Method of identification

In this way the student s knowledge of the organic reactions is consolidated as he proceeds through the sections, his experience of the general method of identification steadily increases, and the investigation of the unknown compounds forms a welcome break from the systematic pursuit of the sectional work. 

Although visual and microscopical examination, together with simple manual tests, are stiU the primary methods of identification, there are many new sophisticated instmmental methods available based on chemical and physical properties. These methods are able to distinguish between closely related fibers which differ only in chemical composition or morphology. 

Instrumental Analysis. It is difficult to distiaguish between the various acryhcs and modacryhcs. Elemental analysis may be the most effective method of identification. Specific compositional data can be gained by determining the percentages of C, N, O, H, S, Br, Cl, Na, and K. In addition the levels of many comonomers can be estabhshed usiag ir and uv spectroscopy. Also, manufacturers like to be able to identify their own products to certify, for example, that a defective fiber is not a competitor s. To facihtate this some manufacturers iatroduce a trace of an unusual element as a built-ia label. 

Acetates. Because of the significant interest in selective acetylation reactions of sucrose, the need for a convenient and unambiguous method of identification has been recognized (34,35). The position of an acetyl group in a partially acetylated sucrose derivative can be ascertained by comparison of its H-nmr acetyl methyl proton resonances after per-deuterioacetylation with those of the assigned octaacetate spectmm. The synthesis of partially acetylated sucroses has generally been achieved either by way of selectively protected derivatives such as trityl ethers and cychc acetals or by direct selective acetylation and deacetylation reactions. 

All known methods of identification of authenticity products of cognac demand presence of such difficult and expensive devices as gas chromatographs, weights - spectrometers application crystallization, extractions, etc. methods of division increases time of carrying out of the analysis. 

The method of identification depends upon the type, size, quantity, or fragility of the product. You can mark the product directly (provided the item is not an appearance item ) or tie a label to it or the container in which it is placed. You can also use records remote from the product providing they bear a unique identity that is traceable to the product. 

Segregation may also be necessary in the packaging of products not only to prevent visible damage but electrical damage, as with electrostatic-sensitive devices. Segregation may be the only way of providing adequate product identity, as is the case with fasteners. While a well-equipped laboratory can determine the difference between products and materials the consumer needs a simple practical method of identification and labeled packets are often a reliable and economic alternative. 

Other methods of identification include the customary preparation of derivatives, comparisons with authentic substances whenever possible, and periodate oxidation. Lately, the application of nuclear magnetic resonance spectroscopy has provided an elegant approach to the elucidation of structures and stereochemistry of various deoxy sugars (18). Microcell techniques can provide a spectrum on 5-6 mg. of sample. The practicing chemist is frequently confronted with the problem of having on hand a few milligrams of a product whose structure is unknown. It is especially in such instances that a full appreciation of the functions of mass spectrometry can be developed. 

Thus, a more complete study of the spectral properties and the structure of intermediates frozen in inert matrices is achieved when the IR, Raman, UV and esr spectroscopic methods are mutually complementary. Since IR spectroscopy is the most informative method of identification of matrix-isolated molecules, this review is mainly devoted to studies which have been performed using this technique. 

Laser-based methods of identification are extremely powerful they are able to provide species and structural information, as well as accurate system temperature values. Spontaneous Raman scattering experiments are useful for detection of the major species present in the system. Raman scattering is the result of an inelastic collision process between the photons and the molecule, allowing light to excite the molecule into a virtual state. The scattered light is either weaker (Stokes shifted) or... 

Polyalphaolefin Hydraulic Fluids. The methods for analyzing polyalphaolefin hydraulic fluids are identical to those for the mineral oil hydraulic fluids (see Table 6-1). Polyalphaolefin oils can be distinguished from mineral oils because they will be present in combinations of the alphaolefin from which they were synthesized (Shubkin 1993). Thus, polyalphaolefins obtained from 1-decene will be present as dimers (C20 alkanes), trimers (C30 alkanes), tetramers (C40 alkanes), pentamers (C50 alkanes), etc., with no alkanes between these isomers (e.g., there will be no C2i alkanes present in the oil). This method of identification will only be possible if the polyalphaolefin hydraulic fluids contain no mineral oils or if the samples being analyzed were not exposed to mineral oils. 

Two identification tests for oxytetracycline hydrochloride are given in the USP 28 [1], one being an ultraviolet absorption test and the other a color test. European Pharmacopoeia [2], British Pharmacopoeia (BP) 2003 [4], International Pharmacopoeia [5], and Pharmacopoeia of the People s Republic of China [6] described a thin-layer chromatography and color tests for identification of oxytetracycline hydrochloride and oxytetracycline dihydrate. For identification of oxytetracycline calcium, USP 28 [1] used Method II under identification of tetracycline <193>, whilst BP 2003 [4] described a TLC, color test, and calcium test as the method of identification. 

Chromatographic methods are used to separate the components in a mixture, but in a complex mixture, a single chromatographic method or step many not separate all components. In these cases, using simple retention time to identify the components will not suffice and the identification of components in the mixture will be incorrect. Thus, the addition of a method of identification such as mass spectrometry (MS) or Fourier transform infrared (FTIR) is essential. In some cases, it may even be necessary to confirm either an FTIR or MS identification by the same method applied in a different way. For example, FTIR may be followed by MS, or electron ionization (El) MS followed by chemical ionization (Cl) MS or by an entirely different method. 

Jean, T. and Chapelain, B. (1999) Method of identification of leads or active compounds. CEREP, International Publication NumberWO-09915894. 

Viscosity measurements are employed as a method of identifing different grades of liquids. Examples ... 

Abstract A simple, accessible and cost effective method of crystallographic identification of microorganisms has been developed. It allows rapid and snfficiently reliable identification of many clinically significant pathogens based on their crystallogenic properties. The nse of the crystallographic method snbstantially accelerated and simplified the identification of Candida spp. when compared with traditional methods of identification of microorganisms. 

Recently a number of more sophisticated methods for identification of microorganisms have been developed. However, alongside their increase in accuracy and complexity their cost has also risen. Widespread biochemical methods of identification are rather labour intensive and the results obtained are not always reliable due to the high variability of microbial species. 

Following the same procedure, the crystallograms were characterized by high reproducibility. It normally takes 16-18 h to obtain crystallograms and to identify Candida spp., whereas traditional methods of identification Candida spp. usually... 

A simple, easily available and cost effective method of identification of microorganisms has been developed. It allows a fast and sufficiently reliable determination of many clinically significant pathogens. 

DNA fingerprinting, also known as DNA typing, is a method of identification that compares fragments of DNA. This technique was first developed in 1985, originally used to detect the presence of genetic diseases. With the exception of identical twins, the complete DNA of each individual is unique. 

The nature of the azo bond is such that only a very limited number of possible functional groups can be considered to have the necessary features to serve as starting materials for reductive methods of preparation. In a sense, the Bogo-slovskii reaction [17, 18] may be considered a reduction of a diazonium salt by copper(I) ions. However, because the reaction resembles the other condensations of diazonium salts, its classification among the condensation reactions seems appropriate. The direct reduction of azoxy compounds as such is of minor preparative importance except as a method of identification of an azoxy compound. However, in the various bimolecular reduction procedures of aromatic nitro compounds, it has been postulated that an azoxy intermediate forms in the course of the reaction. This intermediate azoxy compound is ultimately reduced to an azo compound. 

The natural occurrences of montmorillonites are varied and complex, as is the mineralogy of this mineral group. They are particularly variable chemically, due in part to the completely undefined interlayer ion position which can be occupied in part or entirely by almost any cation except silicon. Definitions and descriptions of these expandable minerals are necessarily vague since the response of these interlayer ions to different chemical and thermal treatments is the most current method of identification for minerals in the group. This leaves the basic 2 1 structure identified in many cases. A broad differentiation of the basic... 

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