Development of a fast MECK method for determination of 5-HMF in honey samples

AbstractIn this study, 5-hydroxymethylfurfural (5-HMF) determination was carried out by a micellar electrokinetic capillary chromatography (MEKC) methodology, using caffeine as the internal standard (IS). The optimisation of the electrolyte composition was approached using a 32 full factorial design with a central point to study the MEKC electrolyte components. Inspection of the response surface indicated that the optimal electrolyte composition was 5mmolL−1 sodium tetraborate (STB, pH 9.3) containing 120mmolL−1 sodium dodecyl sulphate (SDS). Under optimal CE conditions, separation of the investigated substance was achieved in less than 0.7min. Quality parameters, such as linearity (R2>0.99), precision (RSD<5.41%), detection and quantification limits (3.37 and 11.24mgkg−1 for honey samples) and recovery (96.37–99.56%). The proposed methodology was successfully applied to the analysis of 5-HMF in honey samples. The analytical performance of this method makes it suitable for implementation in food laboratories for the routine determination of 5-HMF in honey samples

Determination of catechin in green tea using a catechol oxidase biomimetic sensor

A catechol oxidase biomimetic sensor, based on a novel copper(II) complex, was developed for the determination of catechin in green tea and the results were compared with those obtained by capillary electrophoresis. The dinuclear copper(II) complex, [Cu2(HL)(µ-CH3COO)](ClO4), containing the ligand N,N-[bis-(2-pyridylmethyl)]-N',N'-[(2-hydroxybenzyl)(2-hydroxy-3,5-di-tert-butylbenzyl)]-1,3-propanediamine-2-ol (H3L), was synthesized and characterized by IR, ¹H NMR and elemental analysis. The best conditions for the optimization of the biomimetic sensor were established by square wave voltammetry. The best performance for this sensor was obtained in 75:15:10% (m/m/m) of the graphite powder:nujol:copper(II) complex, 0.05 mol L-1 phosphate buffer solution (pH 7.5) and frequency, pulse amplitude, scan increment at 30 Hz, 80 mV, 3.3 mV, respectively. The analytical curve was linear in the concentration range 4.95 × 10-6 to 3.27 × 10-5 mol L-1 (r = 0.9993) with a detection limit of 2.8 × 10-7 mol L-1. This biomimetic sensor demonstrated long-term stability (9 months; 800 determinations) and reproducibility with a relative standard deviation of 3.5%. The recovery of catechin from green tea samples ranged from 93.8 to 106.9% and the determination, compared with that obtained using capillary electrophoresis, was found to be acceptable at the 95% confidence level

Development of a fast capillary electrophoresis method to determine inorganic cations in biodiesel samples

The aim of this study was to develop a fast capillary electrophoresis method for the determination of inorganic cations (Na(+), K(+), Ca(2+), Mg(2+)) in biodiesel samples, using barium (Ba(2+)) as the internal standard. The running electrolyte was optimized through effective mobility curves in order to select the co-ion and Peakmaster software was used to determine electromigration dispersion and buffer capacity. The optimum background electrolyte was composed of 10 mmol L(-1) imidazole and 40 mmol L(-1) of acetic acid. Separation was conducted in a fused-silica capillary (32 cm total length and 23.5 cm effective length, 50 mu m I.D.), with indirect UV detection at 214 nm. The migration time was only 36 s. In order to obtain the optimized conditions for extraction, a fractional factorial experimental design was used. The variables investigated were biodiesel mass, pH, extractant volume, agitation and sonication time. The optimum conditions were: biodiesel mass of 200 mg, extractant volume of 200 mu L. and agitation of 20 min. The method is characterized by good linearity in the concentration range of 0.5-20 mg kg(-1) (r > 0.999), limit of detection was equal to 0.3 mg kg(-1), inter-day precision was equal to 1.88% and recovery in the range of 88.0-120%. The developed method was successfully applied to the determination of cations in biodiesel samples. (c) 2010 Elsevier B.V. All rights reserved.INCT cataliseINCT-CataliseConselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[576230/2008-1]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[473689/2007-3]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[476386/2007-1]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[130820/2008-3]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[300593/2008-2]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundacao de Amparo a Pesquisa do Estado de Santa Catarina (FAPESC)Fundacao de Amparo a Pesquisa do Estado de Santa Catarina (FAPESC)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Minas Gerais of Brazil (FAPEMIG)Fundacao de Amparo a Pesquisa do Estado de Minas Gerais of Brazil (FAPEMIG)[CEX-APQ 1906-502/07]Fundacao de Amparo a Pesquisa do Estado de Minas Gerais of Brazil (FAPEMIG)[CEX APQ 01837/08]Fundacao de Amparo a Pesquisa do Estado de Minas Gerais of Brazil (FAPEMIG)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Farma Service BioextractFarma Service Bioextrac

In vitro anthelmintic activity of Polygonum acre (Linnaeus, 1754) extracts against the ruminant nematode Haemonchus contortus (Rudolphi, 1803)

The genus Polygonum exhibits a variety of biological and therapeutic properties. The goal of this study was to determine the in vitro anthelmintic activity of Polygonum acre extracts against the nematode Haemonchus contortus, characterizing the phenolic profile of these extracts. Aerial parts of P. acre were subjected to hot aqueous and hydroethanolic extractions obtaining EHW-PA (aqueous) and ETOH-P, (hydroethanolic), respectively. The phenolic content of the extracts was analyzed by using high-performance liquid chromatography with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) and colorimetric assays. The egg hatch test (EHT) and larval migration test (LMT) were used for anthelmintic activity assays. For comparison, chlorogenic acid and rutin were selected for the EHT. The HPLC-ESI-MS/MS analysis revealed the presence of isoquercitrin, myricitrin, quercetin, rosmarinic acid, rutin, and taxifolin in both extracts. EHW-PA and ETOH-PA showed an egg hatch inhibitory effect. EHW-PA had an IC50 of 442.24 µg/mL on the EHT, which was statistically lower (P ≤ 0.05) than ETOH-PA (IC50 = 703.60 µg/mL). Chlorogenic acid had an IC50 of 8.66 µg/mL. Rutin presented no effect over parasite eggs. EHW-PA and ETOH-PA did not show any larvicidal effect. Even though, there is a need of new tests, this study has determined the possibility to develop biofriendly compounds based on Polygonum spp. constituents against H. contortus.

Development of a fast capillary electrophoresis method for the determination of propranolol-Total analysis time reduction strategies

The aim of this study was to develop a fast capillary electrophoresis method for the determination of propranolol in pharmaceutical preparations. In the method development the pH and constituents of the background electrolyte were selected using the effective mobility versus pH curves. Benzylamine was used as the internal standard. The background electrolyte was composed of 60 mmol L(-1) tris(hydroxymethyl)aminomethane and 30 mmol L(-1) 2-hydroxyisobutyric acid,at pH 8.1. Separation was conducted in a fused-silica capillary (32 cm total length and 8.5 cm effective length, 50 mu m I.D.) with a short-end injection configuration and direct UV detection at 214 nm. The run time was only 14 s. Three different strategies were studied in order to develop a fast CE method with low total analysis time for propranolol analysis: low flush time (Lflush) 35 runs/h, without flush (Wflush) 52 runs/h, and Invert (switched polarity) 45 runs/h. Since the three strategies developed are statistically equivalent, Mush was selected due to the higher analytical frequency in comparison with the other methods. A few figures of merit of the proposed method include: good linearity (R(2) > 0.9999); limit of detection of 0.5 mg L(-1): inter-day precision better than 1.03% (n = 9) and recovery in the range of 95.1-104.5%. (C) 2009 Elsevier B.V. All rights reserved.INCT cataliseINCT-CataliseConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq Conselho Nacional de Desenvolvimento Cientifico a Tecnologico[576230/2008-1]CNPq Conselho Nacional de Desenvolvimento Cientifico a Tecnologico[473689/2007-3]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq Conselho Nacional de Desenvolvimento Cientifico a Tecnologico[476386/2007-1]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq Conselho Nacional de Desenvolvimento Cientifico a Tecnologico[300593/2008-2]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundacao de Amparo a Pesquisa do Estado de Santa Catarina (FAPESC)Fundacao de Amparo a Pesquisa do Estado de Santa Catarina (FAPESC)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundacao de Amparo A Pesquisa do Estado de Minas Gerais of BrazilFundacao de Amparo A Pesquisa do Estado de Minas Gerais of Brazil[FAPEMIG-CEX-APQ 1906-502/07]Fundacao de Amparo a Pesquisa do Estado de Minas Gerais of Brazil (FAPEMIG)Fundacao de Amparo A Pesquisa do Estado de Minas Gerais of Brazil (FAPEMIG)[CEX APQ 01837/08]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Farma Service BioextractFarma Service Bioextrac

Exploiting green sorbents in rotating-disk sorptive extraction for the determination of parabens by high-performance liquid chromatography with tandem electrospray ionization triple quadrupole mass spectrometry

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim In this study, the viability of applying cork and montmorillonite clay modified with ionic liquid as biosorbents in the rotating-disk sorptive extraction technique was investigated. Specifically, this was aimed at the determination of methyl paraben, ethyl paraben, propyl paraben, and isobutyl paraben, with separation/determination by high-performance liquid chromatography coupled with mass spectrometry. The optimization of the method for both biosorbents was performed using multivariate procedures. The extraction efficiencies for the target compounds in aqueous matrices were compared to those obtained using the commercial sorbent Octadecil Silano-C18. The optimum extraction conditions for both natural sorbents were the use of an ammonia solution (pH 10) as desorption solvent and an extraction time of 30 min. The proposed methods show limits of quantification of 0.8 μg/L for cork, 3.0 μg/L for montmorillonite clay and 6.0 μg/L for Octa

Characterisation of phenolic compounds of the ethyl acetate fraction from <i>Tabernaemontana catharinensis</i> and its potential antidepressant-like effect

<p>This study evaluates the antidepressant-like effect and analysed the qualitative and quantitative 74 phenolic standards of ethyl acetate fraction from <i>Tabernaemontana catharinensis</i> leaves. Acute administration of fraction in mice reduced the immobility time in forced swimming and tail suspension tests confirming its antidepressant-like activity. The anti-immobility effect elicited by this fraction was prevented by the pretreatment of mice with PCPA (100 mg kg⁻¹), ketanserin (5 mg kg⁻¹), SCH 23,390 (0.05 mg kg⁻¹) or yohimbine (1 mg kg⁻¹). A sub effective dose of the fraction produced a synergistic effect with fluoxetine (5 mg kg⁻¹). Chromatographic analysis identified 4-hydroxybenzoic and <i>p</i>-coumaric acids in the ethyl acetate fraction from <i>T. catharinensis</i>. Capillary electrophoresis presented 7.34 ± 0.02 mg g⁻¹ of <i>p</i>-coumaric acid concentration in the fraction. Therefore, it is possible that antidepressant-like effect elicited by ethyl acetate fraction from <i>T. catharinensis</i> be dependent on the <i>p</i>-coumaric acid.</p