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Author(s): T. M. Makhova [sup.1] , A. I. Arzhanukhina [sup.1] , S. Yu. Doronin [sup.1] Author Affiliations: (1) grid.446088.6, 0000 0001 2179 0417, Institute of Chemistry, Chernyshevsky Saratov State University, [...], New test tools made of nanofibers based on polyamide-6 (PA-6) for the sorption preconcentration of some phenols as their azo derivatives followed by colorimetric determination are obtained. Approaches to the derivatization of phenol and chlorine derivatives by azo coupling with 4-nitrophenyldiazonium and oxidative condensation with 4-aminoantipyrine for improving the sorption characteristics of the studied phenols are proposed. The efficiency of the two derivatization methods is compared. The sorption kinetics of phenol and 2-chlorophenol derivatives and the effect of pH on the nature of their sorption are studied. The features of the sorption of phenol derivatives on nonwoven materials and the corresponding sorption isotherms are interpreted. Examples of the quantitative assessment of the concentration of phenols in aqueous media by the mathematical processing of digital images of the colored areas of test tools are presented. It is shown that the proposed methods can be used for the determination of phenol and 2-chlorophenol with the preconcentration of their derivatives on a PA-6 nanofiber in the range 0.2-1.0 [mu]M ([almost equal to]0.02-0.09 mg/L for phenol, [almost equal to]0.03-0.13 mg/L for 2-chlorophenol) with an error of colorimetric determination of no more than 20% (MAC.sub.hshld phenol is 0.001 mg/L for the amount of volatile phenols in water bodies, provided that water is disinfected with chlorine; in other cases, the MAC is 0.1 mg/L).

ISO/CD 18857-2 (International Organization for Standardization, Geneva) describes a now international standard method for the determination of octylpbenol, nonylphenol, their mono- and diethyoxylates, and bisphenol A in nonfiltered samples of drinking ground, surface, and wastewater. The method is based on the extraction of the analytes from an acidified water sample by solid phase extraction, solvent elution, derivatizafion, and determination by gas chromatography with mass spectrometric detection. For validation of this method, 14 laboratories from 4 different countries in Europe and Canada participated in an interlaboratory trial to determine the performance characteristics of the method, which are intended for publication in the corresponding standard. The interlaboratory trial was evaluated according to ISO 5725-2 and included two duplicate nonfiltered water samples: surface water containing the target compounds in an analyte concentration range from 0.05 to 0.4 [micro]g/L and wastewater containing the target compounds in a concentration ranged from 0.1 to 5 [micro]g/L. The repeatability variation coefficients (within-laboratory precision) varied for all samples and compounds between 1.9 and 7.8%, showing a sufficiently high repeatability of the method. The reproducibility variation coefficients (between-laboratory precision) were found to vary within a satisfactory range of 10.0-29.5% for surface water and 10.8-22.5% for wastewater. The recoveries as a measure of accuracy varied from 98.0 to 144.1% for surface water and from 95.4 to 108.6% for wastewater. The determined concentrations of the samples compared well to the 'true' values, thus showing very satisfactory accuracy of the method. In the chromatogram of the surface water sample, a high unresolved background made up of coextractable matrix compounds was apparent. It is conceivable that compounds from tiffs background may be responsible for enhanced recoveries of 144.1% for 4-nonyiphenol (mixture of isomers) and of 123.4% for 4-nonyiphenol monoethoxylate (mixture of isomers) in the surface water samples. The isotope-marked standard compounds developed in this context proved to be reliable internal standards that allow a precise and accurate quanfitation of all compounds specified in ISO/CD 18857-2. The results of the interlaboratory trial cenfumed that the analytical method is robust and reliable and can be used as a standard method to analyze the target compounds in water samples.

Electrochemical oxidation of phenol was studied in a bipolar trickle tower reactor using Raschig ring shaped boron-doped diamond (BDD) electrodes in recirculated batch mode. The model wastewater was prepared with phenol using distilled water. The effects of initial phenol concentration, concentration of [Na.sub.2]S[O.sub.4] as a supporting electrolyte, current density, flow rate, and initial pH on the removal efficiency were investigated. The removal of phenol of 200 mg/L and chemical oxygen demand (COD) of 480 mg/L were achieved with efficiencies of 99.85 and 88.89%, respectively. In the same study, specific energy consumption of 0.676 kWh/g phenol removed was determined at the current density of 5 mA/[cm.sup.2]. On the other hand, for the initial phenol concentration of 500 mg/L and COD of 1,200 mg/L, 99.69 and 90.83% removal efficiencies were obtained at the current density of 5 mA/[cm.sup.2], respectively. Microtox toxicity tests were performed to investigate the toxicity reduction potential of BDD anodes, and relatively good toxicity reductions were obtained with respect to the initial values. After determining optimum experimental conditions, petroleum refinery wastewater was also studied by monitoring the destruction of phenol and COD. In this study, phenol removal of 99.53% and COD removal of 96.04% were achieved at the current density of 5 mA/[cm.sup.2]. Chemical oxidation studies were also carried out and the results were compared with the electrochemical oxidation studies. According to the whole results, it can be said that Raschig ring shaped BDD anodes exhibited an excellent performance for the degradation of phenol and COD and for the reduction of toxicity. CE Database subject headings: Water pollution; Wastewater management; Oxidation; Reactors; Phenol; Toxicity.

Endogenous estrogen plays a key role in the development of human breast cancer, yet the contribution of specific estrogen metabolites and patterns of estrogen metabolism remains unclear. To determine their individual and joint roles in breast carcinogenesis, it is necessary to be able to measure quantitatively each estrogen metabolite in epidemiologic and clinical biospecimens. In this report, we detail a sensitive, specific, accurate, and precise high-performance liquid chromatography-tandem mass spectrometry method utilizing selected reaction monitoring for measuring the absolute quantities of free (unconjugated) and total (conjugated + unconjugated) endogenous estrogens and estrogen metabolites in human serum from premenopausal and postmenopausal women. The method requires a simple sample preparation and only 0.5 mL of serum, yet is capable of quantifying simultaneously 15 estrogens and estrogen metabolites (EM): estrone and its 2-, 4-, and 16[alpha]-hydroxy and 2- and 4-methoxy derivatives; 2-hydroxyestrone-3-methyl ether; 17[beta]-estradiol and its 2-hydroxy and 2- and 4-methoxy derivatives; and estriol, 17-epiestriol, 16-ketoestradiol, and 16-epiestriol. The lower limit of quantitation for each EM was 0.4 pg on-column, equivalent to 8 pg/mL (26.5-29.6 fmol/mL) in the original serum sample. Calibration curves were linear over a 103-fold concentration range. For a stripped serum sample containing 8 pg/mL of each EM, accuracy (percent recovery of a known added amount) ranged from 91 to 113%. Intrabatch precision (including hydrolysis, extraction, and derivatization steps) ranged from 7 to 30% relative standard deviation (RSD), and interbatch precision ranged from 8 to 29% RSD. Since distinct roles have been proposed for many of these estrogen metabolites, an accurate, precise, sensitive, and specific method for measuring their levels in circulation should suggest new approaches to breast cancer prevention, screening, and treatment.

Byline: Anna Koski (1), Satu Pekkarinen (1), Anu Hopia (1), Kristiina Wahala (2), Marina Heinonen (1) Keywords: Rapeseed oil; Processing; Oxidative stability; Phenolic compounds; Vinylsyringol Abstract: Rapeseed oil is usually expelled from the seed at high temperatures. Refining removes most of the non-triacylglycerol components, including many sinapic acid derivatives typical for rapeseed. The effect of these phenolic constituents on the oxidative stability of the oil was studied using rapeseed and turnip rapeseed oil samples resulting from different expelling conditions and refinement steps. The polar fraction was isolated, analyzed and tested for antioxidative activity in various lipid oxidation models. The amount of phenols was greatest in the post-expelled crude rapeseed oil, decreasing with an increasing degree of refining. The polar phenol content correlated with oxidative stability. The most active antioxidant component of the polar fraction was identified as vinylsyringol, a decarboxylation product of sinapic acid. This is the first report of vinylsyringol in rapeseed oil. It was abundant in the post-expelled crude oils and apparently responsible for their high phenol content and oxidative stability. Some vinylsyringol was present in the superdegummed oil but not in the fully refined oils. Author Affiliation: (1) Department of Applied Chemistry and Microbiology, P.O. Box 27, 00014 , University of Helsinki, Finland (2) Department of Chemistry, P.O. Box 55, 00014, University of Helsinki, Finland Article History: Received Date: 22/01/2003 Online Date: 10/05/2003

The authors report a scheme using liquid chromatography with four-channel electrochemical detection for the identification and quantification of phenolic acids. After a preliminary identity assignment based on spiking samples with [...]

The 'Lab-on-a-Cable' concept, based on scaling down an electrochemical flow system to a cable platform, is described. The system integrates the analyte collection and the sample handling, with the electrochemical detection of the reaction product in a sealed cylindrical unit, connected to a long shielded cable. An enzymatic assay, involving collection of a phenolic substrate, its mixing with an internally delivered tyrosinase solution, and amperometric detection of the liberated quinone product, is used for illustrating the operation of the flow probe and demonstrating its advantages over remote phenol sensors. The internal buffer solution ensures independence of sample conditions such as pH, ionic strength, or natural conditions, that commonly influences the performance of remote sensors. The 'built-in' flow pulsation of the integrated micropump is exploited for a sensitive hydrodynamic-modulation voltammetric detection of hydrazine and peroxide pollutants.

A microbiosensor capable of measuring very low levels of phenol vapor directly in the gas phase has been constructed. The microbiosensor is based on the enzyme polyphenol oxidase, which catalyzes the oxidation of phenols to catechols and then to quinones. Polyphenol oxidase was immobilized in a glycerol-based gel which did not dehydrate significantly over time. An interdigitated microelectrode array was used as transducer. Phenol vapor partitioned into the glycerol gel, where it was enzymatically oxidized to quinone. Signal amplification was achieved by redox recycling of the quinone/catechol couple. This redox recycling produced a biosensor capable of measuring phenol vapor concentrations of 30 ppb. The biosensor produced a constant signal after 5 days of continuous use at room temperature and has potential application in the field of health and safety monitoring, where its ease of use, selectivity, and real-time monitoring would provide personnel with accurate data.

A study conducted to determine the relationship of residential wood burning with the concentration of phenols and methoxylated phenols in urban winter air is discussed. Samples of organic pollutants were collected from three sampling sites. C analysis was used to compare the contribution of wood burning to inhalable particulate carbon. The utility of guaiacol measurements for quantitatively determining the contribution of wood burning to air pollution was demonstrated.