Chlorophenols, analysis

Ghlorophenol Analysis. The chlorophenols can be analy2ed by acidimetric titration of the hydroxyl function (50). This overall method yields only an approximate evaluation for mixtures. To analy2e chlorophenol mixtures, gas chromatography has been the reference method used, as it made it possible to separate and quantify the various chlorophenols (51), but this technique can be a source of errors the gem-chlotinated cyclohexadienones that may be present along with the chlorophenols are broken back down iato lighter chlorophenols under the analysis conditions usually employed. 

Lee [42] determined pentachlorophenol and 19 other chlorinated phenols in sediments. Acidified sediment samples were Soxhlet extracted (acetone-hexane), back extracted into potassium bicarbonate, acetylated with acetic anhydride and re-extracted into petroleum ether for gas chromatographic analysis using an electron capture or a mass spectrometric detector. Procedures were validated with spiked sediment samples at 100,10 and lng chlorophenols per g. Recoveries of monochlorophenols and polychlorophenols (including dichlorophenols) were 65-85% and 80-95%, respectively. However, chloromethyl phenols were less than 50% recovered and results for phenol itself were very variable. The estimated lower detection limit was about 0.2ng per g. 

Three-dimensional quantitative structure activity relationship (3D-QSAR) analysis for in vitro toxicity of chlorophenols to HepG2 cells Y. Liu, J.N. Chen, J.S. Zhao, H.X. Yu, X.D. Wang, J. Jiang, H.J. Jin, J.F. Zhang and L.S. Wang... 

A hydrolysis step is involved in the pulp industry in order to concentrate the cellulose from wood. This uses large-scale processes whereby a liquid fraction, the lignocellulose, is formed as a by-product in the process, and contains high levels of phenolic components and their derivatives. These compounds also constitute an environmental problem due to their possible introduction into rivers, lakes, and/or seas. Chlorophenols from the cellulose bleaching process have traditionally attracted most of the interest in the analysis of industrial waste because of their high toxicity. 

Studying occupational exposure to highly contaminated chlorophenols, the analysis of PCDDs and PCDFs in blood samples seems to be a better parameter to follow than the level of chlorophenol in the urine. 

Figure 3 Major pathways of 4-chlorophenol degradation as derived from product analysis. (From Refs. 58 and 59.)...

In a case-control study in the north of Sweden, Hallquist et al. (1993) compared 188 men and women aged 20-70 years who had thyroid cancer with age- and sex-matched controls (two per case) selected from a register of the local population. The cases were identified retrospectively from a cancer registry and excluded a proportion of patients (19%) who had died by the time of the study. Exposure to potential risk factors, including chlorophenols, was ascertained by postal questionnaire with a supplementary telephone interview if answers were incomplete. The response rates for the cases and controls were 95% and 90%, respectively. Of the 171 cases analysed, 107 had papillary tumours. Four cases and three controls reported exposure to chlorophenols (odds ratio, 2.8 95% CI, 0.5-18). [The Working Group noted that the method of statistical analysis was not the most appropriate for individually matched data, but this is unlikely to have produced serious bias.]... 

Humppi, T., Knuutinen, J. Paasivirta, J. (1984). Analysis of polychlorinated phenoxyphenols in technical chlorophenol formulations and in sawmill environment. Chemosphere, 11, 1235-41. 

The polymers prepared by Hunter from polyhalophenols were undoubtedly highly branched. He examined the decomposition of salts of 2.6-dibromo-4-chlorophenol, 2.6-dichloro-4-bromophenol and 2.6-diiodo-4-chlorophenol (44). By analysis of the resulting polymers he was able to determine qualitatively (Table 6) the order of reactivety of the halogens (I>Br>Cl) and furthermore established that considerable reaction occurs through the o-position. 

Departing from the "conventional extraction cell design, Theibolt et al. (11) used a novel phase segmentor and subsequent phase separator in order to extract 4-chlorophenol and phenol from water. On-line SFC was used for subsequent analysis. Recoveries and reproducibilities for the system were not reported, although with a single pass system 100% recovery would not be expected. We too have demonstrated... 

Product analysis supports these deductions [20]. At lower acidities (pH 2-5), o-cresol gives mainly products by one-electron transfer (PI and P2). At higher acidities (pH < 2), however, 4-chlorophenol forms P4 as the major product, with some P5 and P6, but only a minor amount of P2 and traces of polymers P3. 

Applications of supercritical fluid extraction and headspace analysis are, however, now creeping in. Thus supercritical fluid extraction with carbon dioxide-methanol has been used to extract 2,4-chlorophenol from crops [231 ], sulfonylurea herbicides from plants [161], and organophosphorus pesticides from fruit and vegetables [226]. 

Low volatile, high molecular weight halogenated compounds can be extracted with hexane or iso-octane and determined by GC-ECD. Methylene chloride may be used for extraction if the analysis is done by GC/MS. Purge and trap efficiency will be poor for such compounds, especially those boiling over 200°C. Soils, sediments, and solid wastes may be extracted with methylene chloride by sonication or soxhlett extraction. Interferences from acidic compounds, such as chlorophenol, may be removed by acid-base partitioning cleanup. The extract is then concentrated and analyzed by GC/MS or exchanged to hexane and analyzed by GC-ECD. 

Quantitative analysis of both camphor and para-chlorophenol in champhorated parachlorophenol by high-pressure liquid chromatography is described (186). 

Werkhoven-Goewie, C.E., Boon, W.M., Praat, A.J.J., Frei, R.W., Brinkman, U.A. Th., and Little, C.J., Preconcentration and LC analysis of chlorophenols, using a styrene-divinyl-benzene copolymeric sorbent and photochemical reaction detection, Chromatographia, 16, 53, 1982. 

Nichkova, M. and M.R Marco. 2005. Development and evaluation of C18 and immunosorbent solid-phase extraction methods prior to immunochemical analysis of chlorophenols in human urine. Anal. Chim. Acta 533 67-82. 

For example, in the analysis of chlorophenol in soil by accelerated solvent extraction followed by GC-MS, deuterated benzene may be used as the matrix spike. The deuterated compound will not be present in the original sample and can easily be identified by GC-MS. At the same time, it has chemical and physical properties that closely match those of the analyte of interest. 

Often, the matrix spike cannot be carried out at the same time as the analysis. The spiking is carried out separately on either the same matrix or on one that resembles the samples. In the example above, clean soil can be spiked with regular chlorophenol and then the recovery is measured. However, one should be careful in choosing the matrix to be spiked. For instance, it is easy to extract different analytes from sand, but not so if the analytes have been sitting in clay soil for many years. The organics in the soil may provide additional binding for the analytes. Consequently, a matrix spike may be extracted more easily than the analytes in real-world samples. The extraction spike may produce quantitative recovery, whereas the extraction efficiency for real samples may be significantly lower. This is especially true for matrix-sensitive techniques, such as supercritical extraction. 

Soderstrom, M., Wachtmeister, C.A., Fdrlin, L. (1994) Analysis of chlorophenolics from bleach Kraft Mill effluents (BKME) in bile of perch (Perea fluviatilis) from the Baltic Sea and development of an analytical procedure also measuring chlorocatechols. Chemosphere 28, 1701-1719. 

Schuurmann, G., Quantum chemical analysis of the energy of proton transfer from phenol and chlorophenols to H20 in the gas phase and in aqueous solution, J. Chem. Phys., 109, 9523-9528, 1998b. 

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