Chemical test
Encyclopedia
In chemistry
, a chemical test is a qualitative or quantitative
procedure designed to prove the existence of, or to quantify, a chemical compound
or chemical group
with the aid of a specific reagent
. A presumptive test
is specifically used in medical science.
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, a chemical test is a qualitative or quantitative
Quantitative property
A quantitative property is one that exists in a range of magnitudes, and can therefore be measured with a number. Measurements of any particular quantitative property are expressed as a specific quantity, referred to as a unit, multiplied by a number. Examples of physical quantities are distance,...
procedure designed to prove the existence of, or to quantify, a chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
or chemical group
Substituent
In organic chemistry and biochemistry, a substituent is an atom or group of atoms substituted in place of a hydrogen atom on the parent chain of a hydrocarbon...
with the aid of a specific reagent
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
. A presumptive test
Presumptive test
In medical and forensic science, a presumptive test is an analysis of a sample which establishes either:#The sample is definitely not a certain substance#The sample probably is the substance....
is specifically used in medical science.
Purposes
Chemical testing might have a variety of purposes, such as:- Determine if, or verify that, the requirements of a specification, regulationRegulationRegulation is administrative legislation that constitutes or constrains rights and allocates responsibilities. It can be distinguished from primary legislation on the one hand and judge-made law on the other...
, or contractContractA contract is an agreement entered into by two parties or more with the intention of creating a legal obligation, which may have elements in writing. Contracts can be made orally. The remedy for breach of contract can be "damages" or compensation of money. In equity, the remedy can be specific...
are met - Decide if a new product developmentNew product developmentIn business and engineering, new product development is the term used to describe the complete process of bringing a new product to market. A product is a set of benefits offered for exchange and can be tangible or intangible...
program is on track: Demonstrate proof of conceptProof of conceptA proof of concept or a proof of principle is a realization of a certain method or idea to demonstrate its feasibility, or a demonstration in principle, whose purpose is to verify that some concept or theory that has the potential of being used... - Demonstrate the utility of a proposed patentPatentA patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
- Determine the interactions of a sample with other known substances
- Determine the composition of a sample
- Provide standard dataDataThe term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
for other scientific, medical, and Quality assuranceQuality AssuranceQuality assurance, or QA for short, is the systematic monitoring and evaluation of the various aspects of a project, service or facility to maximize the probability that minimum standards of quality are being attained by the production process...
functions - Validate suitability for end-use
- Provide a basis for Technical communicationTechnical communicationTechnical communication is a method of researching and creating information about technical processes or products directed to an audience through media. The information must be relevant to the intended audience. Technical communicators often work collaboratively to create products for various...
- Provide a technical means of comparison of several options
- Provide evidenceEvidenceEvidence in its broadest sense includes everything that is used to determine or demonstrate the truth of an assertion. Giving or procuring evidence is the process of using those things that are either presumed to be true, or were themselves proven via evidence, to demonstrate an assertion's truth...
in legal proceedings
Biochemical tests
- ClinistripClinistripA clinistrip is a urine test strip to measure levels of glucose in urine for diabetics. The small plastic strip has glucose oxidase and an organic dye on one end. The enzyme oxidizes glucose to gluconic acid with the formation of hydrogen peroxide. The hydrogen peroxide reacts with dye to produce a...
s quantitatively test for sugarSugarSugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
in urineUrineUrine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream... - The Kastle-Meyer testKastle-Meyer testThe Kastle-Meyer test is a presumptive blood test, first described in 1903, in which the chemical indicator phenolphthalein is used to detect the possible presence of hemoglobin...
tests for the presence of bloodBloodBlood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells.... - Salicylate testingSalicylate testingSalicylate testing is a category of drug testing that is focused on detecting salicylates such as acetysalicylic acid for either biochemical or medical purposes.- Analytical :Salicylates can be identified by GC/MS, proton NMR, and IR.- In Vitro :...
is a category of drug testing that is focused on detecting salicylates such as acetysalicylic acid for either biochemical or medical purposes. - The PhadebasPhadebasPhadebas is a substrate used for both qualitative and quantitative assessment of the alpha-Amylase enzyme. The active component of Phadebas is DSM-P, microspheres in which a blue dye has been chemically bound...
test tests for the presence of salivaSalivaSaliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
for forensic purposes - Iodine solutionTincture of iodineTincture of iodine is a disinfectant, usually 2–7% elemental iodine, along with potassium iodide or sodium iodide, dissolved in a mixture of ethanol and water. As in the case of Lugol's iodine, the role of iodide and water in the solution is to increase the solubility of the elemental iodine, by...
tests for starchStarchStarch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store... - The Van Slyke determinationVan Slyke determinationThe Van Slyke determination is a chemical test for the determination of amino acids containing a primary amine group. A sample is brought into contact with a solution of sodium nitrite in glycerol, water and acetic acid. The resulting diazotisation reaction produces nitrogen gas which can be...
tests for specific amino acidAmino acidAmino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s - The Zimmermann test for Ketosteroids
- Seliwanoff's testSeliwanoff's testSeliwanoff’s test is a chemical test which distinguishes between aldose and ketose sugars. Ketoses are distinguished from aldoses via their ketone/aldehyde functionality. If the sugar contains a ketone group, it is a ketose and if it contains an aldehyde group, it is an aldose...
for differentiating between aldose and ketose sugars - Test for lipids: add ethanolEthanolEthanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
to sample, then shake; add water to the solution, and shake again. If fat is present, the product turns milky white.
Reducing sugars
- Barfoed's testBarfoed's testBarfoed's Test is a chemical test used for detecting the presence of monosaccharides. It is based on the reduction of copper acetate to copper oxide , which forms a brick-red precipitate....
tests for reducing polysaccharidePolysaccharidePolysaccharides are long carbohydrate molecules, of repeated monomer units joined together by glycosidic bonds. They range in structure from linear to highly branched. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure,...
s or disaccharideDisaccharideA disaccharide or biose is the carbohydrate formed when two monosaccharides undergo a condensation reaction which involves the elimination of a small molecule, such as water, from the functional groups only. Like monosaccharides, disaccharides form an aqueous solution when dissolved in water...
s - Benedict's reagentBenedict's reagentBenedict's reagent is a chemical reagent named after an American chemist, Stanley Rossiter Benedict....
tests for reducing sugarReducing sugarA reducing sugar is any sugar that either has an aldehyde group or is capable of forming one in solution through isomerisation. This functional group allows the sugar to act as a reducing agent, for example in the Tollens' test or Benedict's test.-Chemistry:...
s or aldehydeAldehydeAn aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....
s - Fehling's solutionFehling's solutionFehling's solution is a chemical test used to differentiate between water-soluble aldehyde and ketone functional groups, and as a test for monosaccharides. The test was developed by German chemist Hermann von Fehling in 1849.-Laboratory preparation:...
tests for reducing sugarReducing sugarA reducing sugar is any sugar that either has an aldehyde group or is capable of forming one in solution through isomerisation. This functional group allows the sugar to act as a reducing agent, for example in the Tollens' test or Benedict's test.-Chemistry:...
s or aldehydeAldehydeAn aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....
s, similar to Benedict's reagentBenedict's reagentBenedict's reagent is a chemical reagent named after an American chemist, Stanley Rossiter Benedict.... - Molisch's testMolisch's testMolisch's Test is a sensitive chemical test for the presence of carbohydrates, based on the dehydration of the carbohydrate by sulfuric acid to produce an aldehyde, which condenses with two molecules of phenol Molisch's Test (named after Austrian botanist Hans Molisch) is a sensitive chemical test...
for carbohydrates
Proteins and polypeptides
- The Bicinchoninic acid assayBicinchoninic acid assayThe bicinchoninic acid assay , also known as the Smith assay, after its inventor, Paul K. Smith at the Pierce Chemical Company, is a biochemical assay for determining the total level of protein in a solution , similar to Lowry protein assay, Bradford protein assay or biuret reagent...
tests for proteinProteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s - Biuret reagent tests for proteinProteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s and polypeptides - Bradford protein assayBradford protein assayThe Bradford protein assay is a spectroscopic analytical procedure used to measure the concentration of protein in a solution. It is subjective, i.e., dependent on the amino acid composition of the measured protein. The Bradford protein assay was developed by Marion M...
measures proteinProteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
quantitative - The PhadebasPhadebasPhadebas is a substrate used for both qualitative and quantitative assessment of the alpha-Amylase enzyme. The active component of Phadebas is DSM-P, microspheres in which a blue dye has been chemically bound...
Amylase Test determines alpha-amylaseAlpha-Amylaseα-Amylase is an enzyme that hydrolyses alpha-bonds of large alpha-linked polysaccharides such as starch and glycogen, yielding glucose and maltose. It is the major form of amylase found in humans and other mammals...
activity
Organic tests
- The Carbylamine reactionCarbylamine reactionThe Carbylamine reaction is a chemical test for detection of primary amines. In this reaction, the analyte is heated with alcoholic potassium hydroxide and chloroform...
tests for primary amineAmineAmines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
s - The Griess test tests for organic nitrite compounds
- The Iodoform reaction tests for the presence of methyl ketoneKetoneIn organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...
s, or compounds which can be oxidized to methyl ketones - The Schiff testSchiff testThe Schiff test invented and named after Hugo Schiff is a chemical test for the detection of aldehydes. An unknown sample is added to the decolorized Schiff reagent and when aldehyde is present a characteristic magenta or purple color develops. The Schiff reagent is the reaction product of...
detects aldehydeAldehydeAn aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....
s - Tollens' reagentTollens' reagentTollens' reagent is a chemical reagent most commonly used to determine whether a known carbonyl-containing compound is an aldehyde or a ketone. It is usually ammoniacal silver nitrate, but can also be other mixtures, as long as aqueous diamminesilver complex is present...
(Silver Mirror) tests for aldehydes - The Zeisel determinationZeisel determinationThe Zeisel determination or Zeisel test is a chemical test for the presence of esters or ethers in a chemical substance. It is named after the Czech chemist Simon Zeisel . In a qualitative test a sample is first reacted with a mixture of acetic acid and hydriodic acid in a test tube...
tests for the presence of esterEsterEsters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s or etherEtherEthers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...
s - Lucas' reagentLucas' reagentLucas' reagent is a solution of zinc chloride in concentrated hydrochloric acid. This solution is used to classify alcohols of low molecular weight. The reaction is a substitution in which the chloride replaces a hydroxyl group. A positive test is indicated by a change from colourless to turbid,...
is used to determine mainly between primaryPrimary alcoholA primary alcohol is an alcohol which has the hydroxyl radical connected to a primary carbon. It can also be defined as a molecule containing a “–CH2OH” group.Examples include ethanol and butanol....
, secondary and tertiary alcohols.
Inorganic tests
- Barium chlorideBarium chlorideBarium chloride is the inorganic compound with the formula BaCl2. It is one of the most common water-soluble salts of barium. Like other barium salts, it is toxic and imparts a yellow-green coloration to a flame. It is also hygroscopic....
tests for sulfateSulfateIn inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
s - The Beilstein testBeilstein testThe Beilstein test is a simple chemical test used in chemistry as a qualitative test for halides. It was developed by Friedrich Konrad Beilstein....
tests for halideHalideA halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...
s qualitatively - Borax bead testBorax bead testThe bead test is a traditional part of qualitative inorganic analysis to test for the presence of certain metals. The oldest one is the borax bead test or blister test. It was introduced by Berzelius in 1812. Since then other salts were used as fluxing agents, such as sodium carbonate or sodium...
tests for certain metalMetalA metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
s - The Carius halogen methodCarius halogen methodThe Carius halogen method in analytical chemistry is a method for the quantitative determination of halogens in chemical substances .In this technique a chemical substance is oxidized with fuming nitric acid under pressure in the presence of silver nitrate at a maximum operating temperature of 230...
measures halideHalideA halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...
s quantitatively - Chemical test for cyanide tests for the presence of cyanideCyanideA cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....
, CN- - Copper sulfate tests for presence of water
- Flame testFlame testA flame test is a procedure used in chemistry to detect the presence of certain metal ions, based on each element's characteristic emission spectrum. The color of flames in general also depends on temperature; see flame color....
s test for metalMetalA metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
s - The Gilman testGilman testThe Gilman test is a chemical test for the detection of Grignard reagents and organolithium reagents.A 0.5 mL sample is added to a 1% solution of Mischler's ketone in benzene or toluene. To this solution is added 1 mL of water for hydrolysis to take place and then several drops of 0.2% iodine in...
tests for the presence of a Grignard reagent - The Kjeldahl methodKjeldahl methodThe Kjeldahl method or Kjeldahl digestion in analytical chemistry is a method for the quantitative determination of nitrogen in chemical substances developed by Johan Kjeldahl in 1883.- Method :...
quantitatively determines the presence of nitrogenNitrogenNitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere... - Nessler's reagentNessler's reagentPotassium tetraiodomercurate is an inorganic compound containing potassium cations and the tetraiodomercurate complex anion. It is mainly used as Neßler's reagent, a 0.09 mol/L solution of potassium tetraiodomercurate in 2.5 mol/L potassium hydroxide, used to detect ammonia.-Nessler's...
tests for the presence of ammoniaAmmoniaAmmonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or... - NinhydrinNinhydrinNinhydrin is a chemical used to detect ammonia or primary and secondary amines. When reacting with these free amines, a deep blue or purple color known as Ruhemann's purple is produced...
tests for ammoniaAmmoniaAmmonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
or primary amineAmineAmines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
s - Phosphate testPhosphate testThis is applicable to laboratory analysis particularly in the determination of water pollution. Such an analytical test may be either qualitative or quantitative....
for phosphatePhosphateA phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in... - The sodium fusion testSodium fusion testThe sodium fusion test is used in elemental analysis for the qualitative determination of elemental halogens, nitrogen and sulfur in a sample. It was developed by J. L. Lassaigne....
tests for the presence of nitrogenNitrogenNitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, sulfurSulfurSulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
, and halideHalideA halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...
s in a sample - The Zerewitinoff determinationZerewitinoff determinationThe Zerewitinoff determination or Zerevitinov determination is a quantitative chemical test for the determination of active hydrogens in a chemical substance. A sample is treated with the Grignard reagent, methylmagnesium iodide, which reacts with any acidic hydrogen atom to form methane. This gas...
tests for any acidic hydrogen - The Oddy testOddy testThe Oddy test is a procedure created at the British Museum by conservation scientist Andrew Oddy in 1973, in order to test materials for safety in and around art objects....
for acid, aldehydes, and sulfides