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Griess Test
The Griess test is an analytical chemistry test which detects the presence of nitrite ion in solution. One of its most important uses is the determination of nitrite in drinking water. The Griess diazotization reaction, on which the Griess reagent relies, was first described in 1858 by Peter Griess.Peter Griess (1858"Vorläufige Notiz über die Einwirkung von salpetriger Säure auf Amidinitro- und Aminitrophenylsäure,"(Preliminary notice of the reaction of nitrous acid with picramic acid and aminonitrophenol), ''Annalen der Chemie und Pharmacie'', 106: 123–125. The test has also been widely used for the detection of nitrates (N-oxidation state = 5+), which are a common component of explosives, as they can be reduced to nitrites (N-oxidation state = 3+) and detected with the Griess test. Method Nitrite is detected and analyzed by the formation of a red pink colour upon treatment of a nitrite-containing sample with the Griess reagent, which consists of two components in an acidi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrite Test
A nitrite test is a chemical test used to determine the presence of nitrite ion in solution. Chemical methods Using iron(II) sulfate A simple nitrite test can be performed by adding 4 M sulfuric acid to the sample until acidic, and then adding 0.1 M iron(II) sulfate to the solution. A positive test for nitrite is indicated by a dark brown solution, arising from the iron-nitric oxide complex ion. This test is related to the brown ring test for the nitrate ion, which forms the same complex in a ring. In contrast, nitrites turn the whole solution brown and therefore interfere with that test. Griess test A common method of quantitative nitrite detection is the Griess test, which relies on the reaction of nitrite with the two components of a Griess reagent to form a red azo dye. This allows the concentration of nitrite to be determined by UV-vis spectroscopy. : Urinary nitrite test A nitrite test is a standard component of a urinary test strip. A positive test for nitrites in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analytical Chemistry
Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separation isolates analytes. Qualitative analysis identifies analytes, while quantitative analysis determines the numerical amount or concentration. Analytical chemistry consists of classical, wet chemical methods and modern, instrumental methods. Classical qualitative methods use separations such as precipitation, extraction, and distillation. Identification may be based on differences in color, odor, melting point, boiling point, solubility, radioactivity or reactivity. Classical quantitative analysis uses mass or volume changes to quantify amount. Instrumental methods may be used to separate samples using chromatography, electrophoresis or field flow fractionation. Then qualitative and quantitative analysis can be performed, often with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Griess Test Reaction
Robert Louis Griess, Jr. (born 1945, Savannah, Georgia) is a mathematician working on finite simple groups and vertex algebras. He is currently the John Griggs Thompson Distinguished University Professor of mathematics at University of Michigan. Education Griess developed a keen interest in mathematics prior to entering undergraduate studies at the University of Chicago in the fall of 1963. There, he eventually earned a Ph.D. in 1971 under the supervision of John Griggs Thompson after defending a dissertation on the Schur multipliers of the then-known finite simple groups. Research Griess' early work focused on group extensions, cohomology and Schur multipliers, as well as on the classification of finite simple groups and their properties. He was awarded a Guggenheim Fellowship in 1981. In 1982, he published the first construction of the monster group using the Griess algebra, for which he was awarded the 2010 AMS Leroy P. Steele Prize for Seminal Contribution to Res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrate 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. The nitrate anion is an oxidizer, and many tests for the nitrate anion are based on this property. However, other oxidants present in the analyte may interfere and give erroneous results. Nitrate can also be detected by first reducing it to the more reactive nitrite ion and using one of many nitrite tests. Brown ring test A common nitrate test, known as the brown ring testEgon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier can be performed by adding iron(II) sulfate to a solution of a nitrate, then slowly adding concentrated sulfuric acid such that the acid forms a layer belo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frank Skuse
Frank Skuse (born ca. 1934) is a British former forensic scientist for the North West Forensic Laboratories based in Chorley, Lancashire. His flawed conclusions, eventually discredited, contributed to the convictions of Judith Ward and the Birmingham Six. Others who claimed they were wrongfully convicted on Skuse's evidence include Ann Gillespie, a native of Donegal, who served almost 10 years of a 15-year sentence for conspiracy and explosive charges after a bomb exploded in a home she and her sister were visiting in Manchester."I don't want English pardon", ''The Sunday Times'', 27 November 2005. Summerland As an employee of the Home Office North-West forensic science laboratory, Skuse helped investigate the Summerland Fire. He concluded that the fire had started in a plastic mini-golf hut. Judith Ward Skuse used the Griess test in which the presence of NO2− (nitrite ions) is detected in a sample by formation of a red azo dye. He used the extraction solvent ether. He analys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birmingham Six
The Birmingham Six were six Irishmen who were each sentenced to life imprisonment in 1975 following their false convictions for the 1974 Birmingham pub bombings. Their convictions were declared unsafe and unsatisfactory and quashed by the Court of Appeal on 14 March 1991. The six men were later awarded financial compensation ranging from £840,000 to £1.2 million. Birmingham pub bombings The Birmingham pub bombings took place on 21 November 1974 and were attributed to the Provisional Irish Republican Army (IRA). Improvised explosive devices were placed in two central Birmingham pubs: the Mulberry Bush at the foot of the Rotunda, and the Tavern in the Town – a basement pub in New Street. The resulting explosions, at 20:25 and 20:27, collectively were the most deadly attacks in the UK since World War II (until surpassed by the Denmark Place fire in 1980); 21 people were killed (ten at the Mulberry Bush and eleven at the Tavern in the Town) and 182 people were injured. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Judith Ward
The M62 coach bombing, sometimes referred to as the M62 Massacre, occurred on 4 February 1974 on the M62 motorway in northern England, when a 25-pound (11 kg) Provisional Irish Republican Army (IRA) bomb hidden inside the luggage locker of a coach carrying off-duty British Armed Forces personnel and their family members exploded, killing twelve people (nine soldiers and three civilians) and injuring thirty-eight others aboard the vehicle. Ten days after the bombing, 25-year-old Judith Ward was arrested in Liverpool while waiting to board a ferry to Ireland. She was later convicted of the M62 coach bombing and two other separate, non-fatal attacks and remained incarcerated until her conviction was quashed by the Court of Appeal in 1992, with the court hearing Government forensic scientists had deliberately withheld information from her defence counsel at her October 1974 trial which strongly indicated her innocence. As such, her conviction was declared unsafe. Ward was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sample (material)
In general, a sample is a limited quantity of something which is intended to be similar to and represent a larger amount of that thing(s). The things could be countable objects such as individual items available as units for sale, or an uncountable material. Even though the word "sample" implies a smaller quantity taken from a larger amount, sometimes full biological or mineralogical specimens are called samples if they are taken for analysis, testing, or investigation like other samples. They are also considered samples in the sense that even whole specimens are "samples" of the full population of many individual organisms. The act of obtaining a sample is called "sampling" and can be performed manually by a person or by automatic process. Samples of material can be taken or provided for testing, analysis, investigation, quality control, demonstration, or trial use. Sometimes, sampling may be performed continuously. Aliquot part In science, a representative liquid sample t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali that decomposes proteins at ordinary ambient temperatures and may cause severe chemical burns. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. It forms a series of hydrates . The monohydrate crystallizes from water solutions between 12.3 and 61.8 °C. The commercially available "sodium hydroxide" is often this monohydrate, and published data may refer to it instead of the anhydrous compound. As one of the simplest hydroxides, sodium hydroxide is frequently used alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students. Sodium hydroxide is used in many industries: in the manufacture of pulp and paper, textiles, drinking water, soap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitroglycerine
Nitroglycerin (NG), (alternative spelling of nitroglycerine) also known as trinitroglycerin (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless, oily, explosive liquid most commonly produced by nitrating glycerol with white fuming nitric acid under conditions appropriate to the formation of the nitric acid ester. Chemically, the substance is an organic nitrate compound rather than a nitro compound, but the traditional name is retained. Invented in 1847 by Ascanio Sobrero, nitroglycerin has been used ever since as an active ingredient in the manufacture of explosives, namely dynamite, and as such it is employed in the construction, demolition, and mining industries. Since the 1880s, it has been used by militaries as an active ingredient and gelatinizer for nitrocellulose in some solid propellants such as cordite and ballistite. It is a major component in double-based smokeless propellants used by reloaders. Combined with nitrocel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forensics
Forensic science, also known as criminalistics, is the application of science to criminal and civil laws, mainly—on the criminal side—during criminal investigation, as governed by the legal standards of admissible evidence and criminal procedure. Forensic science is a broad field that includes; DNA analysis, fingerprint analysis, blood stain pattern analysis, firearms examination and ballistics, tool mark analysis, serology, toxicology, hair and fiber analysis, entomology, questioned documents, anthropology, odontology, pathology, epidemiology, footwear and tire tread analysis, drug chemistry, paint and glass analysis, digital audio video and photo analysis. Forensic scientists collect, preserve, and analyze scientific evidence during the course of an investigation. While some forensic scientists travel to the scene of the crime to collect the evidence themselves, others occupy a laboratory role, performing analysis on objects brought to them by other individuals. Sti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectrophotometry
Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. Spectrophotometry uses photometers, known as spectrophotometers, that can measure the intensity of a light beam at different wavelengths. Although spectrophotometry is most commonly applied to ultraviolet, visible, and infrared radiation, modern spectrophotometers can interrogate wide swaths of the electromagnetic spectrum, including x-ray, ultraviolet, visible, infrared, and/or microwave wavelengths. Overview Spectrophotometry is a tool that hinges on the quantitative analysis of molecules depending on how much light is absorbed by colored compounds. Important features of spectrophotometers are spectral bandwidth (the range of colors it can transmit through the test sample), the percentage of sample-transmission, the logarithmic range of sample-absorption, and sometimes a perc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
