The ferric chloride test is used to determine the presence of phenols in a given sample or compound (for instance natural phenols in a plant extract). Enols, hydroxamic acids, oximes, and sulfinic acids give positive results as well. [1] The bromine test is useful to confirm the result, although modern spectroscopic techniques (e.g. NMR and IR spectroscopy) are far superior in determining the identity of the unknown. The quantity of total phenols may be spectroscopically determined by the Folin–Ciocalteau assay.
The sample is dissolved in water, or a mixture of water and ethanol, and a few drops of neutral ferric chloride (FeCl3) solution, which is prepared by adding de-ionised water. Add sodium hydroxide to the mixture until a permanent brown precipitate is formed. The formation of a red, blue, green, or purple coloration indicates the presence of phenols. Where the sample is insoluble in water, it may be dissolved in dichloromethane with a small amount of pyridine.
Phenols form a complex with ferric ions. This complex has an intense colour, which may vary from blue, green or even red depending upon the nature of the phenol. As an example using the chemical phenol itself:
The ferric chloride test can be used to detect metabolites in urine in case of inborn error of metabolism such as phenylketonuria. Compounds such as phenylpyruvate increase in plasma and are excreted out via urine. Also, it can be used to detect salicylates in urine, quick diagnostic test for aspirin overdose.[ medical citation needed ]
Tannins are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.
In chemistry, Ferric refers to the element iron in its +3 oxidation state. Ferric chloride is an alternative name for iron(III) chloride (FeCl3). The adjective ferrous is used instead for iron(II) salts, containing the cation Fe2+. The word ferric is derived from the Latin word ferrum, meaning "iron".
Benedict's reagent is a chemical reagent and complex mixture of sodium carbonate, sodium citrate, and copper(II) sulfate pentahydrate. It is often used in place of Fehling's solution to detect the presence of reducing sugars. The presence of other reducing substances also gives a positive result. Such tests that use this reagent are called the Benedict's tests. A positive test with Benedict's reagent is shown by a color change from clear blue to brick-red with a precipitate.
Potassium ferricyanide is the chemical compound with the formula K3[Fe(CN)6]. This bright red salt contains the octahedrally coordinated [Fe(CN)6]3− ion. It is soluble in water and its solution shows some green-yellow fluorescence. It was discovered in 1822 by Leopold Gmelin.
Iron(III) chloride describes the inorganic compounds with the formula FeCl3(H2O)x. Also called ferric chloride, these compounds are some of the most important and commonplace compounds of iron. They are available both in anhydrous and in hydrated forms which are both hygroscopic. They feature iron in its +3 oxidation state. The anhydrous derivative is a Lewis acid, while all forms are mild oxidizing agents. It is used as a water cleaner and as an etchant for metals.
In environmental chemistry, the chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution which in SI units is milligrams per litre (mg/L). A COD test can be used to easily quantify the amount of organics in water. The most common application of COD is in quantifying the amount of oxidizable pollutants found in surface water or wastewater. COD is useful in terms of water quality by providing a metric to determine the effect an effluent will have on the receiving body, much like biochemical oxygen demand (BOD).
The Bradford protein assay was developed by Marion M. Bradford in 1976. It is a quick and accurate spectroscopic analytical procedure used to measure the concentration of protein in a solution. The reaction is dependent on the amino acid composition of the measured proteins.
Classical qualitative inorganic analysis is a method of analytical chemistry which seeks to find the elemental composition of inorganic compounds. It is mainly focused on detecting ions in an aqueous solution, therefore materials in other forms may need to be brought to this state before using standard methods. The solution is then treated with various reagents to test for reactions characteristic of certain ions, which may cause color change, precipitation and other visible changes.
Copper(II) chloride, also known as cupric chloride, is an inorganic compound with the chemical formula CuCl2. The monoclinic yellowish-brown anhydrous form slowly absorbs moisture to form the orthorhombic blue-green dihydrate CuCl2·2H2O, with two water molecules of hydration. It is industrially produced for use as a co-catalyst in the Wacker process.
In chemistry, a chemical test is a qualitative or quantitative procedure designed to identify, quantify, or characterise a chemical compound or chemical group.
Salicylate testing is a category of drug testing that is focused on detecting salicylates such as acetysalicylic acid for either biochemical or medical purposes.
In chemistry, the Biuret test, also known as Piotrowski's test, is a chemical test used for detecting the presence of at least two peptide bonds in a molecule. In the presence of peptides, a copper(II) ion forms mauve-colored coordination complexes in an alkaline solution. The reaction was first observed in 1833; In Poland, the biuret test is also known as Piotrowski's test in honor of the Polish physiologist Gustaw Piotrowski who independently rediscovered it in 1857. Several variants on the test have been developed, such as the BCA test and the Modified Lowry test.
A nitrate test is a chemical test used to determine the presence of nitrate ion in solution. Testing for the presence of nitrate via wet chemistry is generally difficult compared with testing for other anions, as almost all nitrates are soluble in water. In contrast, many common ions give insoluble salts, e.g. halides precipitate with silver, and sulfate precipitate with barium.
Iron shows the characteristic chemical properties of the transition metals, namely the ability to form variable oxidation states differing by steps of one and a very large coordination and organometallic chemistry: indeed, it was the discovery of an iron compound, ferrocene, that revolutionalized the latter field in the 1950s. Iron is sometimes considered as a prototype for the entire block of transition metals, due to its abundance and the immense role it has played in the technological progress of humanity. Its 26 electrons are arranged in the configuration [Ar]3d64s2, of which the 3d and 4s electrons are relatively close in energy, and thus it can lose a variable number of electrons and there is no clear point where further ionization becomes unprofitable.
A range of qualitative and quantitative tests have been developed to detect phosphate ions (PO43-) in solution. Such tests find use in industrial processes, scientific research, and environmental water monitoring.
A urine test strip or dipstick is a basic diagnostic tool used to determine pathological changes in a patient's urine in standard urinalysis.
The Trinder spot test is a diagnostic test used in medicine to determine exposure to salicylates, particularly to salicylic acid. The test employs the Trinder reagent which is mixed with a patient's urine. The colour change, resulting from the Trinder reaction, is immediate, enabling rapid bedside assessment.
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 magnitude of a solution by measuring its absorbance of a specific wavelength of light.
Forensic serology is the detection, identification, classification, and study of various bodily fluids such as blood, semen, saliva, and urine, and their relationship to a crime scene. A forensic serologist may also be involved in DNA analysis and bloodstain pattern analysis. Serology testing begins with presumptive tests which gives the analyst an indication that a specific bodily fluid may be present, but cannot completely confirm its presence. Following the presumptive tests, confirmatory tests are done on the same sample to confirm what the unknown substance actually is.