Ketone spectrometry/spectroscopy

Brugmann et al. [680] compared three methods for the determination of copper, cadmium, lead, nickel, and zinc in North Sea and northeast Atlantic waters. Two methods consisted of atomic absorption spectroscopy but with preconcentration using either freon or methyl isobutyl ketone, and anodic stripping voltammetry was used for cadmium, copper, and lead only. Inexplicable discrepancies were found in almost all cases. The exceptions were the cadmium results by the two atomic absorption spectrometric methods, and the lead results from the freon with atomic absorption spectrometry and anodic scanning voltammetric methods. 

Regarding ozonation processes, the treatment with ozone leads to halogen-free oxygenated compounds (except when bromide is present), mostly aldehydes, carboxylic acids, ketoacids, ketones, etc. [189]. The evolution of analytical techniques and their combined use have allowed some researchers to identify new ozone by-products. This is the case of the work of Richardson et al. [189,190] who combined mass spectrometry and infrared spectroscopy together with derivatization methods. These authors found numerous aldehydes, ketones, dicarbonyl compounds, carboxylic acids, aldo and keto acids, and nitriles from the ozonation of Mississippi River water with 2.7-3 mg L 1 of TOC and pH about 7.5. They also identified by-products from ozonated-chlorinated (with chlorine and chloramine) water. In these cases, they found haloalkanes, haloalkenes, halo aldehydes, haloketones, haloacids, brominated compounds due to the presence of bromide ion, etc. They observed a lower formation of halocompounds formed after ozone-chlorine or chloramine oxidations than after single chlorination or chlorami-nation, showing the beneficial effect of preozonation. 

The stereochemistry of enolisation has been mostly examined in cyclic systems where the relative positions of the enolisable hydrogen atoms are fixed. Over the last decade, these studies have benefited from important improvements in the experimental methods, namely mass spectrometry and nmr spectroscopy. Of great interest is the comparison of the relative mobilities of diastereoisomeric axial and equatorial protons from ketones in the cyclohexane series. Indeed, since axial a(C—H) bonds of rigid cyclohexanones are closer than equatorial a(C—H) bonds to the desirable conformation in which the breaking C—H bond is perpendicular to the direction of the C=0 bond, it can be expected that the axial a(C—H) bond-breaking is easier than that of the equatorial one. 

Bernstein et al. have used IR spectroscopy and mass spectrometry to study the products formed from photochemical transformation of naphthalene, anthracene, chrysene, phenanthrene, pyrene, tetracene, pentacene, perylene, benzo(e)pyrene, benzo(ghi)perylene, and coronene in water ices using ultraviolet radiation under astrophysical conditions [27]. The results of their investigation have revealed that peripheral carbon atoms can be oxidized to produce aromatic alcohols, ketones, ethers (when bay region is present,... 

AAS = atomic absorption spectrometry APDC = ammonium pyrrolidine dithiocarbamate APHA = American Public Health Association EPA = Environmental Protection Agency FPD = flame photometric detection ICP/AES = inductivity coupled plasma atomic emission spectroscopy MED = microwave emission detector MIBK = methyl isobutyl ketone NIOSH = National Institute for Occupational Safety and Health XRF = x-ray fluorescence... 

A variety of compounds such as hydrocarbons, alcohols, furans, aldehydes, ketones, and acid compounds are formed as secondary oxidation products and are responsible for the undesirable flavors and odors associated with rancid fat. The off-flavor properties of these compounds depend on the structure, concentration, threshold values, and the tested system. Aliphatic aldehydes are the most important volatile breakdown products because they are major contributors to unpleasant odors and flavors in food products. The peroxidation pathway from linoleic acid to various volatiles is determined in several researchs, - by using various techniques (Gas chromatography mass spectrometry, GC-MS, and electron spin resonance spectroscopy, ESR), identified the volatile aldehydes that are produced during the oxidation of sunflower oil. In both cases, hexanal was the major aldehyde product of hydroperoxide decomposition, whereas pentanal, 2-heptenal, 2-octenal, 2-nonenal, 2,4-nonadienal, and 2,4-decadienal were also identified. 

The second step is the analysis of the gas mixture by any available traditional or modern instrumental techniques. Carbon monoxide and dioxide, sulphur dioxide, hydrogen chloride, hydrogen cyanide as well as saturated and unsaturated hydrocarbons and their oxidation products (such as alcohols, aldehydes, ketones, carboxylic acids) are determined mainly by gas chromatography with the occasional contribution of infrared spectroscopy and mass spectrometry. 

Recently, Baneqee et al. developed an easy synthesis strategy of phos-phonic acid-containing diphosphonated poly(ether ether ketone) (PEEK) by polycondensation of difluorobenzophenone and phosphonated bisphenol A, characterized the structures using NMR, Fourier transform infrared (FTIR) spectroscopy, and electrospray ionization mass spectrometry, and estimated that the degree of phosphonation is about 70% from proton NMR spectra [17]. Jiang et al. studied the proton conductivities of poly(vinylbenzyl phosphonic acid) homopolymer and its statistical... 

AES = atomic emission spectroscopy BPTH = l,5-bis[phenyl-(2-pyridyl)-methylene]-thiocarbonohydrazide] DPTH = l,5-bis(di-2-pyridyl)methylene thiocarbohydrazide FI = flow injection ICP = inductively coupled plasma LA = laser ablation LOD = limit of detection MIBK = methyl isobutyl ketone MS = mass spectrometry QMS = quadrupole mass spectrometry SF-MS = sector field mass spectrometry... 

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