Optical chemical sensor based on immobilesed pararosaniline into sol-gel matrix tetraethyl orthosilicate (TEOS) is a simple tool that can be used to detect the presence of formalin (formaldehide) in food. Pararosaline...Optical chemical sensor based on immobilesed pararosaniline into sol-gel matrix tetraethyl orthosilicate (TEOS) is a simple tool that can be used to detect the presence of formalin (formaldehide) in food. Pararosaline in sol-gel matrix was developed when contacted with food sample that contains formalin. The optical signal was produced by changing color from purple to yellow, that can be used to detect quantitative formaldehide in sample. The results, chemo sensor optic, have characteristic, maximum wave length 576.42 nm, with linier range 0-100 ppm, linearity coefficient R2 = 0.999, limit detection (LOD) 0.504 ppm, limit of quantification (LOQ) 1.680 ppm, sensitivity 0.087, disturbed matrix selectivity 1.716 %. The optimum is operational at pH 4, and response time at 150 seconds of 2 ppm. This sensor can be used to detect formalin in food sample in a simple mode and reusable for 4 times application. In addition, the sensor can be regenerated using展开更多
The stable chromogenic radical 1,1'-diphenyl-2-picrylhydrazyl(DPPH) solution was immobilized on the microwell plate as dry reagent to construct a simple antioxidant sensor. Then, a regular flatbed scanner was used...The stable chromogenic radical 1,1'-diphenyl-2-picrylhydrazyl(DPPH) solution was immobilized on the microwell plate as dry reagent to construct a simple antioxidant sensor. Then, a regular flatbed scanner was used as microplate reader to obtain analytical parameters for antioxidant assay using one-shot optical sensors as scanometry technique. Variables affecting the acquisition of the images were optimized and the analytical parameters are obtained from an area of the sensing zone inside microwell using the average luminosity of the sensing zone captured as the mean of red, green, and blue(RGB)value using Image J~program. By using this RGB value as sensor response, it is possible to determine antioxidant capacity in the range 1–25 ppm as gallic acid equivalent(GAE) with the response time of 9 min. The reproducibility of sensor was good(RSD<1%) with recovery at 93%–96%. The antioxidant sensor was applied to the plant extracts, such as sappan wood and Turmeric Rhizome. The results are good when compared to the same procedure using a UV/Vis spectrophotometer.展开更多
文摘Optical chemical sensor based on immobilesed pararosaniline into sol-gel matrix tetraethyl orthosilicate (TEOS) is a simple tool that can be used to detect the presence of formalin (formaldehide) in food. Pararosaline in sol-gel matrix was developed when contacted with food sample that contains formalin. The optical signal was produced by changing color from purple to yellow, that can be used to detect quantitative formaldehide in sample. The results, chemo sensor optic, have characteristic, maximum wave length 576.42 nm, with linier range 0-100 ppm, linearity coefficient R2 = 0.999, limit detection (LOD) 0.504 ppm, limit of quantification (LOQ) 1.680 ppm, sensitivity 0.087, disturbed matrix selectivity 1.716 %. The optimum is operational at pH 4, and response time at 150 seconds of 2 ppm. This sensor can be used to detect formalin in food sample in a simple mode and reusable for 4 times application. In addition, the sensor can be regenerated using
文摘The stable chromogenic radical 1,1'-diphenyl-2-picrylhydrazyl(DPPH) solution was immobilized on the microwell plate as dry reagent to construct a simple antioxidant sensor. Then, a regular flatbed scanner was used as microplate reader to obtain analytical parameters for antioxidant assay using one-shot optical sensors as scanometry technique. Variables affecting the acquisition of the images were optimized and the analytical parameters are obtained from an area of the sensing zone inside microwell using the average luminosity of the sensing zone captured as the mean of red, green, and blue(RGB)value using Image J~program. By using this RGB value as sensor response, it is possible to determine antioxidant capacity in the range 1–25 ppm as gallic acid equivalent(GAE) with the response time of 9 min. The reproducibility of sensor was good(RSD<1%) with recovery at 93%–96%. The antioxidant sensor was applied to the plant extracts, such as sappan wood and Turmeric Rhizome. The results are good when compared to the same procedure using a UV/Vis spectrophotometer.
