Automatic photometric titration procedure based on multicommutation and flow-batch approaches employing a photometer based on twin LEDs

Abstract

Neste trabalho, é descrito um fotômetro de baixo custo baseado em um par de LEDs idênticos, empregando um, como fonte de luz e o outro como fotodetector. O equipamento, incluindo o fotômetro e o módulo de análises, foi projetado para implementar um procedimento de titulação automático empregando o processo de multicomutação por injeção em fluxo (MCFIA). O sistema proposto dispunha de meios para realizar a titulação fotométrica sem a necessidade de empregar curva analítica. A utilidade foi comprovada analisando amostras de vinagre e sucos de limão, laranja, abacaxi, maracujá e cajú. A exatidão foi verificada comparando os resultados com outros, obtidos empregando procedimento manual, e não foi observada diferença significativa no nível de confiança de 95%. Amostras com diferentes concentrações de ácido, tais como suco de limão (1.084,73 mmol L ) foram tituladas usando a mesma solução titulante, e sem modificação do sistema de titulação.In this work, a reliable and inexpensive photometer based on twin LEDs assembled as a radiation source and as a photodetector is described. The setup including the photometer and flow system module was designed to implement an automated titration procedure employing the multicommuted flow injection analysis (MCFIA) process. The proposed system was able to carry out photometric titration without using analytical curve to achieve the sample concentration. Its usefulness was proven by analyzing vinegar and lemon, orange, pineapple, maracock, and acajou juices. Accuracy was accessed comparing results with those obtained employing a manual procedure and no significant difference was observed at 95% confidence level. Samples presenting different acid concentrations such as lemon juice (1084.73 mmol L -1 ) and pineapple juice (14.42 mmol L -1 ) could be titrated using the same titration solution without any modification of the titrating setup.

Solenoid Micro‐pumps: A New Tool for Sample Introduction in Batch Injection Analysis Systems with Electrochemical Detection

“…Since FIA introduction, different flow techniques have been presented aiming the automation of different analytical procedures as liquid‐liquid extraction and titrations . The potential of these systems was expanded by the use of discrete devices to manage solutions, as solenoid valves and micro‐pumps .…”

Assembling and Using an LED-Based Detector To Monitor Absorbance Changes during Acid–Base Titrations

“…Reis and co-workers , proposed the use of a simple, low-cost apparatus that allows the automatic control of the titrant addition by switching a solenoid valve until the end point is attained. This is detected by the change in the color of the solution due to the presence of an indicator.…”

Development of an automatic photometric titration procedure to determine olive oil acidity employing a miniaturized multicommuted flow-batch setup

“…21,22 These requirements have been achieved by developing analytical procedures employing a miniaturized ow setup. [23][24][25][26][27][28] In this work, we intend to develop a miniaturized ow setup and an analytical procedure for the determination of olive oil acidity, which will be accomplished by employing a photometric titration strategy using a multicommuted ow-batch approach, [29][30][31] which affords facilities to mimic the manual titration procedure, thus eliminating the use of calibration curves to nd the acid concentration. Aiming to comply with the GAC requirements, 21,22 the ow system will be designed with downsized dimensions, which will be done by attaching a radiation source (LED) and a photodetector to the titration chamber in order to form a compact unit.…”