Desenvolvimento de um método portátil de determinação de fosfato utilizando análise por injeção em batelada com detecção colorimétrica

Abstract

Batch Injection Analysis (BIA) is an analytical platform with portable characteristics and great potential to become a routine analytical tool for the determination of different compounds, especially in laboratories where sophisticated equipment is not available. However, in most published articles where the BIA system was used, electrochemical detection was preferentially explored. In this sense, this work proposes the creation of a BIA system with colorimetric detection (reflectance) for phosphate determination in water samples. Therefore, a BIA cell was developed by 3D printing, with space for fitting tubes of a peristaltic pump, responsible for aspiration and renewal of the solution. In addition, instrumental parameters such as injection speed and volume, as well as the vertical and horizontal distance from the injection point to the colorimetric sensor, were optimized. With the optimized instrumental parameters, the proposed method demonstrated performance comparable to that of a commercial spectrophotometer, presenting results with 95% confidence. The method produced a coefficient of determination of 0.999 with a linear range between 0.1 and 1.5 mg L-1 of phosphate. An analytical frequency of 110 injections h-1 was obtained, with a detection limit of 0.03 mg L-1 of phosphate and recovery values between 97% and 102%