Sample records for ion detection
from WorldWideScience.org

Sample records 1 - 19 shown.



1

Determinação de bromato em melhoradores de farinha por cromatografia de troca iônica com detecção espectrofotométrica/ Bromate determination in flour improvers by ion exchange chromatography with spectrophotometric detection

Dallago, Rogério Marcos; Nascimento Filho, Irajá do; Zanella, Renato; Maroneze, Aline Machado
2005-08-01

Resumo em inglês KBrO3 is registered by the FAO/OMS as a genotoxic and carcinogenic compound. In spite of this, KBrO3 is still employed by Brazilian bakeries. Nowadays ion exchange chromatography (IEC) is the most rapid and trustful method for BrO3- analysis. When at high concentrations, chloride ions can interfere in the BrO3- analysis, if the detection is performed by electrical conductivity. On the other hand, spectrophotometric detection, presented here is based on the absorption of B (mais) rO3- in the ultraviolet region (210 - 230 nm) where the absortion of chloride ions is very low, thus making possible the qualitative and quantitative analysis of BrO3- in flour improver samples.

Scientific Electronic Library Online (Portuguese)

2

Determinação de chumbo em álcool combustível por voltametria de redissolução anódica utilizando um eletrodo de pasta de carbono modificado com resina de troca iônica Amberlite IR 120/ Lead ions determination in ethanol fuel by differential pulse anodic stripping voltammetry using a carbon paste electrode modified with ion-exchange resin Amberlite IR120

Bergamini, M. F.; Vital, S. I.; Santos, A. L.; Stradiotto, N. R.
2006-01-01

Resumo em português Um método envolvendo a pré-concentração e redissolução anódica em condições de voltametria de pulso diferencial empregando um eletrodo de pasta de carbono modificado (EPCM) com uma resina de troca iônica Amberlite IR120 foi proposto para a determinação de íons chumbo em álcool combustível. O procedimento é baseado em um pico de oxidação do analito observado em -0,53 V(vs. Ag/AgCl) em solução de HCl. As melhores condições experimentais encontradas for (mais) am: 5% (m/m) da Amberlite IR120 para a construção do eletrodo, solução de HCl 0,1 mol L-1, velocidade de varredura de 10 mVs-1, tempo de pré-concentração de 15 min e amplitude de pulso de 100 mV. Utilizando essas condições, o EPCM apresentou uma resposta linear entre a corrente de pico anódica e a concentração de íons chumbo para o intervalo entre 9,9 x 10-9 e 1,2 x 10-6 mol L-1 e um limite de detecção de 7,2 x 10-9 mol L-1. Valores de recuperação entre 96 % e 102 % foram encontrados para amostras de álcool combustível enriquecidas com Pb2+ em níveis de 10-7 mol L-1. O efeito da presença de outros íons concomitantes sobre a resposta voltamétrica do eletrodo também foi avaliado. Resumo em inglês The use of pre-concentration and differential pulse anodic stripping voltammetry (DPASV) using a carbon paste electrode modified (CPEM) with ion-exchange resin (Amberlite® IR120) has been proposed for the determination of lead ions content in ethanol fuel. The lead oxidation peak was observed at -0.53 V (vs. Ag/AgCl) in HCl solution. The best DPASV response was reached for an electrode composition of 5% (m/m) Amberlite® IR120 in the paste, 0.1 mol L-1 HCl solution, scan (mais) rate of 10 mVs-1, pre-concentration time of 15 min and potential pulse amplitude of 100 mV. In these experimental conditions, the proposed methodology responds to lead ions in the concentration range of 9.9 x 10-9 to 1.2 x 10-6 mol L-1 with a detection limit of 7.2 x 10-9 mol L-1. Recoveries ranged from 96 to 102 % for Pb(II) spiked in an ethanol fuel sample at 10-7 mol L-1 level were achieved. Interferences were also evaluated.

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3

Determinação de esteróides androgênicos anabólicos em urina por cromatografia gasosa acoplada à espectrometria de massas/ Detection of androgenic anabolic steroids (AAS) in urine samples by gas chromatography-mass spectrometry

Campos, Daniel Rossi de; Yonamine, Mauricio; Alves, Maria Janieire de Nazaré Nunes; Moreau, Regina Lucia de Moraes
2005-12-01

Resumo em português Esteróides androgênicos anabólicos (EAA) são substâncias naturais, sintéticas ou semi-sintéticas derivadas da testosterona, utilizadas em atividades esportivas com o objetivo de melhorar o desempenho físico pelo aumento de massa e força muscular. Apesar de causarem efeitos tóxicos graves, principalmente sobre os sistemas cardiovascular, hepático e neuro-endócrino, os EAA têm sido amplamente utilizados no âmbito esportivo. Desta forma, o presente trabalho tev (mais) e como objetivo a validação de um método para a determinação de esteróides e/ou seus produtos de biotransformação em amostras de urina por cromatografia gasosa acoplada à espectrometria de massas (CG-EM). O método baseou-se na hidrólise enzimática de esteróides conjugados, no emprego da extração líquido-líquido e na derivação do extrato para posterior análise por CG-EM, no modo de monitoramento seletivo de íons (SIM). O método validado cumpriu com os princípios de confiança necessários para a determinação de EAA em amostras de urina com a finalidade de controle de dopagem no esporte. Os limites de detecção dos esteróides analizados variaram de 0,5 a 15 ng/mL. Bons valores de precisão (intra e interensaio) também foram obtidos (CV Resumo em inglês Androgenic anabolic steroids (AAS) are defined as natural, synthetic or semi-synthetic drugs chemically derived from testosterone, used with the aim to improve physical performance by increasing both muscle strength and mass. Despite their reported toxicological effects on the cardiovascular, hepatic and neuro-endocrine systems, the AAS have been extensively used in sports activities. The objective of this study was to validate an analytical method for the detection of AA (mais) S and/or their metabolites in urine samples. The method was based on enzymatic hydrolysis, liquid-liquid extraction, derivatization and further analysis by gas chromatography-mass spectrometry (GC-MS) operated in the selected ion monitoring mode (SIM). The validated method agrees with the confidence concepts for AAS detection in urine samples for anti-doping control programs. The limits of detection of AAS varied from 0,5 to 15ng/mL. Good inter and intra-assay precisions were also observed (CV

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4

Qualidade de tubérculos de batatas-semente tratados com paraquat e o desenvolvimento de uma metodologia simplificada de detecção de resíduo do herbicida/ Quality of seed potato tubers treated with paraquat and the development of a simplified methodology for paraquat residue detection

Pereira, Welington; Dantas, Raquel L.
1995-01-01

Resumo em português O objetivo desse trabalho foi avaliar a qualidade de tubérculos de batatas-semente (Solanum tuberosum) tratados com paraquat e desenvolver uma metodologia simplificada de detecção de resíduos de herbicida. Dois ensaios foram realizados no Laboratório da Ciência das Plantas Daninhas do Centro Nacional de Pesquisa de hortaliças, Brasília, DF. No experimento, tubérculos das cultivares Achat e Baronesa foram submersos em soluções de 0 e 200 ppm de paraquat ou injet (mais) ados com 0,5 ml de soluções de 0 e 200 ppm do herbicida. O delineamento experimental foi inteiramente casualizado com 8 repetições e 12 tubérculos por parcela. Os tubérculos foram colocados em câmara fria, após a aplicação com paraquat, para quebra da dormência. Após a brotação dos tubérculos avaliou-se a qualidade interna dos mesmos, amostrando, posteriormente, 2 tubérculos de cada parcela para o plantio em vasos, sob condições de telado, para verificar possíveis danos no crescimento das plantas oriundas dos tubérculos tratados. Os tratamentos de imersão não provocaram, aparentemente, nenhum dano interno nos tubérculos, ou nem mesmo afetaram a nova geração, entretanto, os tubérculos injetados com paraquat foram severamente deteriorados e carbonizados, originando plantas bastante debilitadas. Esses resultados indicam que quando o paraquat for aplicado sob condições que favoreçam sua penetração ou translocação para o interior do tubérculo, atingindo os vasos e a polpa, pode danificá-lo severamente, prejudicar sua aparência, qualidade de produção e reduzir o desenvolvimento da nova geração de plantas oriundas dos tubérculos contaminados . No segundo experimento, desenvolveu-se uma metodologia simplificada para detectar resíduos de paraquat nos tubérculos através de colorimetria, visto que o paraquat é reduzido a um radical de cor azul na presença de ditionito de sódio (Na2S2O4) a 1% em meio básico, a qual se intensifica à medida que a concentração do produto aumenta. A metodologia simplificada desenvolvida permitiu detectar resíduos de paraquat ao nível de 0,06 ppm, indicando uma excelente aproximação, pois, o limite de tolerância do paraquat em tubérculos de batata é de 0,2 ppm, normalmente, determinado pelo método analítico completo, que apresenta limites de detecção em torno de 0,01 ppm e recuperação acima de 70%. Uma avaliação qualitativa da concentração residual de produto nas amostras foi possível através de leitura e comparações visuais entre os diferentes graus de cores desenvolvidas nas soluções visuais entre os diferentes graus de cores desenvolvidas nas soluções padrão e a cor desenvolvida na amostra, não necessitando, portanto, das leituras colorimétricas, podendo ser feita inclusive no campo. Observou-se que a maioria do paraquat permaneceu na região de casca até o período de 4 semanas após a aplicação do paraquat. Resumo em inglês Seed potatoes tubers (Solanum tuberosum) of two cultivars (Achat and Baronesa) were treated with paraquat solutions to evalute the internal tuber quality and to detect its residue by a simplified methodology. Two experiments were carried out at the National Research Center on Vegetables, Brasília, DF. In experiment one some tubers were immersed in 0 and 200 ppm of paraquat solutions and others were injected with 0,5 ml of 0 and 200 ppm solutions of the herbicide. Twelve (mais) tubers were used as plot in a complete randomized design with 8 replications. The internal tuber quality was evaluated after breaking dormancy and sprouting of ten tubers. Also, two tubers were sampled and put in 5 liter pots and grown under greenhouse conditions to observe if the herbicide would affect the growth of the new plant generation. The immersion treatments did not cause any internal damage to the tubers nor did they affect the new plant generation; however, tubers injected with paraquat were severely damaged (carbonization). Also, the next plant generation was affected and the surviving plants were small and not vigorus. These results indicate that paraquat can severely damage those tubers that absorbed and/or translocated the herbicide. In experiment two a simplified methodology to detect paraquat residue in the tubers was set up by colorimetric means. Paraquat was reduced with sodium dithionite (Na2S2O4) in basic solution to a blue radical ion whitch intensified its color with any increase in paraquat concentration. The development of this simplified methodology alowed the detection of paraquat residue above 0,06 ppm, indicating na excellent sensitivity and recovery in comparison with the residue analytical procedure of this herbicide, with a limit of detectability of about 0,01 ppm in crop samples of 200g. In addition to the quantitative determination of paraquat, this methodology allwos to determine qualitatively paraquat concentration by colour comparisons. Most of the paraquat residue was determined from potato skins up to 4 weeks after paraquat application.

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5

Extração de amônio de filtros de amostragem, coleta e determinação pelo método da gota suspensa/ Ammonia extraction of filter pack, collecting and determination in suspended droplet

FRANCO, Alexandre; CARDOSO, Arnaldo Alves; ALLEN, Andrew G.
2000-01-01

Resumo em português A amostragem de amônia no ar é feita usualmente com filtro impregnado com ácido. O ácido ascórbico, quando usado como impregnante, é facilmente oxidado em meio básico e aquoso, gerando uma solução fortemente colorida que inviabiliza a determinação por colorimetria. Este trabalho apresenta um novo procedimento para extração do íon amônio dos filtros de amostragem, transferindo o íon amônio para uma gota de solução contendo ácido sulfúrico 0,1 mol L-1. (mais) A amostra do filtro é inicialmente solubilizada com água. A solução é colocada dentro de uma câmara com posterior adição de solução de NaOH 1,5 mol L-1. Com a ajuda de com borbulhamento de nitrogênio, a amônia formada passa para a fase gasosa, sendo finalmente recolhida para uma gota de ácido sulfúrico. A esta gota é adicionado um reagente e o produto determinado colorimetricamente pela reação do indofenol. Além da eliminação de interferentes, o procedimento apresenta a vantagem de fazer uma nova pré-concentração da amônia, possibilitando melhorar o limite de detecção do método de determinação. Resumo em inglês Particle NH4+ and gaseous are collected simultaneously by filters impregnated with acid. When ascorbic acid is used, it is easily oxidized in alkaline medium. The resulting solution is dark, making impossible colorimetric measurement. Here we present a new procedure to extract ammonium ion from sampling filters, transferring the N (III) to a droplet of sulfuric acid, 0.1 mol L-1. After sampler collection, each filter is agitated with deionized water. The aqueous solution (mais) is transferred to a small chamber where NaOH (1.5 mol L-1 ) is added and nitrogen gas passed. The ammonia changes to the gas phase and is flushed form the aqueous solution. The droplet of sulfuric acid formed at the tip of the glass tube then collects ammonia free of interference. The droplet was analyzed by the indophenol colorimetric technique. Evaluations showed that this procedure could be used at low concentrations and it has the advantage of making a second preconcentration of N (III) , improving the detection limit of the method.

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6

Determinação do íon ferro em preparações farmacêuticas através da cromatografia planar e espectrofotometria/ Determination of ferrous ion in pharmaceutical preparations through planar chromatography and spectrophotometry

MANCINI, Maria Aparecida Donnini; ZUANON NETTO, José; VALLADÃO, Dênia Mendes de Sousa
1997-01-01

Resumo em português Os autores estudaram o comportamento cromatográfico de preparações farmacêuticas comerciais contendo o íon Fe (II). Utilizando celulose microcristalina/Propanol: ácido clorídrico 4 N: ácido acético concentrado: ácido nítrico concentrado: clorofórmio (40: 5: 5: 10: 10), como sistema cromatográfico e alizarina como reagente de detecção, Fe (II), Mn (II), Mg (II), Cu (II), Zn (II) e Ca (II) foram separados e identificados pela Cromatografia Planar. O Fe (II) f (mais) oi determinado pela reação com a ortofenantrolina, resultando em solução adequada para quantificação colorimétrica. Resumo em inglês The authors have studied the chromatographic behavior of pharmaceutical preparations obtained from commercial sources containing the ferrous ion. Using microcrystalline cellulose , propanol: 4 N, H Cl, acetic acid, nitric acid, chloroform mixture (40: 5: 5: 10: 10) as chromatographic system and and Alyzarin as the detection reagent Fe (II), Mn (II), Mg(II), Zn (II) and Ca (II) were separated and identificated by Planar Chromatography. Fe (II) cation was determined by reaction with 1, 10-Phenanthroline, resulting in an appropriate solution for colorimetric quantitation.

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7

Validação do método de determinação simultânea dos íons brometo e bromato por cromatografia iônica em águas de consumo humano/ Validation of simultaneous determination of bromides and bromates by ion chromatography in drinking water

Gonçalves, Maria Edite Pinto; Camões, Maria Filomena; Paiva, João Miguel; Benoliel, Maria João; Carneiro, Rui Neves
2004-06-01

Resumo em inglês European Directive (98/83/CE), compulsory after 2008, states that bromate in drinking water must be controlled at levels below 10 mg L-1. Supporting implementation of the Directive, the European Comission has established project SMT4-CT96 2134, in collaboration with various european institutions, aiming at the identification of the interferents to the current analytical method (Ionic Chromatography with Conductimetric Detection - IC/CD), their removal and the automation o (mais) f pre-treatment and injection steps, as well as the development of alternative methods. EPAL, responsible for the water supply to a great deal of Portuguese regions, has taken steps to meet these requirements. Although not part of such project, this work (the result of a project conducted under a protocol of collaboration between EPAL SA and FCUL - Faculty of Sciences, University of Lisbon), reports on studies of usefulness to laboratories planning to monitor bromate in ozone treated waters, in conditions different from those described in EPA 300.1. Simultaneous determination of bromide is justified by its role as bromate precursor.

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8

Uma célula simples para adaptação de eletrodos seletivos comerciais em sistemas de análises em fluxo/ A simple cell for assembling commercial ion-selective electrodes in continuous flow analyzers

Marin, Maria Angélica Bonadiman; Ganzarolli, Edgard Moreira; Queiróz, Roldão Rooseveld Urzêdo de; Souza, Ivan Gonçalves de
1998-11-01

Resumo em inglês A simple flow cell for potentiometric detection is described. It was assembled by making use of two perspex pieces fixed together by means of four screws, and allow the connection of plane membrane conventional electrodes to flow system. Details about its construction are presented. The device performance was evaluated by making use of a cyanide ion-selective electrode. The relative standard deviation was about 0.5% with a detection limit of 8.0 x 10-6 mol CN- dm-3. Under experimental conditions, the linear range was 10-5 to10-2 mol dm-3.

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9

Sistema automático para determinação seqüencial de cianeto livre e total empregando eletrodo tubular íon-seletivo de membrana homogênea/ Automatic system for sequential determination of free and total cyanide using homogeneous membrane tubular ion-selective electrode

Marin, Maria Angélica Bonadiman; Silva, Reinaldo Carvalho da; Lehmkuhl, Arilson; Silva, José Bento Borba da; Ganzarolli, Edgard Moreira; Queiróz, Roldão Roosevelt Urzêdo de
2000-02-01

Resumo em inglês This study presents an automated system for potentiometric determination of free and total cyanide which employs a homogeneous membrane tubular ion-selective electrode. After the electrode is assembled, it is connected to a system composed of 3 three-way solenoid valves, sample line, carrier line, acid stream, and gas diffusion chamber. A Turbo Pascal® computer program, developed specifically for this task, automatically performs all the steps involved in data acquisitio (mais) n and processing. The proposed analytical procedure offers operational simplicity, since detection is performed by a tubular electrode, whose assembly is fast and easy. The system has shown reproducibility (r.s.d.

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10

Recentes avanços e novas perspectivas dos eletrodos íon-seletivos/ Recent advances and new perspectives of ion-selective electrodes

Torres, Karin Yanet Chumbimuni; Marzal, Percy Calvo; Kubota, Lauro Tatsuo; Bakker, Eric
2006-10-01

Resumo em inglês This paper describes the recent progress in the development of polymeric membranes for ion-selective electrodes. The importance of knowing the mechanism of potential development in membranes for ion-selective electrodes to reach lower detection limits and improve selectivity are discussed. Recent advances and future trends of research on ion-selective electrodes are also reported.

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11

Eletrodo íon-seletivo para determinação potenciométrica de alumínio(III) em meio de fluoreto/ Ion-selective electrode for potentiometric determination of aluminium(III) in fluoride medium

Piccin, Evandro; Fatibello-Filho, Orlando; Ramos, Luiz Antonio
2004-12-01

Resumo em inglês The construction and analytical evaluation of a coated graphite Al(III) ion-selective electrode, based on the ionic pair formed between the Al(F)n3-n anion and tricaprylylmethylammonium cation (Aliquat 336S) incorporated on a poly(vinylchloride) (PVC) matrix membrane are described. A thin membrane film of this ionic pair and dibutylphthalate (DBPh) in PVC was deposited directly on a cylindric graphite rod (2 cm length x 0.5 cm diameter) attached to the end of a glass tube (mais) using epoxy resin. The membrane solution was prepared by dissolving 40% (m/m) of PVC in 10 mL of tetrahydrofuran following addition of 45% (m/m) of DBPh and 15% (m/m) of the ionic pair. The effect of membrane composition, fluoride concentration, and several concomitants as potential interferences on the electrode response were investigated. The aluminium(III) ion-selective electrode showed a linear response ranging from 1.4 x 10-4 to 1.0 x 10-2 mol L-1, a detection limit of 4.0 x 10-5 mol L-1, aslope of -54.3±0.2mV dec-1 and a lifetime of more than 1 year (over 3000 determinations for each membrane). The slope indicates that the ion-selective electrode responds preferentially to the Al(F)4- species. Application of this electrode for the aluminium(III) determination in stomach anti-acid samples is reported.

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12

Determinação turbidimétrica do antidepressivo amitriptilina em sistema fia explorando a formação do par iônico com lauril sulfato de sódio/ Turbidimetric determination of antidepressant amitriptyline in fia system exploiting the ion-pair formation with sodium lauryl sulphate

Silveira, Gustavo; Tarley, César Ricardo Teixeira
2008-01-01

Resumo em inglês The present work purposes the development of an analytical method for amitriptyline determination in pharmaceutical formulations using FIA system. It was based on interaction of amitriplyline with sodium lauryl sulphate in acid medium (pH 2.5) resulting in the ion-pair formation turbidimetrically detected at 410 nm. The fitting regression equation for range curve from 2.0 x 10-3 up to 3.2 x 10-3 mol L-1 was found to be analytical signal = -2.7417 + 0.1538 [amitriptyline] (mais) (r = 0.99991) with a detection limit of 1.8 x 10-3 mol L-1. The precision assessed as relative standard deviation (n = 10) was found to be 2.40 and 1.94%, for the respective concentration of amitriplyline 2.0 x 10-3 and 3.2 x 10-3 mol L-1 and the sample throughout was 60 h-1. The accuracy of method was successfully assessed in pharmaceutical formulation after comparison with a reference analytical method.

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13

Determinação simultânea de precursores de serotonina - triptofano e 5-hidroxitriptofano - em café/ Simultaneous determination of serotonin precursors - tryptophan and 5-hidroxytryptophan - in coffee

Martins, Ana Carolina C. L.; Silva, Tarliane M.; Gloria, M. Beatriz A.
2010-01-01

Resumo em inglês Epidemiological studies attributed positive effects in the central nervous system (CNS) to coffee. Among possible active constituents, serotonin, a neurotransmitter in the CNS, is present; but dietary sources do not cross the blood-brain barrier. Tryptophan and 5-hidroxytryptophan (5-HTP) are serotonin precursors and can affect brain concentrations. An ion-pair-HPLC, post-column derivatization with o-phthalaldehyde and fluorimetric detection before and after hydrolysis wi (mais) th NaOH and extraction with methanol:water was developed for the simultaneous determination of these compounds. It was selective, sensitive (LOD = 0.3 and 0.2 μg/mL), precise (91.3 and 94.2% recovery for tryptophan and 5-HTP, respectively), and linear from 0.3 to 40 μg/mL for both compounds. It was applied to green and roasted arabica and robusta coffees.

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14

Determinação potenciométrica em fluxo de cloreto de cetilpiridinio em desinfectantes bucais/ Potentiometric determination of cetylpyridinium chloride in oral desinfectants by flow injection analysis

Baptista, Paula C. S.; Araújo, Alberto N.; Montenegro, Maria da Conceição B. S. M.
2003-08-01

Resumo em inglês The work describes a new procedure for cetylpyridinium chloride determination in oral disinfectants, based on a flow-injection system with potentiometric detection. The determination was based on the measurement of picrate concentration decrease as result of ion-pair reaction with the analyte present in the injected sample. In the optimised set-up the sample injection volume was kept at 400 µL and merged downstream with the reagent solution containing 1,0 x10-5 mol/L of (mais) picrate adjusted to pH 5.0 with citrate/citric acid buffer. The flow rate was fixed at 8 mL/min and the reactor length at 40 cm. The proposed procedure enables the determination of cetylpyridinium in the analytical range of 5,0x10-6 - 7,5x10-5 mol/L at a sampling rate of 60/h. The results for real samples had a precision better than 3% and were comparable to the labelled values.

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15

Composição iônica majoritária de águas de chuva no centro da cidade de São Paulo/ Composition of rainwater in the central region of São Paulo city

Leal, Tatiana F. M.; Fontenele, Anna P. G.; Pedrotti, Jairo J.; Fornaro, Adalgiza
2004-12-01

Resumo em inglês The chemical composition of rainwater samples collected from March 2002 to February 2003 in downtown São Paulo city (Universidade Presbiteriana Mackenzie) is presented. Potentiometric and conductimetric measurements were used to evaluate the [H+] and the total ionic content. Major anions and cations were determined by ion chromatography with conductivity detection. The rainwater was acidic with a mean pH of 4.99. The volume weighted means, VWM, of the anions nitrate, ace (mais) tate and sulfate were, respectively, 21.2, 16.9 and 12.4 µmol L-1. Ammonium was the most abundant ion with a VWM of 37.6 µmol L-1. The contribution of each anion to the free acidity potential decreases in the following order: SO4(2-) (28.8%), CH3COO- (24.7%), NO3- (22.8%), Cl- (13.4%), HCOO- (7.7%) and C2O4(2-) (2.5%). The relative contribution of the weak organic acids to the free acidity was significant, 34.9%.

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16

CLAE-PI aplicada ao doseamento de vitaminas do complexo B em misturas: fundamentação e validação de método/ Ion-pair HPLC applied to the assay of the vitamin B group mixture: theorical bases and method validation

Donato, Eliane Maria; Zanotto, Ângelo Ricardo; Bergold, Ana Maria
2004-09-01

Resumo em português Um método simples e rápido para determinação simultânea das vitaminas nicotinamida, tiamina, piridoxina, riboflavina e pantotenato de cálcio, em associação com minerais, foi desenvolvido por cromatografia líquida de alta eficiência, utilizando a técnica de pareamento iônico, coluna C-8 Perkin Elmer (150 x 4,6 mm DI, partícula 5 mm, poro 80 Å) e detector de ultravioleta (210 e 270 nm). A fase móvel composta de água e metanol (894:106), contendo 10 mM de hex (mais) anossulfonato de sódio, 0,5% de ácido acético e 0,1% de trietilamina a pH 3,5 promoveu excelente separação das vitaminas. O método foi aplicado com sucesso à forma farmacêutica de comprimidos e drágeas, contendo também minerais. Linearidade, precisão, recuperação e especificidade foram satisfatórias. A taxa de recuperação do método foi de 98% a 102% e os desvios padrão relativos encontrados variaram entre 0,9 e 2,5%. Resumo em inglês A rapid and simple method for the simultaneous determination of nicotinamide, thiamine, pyridoxine, riboflavin and calcium pantothenate, associated with minerals was developed by high performance liquid chromatography. These vitamins were simultaneously assayed by reversed-phase ion-pair HPLC with C-8 column Perkin Elmer (150 x 4.6 mm, 5 mm, 80 Å) and UV detection (210 and 270 nm). A mobile phase of water-methanol (894:106), 10 mM hexanesulfonate, 0,5% acetic acid and 0, (mais) 1% triethylamine at pH 3.5 allowed the most satisfactory separation of these vitamins. The method was successfully applied to the determination of vitamins in tablets and coated tablets. Linearity, precision, recovery and specificity were always satisfactory. The average recoveries were from 98% to 102% and the relative standard deviations were between 0.9 to 2.5%.

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17

Avaliação de contaminantes inorgânicos e orgânicos em álcool combustível utilizando eletroforese capilar/ Evaluation of inorganic and organic contaminants in alcohol fuel by capillary electrophoresis

Pereira, Elisabete A.; Tavares, Marina F. M.; Stevanato, Alessandra; Cardoso, Arnaldo A.
2006-02-01

Resumo em inglês This work reports the analysis of inorganic and organic contaminants in alcohol fuel samples using capillary electrophoresis. Chloride and sulfate were analyzed in nitrate/ monochloroacetic acid at 10 mmol L-1 concentration each under indirect UV detection (210 nm). The analysis of aldehydes is based on the 216 nm detection of 3-methyl-2-benzothiazoline hydrazone adducts. The running buffer consisted of 20 mmol L-1 tetraborate , 40 mmol L-1 sodium dodecyl sufate and 12 mm (mais) ol L-1 beta-ciclodextrin. Both methodologies were applied to real samples indicating inorganic ion concentrations from 0.15 to 6.64 mg kg-1 and aldehydes from 32.0 to 91.3 mg L-1.

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18

Análise química de sais de cobre fabricados entre 1877 e 1995/ Chemical analysis of copper salts manufactured between 1877 and 1995

Afonso, Júlio Carlos; Aguiar, Renata de Melo; Gomes, Lôla Maria Braga
2004-08-01

Resumo em inglês Samples of copper compounds covering all of the XXth century and the end of the XIXth century were submitted to classical and instrumental quantitative analysis. The amount of impurities greatly decreased with time, reaching a constant level since the 1960's. The gravimetric method was suitable for the determination of copper although other procedures also gave good or reasonable results. However, for metal contaminants, atomic absorption spectrometry was the best choice (mais) because of its lower detection limits, being able to determine several elements in the oldest samples. Ion chromatography detected several anions in copper salts manufactured before the 1950's. An increasing quality of raw materials and a better sensitivity of analytical methods led to quality improvement of copper compounds with time.

Scientific Electronic Library Online (Portuguese)

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Alendronato de sódio: metodologias para análise quantitativa/ Sodium alendronate: methods for analytical quantitation

Ribeiro, Ana Ferreira; Volpato, Nadia Maria
2005-10-01

Resumo em inglês This paper presents a review of some published proposals for the analysis of sodium alendronate. The drug is an aminobisphosphonate compound used to inhibit the osteoclastic resorption of bone, and different methods were developed for its quantitative determination. These methodologies employed reversed-phase or ion-exchange HPLC analysis, both associated with different detectors: UV and fluorescence detection after derivatization of the drug, conductivity and refractive (mais) index detectors, as well as the indirect UV detection. Titrimetry and spectrophotometry (with previous complexation of the drug), which are simpler procedures, were also described, but they showed poor specificity when compared to liquid chromatography.

Scientific Electronic Library Online (Portuguese)