A compact flow-batch analyzer equipped with mini piezoelectric pumps and image-based volume control†

Abstract

Flow-batch analyzers demand meticulous volume control for successful application in quantitative determinations, with the incorporation of high-efficiency pumps and valves recommended for their construction. However, routine recalibrations are frequently needed to uphold the accuracy of manipulated volumes, highlighting the value of exploring new alternatives for volume control and measurement, with less sophisticated apparatus. In this work a compact Flow-Batch (FB) analyzer with piezoelectric micropumps was developed to perform standard addition calibration, incorporating image-based detection to perform volume control. The instrument was evaluated by quantitatively determining Cr(VI), NO₂⁻, and Fe(II) in water samples, combining RGB-based colorimetry with established spectrophotometric methods. The results demonstrate that a comprehensive analysis with five standard additions can be completed in approximately 10 minutes, maintaining a suitable linear correlation (R² > 0.99) and precision (0.4 ≤ RSD ≤ 12.1%). Recoveries between 90% and 105% for analyte levels below Brazilian regulatory limits underscore the accuracy of the proposed approach. The study confirms that digital image monitoring provides an elegant alternative for controlling solution volumes in FB systems, eliminating the need for more robust pumps with precisely controlled flow rates.