A fabrication of cost-effective paper-based colorimetric devices for nitrite detection

Abstract

Ubiquitous and cost-effective printing paper was remodeled into a colorimetric paper-based analytical devices (PADs) for nitrite anion (NO2-) detection via Mn7+reduction in acidic conditions for food and environmental samples. The colorimetric PADs fabricated by wax printing required only 10 μL of potassium permanganate (KMnO4) and to detect NO2-. Colorimetry allowed simple visual detection with the naked eye. Image analysis of photographic results revealed the improved detection limit of 0.13 mg/L. Under optimized parameters, including KMnO4 and sulfuric acid (H2SO4) concentrations, and reaction time, it was found that colorimetric data were in a logarithmic relationship with the NO2-amount ranging from 0.50 mg/L to 5.0 mg/L. Moreover, the colorimetric PADs showed a good selectivity toward NO2-among other anions at 100-fold. Application in NO2-detection in meat, animal feed, soil, and water samples using the standard addition method revealed 99.7% accuracy for PADs. The proposed technique was validated by traditional spectrophotometry, and a precision in the range of 95.2% to 104.6% was obtained. Therefore, inexpensive, portable, and feasible colorimetric PADs for NO2-were successfully constructed.