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A chemiluminescence flow-based procedure for determination of carbaryl in natur...

A chemiluminescence procedure for the determination of carbaryl in natural waters using acetylcholinesterase and choline oxidase is described. The flow system designed to implement multicommutation approach controlled by microcomputer comprised five solenoid valves, two columns with immobilized enzymes on controlled pore glass beads and chemiluminometric flow cell. In the best experimental conditions a linear r...

Exploiting gas diffusion for non-invasive sampling in flow analysis: determinat...

A tubular gas diffusion PTFE membrane is exploited for non-invasive sampling in flow analysis, aiming to develop an improved spectrophotometric determination of ethanol in alcoholic beverages. The probe is immersed into the sample, allowing ethanol to diffuse through the membrane. It is collected into the acceptor stream (acidic dichromate solution), leading to formation of Cr(III), monitored at 600 nm. The ana...

The development of Analytical Chemistry in Brazil: retrospective and expectations

The development of Analytical Chemistry in Brazil in the last century is critically evaluated in relation to international achievements. Tendencies for the next century are foreseen, especially in relation to the presently observed shifts in paradigm.

Spectrophotometric flow-injection determination of sulphite in white wines invo...

A flow-injection system is proposed for the spectrophotometric determination of sulphite in white wines. The method involves analyte conversion to SO2, gas diffusion through a Teflon® semi-permeable membrane, collection into an alkaline stream (pH 8), reaction with Malachite green (MG) and monitoring at 620 nm. With a concentric tubular membrane, the system design was simplified. Influence of reagent concentrat...

Classificação e definição dos métodos de análises em fluxo (Recomendações - IUP...

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 ...

Construção e avaliação de um eletrodo tubular sensível ao íon hidrogênio como d...

The construction of a tubular hydrogen ion-selective potentiometric electrode without inner reference solution, based on the tridodecylamine (TDDA) ionophore, and its evaluation in a flow system are described. TDDA was dissolved in 2-nitrophenyl octyl ether, dispersed in a PVC membrane and applied directly to a conducting support which consisted of an epoxy resin and graphite mixture. The electrode was designed...

Editorial

Turbidimetric flow-injection determination of total nitrogen and potassium in v...

A turbidimetric flow-injection system was developed for the determination of total nitrogen and potassium in vegetable samples using a single spectrophotometer as detector. As a precipitating agent, 3.0% (w/v) sodium tetraphenylboron solution prepared in 2.0% (w/v) poly(vinyl alcohol) was used. A gas diffusion process was included in the manifold to separate ammonium ions from the rest of the sample and to allo...

Spectrophotometic flow injection determination of lead in port wine using in-li...

A flow injection system with in-line ion exchange is proposed for the spectrophotometric determination of lead in Port wine. A Chelex-100 resin mini-column (200–400 mesh) is used for lead concentration, and the chromogenic reaction is based on the formation of a ternary complex between lead, Malachite Green and iodide. Forty-five digested wine samples can be run per hour (25–500 µg l–1 Pb) and results are compa...