Titration is a common laboratory method of quantitative chemical analysis to determine the concentration of an identified analyte. A reagent, termed the titrant or titrator, is prepared as a standard solution of known concentration and volume. The titrant reacts with a solution of analyte to determine the analyte's concentration. The volume of titrant that reacted with the analyte is termed the titration volume.
Electrospray ionization (ESI) is a technique used in mass spectrometry to produce ions using an electrospray in which a high voltage is applied to a liquid to create an aerosol. It is especially useful in producing ions from macromolecules because it overcomes the propensity of these molecules to fragment when ionized. ESI is different from other ionization processes since it may produce multiple-charged ions, effectively extending the mass range of the analyser to accommodate the kDa-MDa orders of magnitude observed in proteins and their associated polypeptide fragments.
Cerium(IV) sulfate, also called ceric sulfate, is an inorganic compound. It exists as the anhydrous salt Ce(SO4)2 as well as a few hydrated forms: Ce(SO4)2(H2O)x, with x equal to 4, 8, or 12. These salts are yellow to yellow/orange solids that are moderately soluble in water and dilute acids. Its neutral solutions slowly decompose, depositing the light yellow oxide CeO2. Solutions of ceric sulfate have a strong yellow color. The tetrahydrate loses water when heated to 180-200 °C.
Bisulfide is an inorganic anion with the chemical formula HS−. It contributes no color to bisulfide salts, and its salts may have a distinctive putrid smell. It is a strong base. Bisulfide solutions are corrosive and attack the skin.
Eriochrome Black T is a complexometric indicator that is used in complexometric titrations, e.g. in the water hardness determination process. It is an azo dye. Eriochrome is a trademark of Huntsman Petrochemical, LLC.
Murexide (NH4C8H4N5O6, or C8H5N5O6·NH3), also called ammonium purpurate or MX, is the ammonium salt of purpuric acid. It is a purple solid that is soluble in water. The compound was once used as an indicator reagent. Aqueous solutions are yellow at low pH, reddish-purple in weakly acidic solutions, and blue-purple in alkaline solutions.
Silver chromate is an inorganic compound with formula Ag2CrO4 which appears as distinctively coloured brown-red crystals. The compound is insoluble and its precipitation is indicative of the reaction between soluble chromate and silver precursor salts (commonly potassium/sodium chromate with silver nitrate). This reaction is important for two uses in the laboratory: in analytical chemistry it constitutes the basis for the Mohr method of argentometry, whereas in neuroscience it is used in the Golgi method of staining neurons for microscopy.
Rosocyanine and rubrocurcumin are two red colored materials, which are formed by the reaction between curcumin and borates.
Molybdenum blue is a term applied to:
The Charlot equation, named after Gaston Charlot, is used in analytical chemistry to relate the hydrogen ion concentration, and therefore the pH, with the formal analytical concentration of an acid and its conjugate base. It can be used for computing the pH of buffer solutions when the approximations of the Henderson–Hasselbalch equation break down. The Henderson–Hasselbalch equation assumes that the autoionization of water is negligible and that the dissociation or hydrolysis of the acid and the base in solution are negligible.
The color of wine is one of the most easily recognizable characteristics of wines. Color is also an element in wine tasting since heavy wines generally have a deeper color. The accessory traditionally used to judge the wine color was the tastevin, a shallow cup allowing one to see the color of the liquid in the dim light of a cellar. The color is an element in the classification of wines.
Resazurin is a phenoxazine dye that is weakly fluorescent, nontoxic, cell-permeable, and redox‐sensitive. Resazurin has a blue to purple color above pH 6.5 and an orange color below pH 3.8. It is used in microbiological, cellular, and enzymatic assays because it can be irreversibly reduced to the pink-colored and highly fluorescent resorufin (7-Hydroxy-3H-phenoxazin-3-one). At circum-neutral pH, resorufin can be detected by visual observation of its pink color or by fluorimetry, with an excitation maximum at 530-570 nm and an emission maximum at 580-590 nm.
The pyranoanthocyanins are a type of pyranoflavonoids. They are chemical compounds formed in red wines by yeast during fermentation processes or during controlled oxygenation processes during the aging of wine. The different classes of pyranoanthocyanins are carboxypyranoanthocyanins, methylpyranoanthocyanins, pyranoanthocyanin-flavanols, pyranoanthocyanin-phenols, portisins, oxovitisins and pyranoanthocyanin dimers; their general structure includes an additional ring that may have different substituents linked directly at C-10.
The Walden reductor is a reduction column filled with metallic silver which can be used to reduce a metal ion in aqueous solution to a lower oxidation state. It can be used e.g. to reduce UO22+ to U4+. The method is named after George H. Walden, who developed it jointly with a Ph.D. student, Sylvan M. Edmonds, at Columbia University.
Cerimetry or cerimetric titration, also known as cerate oximetry, is a method of volumetric chemical analysis developed by Ion Atanasiu. It is a redox titration in which an iron(II)–1,10-phenanthroline complex (ferroin) color change indicates the end point. Ferroin can be reversibly discolored in its oxidized form upon titration with a Ce4+ solution. The use of cerium(IV) salts as reagents for volumetric analysis was first proposed in the middle of 19th century, but systematic studies did not start until about 70 years later. Standard solutions can be prepared from different Ce4+ salts, but often cerium sulfate is chosen.
Malvidin glucoside-ethyl-catechin is a flavanol-anthocyanin adduct. Flavanol-anthocyanin adducts are formed during wine ageing through reactions between anthocyanins and tannins present in grape, with yeast metabolites such as acetaldehyde. Acetaldehyde-induced reactions yield ethyl-linked species such as malvidin glucoside-ethyl-catechin.
Jennifer S. Brodbelt is an American chemist known for her research using mass spectrometry to characterize organic compounds, especially biopolymers and proteins.
Hobart Hurd Willard was an analytical chemist and inorganic chemist who spent most of his career at the University of Michigan. He was known for his teaching skill and his authorship of widely used textbooks. His research interests were wide-ranging and involved the characterization of perchloric acid and periodic acid salts.
Calconcarboxylic acid is an azo dye that is used as an indicator for complexometric titrations of calcium with ethylenediaminetetraacetic acid (EDTA) in the presence of magnesium. Structurally, it is similar to eriochrome blue black R, which is obtained from calconcarboxylic acid by decarboxylation and reaction with sodium hydroxide.
Dithiofluorescein is a complexometric indicator used in analytical chemistry. It changes from blue to colorless when it binds to mercury(2+) ions. It thus can indicate the endpoint in the titration of thiols using o-hydroxymercuribenzoic acid or its sodium salt. The reagent can be immobilized t in a polymer on a fiber optic, which might allow development of a detector for sulfide ions in a flow cell. Unlike fluorescein and other related fluoran dyes that have oxygen substituents on the benzene rings, dithiofluorescein, which has sulfur substituents, is not fluorescent.
