A Low-Cost Portable Microcontrolled Nephelometer for Potassium Determination

Abstract

Um nefelômetro microcontrolado portátil e de baixo custo é proposto para a determinação de potássio em água de coco e bebidas energéticas. O nefelômetro foi construído utilizando dois LEDs (diodos emissores de luz) como fontes de radiação em 465 nm e 880 nm, dois fotodiodos como fotodetectores e um controlador de interface periférica (PIC) para aquisição e processamento dos dados. O nefelômetro foi utilizado para determinar íons potássio pelo monitoramento do precipitado formado na reação entre íons K + e tetrafenilborato em meio básico na presença de álcool polivinílico. A curva analítica foi linear para potássio na faixa de concentração de 5,0×10 −6 a 5,0×10 −4 mol L −1 , com um limite de detecção de 4,0×10 −7 mol L −1 . Um desvio padrão relativo de 0,2 % para uma solução de potássio 1,6×10 −4 mol L −1 (n = 10) foi obtido. Respostas rápidas e confiáveis e baixo consumo de energia são outras características do nefelômetro proposto.A low-cost portable microcontrolled nephelometer for the determination of potassium in coconut water and energy beverages is proposed. The nephelometer was constructed using two LEDs (light emitting diodes) as radiation sources at 465 nm and 880 nm, two photodiodes as photodetectors, and a peripheral interface controller (PIC) to acquisition and processing data of the nephelometer. The nephelometer was used to determine potassium ions by monitoring the precipitate formed from the reaction between K + and tetraphenylborate anion in a basic medium in the presence of polyvinyl alcohol. The analytical curve was linear in the potassium concentration range from 5.0×10 −6 to 5.0×10 −4 mol L −1 , with a limit of detection of 4.0×10 −7 mol L −1 . A relative standard deviation of 0.2 % for 1.6 × 10 −4 mol L −1 potassium solution (n = 10) was obtained. Fast and reliable responses, low power consumption are other attractive features of the proposed nephelometer.Keywords: microcontroller, nephelometer, light emitting diode, analytical instrumentation, sodium tetraphenylborate IntroductionA nephelometer measures the turbidity of a solution containing suspended particles by directing a beam of light into the sample and sensing the light scattered, usually at right angles (at a 90° angle with respect to the light beam). [1][2][3] This technique has been applied to determine sulfate in water, 4 aqueous drug solubility, 5 and for immunoassays such as of proteins in maternal milk, 6 cystatin-C in serum, 7 and serum myoglobin in patients with acute pancreatitis. 8 Generally, spectrofluorimeters and fluorimeters are analytical instruments widely applied for this purpose. However, components such as high-intensity radiation sources, sophisticated detectors and wavelength selectors, and other optical devices make such equipments expensive. 1,3 Furthermore, these types of equipment are not portable and need microcomputers for control and data acquisition.LEDs (light emitting diodes) are semiconductor devices with p-n junction that exhibit electroluminescence properties when a current passes through them. LED...

A Portable Microcontrolled Pumping Flow System Developed to In Loco Determination of Diuron at Nanomolar Levels Employing a Disposable Biosensor

“…Recording of experimental data, and visualization of the time of switching on the valves on the LCD screen are others functions developed by the microcontroller. All the functions of the device are previously developed in C programming language [4,5,[7][8][9].…”

“…Firstly, the carrier solution (supporting electrolyte) is pumping from the proper reservoirs (E) by the aquarium air pump (P) with fixed (5); confluence connection (6); electrochemical flow cell (7); control buttons (8) and LCD screen (9).…”

“…This device is able to perform commands and instructions, which are driven by a code that can be loaded and storage into the memory of the microcontroller. In analytical chemistry, microcontrollers have been used for the construction of photometers, [4] spectrophotometers, [5] fluorimeters, [6] turbidimeters, [7,8] nephelometers, [8,9] potentiostats and luminometers [10]. In order to reach a full and more versatility automation, the microcontrolled instrumentation can be coupled to flow analyses procedures.…”

“…In order to reach a full and more versatility automation, the microcontrolled instrumentation can be coupled to flow analyses procedures. Flow analyses with multicommutation procedures is very interesting because presents a good throughput with reducing of waste generation and consumption of reagent [4,[9][10][11].…”

Evaluation of turbidimetric and nephelometric techniques for analytical determination of n-acetylcysteine and thiamine in pharmaceutical formulations employing a lab-made portable microcontrolled turbidimeter and nephelometer

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