Classificação e definição dos métodos de análises em fluxo (Recomendações - IUPAC 1994)

Abstract

Recebido em 23/4/98; aceito em 7/5/98 CLASSIFICATION AND DEFINITION OF ANALYTICAL METHODS BASED ON FLOWINGMEDIA. The aim of this report is to classify analytical methods based on flowing media and to define (standardize) terminology. After the classification and a discussion of terms describing the systems and component parts, a section is devoted to terms describing the performance of flow systems. The list of terms included is restricted to the most relevant ones; especially "self-explanatory" terms are left out. It is emphasised that the usage of terms or expressions that do not adequately describe the processes or procedures involved should be strongly discouraged. Although belonging to the category of methods based on flowing media, chromatographic methods are not comprised in the present document. However, care has been taken that the present text is not in conflict with definitions in that domain. In documents in which flow methods are described, it should be clearly indicated how the sample and/or reagent is introduced and how the sample zone is transported. When introducing new techniques in the field, or variants of existing techniques, it is strongly recommended that descriptive terms rather than trivial or elaborate names are used.Keywords: flow analysis; classification of flow methods; flow analysis systems. ASSUNTOS GERAIS INTRODUÇÃOA crescente necessidade de automação de procedimentos analíticos se deve ao aumento significativo do número de amostras laboratoriais a serem analisadas, por exemplo, nas áreas clínicas e ambientais, e à demanda por técnicas rápidas e confiáveis operando 24 horas por dia, freqüentemente requeridas para controle de processos industriais. Apesar dos esforços para desenvolver sensores seletivos e sensíveis para determinar diretamente a concentração de um analito em uma amostra-teste (para nomenclatura relativa à amostragem, ver 1 ), a grande variedade dos analitos e a complexidade dos produtos a serem analisados tornam altamente improvável que sensores para a maioria dos compostos de interesse se tornem disponíveis em futuro próximo. Desta forma, separação e/ou conversão química permanecem como etapas essenciais na maioria dos procedimentos de análise quantitativa. Nestes casos, a automação dos procedimentos analíticos implica na automação do processamento das amostras-teste. Como a maioria das separações e conversões químicas é normalmente conduzida em fase líquida, o conceito lógico e engenhoso de Skeggs 2,3 possibilitou a execução dos processos analíticos em um fluxo que transporta a alíquota de amostra do ponto de introdução até a unidade de detecção. Esta abordagem tem sido denominada como CFA, Análise em Fluxo Contínuo (segmentado).Durante aproximadamente vinte anos, foi aceito que a segmentação, dividindo o fluxo em compartimentos pequenos, regulares e separados por bolhas de ar, era a melhor estratégia para se evitar o alargamento de uma zona discreta do analito (freqüentemente denominada de dispersão da amostra) no percurso, desde o ponto de sua introdução até o d...

Direct Introduction of Water Sample in Multisegmented Flow-Injection Analysis for Sulfide Determination

“…3,24,25 Sulfide anion can act as a versatile intermediate through which sulfur with other species can be determined, since their high reactivity provides various means of detection. [27][28][29][30][31][32][33][34][35][36][37][38][39] In this sense, the coupling of flow injection analysis (FIA) with different detection strategies can be considered to be a good alternative for sulfide determination. Such a feature is assured to be due to outstanding advantages of the FIA system, such as simplicity, little sample manipulation, low reagents and sample consumption and, consequently, low-waste outcome.…”

“…Such a feature is assured to be due to outstanding advantages of the FIA system, such as simplicity, little sample manipulation, low reagents and sample consumption and, consequently, low-waste outcome. [31][32][33][34][35][36][37] The segmented flow analysis technique is considered to be a precursor of the different models of flow systems available today, based on sequential aspiration of the sample and air bubbles that make the flow dispersion better controlled. 37 Nowadays, there are several flow system configurations, such as: conventional flow-injection analysis with continuous flow and no air bubbles, proposed by Ruzicka; 38 a system with only one liquid segment trapped between two gas segments, which was named monosegmented; a system that employs several solenoid valves, named multicommutation; and a sequential analysis system.…”

“…[31][32][33][34][35][36][37] The segmented flow analysis technique is considered to be a precursor of the different models of flow systems available today, based on sequential aspiration of the sample and air bubbles that make the flow dispersion better controlled. 37 Nowadays, there are several flow system configurations, such as: conventional flow-injection analysis with continuous flow and no air bubbles, proposed by Ruzicka; 38 a system with only one liquid segment trapped between two gas segments, which was named monosegmented; a system that employs several solenoid valves, named multicommutation; and a sequential analysis system. 39 In the present work, FIA strategies/configurations, such as multisegmented, 37 multicommutated 40 and gaseous diffusion, 41 were explored in order to determine sulfide by an in-line sample treatment.…”

“…37 Nowadays, there are several flow system configurations, such as: conventional flow-injection analysis with continuous flow and no air bubbles, proposed by Ruzicka; 38 a system with only one liquid segment trapped between two gas segments, which was named monosegmented; a system that employs several solenoid valves, named multicommutation; and a sequential analysis system. 39 In the present work, FIA strategies/configurations, such as multisegmented, 37 multicommutated 40 and gaseous diffusion, 41 were explored in order to determine sulfide by an in-line sample treatment. The present paper describes an inline flow-injection analysis system for the determination of sulfide in water samples, exploiting the Fischer reaction.…”

Desenvolvimento e avaliação de sistema envolvendo interface de análise por injeção em fluxo com eletroforese capilar

“…O resultado de tal ocorrência é o surgimento da dupla camada elétrica, DCE, região na qual há uma distribuição espacial não homogênea de carga [12,13] . Cabe observar que a análise por injeção em fluxo não abrange, por convenção [14] , a cromatografia nem a eletroforese capilar, apesar destas duas famílias de técnicas se basearem em fluxo de soluções.…”