Search results for "Cresol"
showing 10 items of 30 documents
COMPARATIVE STUDY OF C18- AND STYRENE-DIVINYLBENZENE-BASED SORBENTS FOR THE ENRICHMENT OF PHENOLS FROM WATER
2001
The potential of solid-phase extraction with C18- and styrene divinylbenzene-based sorbents for the preconcentration of phenols from water samples has been evaluated for a variety of phenols of different polarities: phenol, o-, m- and p-cresol, 2-chlorophenol, and 4-chloro-3-methylphenol. The extraction efficiencies have been calculated for different volumes of samples containing the analytes at different concentration levels. The UV limits of detection were of 1–5 ng/mL, for the method using Bond Elut C18 cartridges and sample volumes of 25 mL, and 0.05–0.1 ng/mL (except for 4-chloro-3-methylphenol) for the method using the polymeric sorbent Bond Elut PPL and 1000 mL of the samples. Possib…
Determination of phenolic compounds in air by using cyclodextrin-silica hybrid microporous composite samplers
2015
An analytical method for the determination of phenolic compounds in air samples based on the use of cyclodextrin-silica hybrid microporous composite samplers is proposed. The method allows the determination of phenol, guaiacol, cresol isomers, eugenol, 4-ethylphenol and 4-ethylguaiacol in workplaces according to the Norm UNE-EN 1076:2009 for active sampling. Therefore, the proposed method offers an alternative for the assessment of the occupational exposure to phenol and cresol isomers. The detection limits of the proposed method are lower than those for the NIOSH Method 2546. Storage time of samples almost reaches 44 days. Recovery values for phenol, guaiacol, o-cresol, m-cresol, p-cresol,…
Flow injection-spectrophotometric determination of cresol compounds in water by reaction withp-aminophenol
1993
A spectrophotometric method has been developed for the simultaneous determination ofo-cresol andm-cresol in water by reaction withp-aminophenol (PAP). Three different methodologies have been assayed; (i) batch analysis, after reaction in an alkaline medium in the presence of dissolved molecular oxygen as oxidizing agent, (ii) a stopped-flow procedure, carried out in the presence of KIO4 and (iii) a flow injection method based on the same approach. The batch procedure requires 22 min for the full development of colour witho-cresol and 12 min form-cresol. In the stopped-flow mode, using KIO4 and a reaction time of 12 min, better sensitivity can be obtained for both compounds and limits of det…
Chromatographic Separation of Cresol Isomers by a β‐Cyclodextrin: Application for the Determination of Volatile Phenols in Alcoholic Beverages
2006
Abstract The chromatographic separation of o‐cresol, m‐cresol, and p‐cresol by using β‐cyclodextrin as a chiral reagent has been studied. Conditions for the chromatographic separation of these isomers by using the cyclodextrin in the mobile phase or bonded in the stationary phase were optimized, and both procedures provided good results for the resolution of the chromatographic peaks. The use of fluorimetric detection (λexc 275 nm λem 300 nm) allows detection and quantification limits of the µg/L for eight studied phenols by using both procedures. The determination of volatile phenols in alcoholic beverages must be carried out using the cyclodextrin in the mobile phase because of the co‐elu…
Further development of the β-lactamase MutaGen assay and evaluation by comparison with Ames fluctuation tests and theumu test
2005
A rapid, high-throughput bacterial mutagenicity test system has been developed (MutaGen test) that detects reversions of inactivating base-pair substitutions and frameshifts in a TEM-1 class A β-lactamase (ampicillinase) gene. To quickly and sensitively detect mutagens, the system utilises a series of plasmids that contain the mutated ampicillinase gene and the mucAB operon. Inactivating mutations in the ampicillinase gene include frameshifts integrated into repetitive GC-sequences and G-runs known to be mutagenic hot-spots, and base-pair substitutions inserted in or around the β-lactamase active site. Frameshift mutations completely inactivated the enzyme only when located downstream of th…
Determination of Amitriptyline with Bromocresol Purple and Flow Injection Analysis
1990
Abstract The study of some amitriptyline-dye systems was carried out in order to determine the best precipitate for the turbidimetric determination of amitriptyline using FIA. The reagent selected was bromocresol purple. The chemical and FIA variables were optimized. The calibration graph was linear over the concentration range 30.0–200.0 ppm of amitriptyline hydrochloride. Some interfering substances were also investigated.
Excretion and metabolism of phenol, 4-nitrophenol and 2-methylphenol by the frogs Rana temporaria and Xenopus laevis.
1987
1. Rana and Xenopus excrete 90-95% dose, and metabolize 50-65% dose of phenol, 4-nitrophenol and 2-methylphenol within 24 h, to about the same extent. 2. Kinetic data for the excretion of phenols from both species fit a two-compartment model. The elimination constants of Rana and Xenopus are not significantly different. 3. Metabolism is mostly conjugation by glucuronidation and sulphation of the original phenols. Additionally, oxidations leading to dihydroxyphenols and benzoic acid from 2-methylphenol, and reduction of 4-nitrophenol occur, followed by conjugation. 4. There is an important difference between the metabolite patterns of Rana and Xenopus in that the latter is unable to glucuron…
Syntheses, Characterization, and Magnetic Studies of Copper(II) Complexes with the Ligand N,N,N′,N′-Tetrakis(2-pyridylmethyl)-1,3-benzenediamine (1,3…
2011
The copper(II) complexes [Cu4(1,3-tpbd)2(H2O)4(NO3)4]n(NO3)4n·13nH2O (1), [Cu4(1,3-tpbd)2(AsO4)(ClO4)3(H2O)](ClO4)2·2H2O·0.5CH3OH (2), [Cu4(1,3-tpbd)2(PO4)(ClO4)3(H2O)](ClO4)2·2H2O·0.5CH3OH (3), [C...
The Role of Liver in Determining Serum Colon-Derived Uremic Solutes.
2015
Evidence has shown that indoxyl sulfate (IS) and p-cresyl sulfate (PCS) may be alternative predictors of clinical outcomes in chronic kidney disease (CKD). Both toxins are derived from the gastrointestinal tract and metabolised in the liver. However, it is unclear whether the liver affects the production of IS and PCS. Here, we explore the association between IS and PCS levels in liver cirrhosis and a CKD-based cohort (N = 115). Liver and kidney function was assessed and classified by a Child-Pugh score (child A–C) and a modified version of the Modification of Diet in Renal Disease (MDRD) equation (Stages 1–4), respectively. An animal model was also used to confirm the two toxin levels in a…