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Search Results: 1 - 10 of 3492 matches for " HPLC-DAD "
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Derivation Method for Determining Sorbitol in Fruit Trees  [PDF]
Regina Célia Faria Sim?o Canesin, William Deodato Isique, Salatiér Buzetti, Juliana Aparecida de Souza
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.523361
Abstract:
The goal of this study is to describe a methodology for the analysis of D-sorbitol using benzyl alcohol as derivatizing agent and liquid chromatography equipped with a diode-array detector (HPLC-DAD). The study was performed at the University of São Paulo State (UNESP), Ilha Solteira Campus, Brazil. The axillary buds of fruit trees were collected from the UNESP Teaching and Research Farm. Benzyl alcohol was used as derivatizing agent to extract D-sorbitol from the buds. Next, the D-sorbitol underwent solid phase extraction (SPE) using C18 cartridges and was then analyzed by liquid chromatography (HPLC-DAD). The HPLC-DAD derivatization method proposed showed excellent chromatography resolution and high accuracy in the separation of D-sorbitol (derivatized) for the axillary buds of avocado, black mulberry, Japanese pear and peach and also enabled eliminating the use of hazardous derivatizing agents.
Optimization of Analytical Conditions to Determine Steroids and Pharmaceuticals Drugs in Water Samples Using Solid Phase-Extraction and HPLC  [PDF]
Ramiro Vallejo-Rodríguez, Alberto Lopez-Lopez, Hugo Saldarriaga-Nore?a, Mario Murillo-Tovar, Leonel Hernández-Mena
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.28099
Abstract: Two reliable methods were optimized to determine two steroids (17?-Estradiol and 17?-Ethinylestradiol) and two pharmaceutical drugs (ibuprofen and naproxen) using Solid-Phase Extraction (SPE) for sample preparation and High Performance Liquid Chromatography (HPLC) for analysis. SPE (C18) conditions were evaluated varying elution solvent volume, pH conditions and sample mass in the cartridge and reduction techniques of the extract. The efficiency of the analytical methods was evaluated by spiking ultrapure water samples with compounds at three and four levels of concentration for steroids and pharmaceutical drugs, re- spectively. The recoveries were independent (P > 0.05) of added mass of target analytes with a repeatability lower than 6.5% for steroids and 12.1% for pharmaceutical compounds. The recovery factor (coefficient of variation, CV) was higher than 83% for steroids (CV < 3.8%) and >93% for pharmaceuticals (CV < 5.2%). The optimized analytical method was applied for the evaluation of a steroid degradation test using ozone, finding that the estimated limit of detection is sufficient to determine the residual mass (μg?L–1) of 17β-Estradiol after the experiment.
Development and Distinction of Rhizoma rodgersiae with HPLC-DAD Fingerprint Analysis Combined with Chemical Pattern Recognition Techniques  [PDF]
Yan Wang, Yang Jin
American Journal of Analytical Chemistry (AJAC) , 2017, DOI: 10.4236/ajac.2017.811050
Abstract: In this paper, the feasibility and advantages of employing high performance liquid chromatographic-photodiode array detection (HPLC-DAD) fingerprint combined with chemical pattern recognition for quality consistency evaluation of widely used Rhizoma rodgersiae (RR) were investigated and demonstrated for the first time. The Similarity Evaluation System was employed to evaluate the similarities of 10 batches of RR sample; moreover, hierarchical clustering analysis (HCA) and principal component analysis (PCA) were also successfully applied to discriminate RR samples of different regions and seasons. Our results indicated that the seasonal variation had some influence on the chemical fingerprints of this herbal drug. This approach allowed the discrimination of RR samples from different sources. The current study demonstrated that fingerprint profiling coupled with chemical pattern recognition offered a reliable and efficient way to comprehensively assess the quality consistency of the tested samples.
Seasonal Flavonoid Profile and Kaempferitrin Content in the Leaf Extracts of Bauhinia forficata Subspecies forficata from Two Locations in Southeastern Brazil  [PDF]
Jo?o B. F. Tostes, Antonio C. Siani, Sérgio S. Monteiro, Vinicius F. Melo, Jéssica O. Costa, Ligia M. M. Valente
American Journal of Plant Sciences (AJPS) , 2019, DOI: 10.4236/ajps.2019.101016
Abstract: The leaves of Bauhinia forficata L. (Fabaceae) are used in Brazilian folk medicine mainly as antidiabetic agent. They are rich in polyphenols, and kaempferitrin and other flavonoids are currently considered as basic chemical criteria for the quality and the effectiveness of extracts and phytopharmaceuticals derived from them. Aiming to expand the scope of current data of the chemical profile of B. forficata subsp. forficata, the present study employed HPLC-DAD and HPLC-DAD-ESI/MS to compare the flavonoid profile and kaempferitrin content in the leaves of specimens collected seasonally during one year, in two different locations in Southeastern Brazil: Rio de Janeiro (RJ) and São Paulo (SP) states. The data showed a variation in the flavonoid profile and in the kaempferitrin content depending on the place of collection and the season of the year. The target compound, kaempferitrin, was found to be only a minor constituent in RJ (0.21 - 1.02 μg/mg), and was mostly absent or occurred as trace in SP location (0.00 - 0.12 μg/mg). Some degree of similarity was observed in the flavonoid profiles according to the region of collection. In agreement with some published reports, the low and quite variable kaempferitrin content as well the wide variability of the flavonoid profiles brings into question the dubious matter of using these compounds as chemical markers for this medicinal species.
A Comparative Study on Antiradical and Antimicrobial Properties of Red Grapes Extracts Obtained from Different Vitis vinifera Varieties  [PDF]
Nada El Darra, Joanna Tannous, Paulette Bou Mouncef, James Palge, Joseph Yaghi, Eugène Vorobiev, Nicolas Louka, Richard G. Maroun
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.310186
Abstract: The present work is devoted to the study of antiradical and antimicrobial activities of phenolic compounds extracted from different grapevine varieties grown in the Bekaa plane-Lebanon. The amount of phenolic compounds in selected grape extracts was determined by the Folin-Ciocalteau method. Phenolic composition was specified by high performance liquid chromatography. Free radical scavenging activity was examined by using the (2,2’-diphenyl-1-picrylhy-drazyl) DPPH assay. The potential antimicrobial activity was studied using a new quantitative method developed during this work. This activity was tested against several microbial pathogens, including a Gram-positive strain (Listeria monocytogenes), two Gram-negative strains (Escherichia coli and Salmonella arizonae) and a fungal strain (Candida albicans). According to the results of the present screening study, a great variability in the composition of phenolic com-pounds in red grape extracts was detected. All phenolic compounds extracts, demonstrated important scavenging properties and antimicrobial effect against bacterial and fungal strains. Yet, a different response degree was noticed depending on the tested microorganism and the phenolic composition of grape extracts. Antimicrobial activity was more effective against Gram-positive than Gram-negative and yeast strains. Furthermore, our results highlighted a significant role of synergistic effect between various phenolic compounds in the free radical scavenging and antimicrobial activities.
Rapid Analysis of Morusin from Ramulus mori by HPLC-DAD, Its Distribution in Vivo and Differentiation in the Cultivated Mulberry Species  [PDF]
Bin Ma, Fenying Cui, Yuqing Zhang
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.42026
Abstract:

The distribution and content differentiation of morusin in the cultivated species of mulberry by HPLC-DAD are described in this paper. The experimental results showed that morusin is present in all parts of the mulberry bush. The content of morusin was highest in root bark and second highest in branch bark. The difference in morusin content of 20 different species of cultivated mulberry branch bark was significant. The level of morusin was highest in the branch bark of cultivated mulberry No. 404, a tetraploid cultivar, and third in the Husang 32 cultivar of Morus multicaulis. The method used in this study for determining morusin content exhibited good repeatability (RSD 6.02%) and recovery (100.62%). Therefore, the results from this study provide reliable data, for research and development in the future, on the level and distribution of morusin in mulberry in general and the differences found between various cultivated mulberries in particular. Furthermore, the HPLC-DAD method to determine morusin content is fast and reliable and is applicable not only to mulberry bushes but also to other plants.

Validation of a method using solid phase extraction and liquid chromatography for the determination of pesticide residues in groundwaters
Caldas, Sergiane S.;Demoliner, Adriana;Primel, Ednei G.;
Journal of the Brazilian Chemical Society , 2009, DOI: 10.1590/S0103-50532009000100020
Abstract: a method is described for the determination of the pesticides carbofuran, clomazone, 2,4-d and tebuconazole in groundwaters. the method involves solid phase extraction (spe) with c18 cartridges and quantification by high performance liquid chromatography with diode array detector (hplc-dad). after the optimization of the extraction and separation parameters, the method was validated by evaluating the analytical curve, linearity, limits of detection and quantification, precision and accuracy (recovery). the method presents an average recovery of 87.9% and 96.9%, in repeatability and intermediate precision conditions, respectively, with adequate precision (rsd from 0.8 to 20.7%), for all compounds. the method will be applied to determine pesticides in groundwater samples with limit of quantification of 0.2 μg l-1.
Valida??o de método para determina??o de ácidos organicos voláteis em efluentes de reatores anaeróbios empregando cromatografia líquida
Cerqueira, Maristela Barnes Rodrigues;Dias, Adriana Neves;Caldas, Sergiane Souza;Santana, Fabrício Butierres;D'Oca, Marcelo Gon?alves Montes;Primel, Ednei Gilberto;
Química Nova , 2011, DOI: 10.1590/S0100-40422011000100029
Abstract: this work deals with the method validation for the determination of acetic, propionic and butyric acids (vfas) in wastewaters from anaerobic reactors by hplc-dad. separation was performed using a c18 column and the mobile phase composition were water ph 3.0 and methanol 90:10 (v/v). the detection and quantification was carried out at 220 nm. the method shows good linearity (r2>0.996), with adequate accuracy (89-102%) and relative standard deviations lower than 18%. the matrix effect was considered low (-4.1, -3.9 and 1.4%). the developed method is fast, simple and cheap; and it was applied in wastewater samples from anaerobic reactor.
Determina??o de ácido valpróico em soro por cromatografia líquida de alta eficiência com detector de arranjo de diodos (CLAE-DAD), após derivatiza??o com brometo de fenacila
Antunes, Marina Venzon;Nagel, Viviane;Linden, Rafael;Werlang, Helenice Orosco;Hermes, Daniela;
Química Nova , 2009, DOI: 10.1590/S0100-40422009000500027
Abstract: valproic acid (va) is a drug used to control seizures in several epileptic conditions. in va pharmacotherapy, therapeutic drug monitoring is recommended to obtain adequate seizure control and avoid toxicity. the aim of this study was to validate a method for the determination of valproic acid in serum, employing high performance liquid chromatography with diode array detection (hplc-dad), after derivatization with phenacyl bromide. the calibration curve (y=0.0133x-0.0025) presented good linearity with r2=0.9999. accuracy (101-115%), intra-assay precision (4.53-8.15%) and inter-assay precision (3.15-6.77%) were acceptable. the quantification limit was 2.0 μg/ml. the method presented similar results to enzyme immunoassay.
Determina??o de horm?nios estrógenos em água potável usando CLAE-DAD
Verbinnen, Raphael Teixeira;Nunes, Gilvanda Silva;Vieira, Eny Maria;
Química Nova , 2010, DOI: 10.1590/S0100-40422010000900003
Abstract: an analytical procedure for determination of estriol, 17β-estradiol, estrone and 17α-ethinylestradiol in drinking water is presented. the method employs solid phase extraction (spe) and sample dechlorination as cleanup procedures, followed by hplc-dad analysis. validation was carried out using re no. 899/2003 guidelines established by the agência nacional de vigilancia sanitária (national agency of sanitary surveillance, brazil), with some adaptations. the statistically evaluated results have shown that the method is selective, precise (0,06% to 19,40% cv) and accurate (91,52% to 109,41% average recoveries). the developed method was applied to the analysis of these contaminants in drinking water from s?o luís, ma.
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