Analytical Comparison of Conventional, Portable, and Smartphone-Based UV-Vis Spectrophotometer for the Quantitative Determination of Chromium (III) Nitrate Solution and Potassium Permanganate (VII) Solution

Wong, Chong Fei (2025) Analytical Comparison of Conventional, Portable, and Smartphone-Based UV-Vis Spectrophotometer for the Quantitative Determination of Chromium (III) Nitrate Solution and Potassium Permanganate (VII) Solution. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

This study aimed to compare the analytical performance of conventional, portable, and smartphone-based ultraviolet-visible (UV-Vis) spectrophotometric systems in the quantification of chromium (III) nitrate and potassium permanganate. The objectives were to design a dilution-based quantification approach applicable across the three platforms, to assess the relative performance of portable visible device and smartphone-assisted instruments against the conventional spectrophotometer, to examine the role of sample dilution on detection thresholds, to evaluate the limitations of dilution-based analysis, and to explore the potential of the portable system in time-scan kinetics applications. The experimental design involved preparing serially diluted standards of chromium (III) nitrate and potassium permanganate, with both laboratory and commercially available potassium permanganate samples tested. Calibration studies were used to evaluate sensitivity, linearity, and detection capability, while time-scan kinetic experiments were performed on the KMnO4−Na2S2O3 reaction. The instruments employed included the HITACHI UH5300 double-beam spectrophotometer, a DIY LED-based portable visible spectrophotometer, and a smartphone system with app-based absorbance measurement. The results demonstrated that the conventional spectrophotometer offered superior sensitivity, precision, and reproducibility, maintaining strong compliance with the Beer-Lambert law. The portable spectrophotometer achieved moderate performance, proving capable of semi-quantitative analysis and basic time-scan measurements, though with reduced linearity and precision. The smartphone-based system was highly limited, primarily due to ambient light interference and detector instability, restricting its usefulness to preliminary or educational contexts. Overall, the study confirmed that portable and smartphone-based UV-Vis spectrophotometers, while not replacements for conventional instruments but hold the promise as accessible tools for field-based or resource-limited settings.