Halogens, analytical method development

The isotope dilution technique in LA-ICP-MS has been applied for the direct analysis of sulfur species in gas oil, diesel or heating fuel as described by Boulyga et al. In addition, these authors have developed an analytical method for the direct determination of halogens (Cl, Br and I) in powdered geological and environmental samples using isotope dilution laser ablation ICP-MS. The detection limits of LA-ICP-IDMS are in the low and sub-p,gg range for halogens. ... 

A recent method of detection is electron capture negative ionisation (ECNI) as ionization technique in combination with GC-MS analysis. This method is advantageous because it offers a high sensitivity for compounds with four or more bromine atoms [36]. The sensitivity of ECNI for these compounds is approximately 10 times higher than with the use of an electron capture detector (ECD) [5]. In the analytical method which was developed to quantitate PCBs and PBBs in human serum, GC/ECD was used [30]. Because the response, and therefore the sensitivity, of the ECD depends on the position of the halogen on the biphenyl nucleus as well as the number of halogen atoms, it is necessary to run a standard for each compound to be determined [2], The use of narrow bore (0.15 mmi.d.) capillary columns is advised to obtain the required resolution [5]. 

The action of the halogens on the simple sugars may be obscured for several reasons. The nature of some of the oxidants may be difficult to determine the transient character of several of the oxyhalogen acids often serves to hide the real mechanism of the oxidation. In addition, it is often rather difficult to isolate the oxidation products of a sugar, especially when more than one product is produced in a reaction or when suitable analytical methods have not been developed. 

Various chemical processes of limonene, which lead to the obtainment of useful chemicals and some analytical methods, are based on these reactions. Many flavor chemicals are synthesized from limonene by reaction with water, sulfur and halogens, or hydrolysis, hydrogenation, boration, oxidation and epoxide formation (Thomas and Bessiere, 1989). Hydroperoxides have also been studied and isolated because of their effect on off-flavor development in products containing citrus oil flavoring agents (Clark et al., 1981 Schieberle et al., 1987). Hydration of d-limonene produces alpha-terpineol, a compound that gives off an undesirable aroma in citrus-flavored products. It is also possible to produce alpha-terpineol and other useful value-added compounds... 

Perbromate ions have been extracted into chlorobenzene as ion-associates with Crystal Violet [31], or with Brilliant Green [32]. The analytical properties of perbromate (Br04 ), have been compared with the properties of perchlorate and periodate ions [33]. Chromatographic and electrophoretic methods have been developed for the separation of perbromate from other halogen compounds [34]. 

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