Abstract:
New thread-based and paper-based devices for the determination of nitrite ions based on modified Griess reagent were developed. The surface of the materials was chemically modified with p-aminobenzoyl moiety and chromotropic acid was used as a coupling reagent. The functionalization of the materials was confirmed by Raman spectroscopy. By using the thread-based device, the detection of nitrite was achieved by measuring the color band length. The optimum concentration of chromotropic acid was 5 mM in 0.10 M sulfuric acid mixed with 0.2 M citric acid. The working range was from 50 to 1,000 µM with a sample volume of 15 µL, where the lowest concentration that produced observable color on the thread was 25 µM. The recoveries using the spiked samples were in the range of 92.4 – 115.4 %. By using the paper-based device, the detection of nitrite was achieved by measuring the color intensity. The optimum concentration of citric acid and chromotropic acid was 0.20 M and 100 µM, respectively with 15-minute extraction. The working range was from 0.5 to 20 µM with a sample volume of 3.00 mL, where LOD and LOQ were 0.44 µM and 1.47 µM, respectively. The recoveries using the spike samples were in the range of 81.3 – 103.5 %. When the results of the sample analysis by the proposed methods were compared to those by the ion chromatography method, it was found that the recoveries and RSD of the results obtained from the proposed methods were in acceptable ranges.
