Chemical testing spectroscopy

Many divalent and trivalent oxides form cements with PAA (Crisp, Prosser Wilson, 1976 Hodd Reader, 1976 Hornsby, 1977). Cement formation was observed using infrared spectroscopy and physical and chemical tests. Of these cements that of ZnO (Smith, 1968) was the first and remains by far the most important it is given detailed treatment in Section 5.7. 

Modern Fourier Transform Infrared Spectroscopy Chemical Test Methods of Analysis... 

Determining them with spectroscopy and chemical tests... 

Another general advantage is that optical sensing requires no physical or chemical contact with the sample. After a spectroscopic measurement is performed, the sample can be sent on to other diagnostic instruments, recycled into the body (e.g., dialysis), or archived for future analysis. Such options do not exist when chemical tests are used. The non-contact nature of optical spectroscopy also eliminates the need for reagents and reduces the number of components that need to be cleaned (for a multi-use instrument). 

Since bonds between specific atoms have particular frequencies of vibration, IR spectroscopy provides a means of identifying the type of bonds in a molecule, e.g. all alcohols will have an O-H stretching frequency and all compounds containing a carbonyl group will have a C=0 stretching frequency. This property, which does not rely on chemical tests, is extremely useful in diagnosing the functional groups within a covalent molecule. 

Elemental Spedation - New Approaches for Trace Element Analysis Discrete Sample Introduction Tbchniques for Inductively Coupled Plasma Mass Spectrometry Modem Fourier Transform Infrared Spectroscopy Chemical Test Methods of Anal3rsis... 

A technique for applying infrared measurements to insulating oil is available (ASTM D-2144), and considerable information about mineral oil composition can be gained from infrared spectroscopy. Oxygenated bodies formed when oil deteriorates can be recognized, and hence this procedure can be used for surveillance of oils in service. An infrared spectrum can also give information as to the aromaticity of an oil and can detect antioxidants such as 2,6 di-tertiary butyl p-cresol. A chemical test for the latter is, however, available and is preferable for quantitative purposes (ASTM D-1473). 

Today, a number of different instrumental techniques are used to identify organic compounds. These techniques can be performed quickly on small amounts of a compound and can provide much more information about the compound s structure than simple chemical tests can provide. We have already discussed one such technique ultraviolet/visible (UVA/is) spectroscopy, which provides information about organic compounds with conjugated double bonds. In this chapter, we will look at two more instrumental techniques mass spectrometry and infrared (IR) spectroscopy. Mass spectrometry allows us to determine the molecular mass and the molecular formula of a compound, as well as certain structural features of the compound. Infrared spectroscopy allows us to determine the kinds of functional groups a compound has. In the next chapter, we will look at nuclear magnetic resonance (NMR) spectroscopy, which provides information about the carbon-hydrogen framework of a compound. Of these instrumental techniques, mass spectrometry is the only one that does not involve electromagnetic radiation. Thus, it is called spectrometry, whereas the others are called spectroscopy. 

Identifications and analyses of azo dyes can be performed by several techniques. These are absorption spectroscopy (i.e., visible, UV, and IR spectroscopy), fluorescence analysis, and GC. Chemical testings involve reduction methods. Reducing agents such as zinc dust, stannous chloride, and sodium hydrosulfite can split the azo linkage, producing the diazonium and the coupling fragments. The cleaved products may be... 

The spectra in Figs 20.17-20.25 showthe potential of infrared spectroscopy for distinguishing between common types of organic molecule, particularly if combined with information from other techniques such as mass spectrometry, nuclear magnetic resonance (NMR) and with the results of chemical tests. 

R. L., Shriner, R. C., Fuson, D. Y., Curtin, T. C. Morrill. The Systematic Identification of Organic Compounds. 6th Ed. New York Wiley, 1980. Contains a brief section on IR spectroscopy. Mainly a text for identification of compounds by chemical tests. 

The presence of functional groups can be established using chemical tests, for example bromine water for alkenes, and by infrared spectroscopy (Chapter 21). 

Iodoform is a yellow solid that wiU precipitate out of solution. Therefore, this reaction can be used to probe the identity of an unknown compound. If the unknown compound is a methyl ketone, then it will produce iodoform under these conditions (NaOH and I2). This iodoform test is not really used anymore (we now have spectroscopy techniques that give us this information and much, much more). So, this chemical test is really a relic of the past. But for some reason, it is stUl used in textbook problems. You will usually see it like this An unknown compound tests positive for iodoform, and.. . . The beginning of this problem is telhng you that you have a methyl ketone. If you see this in a problem in your textbook, you should know what it means. 

The entire spectrum of analytical methods used for the chemical testing of paper ranges from gravimetric methods to spectroscopy, electrochemical and enzymatic methods, as well as sensoric tests on taste and odour and microbiological tests. 

Cano and Marin (1992) studied differences in pigment profiles between fresh (uiuipe and ripe), frozen and canned kiwi fruit shces, using thin-layer chromatography (TLC), HPLC, UV-visible spectroscopy, and chemical tests. Pigments present in fresh and frozen kiwi fruit shces were xanthophyUs (9 -cis-neoxanthin, trans-violaxanthin, cw-violaxanthin, auroxanthin, lutein epoxide, and lutein), chlorophylls and their derivatives, and one hydrocarbon carotenoid... 

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