Search results for "Benzoic acid"
showing 10 items of 161 documents
Development of an ICP−IDMS Method for Dissolved Organic Carbon Determinations and Its Application to Chromatographic Fractions of Heavy Metal Complex…
1998
A sensitive and fast method for direct determinations of dissolved organic carbon (DOC) in bulk samples and in chromatographically separated fractions by inductively coupled plasma isotope dilution mass spectrometry (ICP−IDMS) is developed. A 13C-enriched spike solution of benzoic acid is used for the isotope dilution step. Equal ionization efficiencies are obtained for carbon, independent of the type and molecular weight of the dissolved organic substance, which is the most important precondition for DOC determinations by ICP−IDMS. The detection limits achieved are 0.3 mg L-1 for bulk analyses and 7 × 10-4 μg s-1 for transient signals of chromatographic peaks. The results for different wat…
Indirect spectrophotometric determination of p-aminobenzoic acid in sunscreen formulations by sequential injection analysis
2003
Abstract A simple indirect sequential injection spectrophotometric method for the determination of the UV-filter p -aminobenzoic acid (PABA) in sunscreen formulations is proposed. The determination is based on the reaction of PABA with hypochlorite in acidic medium and the subsequent measurement of the residual chlorine by using the well-known reaction with o -tolidine. The experimental variables involved in the sequential injection analysis (SIA) system (sandwich arrangement, volumes of sample and reagents, propulsion flow rate, reaction coil length) and adequate concentrations of reagents were studied. The SIA method has a linear range up to 20 μg ml −1 (3 s y / x / b detection limit) of …
Novel modified poly vinyl chloride blend membranes for removal of heavy metals from mixed ion feed sample
2017
Herein, an attempt has been made to prepare a novel membrane with good efficiency for removal of heavy metal ions namely lead (Pb), cadmium (Cd) and chromium (Cr). 4-amino benzoic acid (ABA) was covalently grafted onto the poly vinyl chloride (PVC) backbone by CN bond to enhance the hydrophilicity. 1H NMR and ATR-IR spectroscopy analysis confirmed the chemical modification of PVC. Further the modified polymer was blended in different compositions with polysulfone (PSf) for optimization. Morphological changes that occurred in blend membranes, due to the incorporation of modified PVC was studied by AFM and SEM techniques. The effect on hydrophilicity and performance of blends owing to incorpo…
Synthesis and evaluation of (S)-2-(2-[18F]fluoroethoxy)-4-([3-methyl-1-(2-piperidin-1-yl-phenyl)-butyl-carbamoyl]-methyl)-benzoic acid ([18F]repaglin…
2004
18F-labeled non-sulfonylurea hypoglycemic agent (S)-2-(2-[(18)F]fluoroethoxy)-4-((3-methyl-1-(2-piperidin-1-yl-phenyl)-butylcarbamoyl)-methyl)-benzoic acid ([(18)F]repaglinide), a derivative of the sulfonylurea-receptor (SUR) ligand repaglinide, was synthesized as a potential tracer for the non-invasive investigation of the sulfonylurea 1 receptor status of pancreatic beta-cells by positron emission tomography (PET) in the context of type 1 and type 2 diabetes. [(18)F]Repaglinide could be obtained in an overall radiochemical yield (RCY) of 20% after 135 min with a radiochemical purity higher than 98% applying the secondary labeling precursor 2-[(18)F]fluoroethyltosylate. Specific activity w…
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…
Reproductive effects in German cockroaches by ecdysteroid agonist RH-0345, juvenile hormone analogue methoprene and carbamate benfuracarb
2004
1379-1176 (Print) Journal Article Research Support, Non-U.S. Gov't; Blatta germanica is the more prevalent cockroach species in Algeria. In the present study, we tested the effect on reproduction in B. germanica of two insect growth regulators, RH-0345, a benzoylhydrazine analogue that mimics the action of 20-hydroxyecdysone, and methoprene, one of the most commercially important juvenile hormone analogues, and a novel carbamate insecticide, benfuracarb. The compounds were applied topically (10 and 20 microg/insect for RH-0345, and 1 and 10 microg/insect for methoprene) or orally administrated (at 2% for benfuracarb) on newly emerged females and evaluated on reproductive events during the a…
Untargeted screening of the bound / free phenolic composition in tomato cultivars for industrial transformation
2019
BACKGROUND Tomato is one of the most important agricultural crops and it is characterized by a wide bioactive compound profile. However, little information is reported on its comprehensive polyphenol profile. In this work, 13 commercial tomato cultivars for industrial transformation were screened by ultra-high-pressure liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS) for both free and bound phenolic profiles. Thereafter, the in vitro antioxidant activity of each cultivar was assessed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance activity (ORAC) assays. Multivariate statistics, i.e. orthogonal projection to latent struct…
Synthesis and characterization of triorganotin(IV) complexes of 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids.
2001
Abstract The triphenyltin and tri-n-butyltin complexes of some 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids have been synthesized and characterized by 1H-, 13C-, 119Sn-NMR, IR and 119mSn Mossbauer spectroscopic techniques in combination with elemental analysis. The crystal structures of triphenyltin 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoates (aryl=phenyl, 2-methylphenyl, 3-methylphenyl and 4-methoxyphenyl) are reported. Both X-ray and 119Sn Mossbauer data indicate that the triphenyltin complexes adopt a monomeric distorted tetrahedral configuration with the carboxylate ligand coordinating in a monodentate mode. By contrast, 119Sn Mossbauer spectroscopy shows that each tributyltin …
Properties of radiation-modified blends of polyethylene with elastomers and liquid crystalline copolyester
2001
The results are given on the effect of γ-irradiation on properties of blends of high and low-density polyethylene (HDPE, LDPE) with elastomers -ethylene/propylene/diene rubber (EPDM) and chlorinated polyethylene (CPE), and thermotropic liquid crystalline polymer (LCP). The morphological, thermal, mechanical properties (including thermosetting properties) and adhesion properties of blended composites were investigated. A special attention was paid to the applicability of the blends as thermosetting materials (TSM). The LCP used was a copolyester of poly(ethylene terephthalate) with p-(hydroxybenzoic acid) in the ratio 40: 60. It was found that addition of LCP essentially influenced the therm…
Synthesis and characterization of bis[dicarboxylatotetraorganodistannoxane] units involving 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids: an in…
2006
Abstract Reactions of 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids (LHH′, where the aryl group is an R-substituted phenyl ring such that for L1HH′: R = H; L2HH′: R = 2′-CH3; L3HH′: R = 3′-CH3; L4HH′: R = 4′-CH3; L5HH′: R = 4′-Cl; L6HH′: R = 4′-Br) with nBu2SnO in a 1:1 molar ratio yielded complexes of composition {[nBu2Sn(LH)]2O}2. The complexes have been characterized by 1H, 13C, 119Sn NMR, ESI-MS, IR and 119mSn Mossbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of {[nBu2Sn(L1H)]2O}2 (1), {[nBu2Sn(L4H)]2O}2 (4), {[nBu2Sn(L5H)]2O}2 (5) and {[nBu2Sn(L6H)]2O}2 (6) were determined. The compounds are centrosymmetric tetranuclear bis(dicarboxy…