Chloroform Hexane Research Articles

Agent orange herbicides, organophosphate and triazinic pesticides analysis in olive oil and industrial oil mill waste effluents using new organic phase immunosensors

New immunosensors working in organic solvent mixtures (OPIEs) for the analysis of traces of different pesticides (triazinic, organophosphates and chlorurates) present in hydrophobic matrices such as olive oil were developed and tested. A Clark electrode was used as transducer and peroxidase enzyme as marker. The competitive process took place in a chloroform–hexane 50% (V/V) mixture, while the subsequent enzymatic final measurement was performed in decane and using tert-butylhydroperoxide as substrate of the enzymatic reaction. A linear response of between about 10nM and 5.0μM was usually obtained in the presence of olive oil. Recovery tests were carried out in commercial or artisanal extra virgin olive oil. Traces of pesticides were also checked in the oily matrix, in pomace and mill wastewaters from an industrial oil mill. Immunosensors show good selectivity and satisfactory precision and recovery tests performed in olive oil gave excellent results.

New Immunosensors Operating in Organic Phase (OPIEs) for Analysis of Triazinic Pesticides in Olive Oil

AbstractSeveral tests were carried out on the possibility of fabricating immunosensors working in organic solvents or solvent mixtures and aimed at developing new immunosensors for the analysis of triazinic pesticides present in hydrophobic matrices such as olive oil. Initially, an immunosensor for atrazine was tested in which a hydrogen peroxide electrode was used as transducer and peroxidase enzyme as marker. The competitive process took place in a chloroform–hexane 50 % (V/V) mixture, while the subsequent enzymatic measurement was performed in an aqueous buffer solution. A linear response of between about 50 nM and 5.0 µM was obtained versus atrazine in presence of oil. Subsequently, attempts were also made using a Clark electrode as transducer and performing not only the competition but also the final enzymatic measure in organic solvent. The latter enzymatic measurement was thus carried out in several different organic solvents, such as decane, hexane, chloroform and chloroformhexane mixture. The best analytical results were obtained using decane as solvent and tert‐butylhydroperoxide as substrate of the enzymatic reaction.

Validated TLC-Image Analysis Method for Simultaneous Quantification of Curcuminoids in Curcuma longa

A simple and rapid thin layer chromatographic (TLC)-image analysis method was developed for simultaneous quantification of three curcuminoids; curcumin (CUR), desmethoxycurcumin (DES) and bisdesmethoxycurcumin (BIS), in Curcuma longa (turmeric). Chromatographic separation of the curcuminoids was achieved on silica gel 60 F254 TLC plates, using chloroform–hexane–methanol (1:1:0.1, v/v/v) as the mobile phase. Image analysis of the scanned TLC plate was performed by Photoshop 7.0 to quantify the amount of each curcuminoid. The method was validated and found to be accurate, reliable and convenient for the analysis of CUR, DES and BIS in turmeric.

Simultaneous determination of haloperidol and bromperidol and their reduced metabolites by liquid–liquid extraction and automated column-switching high-performance liquid chromatography

This study describes a new simultaneous determination of haloperidol and bromperidol and their reduced metabolites by modification of automated column-switching high-performance liquid chromatography. The test compounds were extracted from 1 ml of plasma using chloroform–hexane (30:70 (v/v)), and the extract was injected into a hydrophilic metaacrylate polymer column for clean-up and a C 18 analytical column for separation. The mobile phases consisted of phosphate buffer (0.02 M, pH 4.6), perchloric acid (60%) and acetonitrile (54:1:45 (v/v)) and was delivered at a flow-rate of 0.6 ml/min. The peak was detected using a UV detector set at 215 nm. The method was validated for the concentration range 1–100 ng/ml, and good linearity ( r>0.999) was confirmed. Intra-day coefficient variations (CVs) for haloperidol, reduced haloperidol, bromperidol and reduced bromperidol were less than 2.5, 3.1, 2.4 and 2.5%, respectively. Inter-day CVs for corresponding compounds were 3.9, 5.1, 2.6 and 4.4%, respectively. Relative errors ranged from −5 to 10% and mean recoveries were 96–100%. The limit of quantification was 1.0 ng/m for each compound. This method shows good specificity with respect to commonly prescribed psychotropic drugs, and it could be successfully applied for pharmacokinetic studies and therapeutic drug monitoring, particularly in patients receiving both haloperidol and bromperidol.

Quantification of Bacillus cereus Emetic Toxin (Cereulide) in Figs Using LC/MS

An LC/MS method is described for the quantification of cereulide, the emetic toxin of Bacillus cereus in figs. The method can also be used for the determination of cereulide in rice. The sample was extracted with a mixture of acetone–tetrahydrofurane, methanol, and water, after which the organic layer was separated from water with chloroform and evaporated to dryness. The dry residue was diluted in chloroform–hexane and purified using a silica solid phase extraction column. The detection limit was 1 ng/g.

Synthesis and molecular structure of 4-methoxyphenyl-2′-pyrrolylthione and its rhenium complex

A bidentate monoanionic N,S-ligand, 4-methoxyphenyl-2′-pyrrolylthione ( 1) was synthesised via an oxygen-to-sulphur exchange in the corresponding ketone and then fully characterised. A trinuclear complex ( 2) of rhenium with this compound was obtained in a reaction of KReO 4 with 1 in the presence of a reducing agent in aqueous ethanol, followed by slow precipitation from chloroform–hexane. The structure of compound 2 corresponds to the formula [Re 3O 4(C 12H 10NOS) 6] +1[ReO 4] −1·2CH 3CH 2OH. A single crystal X-ray diffraction study was performed for this complex. The following crystal data were obtained for 2: M r=2262.556, monoclinic, space group C2/ c, a=34.6651(2) Å, b=11.5694(1) Å, c=24.6839(2) Å, β=128.0350(4)°, V=7797.3(1) Å 3, Z=4. The molecule contains a linear backbone [OReOReOReO] +7 with six bidentate ligands 1 bonded by three rhenium coordination centres in equatorial planes. Such structures are uncommon for Re (V) complexes with heterocyclic bidentate nitrogen-containing ligands, which often exist as binuclear molecules.

Determination of a new atypical antipsychotic agent perospirone and its metabolite in human plasma by automated column-switching high-performance liquid chromatography

A simple and sensitive column-switching high-performance liquid chromatographic (HPLC) method with fluorescence detection is described for the quantification of perospirone, a serotonin and dopamine antagonist, and its metabolite ID-15036 in human plasma. The test compounds were extracted from 2 ml of plasma using chloroform–hexane (30:70, v/v) and the extract was injected into a column I (TSK-PW precolumn, 10 μm, 35×4.6 mm I.D.) for clean-up and column II (C 18 STR ODS-II analytical column, 5 μm, 150×4.6 mm I.D.) for separation. The peak was detected using a fluorescence detector set at Ex 315 nm and Em 405 nm, and the total time for a chromatographic separation was ∼30 min. The method was validated for the concentration range from 0.1 to 100 ng/ml. Mean recoveries were 97% for perospirone and 96% for ID-15036. Intra- and inter-day relative standard deviations were less than 2.8 and 5.3% for perospirone and 2.4 and 4.4% for ID-15036, respectively, at the concentration range from 0.3 to 30 ng/ml. This method shows good specificity with respect to commonly prescribed psychotropic drugs, and it could be successfully applied for pharmacokinetic studies and therapeutic drug monitoring.

Acylation of monolysocardiolipin in rat heart

Cardiolipin is a major mitochondrial membrane glycerophospholipid in the mammalian heart. In this study, the ability of the isolated intact rat heart to remodel cardiolipin and the mitochondrial enzyme activities that reacylate monolysocardiolipin to cardiolipin in vitro were characterized. Adult rat heart cardiolipin was found to contain primarily linoleic and oleic acids. Perfusion of the isolated intact rat heart in the Langendorff mode with various radioactive fatty acids, followed by analysis of radioactivity incorporated into cardiolipin and its immediate precursor phosphatidylglycerol, indicated that unsaturated fatty acids entered into cardiolipin mainly by deacylation followed by reacylation. The in vitro mitochondrial acylation of monolysocardiolipin to cardiolipin was coenzyme A-dependent with a pH optimum in the alkaline range. Significant activity was also present at physiological pH. With oleoyl-coenzyme A as substrate, the apparent K(m) for oleoyl-coenzyme A and monolysocardiolipin were 12.5 microm and 138.9 microm, respectively. With linoleoyl-coenzyme A as substrate, the apparent K(m) for linoleoyl-coenzyme A and monolysocardiolipin were 6.7 microm and 59.9 microm, respectively. Pre-incubation at 50 degrees C resulted in different profiles of enzyme inactivation for the two activities. Both activities were affected similarly by phospholipids, triacsin C, and various lipid binding proteins but were affected differently by various detergents and myristoyl-coenzyme A. [(3)H]cardiolipin was not formed from monolyso[(3)H]cardiolipin in the absence of acyl-coenzyme A. Monolysocardiolipin acyltransferase activities were observed in mitochondria prepared from various other rat tissues. In summary, the data suggest that the isolated intact rat heart has the ability to rapidly remodel cardiolipin and that rat heart mitochondria contain coenzyme A-dependent acyltransferase(s) for the acylation of monolysocardiolipin to cardiolipin. A simple and reproducible in vitro assay for the determination of acyl-coenzyme A- dependent monolysocardiolipin acyltransferase activity in mammalian tissues with exogenous monolysocardiolipin substrate is also presented.

A new organic phase bienzymatic electrode for lecithin analysis in food products

The aim of the present research was to examine the possibility of constructing a bienzymatic sensor for lecithin determination, which must be capable of operating in organic solvents, in which lecithin is more readily soluble, as well as to evaluate the possibility of applying it to the analysis of food matrices. The new OPEE (organic phase enzyme electrode) was obtained by using as electrochemical transducer a gas diffusion amperometric electrode for oxygen while the enzymes (phospholipase D and choline oxidase) were both immobilised either in a dialysis membrane or in kappa-Carrageenan gel. This biosensor was used to study the possibility of determining lecithin content in several food samples (egg yolk, soya flour and oil, etc.) as well as in some diet integrators, operating in a chloroform–hexane (1+1 by volume), or chloroform–hexane–methanol (1+1+0.02 by volume) mixture.

Determination of levamisole in animal tissues using liquid chromatography–thermospray mass spectrometry

A method is described for the determination of the anthelmintic levamisole in liver, kidney and muscle using liquid chromatography–thermospray mass spectrometry. Samples are extracted by homogenizing with ethyl acetate, applied to Bakerbond CN solid-phase extraction columns, washed with chloroform–hexane and eluted with methanol. The extracts are evaporated to dryness under nitrogen and the residues are dissolved in mobile phase and injected into the LC–MS system. The positive M + 1 ion at m/z 205 is monitored. The detection limit for the assay is 5 ng g–1. Mean recoveries were about 93% for liver, 85% for kidney and 79% for muscle. The assay has been used for statutory testing purposes and for measuring levamisole concentrations in liver, kidney and muscle from sheep dosed with a commercial drench containing levamisole.

Determination of carotenoids and chlorophylls in water convolvulus ( Ipomoea aquatica) by liquid chromatography

The carotenoids and chlorophylls present in water convolvulus (Ipomoea aquatica) were analyzed by high-performance liquid chromatography (HPLC) with photodiode-array detection and their identify confirmed by thin-layer chromatography (TLC). An HPLC quaternary solvent system of acetonitrile methanol chloroform hexane (75 : 12.5 : 7.5 : 7.5, v/v/v/v) resolved 14 peaks in 20 min by using a 25 cm reversed-phase column, of which 12 pigments were identified. These pigments include carotenoids, chlorophylls and their isomers. The coefficient of variation for pigment concentrations was less than 12% in five sample analyses. A TLC quaternary solvent system of hexane acetone chloroform methanol in different proportions also resolved 10 pigments on silica gel layers. In addition to cis-lutein and cis-β-carotene, all major pigments were adequately resolved by TLC.

Surface-induced chromism and enhanced fluorescence of the soluble polydiacetylene, poly(4-butoxycarbonylmethylurethane), at a solid/solution interface: an evanescent-wave induced fluorescence study

Using evanescent-wave induced fluorescence (EWIF) spectroscopy, from the soluble polydiacetylene, poly(4-butoxycarbonylmethylurethane)(poly-4BCMU), has been studied in solutions of 2-methyltetrahydrofuran and a chloroform–hexane mixture, in contact with a fused silica surface.The system requires up to 4 h to attain equilibrium, at which point the EWIF emission intensity is observed to be 20 and 60 times greater than expected for the yellow (Y) and red (R) form solutions, respectively. This has been interpreted as adsorption of the polymer onto the glass surface which leads to a reduction in the efficiency of the non-radiative, internal conversion deactivation mechanism of the excited state, with consequent increase in the fluorescence quantum yield.In the case of a Y-form poly-4BCMU solution, at times less than 10 min, following the introduction of the solution to the surface, the EWIF spectrum resembles the R-form of the polymer. This spectrum grows in with a rate constant of ca. 0.7 min–1 and is attributed to a transient effect induced by a hydrophilic, non-solvent-conditioned glass surface, causing the equilibrium between the Y- and R-forms of the polymer to be shifted in favour of the R-form. The spectrum then disappears with a rate constant of 0.025 min–1 as equilibrium is reattained and the glass surface becomes conditioned, or ‘solvated’. The kinetic data support the theory of an intramolecular fringed micellar structure for the R-from of poly-4BCMU in solution.

Polydiacetylenes in solution; charged rods and neutral coils

We report experimental results on several polydiacetylenes and a polythiophene in solution which demonstrate a change in charge state associated with solvatochromic and thermochromic transitions. The planar conformations are charged and the nonplanar conformations are neutral. When fields of ≊600 V/cm were applied to solutions of polymer in chloroform–hexane mixtures or toluene (i.e., the polymer is in the extended state), the polymers plated out on one electrode. We have measured the current as a function of time associated with the deposition of the polymer to determine the quantity of charge per polymer. The time dependence of the current had two regimes which can be associated with two types of charged material in the solution: the charged polymer, which plates out, and an unidentified charge transfer species which does not plate out. Polydiacetylenes 4BCMU and 3BCMU in solutions of chloroform/hexane became positively charged. Poly-3-hexyl-thiophene also became positively charged. PDA-9PA and PDA-92NA became negatively charged. We found a charge of 3×10−4 e/monomer for 4BCMU, 7×10−3 e/monomer for 3BCMU, and 4×10−2 e/monomer for PDA-9PA. Using this effect, we can demonstrate that both rod and coil segments coexist on the same polymer chain in the intermediate stages of the rod–coil transition. We suggest a mechanism which can qualitatively account for this unusual behavior. We also describe novel experiments in which an electric field was used to drive the polymers across a boundary between two nonmiscible solvents. When the polymer crosses the boundary, it changes color. The possibility of using the plating effect for precise fractionation by electrophoresis is suggested.

Characterization of epoxy novolac resins using phenyl-bonded phase high-performance liquid chromatography

Epoxy novolac resins can be characterized using a 5-μm phenyl-bonded phase column. Both reversed-phase (tetrahydrofuran—water) and normal phase (tetrahydrofuran—hexane and chloroform—hexane) elutions can be used to obtain a qualitative fingerprinting-type of identification and a quantitative measurement of molecular-weight distribution. The retention of epoxy novolac resins is proportional to the degree of polymerization and the mobile phase compositions.

Determination of Theophylline in Plasma by High Performance Liquid Chromatography

Abstract We describe a rapid and highly specific method for determining theophylline in plasma. Following addition of ammonium sulfate and β-Hydroxy-ethyl-theophylline as internal standard, theophylline is extracted into a mixture of chloroform hexane (70 : 30) and evaluated by high performance liquid chromatography, using Microporasil “Waters” 10 μm as stationnary phase and N-hexane-ethanol (76 : 24) mixture as mobile phase. Absorption at 280 nm is monitored. The method has a good precision (coefficients of variation between 3% and 4% for 1 mg/1 and 10 mg/1) and its sensitivity is about 0.25 mg/1. No interferences from endogenous compounds, metabolites of theophylline, or from drugs commonly co-administrated with theophylline have been encountered. This technique can be used in analytical toxicology, and also for therapeutic controls and pharmacokinetic studies.

Adducts of co-ordination compounds. Part XI. Isomerism and solvation of dichlorobis(triphenylphosphine)platinum(II)

The complex cis-[Pt(PPh3)2Cl2] forms distinct adducts with chloroform and NN-dimethylformamide. The existence of these adducts, for which X-ray powder results are given, accounts for several discrepancies in the literature. In particular, the product (recrystallised from chloroform–hexane) of reaction of carbon tetrachloride with tetrakis(triphenylphosphine)platinum(0), previously incorrectly formulated as [Pt(PPh3)2(CCl3)Cl], is in fact a partly desolvated sample of the chloroform adduct of the cis-dichloro-complex. In solution, cis–trans-isomerisation is easily set up providing access to the trans-isomer. Two further methods, which give much better yields of the trans-isomer, are described.