Development of Colloidal Silver-based Mercury Sensors in Whitening Cream

Abstract

Abstract Background: Mercury, a hazardous heavy metal known for its toxicity to the human body, finds application in cosmetics due to its capacity to inhibit melanin formation. Traditional mercury analysis relies on resourceintensive and time-consuming instrumentation. Objective: This study aims to devise cost-effective and practical sensors for mercury detection. Methods: The sensor development process involves immobilizing the sensor onto paper, reacting it with mercury, scanning the outcome using a scanner, and subsequently quantifying RGB values using the ImageJ software. Results: Optimization of reagent concentrations gave a ratio of methylene blue, AgNO3, gallic acid, and ascorbic acid at 0.5:7:1.5:1 generating the best results. Additionally, pH optimization within the range of 5 to 9 demonstrates stability without necessitating the inclusion of a buffer solution. Notably, the blue variant exhibits superior responsiveness during concentration optimization. Characterization of the sensor reveals a response time of 3 minutes and minimal interference of 2.145% from other substances. The sensor exhibits a linearity range of 0.5-250 ppm, regression equation y = 8.603x + 21.124, an R-value of 0.994, and an exceedingly low p-value of 6.9924589548512 x 10-9 . The sensor boasts a limit of detection (LOD) of 0.206 and a limit of quantification (LOQ) of 0.265, indicative of its precision. Further assessments reveal a percent relative standard deviation (% RSD) precision of 2.017% and a recovery rate of 96.14%. Conclusion: The sensor has exhibited stability for over one month under room temperature storage conditions. A comparison between the UV-Vis spectrophotometer and the sensor signifies no significant difference between the two methods. Keywords: AgNO3, colloidal silver, mercury, methylene blue, sensor