Phenols, determining

ISO 6842 1989, Surface active agents Sulfated ethoxylated alcohols and alkyl-phenols—Determination of total active matter content. 

B. Wang and S.J. Dong, Organic-phase enzyme electrode for phenolic determination based on a functionalized sol-gel composite. J. Electroanal. Chem. 487, 45-50 (2000). 

Analytical methods for detecting phenol in environmental samples are summarized in Table 6-2. The accuracy and sensitivity of phenol determination in environmental samples depends on sample preconcentration and pretreatment and the analytical method employed. The recovery of phenol from air and water by the various preconcentration methods is usually low for samples containing low levels of phenol. The two preconcentration methods commonly used for phenols in water are adsorption on XAD resin and adsorption on carbon. Both can give low recoveries, as shown by Van Rossum and Webb (1978). Solvent extraction at acidic pH with subsequent solvent concentration also gives unsatisfactory recovery for phenol. Even during carefully controlled conditions, phenol losses of up to 60% may occur during solvent evaporation (Handson and Hanrahan 1983). The in situ acetylation with subsequent solvent extraction as developed by Sithole et al. (1986) is probably one of the most promising methods. 

Etievant, P.X., Volatile phenol determination in wine. J. Agric. Food Chem. 29, 65, 1981. 

The spectra of alcohols and phenols determined in the liquid state, show a broad absorption band in the 769-650 cm-1 region because of out-of-plane bending of the bonded O—H group. Some spectra showing typical alcoholic absorptions are shown in Appendix B ethyl alcohol (No. 16) and methanol (No. 15). 

Reviewed previous SCWO research with model pollutants and demonstrated that phenolic compounds are the model pollutants studied most extensively under SCWO conditions Studied supercritical water oxidation of aqueous waste Explored reaction pathways in SCWO of phenol Studied catalytic oxidation in supercritical water Explored metal oxides as catalysts in SCWO Studied decomposition of municipal sludge by SCWO Investigated the SCWO kinetics, products, and pathways for CH3- and CHO-substituted phenols Determined oxidation rates of common organic compounds in SCWO... 

Parker VD (1998) Radical reactivity of radical ions in solution. Radical-radical and radical-substrate coupling mechanisms. Acta Chem Scand 52 154-159 Poskrebyshev GA, Neta P, H uie RE (2002) Temperature dependence of the acid dissociation constant of the hydroxyl radical. J PhysChem A 106 11488-11491 Pou S, Hassett DJ, Britigan BE, Cohen MS, Rosen GM (1989) Problems associated with spin trapping oxygen-centered free radicals in biological systems. Anal Biochem 177 1-6 Raghavan NV, Steenken S (1980) Electrophilic reaction of the OH radical with phenol. Determination of the distribution of isomeric dihydroxycyclohexadienyl radicals. J Am Chem Soc 102 3495-3499... 

The superior separation capacity of GC comes with one prominent disadvantage in phenolic determination. Namely, since phenolics are not readily volatile, an additional derivatization step is necessary prior... 

Keywords Citrus flavonoids health benefits phenolics determination sample preparation identification HPLC LC-MS NMR... 

Analytical control followed the Standard Methods recommendations [ 4 ]. Metal ion concentrations were determined by a Perkin-Elmer Model 4000 Atomic Absorption Spectrophotometer with zinz lamp 303-6081, lead lamp 303-6039, and copper lamp 303-6024. Determination of dissolved sulfide was done by titrimetric iodine methods. Phenol determination was performed by distillation/ex-traction method. Total cyanide and ammonia nitrogen were detrmined by the respective distillation/titrimetric methods. 

In a study of 92 Finnish edible and nonedible plant materials, a total of 15 berry samples were screened for antioxidant activity (Kahkonen et al., 1999). The activity was compared with the total phenolic content of the samples. Inhibition of methyl linoleate oxidation was used as a measure of antioxidant activity of berry acetone extracts and total phenolics determined by the Folin-Ciocalteau method as GAE/g dry matter of extracts. Berry extracts were high in antioxidant activity among the... 

Total antioxidant activities in 13 typical Italian wines were determined with an average of 12.3 pM Trolox equivalents for red wines and 1.6 pM for white wines (Simonetti et al., 1997). The values correlated well with total phenols (r = 0.9902) and flavanols (r = 0.9270) and clearly demonstrated that red wine polyphenols are significant in vitro antioxidants. The antioxidant capacity of 16 red wines from several countries was tested using electron spin resonance (ESR) spectroscopy (Bums et al., 2000). The antioxidant activity ranged from 4.13 x 1021 to 9.29 x 1021 number of Fremy s radicals reduced by 1 L of wine. The antioxidant capacity was associated with the phenolic content of the wines, determined either by Folin-Ciocalteau or by summation of the individual phenolics determined by HPLC or by spectroscopy. Total phenolics as measured by the Folin-Ciocalteau method ranged from 6.47 to 18.6 mM GAE per liter. The anthocyanin levels ranged from 101.5 to 325.7 pM. There were substantial differences in the proportion of polymeric pigments in the wines. 

Kulys, J. Vidziunaite, R., Amperometric biosensors based on recombinant laccases for phenols determination, Biosens. Bioelectron. 2003, 18, 319-325... 

One of the phenol determination methods described in Standard Methods , the so-called phenol index nnmber, inclndes all, water stream distillable, phenolic compounds, which are detected photometrically after derivatization with 4-aminoantipyrine and extraction with chloroform . Here, only the total amonnt of phenols is measnred. It is impossible to distingnish between individnal phenols or to estimate the probable toxicity of the analyzed water sample. This method is important only for preliminary information about possible phenol pollution and to determine if further tests are necessary. 

The American Water Work Association (AWWA) and US ERA developed a number of methods for phenol determination . ERA Method 528 is dedicated to the determination of phenols in drinking water by solid-phase extraction and GC/MS analysis and is developed for 12 phenols, mainly chlorophenols, nitro- and methyl-substituted phenols . Unfortunately, users have to take into account that the recommended internal standard tetrachlorophenol can also be found in water samples and has to be used with precaution or, better, substituted with another compound. The same problem applies in the case of the recommended surrogate 2,4,6-tribromophenol, which cannot be used in the analysis of water in areas with high bromine ion content. (Some examples of tribromophenol formation by humic or fulvic acid chlorination was mentioned by Richardson °°.)... 

Etidvant, P.X. 1981. Volatil phenols determination in wines. J Agric Food Chem. 29, 65-67. 

An important application of derivative spectroscopy lies in the determination of analytes in turbid media. Turbid solutions usually present a continuous increase of the absorbance towards shorter wavelengths and, as a consequence, do not produce any sudden spectral change either in the first or in the second derivative spectrum. Phenol determination in wastewater was one of the first practical applications of the derivative spectroscopy in turbid media [19], Another study, more recent, deals with the evaluation of the second-derivative determination of nitrate and total nitrogen [20],... 

Carboxylic acids, alcohols, and phenols are neutral in their acidic forms (HB) and charged in their basic forms (B ). A polar protic solvent will stabilize B and H more than it will stabilize HB, thereby increasing Kg. Therefore, Kg will be larger in water than in a less polar solvent, which means that the Kg value will be lower in water. So the pK values of carboxylic acids, alcohols, and phenols determined in a less polar solvent than water will be higher than those determined in water. 

The effect of cigarette design parameters on delivery of MSS phenols Determinations of which cigarette design parameters enabled significant control of the levels of phenols in MSS needed to be conducted. 

The phenol data (Code No. 82 vs. Code No. 83) in Table XXV-25 indicate the prediction by Schlotzhauer (3447) appears to be valid Inclnsion of nominal levels of cocoa in the cigarette blend produced little change in the MSS phenol yield. Addition of 1% cocoa (Code No. 82 vs. Code No. 83) increased the phenol yield (mg/g of CSC) by 0.13 mg/g. This is about a 3% increase relative to Cigarette coded No. 83 well within the experimental error of the phenol determination. 

TABLE 7.2b. f ,Parameters for phenol Determined Using the Set of Equations (7-6) and (7-7) (adapted from Serrano (1998))... 

Below are two sets of data on the hydrogenation of benzene and of phenol. Determine a means for the interpretation of the lowest and highest pressure data, and use your correlation to predict the middle-pressure results. Note that the original charge was apparently partially hydrogenated. Temperature in both cases was 120°C. 

Fig. 7a-c. Profiles of organic classes in a core taken near Clarenville. a High molecular weight/low molecular weight n-alkanes, b total saturated+branched fatty acids, and c total phenolics determined by TMAH thermochemolysis. Pb dates were obtained for the top 26 cm of the core. (After [92,106])... 

K. Nakamura, K. Hayashi, I. Ueda and H. Fujiwara, M/ce//e Water Partition Properties of Phenols Determined by MLC. Proposalfor a Versatile Measure ofHydrophobycity, Chem. Pharm. Bull, 43 369 (1995). 

Chen J, Jin Y (2010) Sensitive phenol determination based on co-modifying tyrosinase and palygorskite on glassy carbon electrode. Microchim Acta 169 249-254... 

Several alternative applications for the determination of this total index have also been proposed based on chemiluminescence or electrochemical detection [188]. Phenol determination is... 

M.C.B. Quaresma, R.J. CasseUa, M.F.B. Carvalho, R.E. SanteUi, Focussed microwave-assisted sample preparation total phenol determination in petroleum refinery effluents by flow injection spectrophotometry, Microchem. J. 78 (2004) 35 0. 

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