Página 1 dos resultados de 60 itens digitais encontrados em 0.000 segundos

Triacylglycerol composition of walnut (Juglans regia L.) cultivars: characterization by HPLC/ELSD and chemometrics

Amaral, J.S.; Cunha, S.C.; Alves, M.R.; Pereira, J.A.; Seabra, R.M.; Oliveira, M.B.P.P.
Fonte: ACS Publicador: ACS
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.321047%
A total of 26 walnut ( Juglans regia L.) samples from 9 cultivars (Arco, Franquette, Hartley, Lara, Marbot, Mayette, Mellanaise, Parisienne, and Rego) harvested in the 2001, 2002, and 2003 crop years and grown in two geographical origins (Bragancüa and Coimbra, Portugal) were evaluated with regard to their triacylglycerol composition. The methodology employed was reversed-phase highperformance liquid chromatography coupled to an evaporative light-scattering detector (RP-HPLCELSD) after extraction of the lipidic fraction of the nuts. Nine compounds were separated, identified, and quantified. All samples presented an identical qualitative profile composed by LLnLn, LLLn, LLL, OLLn, OLL, PLL, OOL, and PLO (P ) palmitoyl; O ) oleoyl; L ) linoleoyl; Ln ) linonenoyl). Trilinolein (LLL) was the major triglyceride, followed by dilinoeoyl-oleoyl-glycerol (OLL) and dilinoleoyl-linolenoylglycerol (LLLn), with mean values of 37.7, 18.5, and 18.4%, respectively. Significant differences in composition were found between cultivars, and these differences were also significant when cultivars were grouped by year of production, showing that besides genetic factors, the triacylglycerol composition can be strongly influenced by environmental factors.

Determinação do perfil de triacilgliceróis das nozes

Amaral, J.S.; Cunha, S.C.; Neves, N.; Oliveira, M.B.P.P.; Seabra, R.M.
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Conferência ou Objeto de Conferência
Português
Relevância na Pesquisa
27.652627%
Neste trabalho determinou-se o perfil em triacilgliceróis de nove cultivares de nozes (Arco, Franquette, Hartley, Lara, Marbot, Mayette, Mellanaise, Parisienne e Rego) utilizando uma técnica de HPLC/ELSD para a separação e quantificação dos compostos. A separação cromatográfica decorreu numa coluna Kromasil 100 C18 (5 μm; 250 x 4,6 mm) e uma mistura de acetona/acetonitrilo (70:30, v/v) foi utilizada como fase móvel, eluindo com um fluxo de 1ml/min num programa isocrático. O detector ELSD foi programado com os seguintes parâmetros: temperatura de evaporação 40 ºC, pressão do ar 3,5 bar e sensibilidade do fotomultiplicador 6. Foram identificados e quantificados 9 triacilgliceróis: LLnLn, LLLn, LLL, OLLn, OLL, PLL, OOL and PLO (P: ác. palmitico; O: ác. oleico; L: ác. linoleico; Ln: ác. linolénico). Na generalidade das amostras, foi detectado OOO em quantidades vestigiais, pelo que não foi quantificado. Em todas as amostras analisadas, LLL foi o TAG presente em maior percentagem, seguido pelos triacilgliceróis OLL e LLLn.

EVAPORATIVE LIGHT-SCATTERING DETECTOR FOR ANALYSIS OF NATURAL PRODUCTS

Urano, Raquel P. Morais; Rodrigues, Fabiana T.; Berlinck, Roberto G. S.
Fonte: SOC BRASILEIRA QUIMICA; SAO PAULO Publicador: SOC BRASILEIRA QUIMICA; SAO PAULO
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
28.094731%
EVAPORATIVE LIGHT-SCATTERING DETECTOR FOR ANALYSIS OF NATURAL PRODUCTS. The interest in the use of evaporative light scattering detector (ELSD) for the analysis of different classes of natural products has grown over the years. This is because this detector has become an excellent alternative compared to other types of detectors, such as the refractive index detector and the ultraviolet (UV) detector. This review describes the basic principles of ELSD functioning and discusses the advantages and disadvantages in using an ELSD for the analysis of organic compounds. Additionally, an overview, covering the last 23 years, of ELSD applications in natural products analysis (saponins, terpenes, carbohydrates, glycosides, alkaloids, steroids, flavonoids, peptides, polyketides, coumarins and iridoids) is presented and discussed.

Utilização de detecção por espalhamento de luz evaporativo para a análise de produtos naturais; Evaporative light-scattering detector for analysis of natural products

Urano, Raquel P. Morais; Rodrigues, Fabiana T.; Berlinck, Roberto Gomes de Souza
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.9949%
The interest in the use of evaporative light scattering detector (ELSD) for the analysis of different classes of natural products has grown over the years. This is because this detector has become an excellent alternative compared to other types of detectors, such as the refractive index detector and the ultraviolet (UV) detector. This review describes the basic principles of ELSD functioning and discusses the advantages and disadvantages in using an ELSD for the analysis of organic compounds. Additionaly, an overview, covering the last 23 years, of ELSD applications in natural products analysis (saponins, terpenes, carbohydrates, glycosides, alkaloids, steroids, flavonoids, peptides, polyketides, coumarins and iridoids) is presented and discussed.

Avaliação do potencial metabólico de linhagens de fungos isolados de uma espécie de alga marinha do gênero Sargassum; Evaluation of the metabolic potential of fungal lineages isolated from a species of marine algae of the Sargassum genus

Romminger, Stelamar
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 20/11/2008 Português
Relevância na Pesquisa
27.856675%
Os fungos são microrganismos amplamente dispersos, podendo ser encontrados em vegetais, animais, solo e ambientes aquáticos, participando do ciclo de elementos na natureza. Embora muitos papéis ecológicos tenham sido estudados e descritos para os fungos terrestres, a ecologia de fungos marinhos ainda é pouco conhecida. Assim, os oceanos, que representam aproximadamente metade da biodiversidade global, são uma fonte enorme e virtualmente inexplorada de microrganismos produtores de novos produtos naturais. O objetivo deste trabalho foi isolar linhagens de fungos derivados de uma espécie de alga marinha do gênero Sargassum, visando à avaliação do seu potencial para a produção de metabólitos secundários bioativos. Ao todo foram isoladas 58 linhagens, das quais 52 foram crescidas em meio de cultura líquido e, após a extração com solventes orgânicos, deram origem a 99 extratos. Tais extratos foram avaliados por ensaios de atividade biológica, cromatografia em camada delgada (CCD), ressonância magnética nuclear (RMN) e cromatografia líquida acoplada a detectores de arranjo de diodos, espalhamento de luz evaporativo e espectrômetro de massas (LC - PDA - ELSD - MS). A avaliação pelo ensaio antibiótico foi o que resultou no maior número de extratos ativos (n = 13)...

Otimização das condições de produção microbiológica de destruxinas por Beauveria felina; Optimal conditions for the microbial production of destruxins by Beauveria felina

Urano, Raquel Peres de Morais
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 21/10/2010 Português
Relevância na Pesquisa
27.321047%
O fungo entomopatogênico Beauveria felina produz as destruxinas, hexadepsipeptídeos cíclicos que apresentam diversas atividades biológicas, como por exemplo: atividade inseticida, fitotóxica, citotóxica contra células tumorais, atividade antiviral contra o vírus da hepatite B, dentre outras. Devido à atividade inseticida das destruxinas, os fungos que as produzem têm grande importância econômica. Assim, o objetivo deste trabalho foi realizar a otimização das condições de crescimento e produção das destruxinas pelo fungo Beauveria felina utilizando diferentes meios de cultivo, a fim de se isolar destruxinas em maiores quantidades para a avaliação de seu potencial tóxico. Foram utilizados métodos de planejamento experimental e análise multivariada para a otimização das condições de crescimento, resultando em três condições ótimas de cultivo para cada um dos meios de cultura MF, PDB e SBD. Em todas as condições ótimas de cultivo foram observadas destruxinas conhecidas, desconhecidas e destruxinas que não foram isoladas anteriormente de Beauveria felina. O cultivo de Beauveria felina no meio PDB foi o que mais apresentou destruxinas desconhecidas (5). Em seguida foi realizada uma otimização das condições de análise cromatográfica de destruxinas por CLAD-DAD-DELE-EM e a validação deste método. Uma das frações obtidas do meio de cultura de Beauveria felina apresentou atividade vermífuga contra Haemonchus contortus. Duas de suas frações purificadas...

Método de cromatografia líquida de alta eficiência com detector evaporativo de espalhamento de luz para a determinação de biciclo [2.2.1] heptano-2,3-dicarboxilato de sódio

Santos, Paulo Cezar dos
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
18.09473%
Os polímeros têm substituído materiais tradicionais como os metais, o vidro e a madeira. O polipropileno isotático (i-PP) é um termoplástico semicristalino largamente utilizado, e suas propriedades podem ser modificadas através de substâncias que tem como função melhorar suas propriedades finais. O biciclo [2.2.1] heptano-2,3-dicarboxilato de sódio conhecido comercialmente como Hyperform® HPN-68L representa um avanço tecnológico significativo em relação à tecnologia de nucleação convencional e tradicional em uso. A cromatografia líquida de alta eficiência com detector evaporativo de espalhamento de luz (HPLC-ELSD) é um dos métodos de análise preferido para a separação e quantificação de analitos orgânicos. O objetivo do presente trabalho foi avaliar a possibilidade de utilizar a cromatografia líquida com detector de espalhamento de luz (HPLC-ELSD) como metodologia analítica para determinar biciclo [2.2.1] heptano-2,3-dicarboxilato de sódio, em polipropileno homopolímero. O presente trabalho foi realizado no laboratório de controle de qualidade da unidade de Polipropileno da Braskem S.A. no estado do Rio Grande do Sul e de São Paulo e na Universidade Federal do Rio Grande do Sul (UFRGS). Utilizou-se para este trabalho amostras de polipropileno comercial fornecidas pela Braskem S.A. Seis tipos de solventes orgânicos foram utilizados na avaliação da dissolução do HPN-68L e quatro aditivos de diferentes funções para avaliar a sua possível interferência no método proposto. Foi avaliada a eficiência da extração do agente nucleante Hyperform® HPN-68L da matriz polimérica de polipropileno homopolímero pelas técnicas de microondas...

Utilização de detecção por espalhamento de luz evaporativo para a análise de produtos naturais

Urano,Raquel P. Morais; Rodrigues,Fabiana T.; Berlinck,Roberto G. S.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 Português
Relevância na Pesquisa
27.9949%
The interest in the use of evaporative light scattering detector (ELSD) for the analysis of different classes of natural products has grown over the years. This is because this detector has become an excellent alternative compared to other types of detectors, such as the refractive index detector and the ultraviolet (UV) detector. This review describes the basic principles of ELSD functioning and discusses the advantages and disadvantages in using an ELSD for the analysis of organic compounds. Additionaly, an overview, covering the last 23 years, of ELSD applications in natural products analysis (saponins, terpenes, carbohydrates, glycosides, alkaloids, steroids, flavonoids, peptides, polyketides, coumarins and iridoids) is presented and discussed.

A method for dextruxin analysis by HPLC-PDA-ELSD-MS

Morais,Raquel P.; Lira,Simone P.; Seleghim,Mirna H. R.; Berlinck,Roberto G. S.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 Português
Relevância na Pesquisa
37.9949%
Destruxins (Dtx) are cyclodepsipeptides produced by enthomopathogenic fungi, which are used in biological control of different agricultural insect plagues. The present investigation reports a new approach for analysis of destruxins produced by the fungal strain Beauveria felina, using LC-PDA-ELSD-MS. Compared to previous methods, the new approach uses a clean-up on C18 cartridges, which effectively removes growth media constituents. Moreover, the use of 50:50 (v/v) MeCN/MeOH as the strongest eluting solvent in a gradient system over 0.1% H2O proved to give a better resolution of chromatographic peaks. Simultaneous detection using photodiode array (PDA), evaporative light scattering detector (ELSD) and mass spectrometry (MS) indicated a practically identical response of all detectors for destruxins analysis. Five samples obtained from the culture media of B. felina were analysed, and indicated the presence of twenty known destruxins and six yet unreported cyclodepsipeptides. Considering the reduced use of MeCN, and the effectiveness of ELSD as a detector for destruxins, the method proved to be valuable and cost-effective for quality control analysis of destruxin-producing fungal strains.

Myxobacteria vs. Sponge-Derived Alkaloids: The Bengamide Family Identified as Potent Immune Modulating Agents by Scrutiny of LC-MS/ELSD Libraries

Johnson, Tyler A.; Sohn, Johann; Vaske, Yvette M.; White, Kimberly N.; Cohen, Tanya L.; Vervoort, Helene C.; Tenney, Karen; Valeriote, Frederick A.; Bjeldanes, Leonard F.; Crews, Phillip
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.321047%
A nuclear factor-κB (NF-κB) luciferase assay has been employed to identify the bengamides, previously known for their anti-tumor activity, as a new class of immune modulators. A unique element of this study was that the bengamide analogs were isolated from two disparate sources, Myxococcus virescens (bacterium) and Jaspis coriacea (sponge). Comparative LC-MS/ELSD and NMR analysis facilitated the isolation of M. viriscens derived samples of bengamide E (8) and two congeners, bengamide E’ (13) and F’ (14) each isolated as an insperable mixture of diastereomers. Additional compounds drawn from the UC Santa Cruz repository allowed expansion of the structure activity relationship (SAR) studies. The activity patterns observed for bengamide A (6), B (7), E (8), F (9), LAF 389 (12) and 13–14 gave rise to the following observations and conclusions. Compounds 6 and 7 display potent inhibition of NF-κB (at 80 and 90 nM respectively) without cytotoxicity to RAW264.7 macrophage immune cells. Western blot and qPCR analysis indicated that 6 and 7 reduce the phosphorylation of IκBα and the LPS-induced expression of the pro-inflammatory cytokines/chemokines TNFα, IL-6 and MCP-1 but do not effect NO production or the expression of iNOS. These results suggest that the bengamides may serve as therapeutic leads for the treatment of diseases involving inflammation...

Chemical and biological analysis of active free and conjugated bile acids in animal bile using HPLC-ELSD and MTT methods

WANG, NING; FENG, YIBIN; XIE, TANG NING; SU, WEIWEI; ZHU, MEIFEN; CHOW, OIYEE; ZHANG, YANBO; NG, KWAN-MING; LEUNG, CHUNG-HANG; TONG, YAO
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.321047%
The aim of the present study was to determine the chemical composition and in vitro cytotoxic activity of seven bile samples and bile acids using the high-performance liquid chromatography (HPLC)-evaporative light scattering detector (ELSD) method. Free and conjugated bile acid standards were used to identify and quantify the chemical components of the seven animal bile samples. The MTT assay was used to determine the cytotoxic effect of the animal bile samples and the free and conjugated bile acids on hepatocellular carcinoma MHCC97-L cells. Chemical analysis revealed that the bile samples from the different animals shared little similarity in terms of their composition. A cell viability assay revealed that cattle bile, as well as its major components, DCA, CDCA and TCDCA, exhibited a marked cytotoxic effect on the hepatocellular carcinoma MHCC97-L cells. The bear bile samples that originated from the Asian black bear and the American black bear contained a unique component, TUDCA, which distinguished them from the other animal bile, though their inhibitory action on MHCC97-L cells was not markedly distinct. The present study reveals that cattle bile may be a potential alternative to bear bile for hepatocarcinoma therapy.

Identification and determination of major constituents in a traditional Chinese medicine compound recipe Xiongdankaiming tablet using HPLC-PDA/ESI-MSn and HPLC-UV/ELSD* #

Wang, Shu-fang; Leng, Jing; Xu, Yi-min; Feng, Mei-ling
Fonte: Zhejiang University Press Publicador: Zhejiang University Press
Tipo: Artigo de Revista Científica
Publicado em /07/2013 Português
Relevância na Pesquisa
27.652627%
Xiongdankaiming tablet (XDKMT), a well-known compound in traditional Chinese medicine, is widely used for the treatment of acute iridocyclitis and primary open-angle glaucoma. In this paper, accurate and reliable methods were developed for the identification of 20 constituents using high-performance liquid chromatography with photo-diode array and electron spray ionization-mass spectrometry (HPLC-PDA/ESI-MSn), and determination of nine of the constituents (chlorogenic acid, gentiopicroside, isochlorogenic acid B, diosmetin-7-O-β-D-glucopyranoside, apigenin, diosmetin, tauroursodeoxycholic acid, acacetin, and taurochenodeoxycholic acid) was developed using HPLC with ultraviolet absorption detector and evaporative light scattering detector (HPLC-UV/ELSD) for the first time. The best results were obtained on a Zorbax SB-C18 column with gradient elution using water (0.1% formic acid) (A) and methanol (0.1% formic acid) (B) at a flow rate of 0.7 ml/min. Tauroursodeoxycholic acid and taurochenodeoxycholic acid, owing to their low UV absorption, were detected by ELSD. The other seven compounds were analyzed by HPLC-UV with variable wavelengths. The calibration curves of all nine constituents showed good linear regression (R 2>0.9996) within the linearity ranges. The limits of detection and quantification were in the ranges of 0.0460–9.90 μg/ml and 0.115–24.8 μg/ml...

Rapid Detection and Quantification of Triacylglycerol by HPLC–ELSD in Chlamydomonas reinhardtii and Chlorella Strains

Kobayashi, Naoko; Noel, Eric A.; Barnes, Austin; Rosenberg, Julian; DiRusso, Concetta; Black, Paul; Oyler, George A.
Fonte: Springer Berlin Heidelberg Publicador: Springer Berlin Heidelberg
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.9949%
Triacylglycerol (TAG) analysis and quantification are commonly performed by first obtaining a purified TAG fraction from a total neutral lipid extract using thin-layer chromatography (TLC), and then analyzing the fatty acid composition of the purified TAG fraction by gas chromatography (GC). This process is time-consuming, labor intensive and is not suitable for analysis of small sample sizes or large numbers. A rapid and efficient method for monitoring oil accumulation in algae using high performance liquid chromatography for separation of all lipid classes combined with detection by evaporative light scattering (HPLC–ELSD) was developed and compared to the conventional TLC/GC method. TAG accumulation in two Chlamydomonas reinhardtii (21 gr and CC503) and three Chlorella strains (UTEX 1230, CS01 and UTEX 2229) grown under conditions of nitrogen depletion was measured. The TAG levels were found to be 3–6 % DW (Chlamydomonas strains) and 7–12 % DW (Chlorella strains) respectively by both HPLC–ELSD and TLC/GC methods. HPLC–ELSD resolved the major lipid classes such as carotenoids, TAG, diacylglycerol (DAG), free fatty acids, phospholipids, and galactolipids in a 15-min run. Quantitation of TAG content was based on comparison to calibration curves of trihexadecanoin (16:0 TAG) and trioctadecadienoin (18:2 TAG) and showed linearity from 0.2 to 10 μg. Algal TAG levels >0.5 μg/g DW were detectable by this method. Furthermore TAG content in Chlorella kessleri UTEX 2229 could be detected. TAG as well as DAG and TAG content were estimated at 1.6 % DW by HPLC–ELSD...

Quantitative analysis of betaine in Lycii Fructus by HILIC-ELSD

Zhao, Bing Tian; Jeong, Su Yang; Hwangbo, Kyoung; Moon, Dong Cheul; Seo, Eun-Kyoung; Lee, Dongho; Lee, Je-Hyun; Min, Byung-Sun; Ma, Eun-Sook; Son, Jong Keun; Woo, Mi Hee
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.856675%
A rapid and simple high-performance liquid chromatography (HPLC) method with evaporative light scattering detection (ELSD) was developed for the determination of betaine from Lycii Fructus. Betaine was separated with an Atlantis hydrophilic interaction liquid chromatography silica column (4.6 × 150 mm, 5 μm, 100 Å) by isocratic elution using 30 mM ammonium acetate buffer and acetonitrile (20:80, v/v %) as the mobile phase. The flow rate was 1.0 mL/min, and the temperature for the spray chamber and drift tube was set at 30 and 50 °C, respectively. The method was fully validated with respect to linearity, precision, accuracy, stability and robustness. The HPLC/ELSD method was applied successfully to the quantification of betaine in the extract of Lycii Fructus. The HPLC analytical method for pattern recognition analysis was validated by repeated analysis of twenty-six L. barbarum L. from China (BC01–BC26), 3 L. barbarum L. (BJ27–BJ29) from Japan, 12 L. chinense Miller from China (CC30–CC41) and 51 L. chinense Miller samples (CK42–CK92) from Korea. The results indicate that the established HPLC/ELSD method is suitable for quality evaluation of Lycii Fructus.

Identification of Unknown Impurity of Azelaic Acid in Liposomal Formulation Assessed by HPLC-ELSD, GC-FID, and GC-MS

Han, Stanisław; Karłowicz-Bodalska, Katarzyna; Potaczek, Piotr; Wójcik, Adam; Ozimek, Łukasz; Szura, Dorota; Musiał, Witold
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 29/10/2013 Português
Relevância na Pesquisa
27.856675%
The identification of new contaminants is critical in the development of new medicinal products. Many impurities, such as pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, and tetradecanedioic acid, have been identified in samples of azelaic acid. The aim of this study was to identify impurities observed during the stability tests of a new liposomal dosage form of azelaic acid that is composed of phosphatidylcholine and a mixture of ethyl alcohol and water, using high-performance liquid chromatography with evaporative light-scattering detector (HPLC-ELSD), gas chromatography–flame ionisation detection (GC-FID), and gas chromatography–mass spectrometry (GC-MS) methods. During the research and development of a new liposomal formulation of azelaic acid, we developed a method for determining the contamination of azelaic acid using HPLC-ELSD. During our analytical tests, we identified a previously unknown impurity of a liposomal preparation of azelaic acid that appeared in the liposomal formulation of azelaic acid during preliminary stability studies. The procedure led to the conclusion that the impurity was caused by the reaction of azelaic acid with one of the excipients that was applied in the product. The impurity was finally identified as an ethyl monoester of azelaic acid. The identification procedure of this compound was carried out in a series of experiments comparing the chromatograms that were obtained via the following chromatographic methods: HPLC-ELSD...

Counter-Current Chromatographic Separation of Nucleic Acid Constituents with a Polar Volatile Organic-Aqueous Two-Phase Solvent Systems with ELSD Detection

Shibusawa, Yoichi; Morikawa, Go; Yanagida, Akio; Ito, Yoichiro
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
Relevância na Pesquisa
27.321047%
Highly hydrophilic volatile organic/aqueous two-phase solvent systems containing an organic salt such as, acetonitrile/800 mM and 1200 mM ammonium acetate (1 : 1, v/v) were efficiently utilized for high-speed counter-current chromatography (HSCCC) to separate hydrophilic compounds. The retention of the upper and the lower stationary phases in the column of the cross-axis coil planet centrifuge (CCC instrument) was studied by changing the flow-rate of the mobile phase (1.0–3.0 ml/min). Using the acetonitrile/800 mM ammonium acetate two-phase solvent system, the stationary phase was retained at 46.3% relative to the total column capacity of 65 ml by the reversed-phase elution mode at a flow-rate of 1.0 ml/min. The best retention of the stationary upper phase of 51.5% was obtained by the solvent system of the acetonitrile/1200 mM ammonium acetate at the above flow-rate. With the acetonitrile/800 mM ammonium acetate system the base line separation of adenine and adenosine monophosphate (AMP) detected by evaporative light scattering detector (ELSD) and UV was achieved with lower phase mobile at a flow-rate of 1.0 ml/min within 70 min.

Extração e caracterização de pectinas por método químico, inflavermelho e HPLC - ELSD

Barboza, Marianne de Lima
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Outros
Português
Relevância na Pesquisa
37.856675%
Este trabalho consiste numa abordagem metodológica de caracterização visando a viabilização de fontes naturais de pectina. Utilizou-se o mesocarpo da melancia (e demais frutos tropicais) como fonte de pectinas para demonstrar a caracterização estrutural por distintos métodos analíticos, considerando desde a etapa de extração até a caracterização estrutural. Foi avaliado o potencial do ácido cítrico e do HCl, em diferentes forças, em temperaturas distintas sobre o rendimento de extração (%) e o grau de metoxilação GM (%). Verificou-se também a influência da cadeia carbônica do álcool durante a precipitação de pectinas isoladas. Os métodos de caracterização estrutural de pectinas (padrões e extraídas de diversas frutas) foram o titulométrico, infravermelho e HPLC acoplado a detecção pelo espalhamento de luz (ELSD). A determinação do GM por infravermelho (IV) foi obtida a partir dos valores de absorbância das bandas 1750 cm-1 e 1650 cm-1. Para determinação por HPLC foram avaliadas as fases estacionárias (ODS-2 e Hiplex) e fases móveis diferenciadas para otimizar a separação e detecção. As melhores condições foram ajustadas ao uso da fase estacionária Hiplex em fase móvel H2SO4 50 mM. As condições de desesterificação dos padrões comerciais de pectinas foram ajustadas variando a força do NaOH...

Préparations de docosanol nanoformulées pour usage topique

Soukrati, Mina
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
Relevância na Pesquisa
28.094731%
La réduction de la taille des particules jusqu’à l’obtention de nanocristaux est l’une des approches utilisées afin d’améliorer la pénétration cutanée des médicaments à usage topique. Nous proposons que la fabrication d’une formulation semi solide (hydrogel) à base de nanosuspension de docosanol, aboutira à une diffusion du principe actif supérieure à celle du produit commercial Abreva®, à travers des membranes synthétiques de polycarbonates. Le broyage humide est la technique proposée pour la production des nanoparticules de docosanol. Nous proposons aussi la préparation d’une formulation semi-solide (hydrogel) à usage topique à partir de la nanosuspension de docosanol. La nanosuspension de docosanol est obtenue par dispersion du docosanol en solution aqueuse en présence du polymère stabilisant hydroxypropylcellulose (HPC) et du surfactant laurylsulfate de sodium (SDS) suivi d’un broyage humide à faible ou à haute énergie. L’hydrogel de docosanol nanoformulé est préparé à l’aide de la nanosuspension de docosanol qui subit une gélification par le carbopol Ultrez 21 sous agitation mécanique suivie d’une neutralisation au triéthanolamine TEA. La taille des particules de la nanosuspension et de l’hydrogel a été déterminée par diffusion dynamique de la lumière (DLS). Une méthode analytique de chromatographie liquide à haute performance (HPLC) munie d’un détecteur évaporatif (ELSD) a été développée et validée pour évaluer la teneur de docosanol dans les préparations liquides...

Application of the Evaporative Light Scatter Detector (ELSD) in Food Analysis.

LIPP Markus; ANKLAM Elke
Fonte: Centro Comum de Pesquisa da Comissão Européia Publicador: Centro Comum de Pesquisa da Comissão Européia
Tipo: Articles in Journals Formato: Printed
Português
Relevância na Pesquisa
27.321047%
The evaporative light scattering detector (ELSD) is increasingly applied in combination with high performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). It was found that he has an advantage especially in the field of the analysis of triacylglycerols and other neutral lipids, showing no or only weak ultraviolet absorption. The main advantage is the possibility to apply a gradient for the better separation of these compounds. Care must be taken for the quantitative evaluation of the results. While some authors state low detection limits and linear response functions, others reported frequently non-linear response of the detector. The published data indicates, that this seems to be attributed to the design of the detector and the exact conditions of separation.; JRC.(ISIS)-Institute For Systems, Informatics And Safety

Validation of an Analytical Method for the Simultaneous Determination of Nine Intense Sweeteners by HPLC-ELSD

BUCHGRABER MANUELA; WASIK Andrzej
Fonte: Centro Comum de Pesquisa da Comissão Européia Publicador: Centro Comum de Pesquisa da Comissão Européia
Tipo: EUR - Scientific and Technical Research Reports Formato: Printed
Português
Relevância na Pesquisa
27.321047%
A collaborative trial was conducted to validate an analytical method for the simultaneous determination of nine intense sweeteners, i.e., acesulfame-K, alitame, aspartame, cyclamic acid, dulcin, neotame, neohesperidine dihydrochalcone, saccharin and sucralose in carbonated and non-carbonated soft drinks, and canned or bottled fruits. The procedure involves an extraction of the nine sweeteners with a buffer solution, sample clean-up using solid-phase extraction cartridges followed by an HPLC-ELSD analysis. Trueness, expressed in terms of recovery rates, was demonstrated in most cases by values ranging from 90 to 108%. High comparability of results obtained by individual testing laboratories was ensured by RSDR values <10% for the majority of results. Moreover, HorRAT values of less than 1.1 suggested for all sweeteners and matrices tested good performance of the method.; JRC.D.8-Food safety and quality