Validation of High Performance Liquid Chromatography with Fluorescence Detector Methods for Determination of Aflatoxins in Different Food and Animal Feed Samples

Method validation for quantitative analysis of aflatoxins, AFB1, AFB2, AFG1 and AFG2 in sorghum, peanut butter, groundnut and animals feed is presented. Aflatoxins were extracted with a mixture of methanol: acetonitrile: water (60:30:10) and cleaned with Alfa test IAC chromatography before analysis by High Performance Liquid Chromatography coupled with fluorescence detection (HPLC-FLD) by adopting an isocratic chromatographic system using a mobile phase consisting acetic acid: acetonitrile: methanol (59:14:27), the separation of the four aflatoxins was achieved in less than 15 minutes. Calibration curves were linear over the concentration range from 2 - 18 ng/mL for AFB1 and AFG1, 0.4 - 3.6 ng/mL for AFB2 and AFG2, respectively. The LOD and LOQ in spiked samples were found to be 0.02 and 0.05 μg/kg for both AFB1 and AFG1, 0.01 and 0.03 μg/kg for both AFB2 and AFG2. The mean recovery values were in range from 84.2% to 96.9% was obtained. Five samples were found to be contaminated with aflatoxins and the total aflatoxins ranged from 0.02 to 3.26 μg/kg were obtained. Nineteen different samples were found to be contaminated with aflatoxins;the total aflatoxins ranged from 0.27 to 10.48 μg/kg were obtained. The highest total aflatoxins value was obtained in animal feeds.

Esterification of levulinic acid to n-butyl levulinate over heteropolyacid supported on acid-treated clay

Levulinic acid has been identified as a promising green, biomass-derived platform chemical. n-Butyl levulinate is used as an important intermediate having diverse applications. The present work focuses on the synthesis of n-butyl levulinate by esterification of levulinic acid with n-butanol using heteropolyacid （HPA） supported on acid-treated clay montmorillonite （K10）. 20% （w/w） dodecatungestophosphoric acid （DTPA） supported on K10 was found to be the most efficient catalyst with 97% levulinic acid conversion and 100% selectivity towards n-butyl levulinate. Effects of various process parameters were studied to examine the efficacy of 20% （w/w） DTPA/K10 for optimization of the activity.

Synthesis of ethyl acetate by esterification of acetic acid with ethanol over a heteropolyacid on montmorillonite K10

In present work,liquid phase esterification of acetic acid with ethanol over dodecatungestophosphoric acid （DTPA） supported on K10 montmorillonite was systematically studied and optimization of process parameters was carried out.The 20% m/m DTPA/K10 was found to be the optimum catalyst with 90% acetic acid conversion and 100% ethyl acetate selectivity.The study was also explored to see the feasibility of 20% m/m DTPA/K10 as a catalyst for the alkylation of acetic acid with other alcohols like methanol,iso-propanol and n-butanol.The 20% m/m DTPA/K10 has shown increased activity with the increase in carbon number,at the same alcohol reflux.The results are novel.

Toluene Alkylation to Selective Formation of p-Xylene over Co-Crystalline ZSM-12/ZSM-5 Catalyst

The alkylation of toluene with methanol to selective formation of p-xylene has been systematically studied. ZSM-12 （MTW）/ZSM-5 co-crystalline zeolite in 40：60 proportions have been synthesized by the same molar gel composition, but at different temperatures and periods than that of ZSM-12 and ZSM-5, separately. All the prepared samples are characterized by XRD, SEM, BET, and XRF. The activity of toluene alkylation was investigated with a mixture of toluene and methanol as a feed over the ZSM-12, ZSM-12/ZSM-5 co-crystalline, ZSM-5, and physical mixture of ZSM-12/ZSM-5. From characterization, it is observed that the ZSM-12/ZSM-5 co-crystalline material is different from that of ZSM-12, ZSM-5, and their physical mixture. Further, the ZSM-12/ZSM-5 co-crystalline zeolite produces the highest content of xylene and has better selectivity for p-xylene than ZSM-12, ZSM-5, and their physical mixture.

Influence of alkali metal doping on surface properties and catalytic activity/selectivity of CaO catalysts in oxidative coupling of methane

Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.

Toluene Alkylation with Methanol to p-Xylene over Heteropoly Acids Supported by Clay

The alkylation of toluene with methanol for the selective formation of p-xylene was systematically studied. Very few studies have been reported on the use of superacids such as heteropolyacids on cheap supports, such as clay. This article deals with the use of different heteropoly acids （HPAs）, viz, Dodeca-Tungstophosphoric acid [H3PO4.12WO3.xH2O] （TPA）, Dodeca-Molyhdo phosphoric acid ammonium salt hydrate [H12Mo12N3O40P＋aq] （DMAA）, Dodeca-Molyhdo Phosphoric acid （PMA） on clay （MontmoriUonite, K-10） and as such plain clay. This comparative study reveals that 20%PMA/Clay shows 62% toluene conversion and 100% selectivity toward p-xylene.

Molecular dynamics study on growth of carbon dioxide and methane hydrate from a seed crystal

In the current work,molecular dynamics simulation is employed to understand the intrinsic growth of carbon dioxide and methane hydrate starting from a seed crystal of methane and carbon dioxide respectively.This comparison was carried out because it has relevance to the recovery of methane gas from natural gas hydrate reservoirs by simultaneously sequestering a greenhouse gas like CO2.The seed crystal of carbon dioxide and methane hydrate was allowed to grow from a super-saturated mixture of carbon dioxide or methane molecules in water respectively.Two different concentrations(1:6 and 1:8.5)of CO2/CH4 molecules per water molecule were chosen based on gas–water composition in hydrate phase.The molecular level growth as a function of time was investigated by all atomistic molecular dynamics simulation under suitable temperature and pressure range which was well above the hydrate stability zone to ensure significantly faster growth kinetics.The concentration of CO2 molecules in water played a significant role in growth kinetics,and it was observed that maximizing the CO2 concentration in the aqueous phase may not result in faster growth of CO2 hydrate.On the contrary,methane hydrate growth was independent of methane molecule concentration in the aqueous phase.We have validated our results by performing experimental work on carbon dioxide hydrate where it was seen that under conditions appropriate for liquid CO2,the growth for carbon dioxide hydrate was very slow in the beginning.

Synthesis of Pharmaceutical Intermediates by Toluene Benzylation over Heteropoly Acids on Different Support

Selective formation of pharmaceutical intermediates like diphenylmethane, dimethyldiphenylmethane, benzyl toluene and benzoic acid by liquid phase, toluene benzylation with benzyl chloride as a benzylating agent, was systematically studied over plane clay （K-10, montmorillonite）, plane H-Beta, plane MFI structured titanosilicate （TS-1） and heteropoly acids [HPA, namely dodecatungstophosphoric acid [H3PO4.12WOa-xH2O] （TPA）, dodeca-molybdo phosphoric acid ammonium salt hydrate [H12Mo12N3040P＋aq] （DMAA）, sodium tungstate hydrated purified [Na12WO4.2H2O] （STH）] supported on clay, H-beta and TS-1. The 20%TPA/Clay, 30%TPA/H-Beta and 30%TPA/TS-1, were observed to be the best catalyst samples over plane clay, plane H-Beta and plane TS-1. The catalyst samples are compared with respect to benzyl chloride conversion and selectivities for diphenylmethane, dimethyl-diphenylmethane, benzyl toluene and benzoic acid. The reaction follows the pseudo-first order rate power law model. The apparent rate constants are calculated and compared with the reported ones.

Oxidation of propane to acrylic acid and acetic acid over alkaline earth-doped Mo-V-Sb-O_x catalysts

Alkaline earth metal （Mg,Ca,Sr and Ba）-doped Mo-V-Sb-O x catalysts,prepared by a dry-up method,have been investigated for their catalytic performance in the oxidation of propane under different reaction conditions.The catalysts have been characterized by N2 adsorption-desorption,temperature-programmed desorption （TPD） of NH3,SEM and XRD.Influence of water vapor on the catalytic performance,particularly on the selectivities to acetic acid and acrylic acid,has also been studied.The selectivity to acrylic acid was improved significantly by the doping of alkaline earth metals to Mo-V-Sb-O x catalysts.The surface acidic sites of the catalyst decreased with the doping of the catalyst with alkaline earth metals,which ultimately was found to be beneficial for obtaining high selectivity to acrylic acid.The catalytic activity and product selectivities were found to be influenced by the reaction temperature,C3H8/O2 ratio and space velocity.A significant improvement in the selectivity to acrylic acid has also been observed by the addition of water vapor in the feed of propane and oxygen in the oxidation of propane.

Studies on Pongamia pinnata (L.) Pierre leaves: understanding the mechanism(s) of action in infectious diarrhea

While data are available on the effect of medicinal plants on intestinal motility and their antibacterial action, there is a paucity of information on their mode of action on various aspects of diarrheal pathogenicity, namely colonization to intestinal epithelial cells and production/action of enterotoxins. Crude decoction of dried leaves of Pongamia pinnata was evaluated for its antimicrobial (antibacterial, antigiardial and antirotaviral) effect; and its effect on production and action of enterotoxins (cholera toxin, CT; Escherichia coli labile toxin, LT; and E. coli stable toxin, ST); and adherence of enteropathogenic E. coli and invasion of enteroinvasive E. coli and Shigella flexneri to epithelial cells. The decoction had no antibacterial, antigiardial and antirotaviral activity, but reduced production of CT and bacterial invasion to epithelial cells. The observed results indicated that the crude decoction of P. pinnata has selective antidiarrheal action with efficacy against cholera and enteroinvasive bacterial strains causing bloody diarrheal episodes.

Disproportionation of ethylbenzene in the presence of C_8 aromatics

The selective synthesis of p-diethylbenzene （p-DEB） by disproportionation of ethylbenzene （EB） in the presence of aromatics like m- and p- xylene isomers has been studied over a pore size regulated HZSM-5 catalyst. The industrial feed having different compositions of ethylbenzene and xylene isomers was used for the experimentation. Hence, they were expected to hinder the movement of reactant molecules both on the external surface and within the zeolite channels. It was observed that irrespective of the different feed compositions the concentration of the xylene isomers was intact in the product. There is no other byproducts formation like para-ethylmethyl benzene. The effects of varying the concentration of aromatic compounds in the feed on ethylbenzene conversion and product distribution over the parent and modified H-ZSM-5 catalyst have been discussed. Ethylbenzene disproportionation reaction follows the pseudo first order reaction with an activation energy of 8.6 kcal/mol.

Phosphonated USY,a promising catalyst for the development of environmentally benign biodiesel(methyl acetate) process

The present study focuses on the evaluation of the potential applicability of Ultra Stable Y（USY） and phosphonated USY（1 wt%-4 wt%phosphorous loading） as heterogeneous catalysts for biodiesel（methyl acetate） production.The synthesized catalysts were characterized by powder X-ray diffraction（XRD）,Brunaer-Emmett-Teller（BET） surface area,total acidity by temperature-programmed desorption of ammonia（TPD-NH3） and Fourier Transform Infrared（FTIR） spectra.The performances of catalysts were evaluated for the transesterification of butyl acetate with methanol（a model reaction in biodiesel production）.In view to obtain a maximum yield of methyl acetate,the optimization of process parameters such as reactant molar ratio,catalyst loading,reaction temperature and reaction time was performed.All the phosphonated USY catalysts showed higher catalytic activity than the parent USY,which can be attributed to the increase of total acidity due to phosphonation.2 wt% P/USY（2% phosphorous loaded on USY） exhibited 92% methyl acetate yield with 100% selectivity,which was proved to be a potential catalyst for biodiesel production.The invented catalyst was found to be stable and reusable for five catalytic cycles,demonstrating that it might be a environmentally benign catalytic process.

Oxidative coupling of methane over La-promoted CaO catalysts:Influence of precursors and catalyst preparation method

The oxidative coupling of methane to C2 hydrocarbons has been studied over a series of La-promoted CaO （La/Ca = 0.05） catalysts, prepared using different precursor salts for CaO and La2O3 （viz. acetates, carbonates, nitrates and hydroxides） and catalyst preparation methods （viz. physical mixing of precursors, co-precipitation using ammonium carbonate/sodium carbonate as a precipitating agent）, under different reaction conditions （temperature： 700-850 ℃, CH4/O2 ratio： 4.0 and 8.0, and GHSV： 51360 cm^3·g^-1·h^- 1）. The surface area and surface basicity/base strength distribution of the catalysts have also been investigated. The surface properties and catalytic activity/selectivity of the La-promoted CaO catalysts vary from catalyst to catalyst depending on the catalyst precursors used and catalyst preparation method. The basicity/base strength distribution is strongly influenced by the precursors （for CaO and La2O3） and catalyst preparation method. Basicity （total and strong basic sites measured in terms of CO2 chemisorbed at 50℃ and 500 ℃, respectively） observed for the catalyst prepared by co-precipitation method is higher than that of the catalysts prepared by physical mixing method. The catalysts prepared by the nitrates of La- and Ca- and co- precipitated by the solution of sodium carbonate and ammonium carbonate exhibit different catalytic performance in OCM. The finding that no direct relationship between the surface basicity and catalytic activity/selectivity in OCM exists indicates that basicity is not solely responsible for obtaining high selectivity to C2 hydrocarbons.

Isolation,fractionation and evaluation of the antiplasmodial properties of Phyllanthus niruri resident in its chloroform fraction

Objective:To investigate the antiplasmodial activity of Phyllanthus niniri(P.niruri) methanol extract(ME) and its fractions in mice.Methods:P.niruri methanol extract and its chloroform. ethanol and aqueous portions were tested against chloroquine-sensitive Plasmodium berghei berghei in early,established and repository models of infection using Knight and Peter’s 4-day suppressive model,Rvlev and Peters curative model and Peters prophylactic model respectively. Results:Chemosuppression of parasitemia(37.65%-50.53%) was elicited by 100-400 mg/kg(b.w.) of ME.Al doses of 100 mg/kg b.w..the chloroform fraction(F1) significantly(P【0.01) suppressed parasitaemia by 85.29%,while ethanol and aqueous fractions(F2 and F3.respectively) elicited 67.06%and 51.18%chemosuppression.the most active fraction.F1 was selected for further antiplasmodial screening.In established infection.ME reduced parasitaemia(15.81%- 62.96%) while F1 significantly(P【0.01) reduced parasitaemia(44.369—90.48%).with effects comparable to that of chloroquine(96.48%).The prophylactic antiplasmodial activity of ME(92.50%suppression) was also significant(P【0.01) and was more effective than pyrimethamine(85.00%).additionally, cell membrane integrity of non-parasitized erythrocytes intubated with 125-500 mg/mL F1 was maintained.Conclusions:These findings indicate the antiplasmodial efficacy of P.niruri methanol extract,and the localization of this effect in its chloroform fraction.

Transport of yttrium metal ions through fibers supported liquid membrane solvent extraction

A novel idea of transport of yttrium(Ⅲ) metal ions through fibers supported liquid membrane in two stage processes namely source to membrane and membrane to receiving phase has been proposed.The fibers supported liquid membrane was impregnated with different concentrations carrier.The experimental variables explored were concentration of yttrium(Ⅲ) ions,pH of source phase,PC-88A concentration in membrane phase,acid concentration in receiving phase and stirring speed.The pre-concentration of yttrium(Ⅲ) ions ...

Transport of Indium, Gallium and Thallium Metal Ions Through Chromatographic Fiber Supported Solid Membrane in Acetylacetone Containing Mixed Solvents

The transport of metal ions of indium, gallium and thallium from source solution to receiving phase through the chromatographic fiber supported solid membrane in the acetylacetone （HAA） containing mixed solvent system has been explored. The fibers supported solid membranes were prepared with chemical synthesis from cellulose fibers and citric acid with the carboxylic acid ion exchange groups introduced. The experimental variables, such as concentration of metal ions （10^-2 to 10^-4 mol.L^-1） in the source solution, mixed solvent composition [for exampl, e, acetylacetone, （2,4-pentanedione）, （HAA） 20% （by volume）, 1,4-dioxane 10% to 60% and HC1 0.25 to 2 mol.L^-1] in the receiving phase and stirring speed （50-130 r.min ） of the bulk source and receiving phase, were explored. The efficiency of mixed solvents for the transport of metal ions from the source to receiving phase through the fiber supported solid membrane was evaluated. The combined ion exchange solvent extraction （CIESE） was observed effective for the selective transport of thallium, indium and gallium metal ions through fiber supported solid membrane in mixed solvents. The oxonium salt formation in the receiving phase enhances thallium, indium and gallium metal ion transport through solid membrane phase. The selective transport of thallium metal ions from source phase was observed from indium and gallium metal ions in the presence of hydrochloric acid in organic solvents in receiving phase. The separation of thallium metal ions from the binary mixtures of Be（II）, Ti（IV）, AI（III） Ca（II）, Mg（II）, K （I）, La（III） and Y（III） was carried out in the mixed solvent system using cellulose fiber supported solid membrane.

Alum:An efficient catalyst for one-pot synthesis of α-aminophosphonates

Alum （KAl（SOa）E.12H2O） is an inexpensive, efficient, non-toxic and mild catalyst for the one-pot synthesis of α-aminopho- sphonates. A three component reaction of an aldehyde/ketone, an amine and triethyl phosphite was carried out under solvent-free conditions to afford the corresponding α-aminophosphonates in short reaction times and high yields with the green aspects by avoiding toxic catalysts and solvents. 2009 Murlidhar S. Shingare. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Identification of sitosteryl glucoside palmitate in a chloroform-derived fraction of Phyllanthus niruri with antiplasmodial and peripheral antinociceptive properties

Objective:To evaluate the antiplasmodial properties of fractions of chloroform portion of Phyllanthus niruri(P.niruri) methanol extract and identify a suitable chemical marker present therein.Methods:Chloroform portion of P.niruri methanol extract was separated from silica gel using gradient systems of hexane,ethylacetate and methanol.The fractions were screened for antiplasmodial activity against Plasmodium falciparum HB3 and FcM29.Fractions with IC_(50)<10μg/ml.against parasites were further screened for peripheral analgesic activity,while cytotoxicity was evaluated using THP-1 cells.Results:Fractions 12-14 were very active(IC_(50)<10 μg/mL) against Plasmodium falciparum and showed no significant cytotoxicity.Fractions 12 and 13 exhibited significant(P<0.01) reduction in acetic acid-induced writhing in mice,decreasing the number of writhes by 66.67% and 65.22% respectively and comparable with 100 mg/kg aspirin(65.22%).From fraction 12,a compound was isolated and identified as sitosteryl-6-β-D-glucoside-6'-palmitate by ~1H,^(13)C nuclear magnetic resonance and mass spectroscopies.Conclusions:Our findings illustrate antiplasmodial column fractions of P.niruri with analgesic activity and identify sitosteryl glucoside pahmitate as a chemical marker of activity.

ZnO-beta zeolite:As an effective and eco-friendly heterogeneous catalyst for the synthesis of benzothiazole derivatives

A cheap and recyclable ZnO-beta zeolite was used as catalyst for the synthesis of benzothiazole derivatives.This method provides several advantages such as environmental friendliness,short reaction times,high yields,simple work-up procedure and catalyst was successfully reused for four cycles without significant loss of activity.

Microwave assisted convenient synthesis of quino[2,3-b][1,5]benzoxazepines

A convenient synthesis of quino[2,3-b] [ 1,5]benzoxazepines from substituted 2-chloroquinoline-3-carbaldehyde and 2-hydroxy- aniline by using stable, non-toxic and inexpensive catalyst 1,8-diazabicyclo-undecan-7-ene （DBU）/silica gel is described. This method affords the quino[2,3-b][1,5]benzoxazepines under the influence of microwave irradiation （360 W） in solvent-free conditions within short reaction times （2-3 min）, giving high yields of products （93-96%）.