Chlorophenols extraction

Ion-pair extraction and IPC were combined to analyze phosphoric acid mono- and diesters originating from the microbial hydrolysis of flame retardants. Even tertiary treatment did not ensure complete removal of the studied compounds detected in municipal wastewater [107], Chlorophenols extracted from water samples as anionic chlorophenolates were studied by IPC because the anionic forms of these analytes provide better UV ultraviolet absorption than uncharged chlorophenol based on their auxochromic effects. IPC conditions yielded adequate retention of the charged analytes and good sensitivity [108]. 

Properties of PCDEs, including physicochemical ones, are not well known as the literature reviews of PCDEs have shown [4, 11,40,46]. PCDEs resemble PCBs structurally and in their chemical and physical properties, which, like PCDDs, PCDFs, and related compounds, are known to be stable and resistant to breakdown by heat, hydrolysis, bases, and acids. PCBs are also quite stable to oxidation under moderate conditions [3], but there is not much data about PCDEs concerning their stability. There is some evidence that PCDEs are resistant to bases and acids and the occurrence of PCDEs in the environment indicates that PCDEs are persistent and bioaccumulating compounds. The study of Firestone et al. [37] already showed that PCDEs are quite stable, since PCDEs could be measured in chlorophenol extracts after sulfuric acid treatment. Tetra- and octachlorinated PCDE congeners were later proven resistant in treatment with... 

Bulk matrix removal aims to remove material such as lipids which can disturb final analysis. This can be performed by acid treatment of the extract or by liquid-solid chromatography. Alumina fractions of chlorophenol extracts have been purified with concentrated sulfuric acid [37,38] and it has been used to remove lipid and organic coextractives in sediment, biota, and human extracts [33,43,57,58,113,114,120,122-125]. The sulfuric acid treatment of PCDEs has been reported not to affect their recoveries [58]. 

Activated alumina (260 °C) column has been used for isolation of PCDEs, PCDDs, and PCDFs from chlorophenol extracts [37,38]. Four fractions were collected from an alumina column (50 g) petroleum ether (400 ml), 5% ethyl ether in petroleum ether (200 ml), 25% ethyl ether in petroleum ether (400 ml), and ethyl ether (400 ml). PCDEs, PCDDs, and PCDFs were determined in the third and fourth fractions after sulfuric acid cleanup. 

Figure 13.15 Chromatograms obtained by on-line ti ace enrichment of 50 ml of Ebro river water with and without the addition of different volumes of 10% Na2S03 solution for every 100 ml of sample (a) blank with the addition of 1000 p.1 of sulfite (b) spiked with 4 p.g 1 of the analytes and 1000 p.1 of sulfite (c) spiked with 4 p.g 1 of the analytes and 500 p.1 of sulfite (d) spiked with 4 p.g 1 of the analytes without sulfite. Peak identification is as follows 1, oxamyl 2, methomyl 3, phenol 4, 4-niti ophenol 5, 2,4-dinitrophenol 6, 2-chlorophenol 7, bentazone 8, simazine 9, MCPA 10, atrazine. Reprinted from Journal of Chromatography, A 803, N. Masque et ai, New chemically modified polymeric resin for solid-phase extraction of pesticides and phenolic compounds from water , pp. 147-155, copyright 1998, with permission from Elsevier Science.

Dichlorodibenzo-p-dioxin was prepared from isotopic potassium 2,4-dichlorophenate uniformly labeled with Ullman conditions gave a 20.5% yield. Small amounts of dichlorophenoxy chlorophenol were removed from the product by extraction with sodium hydroxide before purification by fractional sublimation and recrystallization from anisole. Chlorination of 2,7-dichlorodibenzo-p-dioxin in chloroform solution containing trace amounts of FeCls and 12 yielded a mixture of tri-, tetra-, and pentachloro substitution products. Purification by digestion in boiling chloroform, fractional sublimation, and recrystallization from anisole was effective in refining this product to 92% 2,3,7,8-tetrachloro isomer, which also contained 7% of the tri- and 1% of the penta-substituted dibenzo-p-dioxin. Mass spectroscopy was used exclusively to monitor the quality of the products during the synthesis. 

Uniformly labeled 2,4-dichlorophenol- C (purchased from New England Nuclear Corp, Boston, Mass.) was used in the tracer preparation. This provided a label at all carbon positions in the dibenzo-dioxin structure. 2,7-Dichlorodibenzo-p-dioxin- C after initial cleanup by fractional sublimation, contained approximately 5% of an impurity, detected by thin layer chromatography (TLC) which gave mass peaks at 288, 290, 292, and 294 in the mass spectrometer, consistent with a trichloro-hydroxydiphenyl oxide. This is probably the initial condensation product of the Ullman reaction and is most likely 2-(2,4-dichlorophenoxy)-4-chlorophenol. It was removed easily by extractions with aqueous... 

Only the R(+) enantiomer of the herbicide 2-(2-methyl-4-chlorophenoxy)propionic acid was degraded (Tett et al. 1994), although cell extracts of Sphingomonas herbicidovorans grown with the R(-) or S -) enantiomer, respectively, transformed selectively the R -) or S(-) substrates to 2-methyl-4-chlorophenol (Nickel et al. 1997). 

Wei M-C, Jen J-F. Determination of chlorophenols in soil samples by microwave-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-electro-capture detection. J. Chromatogr. A 2003 1012 111-118. 

Renberg [35] used an ion-exchange technique for the determination of chlorophenols and phenoxy acetic acid herbicides in soil. In this method the soil extracts are mixed with Sephadex QAE A-25 anion exchanger and the adsorbed materials are then eluted with a suitable solvent. The chlorinated phenols are converted into their methyl ethers and the chlorinated phenoxy acids into their methyl or 2-chloroethyl esters for gas chromatography. 

An etherial solution of diazomethane is added to the benzene extract to form the methyl ester of the chlorophenols. After about lh, the solution is evaporated to the original volume. The extract is injected into the gas chromatograph and the result compared with a standard treated the same way. 

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. 

Xie [39] determined trace amounts of chlorophenols and chloroguaiacols in marine sediments collected off the Swedish coast. The compounds were desorbed from sediment surfaces by a mixture of acetic anhydride and hexane, after buffering with O.lmol L 1 sodium carbonate. The optimal pH was achieved by a 1 4 ratio of buffer to acetic anhydride. The acetylated extracts were analysed by glass capillary gas chromatography with electron capture detection. The recoveries, at the pg kg-1 level, ranged from 85-100% with standard deviations of 4-11%. 

Fig. 20. A typical GC-MS trace of a phenol contaminated soil sample, Bitterfeld, Germany (after [254] with permission). Chlorophenols were extracted using ASE-SPME upper chromatogram, procedure B lower chromatogram, ASE conditions of water, 150°C, 15 min. Peak identifications (1) 2-chlorophenol, (2) 2,4-dichlorophenol, (3) 4-chlorophenol, (4) 4-chloro-3-methylphenol, (5) 2,3,5-trichlorophenol, (6) 2,4,6-trichlorophenol, (7) 2,3,4-trichlo-rophenol, (8) 2,3,4,6-tetrachlorophenol, (9) pentachlorophenol... 

The extraction of aromatic chlorophenols (e.g., chloroguaiacols, chloro-catechols) is complicated by the different sorption processes that control their binding within the soil-sediment structure [411-413]. The free, physically adsorbed chlorophenolics can be extracted with solvent, but this may only account for 1-5% of the total concentration of these pollutants in the sediment. Martinsen et al. [414] found that -hexane or cyclohexane and iso-propanol... 

It is difficult to compare recoveries obtained by different laboratories because their extraction conditions (pH, phase ratio, number and time-length of extractions, salinity) are generally different. Sample volumes can be very high, up to 200 1 [433], and 50 1 of surface water [434] or 201 of sea water allow the extraction of 5 ng/1 of alkanes. When using a specific detection method, the sample volume can be lower 2 ng/1 of PAH was determined from 11 of river water using liquid chromatography and fluorescence detection [435]. Chlorophenols below the 10 ng/1 level were determined from 100 ml of sea water with electron capture detection (ECD) GC [436]. 

Hexachlorobenzene, shown in Figure 8.3, reacts further to chlorophenols and PCDD/F, which stay adsorbed on the copper species but can be further extracted in the turbular furnace reactor. All low volatile chlorinated compounds shown in Figure 8.3 are eluted with the gas flow. The lower... 

Biological. In activated sludge, 31.5% of the applied chlorobenzene mineralized to carbon dioxide after 5 d (Freitag et al., 1985). A mixed culture of soil bacteria or a Pseudomonas sp. transformed chlorobenzene to chlorophenol (Ballschiter and Scholz, 1980). Pure microbial cultures isolated from soil hydroxylated chlorobenzene to 2- and 4-chlorophenol (Smith and Rosazza, 1974). Chlorobenzene was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum. At a concentration of 5 mg/L, biodegradation yields at the end of 1 and 2 wk were 89 and 100%, respectively. At a concentration of 10 mg/L, significant... 

Typical procedure A mixture of p-chlorophenol (128 mg, 1 mmol), NaOH (40 mg, 1 mmol) and THF (10 mL) was stirred for 10 min allyldiisobutylteUuronium bromide (360 mg, 1 mmol) was then added. The reaction mixture was stirred for another 5 h at room temperature under nitrogen. Aqueous saturated NaHCOj solution was added and extracted with CH2CI2. The extract was dried over anhydrous MgS04 and concentrated in vacuo. The residue was chromatographed on sihca gel with 95 5 hexane-ethyl acetate as eluent to give a colourless oil of allyl p-chlorophenyl ether (145 mg, 86%). 

Peng, J.-R, Liu, J.-R, Hu, J.-T., and Jiang, G.-B., Direct determination of chlorophenols in environmental water samples by hollow fiber supported ionic liquid membrane extraction coupled with high-performance liquid chromatography, J. Chromatogr. A, 1139,165-170, 2007. 

The pH values of efficient extraction correspond to the pH range where the molecular form of the respective phenol dominates. The recovery of 4-nitro-phenol, 2,4-dinitrophenol, 2,6-dinitrophenol, 4-chlorophenol, 1-naphthol, and 2-naphthol is above 90% (the ratio of aqueous organic phase volume is 3 1). The extraction of naphthol and 4-chlorophenol is significant even at pH > pffa, more than 40 and 24% at pH > 10, respectively. Recovery of picric acid (2,4,6-trinitrophenol) is about 90% at pH 1.5-12.0, where the anionic form of picric acid dominates. Obviously, the high extraction is caused by high hydrophobicity of picrate anions. Recovery of the phenol itself and diatomic phenols, catechol and resorcinol is rather moderate (79,58, and 20%, respectively pH 1-7), which could be explained by relatively high hydrophi-licity of these compounds. 

Bekou, E., Dionysiou, D.D., Qian, R.-Y., Botsaris, G.D., Extraction of chlorophenols from water using room temperature ionic liquids, ACS Sympos. Ser., 856, 544-560,2003. 

Aqueous samples were extracted for phenol and 4-chlorophenol using pure carbon dioxide in a specially designed phase separator apparatus (111). The extraction efficiency for these phenols was reported to be over 85%, with a RSD of 8% for eight samples. Additional liquid sample extractions have been investigated for the extraction of phenol from a 6M sulfuric acid solution as well as the extraction of the components of commercial soft drinks and orange juice (112-113). In all cases, specifically designed extraction vessels were utilized. 

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