliant blue G-250 differs from Coomassie brilliant blue R-250 by the addition of two methyl groups. The name "Coomassie" is a registered trademark of Imperial Chemical Industries. Name and discovery The name Coomassie was adopted at the end of the 19th century as a trade name by the Blackley-based dye manufacturer Levinstein Ltd, in marketing a range of acid wool dyes. In 1896 during the Fourth Anglo–Ashanti War, British forces had occupied the town of Coomassie (modern-day Kumasi in Ghana). In 1918 Levinstein Ltd became part of British Dyestuffs, which in 1926 became part of Imperial Chemical Industries. Although ICI still owns the Coomassie trademark, the company no longer manufactures the dyes. The blue disulfonated triphenylmethane dyes were first produced in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkaline Phosphatase
The enzyme alkaline phosphatase (EC 3.1.3.1, alkaline phosphomonoesterase; phosphomonoesterase; glycerophosphatase; alkaline phosphohydrolase; alkaline phenyl phosphatase; orthophosphoric-monoester phosphohydrolase (alkaline optimum), systematic name phosphate-monoester phosphohydrolase (alkaline optimum)) catalyses the following reaction: : a phosphate monoester + H2O = an alcohol + phosphate Alkaline phosphatase has the physiological role of dephosphorylating compounds. The enzyme is found across a multitude of organisms, prokaryotes and eukaryotes alike, with the same general function but in different structural forms suitable to the environment they function in. Alkaline phosphatase is found in the periplasmic space of '' E. coli'' bacteria. This enzyme is heat stable and has its maximum activity at high pH. In humans, it is found in many forms depending on its origin within the body – it plays an integral role in metabolism within the liver and development withi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Para-Nitrophenylphosphate
''para''-Nitrophenylphosphate (pNPP) is a non-proteinaceous chromogenic substrate for alkaline and acid phosphatases used in ELISA The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence ... and conventional spectrophotometric assays. Phosphatases catalyze the hydrolysis of pNPP liberating inorganic phosphate and the conjugate base of ''para''-nitrophenol (pNP). The resulting phenolate is yellow, with a maximal absorption at 405 nm. This property can be used to determine the activity of various phosphatases including alkaline phosphatase (AP) and protein tyrosine phosphatase (PTP). The substance is sensitive to light, and thus should be stored protected from light. This is also important after adding the substrate to the mixture and before reading. −20 °C is the optimal stora ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distilled Water
Distilled water is water that has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, distilled water is a type of purified water. History Drinking water has been distilled from seawater since at least about AD 200, when the process was clearly described by Alexander of Aphrodisias. Its history predates this, as a passage in Aristotle's ''Meteorologica'' refers to the distillation of water. Captain Israel Williams of the ''Friendship'' (1797) improvised a way to distill water, which he described in his journal. Applications In chemical and biological laboratories, as well as in industry, in some appliances deionised water can be used instead of distilled water as a cheaper alternative. If exceptionally high-purity water is required, double distilled water is used. In general, non-purified water could cause or interfere wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
