Consulta: subjectFacets:"Spectrophotometry"
Registros recuperados: 20
Data/hora: 11/06/2024 01:02:03

Análisis químico del extracto celular de peciolo en fresa mediante laboratorios portátiles.
Provedor de dados: 32
Autores: Janeiro Cid, Ricardo.
El objetivo de la presente investigación fue establecer  métodos de diagnóstico rápidos y confiables para el análisis químico del extracto celular de pecíolo en fresa mediante el uso de equipos portátiles. Se realizaron tres ensayos a nivel de invernadero, laboratorio y campo. Primero, con la finalidad de estandarizar el muestreo del extracto celular de peciolo en fresa se realizó un experimento en invernadero donde se tomó en cuenta la concentración de nitratos en el extracto celular de pecíolo (ECP) y su relación con la temperatura, luminosidad y humedad de suelo. Estas variables fueron medidas con un ionómetro portátil marca Horiba®, un termómetro, luxómetro y medidor de humedad marca Vernier®, respectivamente. Los resultados indicaron que la...
Palavras-chave: Edafología; Maestría; Temperatura del ambiente; Luminosidad; Humedad de la hoja; Environmental temperature; Luminosity; Leaf wetness; Espectrofotometría; Potenciometría; ICP-AES; Spectrophotometry; Potentiometry.
Ano: 2014
URL: http://hdl.handle.net/10521/2315

Spectrophotometric Winkler determination of dissolved oxygen: re-examination of critical factors and reliability
Provedor de dados: 5
Autores: Labasque, Thierry; Chaumery, Christian; Aminot, Alain; Kergoat, Gilles.
The spectrophotometric iodine measurement for oxygen determination by the Winkler method is re-examined for theoretical and operational aspects. It is shown that the selection of an isobestic point for measuring the mixture of iodine and tri-iodide in the solution enhances reliability. The wavelength value of 466 nm was selected after a spectrum study. Then, performances are assessed by mean of statistical approach based on repeated standardization curves at the isobestic point compared with other wavelengths. At 466 nm, the method is linear up to about 1000 mumol kg(-1) of O-2. Optimization and validation of the spectrophotometric method is realized through a robustness study based on factors that may alter the results (temperature, reagent volumes,...
Tipo: Text
Palavras-chave: Isobestic point; Sea water; Spectrophotometry; Dissolved oxygen.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-1694.pdf

Effects of 16 pure hydrocarbons and two oils on haemocyte and haemolymphatic parameters in the Pacific oyster, Crassostrea gigas (Thunberg)
Provedor de dados: 5
Autores: Bado Nilles, A; Gagnaire, Beatrice; Thomas-guyon, Helene; Le Floch, S; Renault, Tristan.
The in vitro effects of polycyclic aromatic hydrocarbons (PAHs) on haemocyte and haemolymphatic parameters of the Pacific oyster, Crassostrea gigas, were tested using field concentrations (10(-7) and 10(-9) mg mL(-1)) observed in the Marennes-Oleron Basin (Charente-Maritime, France) and high concentrations (10(-3) and 10(-5) mg mL(-1)) observed during oil spills. As a first step, the effects of pollutants, after a 24 h contamination period, were monitored on individual and pooled haemolymph samples and similar results were observed for both sample types. In a second step, haemolymphs from 45 oysters were withdrawn and pooled. Eighteen pollutants were tested in vitro after a 4 and 24 h contamination period and 10 of them showed significant modulations of...
Tipo: Text
Palavras-chave: Toxicity; PAHs; Pacific oyster; Spectrophotometry; Flow cytometry; Haemocyte activity.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-4696.pdf

Dosage rapide de l'histamine dans le thon : mise au point, optimisation, applications
Provedor de dados: 5
Autores: Bregeon, Nelly.
After a bibliographic analysis about histamine in tuna and thanks to a high matematical process - the experimental design method - the author has adjusted a quick proportioning method for histamine. The enzymatic technique used in this case requires a microplates reader. It was afterwards valided by comparison with HPLC methode consideres as reference.
Tipo: Text
Palavras-chave: Thon Histamine; Plans cxperimentaux; Dosage enzymatiquc; Colorimetre; Test rapide; Tuna; Histamine; Experimental design method; Enzymatic analysis; Spectrophotometry; Quick test.
Ano: 1992
URL: https://archimer.ifremer.fr/doc/00464/57524/59714.pdf

Development of Alternative Methods for Determining Soil Organic Matter
Provedor de dados: 90
Autores: Souza,Diego Mendes de; Morais,Pedro Augusto de Oliveira; Matsushige,Ivã; Rosa,Luismar Alves.
ABSTRACT Soil organic matter (SOM) is important to fertility, since it performs several functions such as cycling, water and nutrient retention and soil aggregation, in addition to being an energy requirement for biological activity. This study proposes new trends to the Embrapa, Walkley-Black, and Mebius methods that allowed the determination of SOM by spectrophotometry, increasing functionality. The mass of 500 mg was reduced to 200 mg, generating a mean of 60 % saving of reagents and a decrease of 91 % in the volume of residue generated for the three methods without compromising accuracy and precision. We were able to optimize conditions for the Mebius method and establish the digestion time of maximum recovery of SOM by factorial design and response...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: SOM; Spectrophotometry; Increase in functionality; Response surface.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832016000100419

Organic sulfur oxidation to sulfate in soil samples for total sulfur determination by turbidimetry
Provedor de dados: 90
Autores: Rossete,Alexssandra Luiza Rodrigues Molina; Bendassolli,José Albertino; Trivelin,Paulo Cesar Ocheuze.
Sulfur in the soil occurs in two basic forms, organic and inorganic S. The organic form accounts for 95 % of S in most soils. The effectiveness of organic S to oxidate to sulfate was evaluated for total S determination in soil samples by wet (acid) and dry-ash (alkaline) oxidation methods. To evaluate the wet method and the possible use as a reference when evaluating the dry method proposed here, a reference standard from the US National Institute of Standards and Technology (NIST) was used (Montana Soil - NIST 2710). The dry-ash oxidation process with alkaline oxidizing agents is one of the simplest oxidation methods of organic S to the sulfate form and was compared with the wet process. The objective of the study was to develop a dry method that would be...
Tipo: Info:eu-repo/semantics/report
Palavras-chave: Sample preparation; Turbidimetric method; Spectrophotometry.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832008000600031

Colorimetric method as alternative to chromium (III) quantification in cattle feces
Provedor de dados: 2
Autores: Torres Ospina, Alexandra; Zapata, Julian Andrés; Gil Gonzalez, Jesus Humberto; Giraldo, Luis; Valencia, Diana Marcela.
&amp;nbsp;One of the main factors to establish productivity of grazing cattle is the estimation of forage intake. For this, the most widely used technique is based on the estimation of fecal output using chromium dioxide as external marker. However, quantification can be expensive and sometimes not precise due to the methodology used for this purpose. Therefore, the aim of this study was to validate the colorimetric method for chromium quantification and to implement it in the estimation of fecal output in grazing cattle. The temperature, the digestion time and the wavelength for the measurement were evaluated. The method was validated for selectivity, linearity, detection and quantification limits, precision, accuracy, and stability. Results showed that...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Spectrophotometry; Fecal output; External marker; Chromium dioxide; Validation. spectrophotometry; Fecal output; External marker; Chromium dioxide; Validation.
Ano: 2020
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAnimSci/article/view/48096

Sensitive and rapid titrimetric and spectrophotometric methods for the determination of stavudine in pharmaceuticals using bromate-bromide and three dyes
Provedor de dados: 42
Autores: Basavaiah,Kanakapura; Ramakrishna,Veeraiah; Somashekar,Chikkaswamy; Kumar,Urdigere R. Anil.
Four sensitive and rapid methods for the determination of stavudine (STV) in bulk drug and in dosage forms were developed and optimized. In titrimetry, aqueous solution of STV was treated with a known excess of bromate-bromide in HCl medium followed by estimation of unreacted bromine by iodometric back titration. Spectrophotometric methods involve the addition of a measured excess of bromate-bromide in HCl medium and subsequent estimation of the residual bromine by reacting with a fixed amount of methyl orange, indigocarmine or thymol blue followed by measurement of absorbance at 520 nm (method A), 610 nm (method B) or 550 nm (method C). In all the methods, the amount of bromate reacted corresponds to the amount of STV. Calculations in titrimetry were...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Stavudine determination; Titrimetry; Spectrophotometry; Bromate-bromide; Dyes; Pharmaceuticals.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652008000200003

Application of Scharer's quantitative method for the determination of residual alkaline phosphatase activity in standard Minas
Provedor de dados: 45
Autores: Soares,C.F.; Fonseca,L.M.; Leite,M.O.; Oliveira,M.C.P.P.
Milk pasteurization is a critical issue in the dairy industry, and failures in this process can affect final product safety. Scharer's enzymatic method is still traditionally used to verify pasteurization efficiency compliance, and it is based on screening for residual alkaline phosphatase in milk. Although several methods are used to quantify enzymatic activity to assess milk pasteurization efficiency, there is a small amount of published data regarding the use of these methods to quantify alkaline phosphatase in cheese. In this study, the Scharer's modified method was used to determine the levels of residual alkaline phosphatase in standard minas cheese, before and after 20 days of ripening. The cheeses were made using raw or pasteurized milk with the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Alkaline phosphatase; Standard Minas cheese; Scharer's modified method; Spectrophotometry.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-09352013000400039

Coenzyme Q10 defects may be associated with a deficiency of Q10-independent mitochondrial respiratory chain complexes
Provedor de dados: 48
Autores: Fragaki,Konstantina; Chaussenot,Annabelle; Benoist,Jean-François; Ait-El-Mkadem,Samira; Bannwarth,Sylvie; Rouzier,Cécile; Cochaud,Charlotte; Paquis-Flucklinger,Véronique.
BACKGROUND: Coenzyme Q10 (CoQ10 or ubiquinone) deficiency can be due either to mutations in genes involved in CoQ10 biosynthesis pathway, or to mutations in genes unrelated to CoQ10 biosynthesis. CoQ10 defect is the only oxidative phosphorylation disorder that can be clinically improved after oral CoQ10 supplementation. Thus, early diagnosis, first evoked by mitochondrial respiratory chain (MRC) spectrophotometric analysis, then confirmed by direct measurement of CoQ10 levels, is of critical importance to prevent irreversible damage in organs such as the kidney and the central nervous system. It is widely reported that CoQ10 deficient patients present decreased quinone-dependent activities (segments I + III or G3P + III and II + III) while MRC activities...
Tipo: Journal article
Palavras-chave: Mitochondrial disease; CoQ10 deficiency; Respiratory chain; Spectrophotometry; LC-MSMS.
Ano: 2016
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602016000100004

Extraction of Indigo from Some Isatis species and Dyeing Standardization Using Low-technology Methods
Provedor de dados: 52
Autores: Comlekcioglu,Nazan; Efe,Lale; Karaman,Sengul.
Fresh leaves of four Isatis species culture form of I. tinctoria L and wild forms of I. buschiana Schischkin, I. candolleana Boiss. (endemic) and I. tinctoria L. subsp. corymbosa. (Boiss.) were used for indigo production. Dyes were extracted by fermentation and hot water application. The extracted dyes were optimized with different pH and reducing agents. Results showed that the dye from hot water application produced the desired dying quality at pH 11. Reducing agent concentrations had no significant effect on color quality. Dark blue and blue colors were obtained from I. tinctoria and I. candolleana extracts although I. tinctoria subsp. corymbosa and I. buschiana produced mostly yellow-gray colors. Light, dry and wet rubbing fastness values varied...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Isatisspp.; Woad; Indigo; Natural dye; Fermentation; Fastness; Spectrophotometry.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132015000100096

Evaluation of the Folin-Ciocalteu Method and Quantification of Total Tannins in Stem Barks and Pods from Libidibia ferrea (Mart. ex Tul) L. P. Queiroz
Provedor de dados: 52
Autores: Galvão,Marcos Aurelio Morais; Arruda,Alice Oliveira de; Bezerra,Isabelle Cristinne Ferraz; Ferreira,Magda Rhayanny Assunção; Soares,Luiz Alberto Lira.
ABSTRACT The stem bark and pods of “jucá” are widely used in Brazilian folk medicine and, despite their therapeutic relevancies, there are insufficient reports about their quality control. Both herbal drugs from the species are rich in tannins, which showed a lot of biological and economic interest. Thus, the purpose of this study was to evaluate the method for quantification of tannins in the stem bark and pods from L. ferrea. The performance of the method was tested against the influence of the most relevant parameters (reaction time; amount of drug; type and amount of precipitationagents; and, concentration of the reagents). The procedure was validated according to the literature. After optimization, the experimental conditions were established as: 30...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Libidibia ferrea; Quality control; Spectrophotometry; Tannins.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132018000100431

Spectrophotometric determination of total proteins in blood plasma: a comparative study among dye-binding methods
Provedor de dados: 52
Autores: Zaia,Dimas Augusto Morozin; Marques,Fábio Rangel; Zaia,Cássia Thaïs Bussamra Vieira.
A comparative study between the biuret method (standard method for total proteins) and spectrophotometric methods using dyes (Bradford, 3',3",5',5"-tetrabromophenolphthalein ethyl ester-TBPEE, and erythrosin-B) was carried out for the determination of total proteins in blood plasma from rats. Bradford method showed the highest sensitivity for proteins and biuret method showed the lowest. For all the methods, the absorbance for different proteins (BSA, casein, and egg albumin) was measured and Bradford method showed the lowest variation of absorbance. The concentration of total protein obtained by using Bradford method was not statistically different (p&gt;0.05) from concentration of total protein obtained by the biuret method. But in regard to erythrosin-B...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Total proteins; Spectrophotometry; Blood plasma; Dye-binding methods.
Ano: 2005
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132005000300008

Evaluation of red cabbage anthocyanins after partial purification on clay
Provedor de dados: 52
Autores: Lopes,Toni Jefferson; Yaginuma,Sandra Regina; Quadri,Mara Gabriela Novy; Quadri,Marintho Bastos.
The aim of this work was to evaluate the red cabbage anthocyanins quality after purification by static adsorption assays on clay (Tonsil Terrana 580FF). Thin-layer chromatography analysis and scan spectrometry on UV-Visible showed a good dye stability of the pigment interacting with the clay. The use of pH 3.0 buffer during the batch assays provided a protective effect on the cabbage anthocyanins, limiting the dye acid hydrolyses. Analyses of the reducing sugars contents of the extract showed that clay retained 20% average of total free sugars under the test conditions.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Thin-layer chromatography; Spectrophotometry; Purification; Batch conditions.
Ano: 2011
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132011000600022

Sensitive spectrophotometric assay of simvastatin in pharmaceuticals using permanganate
Provedor de dados: 60
Autores: Tharpa,Kalsang; Basavaiah,Kanakapura; Rajedraprasad,Nagaraju; Vinay,Kanakapura Basavaiah; Hiriyanna,Salmara Ganeshbhat.
Two simple, sensitive, selective and inexpensive spectrophotometric methods are described for the determination of simvastatin (SMT) in bulk drug and in tablets using permanganate as the oxidimetric reagent. In method A, SMT is treated with a measured excess of permanganate in acetic acid medium and the unreacted oxidant is measured at 550 nm, whereas in method B the reaction is carried out in alkaline medium and the resulting manganate is measured at 610 nm. In method A, the amount of permanganate reacted corresponds to the SMT content and the absorbance is found to decrease linearly with the concentration; and in method B, the absorbance increases with concentration. The working conditions of assays were optimized, and the methods were validated...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Simvastatin assay; Spectrophotometry; Permanganate; Pharmaceutical products.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502010000100010

Dissolution test optimization for meloxicam in the tablet pharmaceutical form
Provedor de dados: 60
Autores: Oliveira,Érika de Fátima Silva; Azevedo,Roberta de Cássia Pimentel; Bonfilio,Rudy; Oliveira,Diego Borges de; Ribeiro,Gislaine Pereira; Araújo,Magali Benjamim de.
Meloxicam is a broadly used drug in the therapeutics for the osteoarthritis and rheumatoid arthritis treatments in adults, and it is available in the Brazilian market, as tablet and capsule pharmaceutical forms. The present work aimed to establish conditions for accomplishment of the dissolution test of 15 mg meloxicam tablets (A and B test products), compared with the reference product, since there is no monograph about dissolution assays for meloxicam in official summaries. To optimize the conditions several parameters were tested and, according to obtained results, the use of pH 7.5 phosphate buffer (900mL, at 37 ± 0.5ºC) as dissolution medium, paddle method (apparatus 2), stirring speed of the dissolution medium at 100 rpm and collect time of 60...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Meloxicam/dissolution; Dissolution kinetics; Tablet pharmaceutical forms/dissolution test; Spectrophotometry.
Ano: 2009
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502009000100008

Total polyphenols from Syzygium cumini (L.) Skeels fruit extract
Provedor de dados: 60
Autores: Migliato,Ketylin Fernanda; Carvalho,Elisângela Simões de; Sacramento,Luis Vitor Silva do; Mello,João Carlos Palazzo de; Baby,André Rolim; Velasco,Maria Valéria Robles; Salgado,Hérida Regina Nunes.
A precise, accurate and low cost spectrophotometric method was developed and validated for routine determination of total polyphenols, as pyrogallic acid equivalents, from the percolated and lyophilized extract of Syzygium cumini (L.) Skeels fruits. Validation was assessed experimentally and data were rigorously treated by statistical analysis. Analytical parameters were: linearity, interval (range), precision and recovery/accuracy, limit of detection (LOD, μg mL-1) and limit of quantification (LOQ, μg mL-1). The visible spectrophotometric method presented linearity (r² = 0.9979 ± 0.0010) over the concentration range 0.25-7.5 μg mL-1 of standard pyrogallic acid, precision &lt; 2.918171%, recovery/accuracy ranging from 96.228693 to 107.17701%, LOD = 0.21 μg...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Total polyphenols; Syzygium cumini; Botanical extract; Analytical method validation; Spectrophotometry.
Ano: 2009
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502009000100015

Development and validation of analytical methodology with focus on the qualification of powder mixers
Provedor de dados: 60
Autores: Fiorante,Pedro de Freitas; Martins,Rodrigo Dias; Palma,Mauri Sergio Alves.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Powder mixers/analytical validation; Spectrophotometry; Ferric oxide/quantification; Lactose monohydrate/quantitative analysis.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502015000200273

Determination of olanzapine by spectrophotometry using permanganate
Provedor de dados: 60
Autores: Rajendraprasad,Nagaraju; Basavaiah,Kanakapura.
Two new spectrophotometric methods using permanganate as the oxidimetric reagent for the determination of olanzapine (OLP) were developed and validated as per the current ICH guidelines. The methods involved the addition of known excess of permanganate to OLP in either acid or alkaline medium followed by the determination of unreacted permanganate at 550 nm (method A) or bluish-green color of manganate at 610 nm (method B). The decrease in absorbance in method A or increase in absorbance in method B as a function of concentration of OLP was measured and related to OLP concentration. Under optimized conditions, Beer's law was obeyed over the ranges 2.0 to 20 and 1.0 to 10 μg mL-1 in method A and method B, respectively. The calculated molar absorptivity...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Olanzapine/determination; Spectrophotometry; Permanganate; Pharmaceuticals.
Ano: 2009
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502009000300020

Steroidal saponin concentrations in Brachiaria decumbens and B. brizantha at different developmental stages
Provedor de dados: 65
Autores: Brum,Karine Bonucielli; Haraguchi,Mitsue; Garutti,Mirella Biasoli; Nóbrega,Fernanda Nogarol; Rosa,Beneval; Fioravanti,Maria Clorinda Soares.
Brachiaria species contain steroidal saponins and are involved in outbreaks of hepatogenous photosensitization. This research presents the levels of a steroidal saponin, protodioscin, in the seeds and aerial parts of B. brizantha and B. decumbens during different developmental stages (growth, bloom, fructification and seed fall). The butanolic fraction of the ethanolic extract of each stage was submitted to thin layer chromatography (TLC) and spectrophotometric analysis through the Ehrlich reagent in 515nm. The chromatograms in TLC of the butanolic fraction of B. brizantha and B. decumbens showed similar spots as the protodioscin standard. The estimated level of protodioscin isomers in B. brizantha and B. decumbens ranged from 0.5% to 2.1%, having the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Brachiaria spp.; Photosensitization; Protodioscin; Spectrophotometry; Steroidal saponins.
Ano: 2009
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782009000100049