We introduce a rapid anthocyanin-based paper sensor with very high sensitivity and optical visibility for colorimetric detection of urea. The working principle is based on a colour change from purple to blue upon sensor exposure to ammonia generated from urea hydrolysis in the presence of urease as a catalyst. To improve sensor sensitivity and optical visibility, anthocyanin storage, urease solvent, urea hydrolysis time, and temperature were investigated. The results indicated that the anthocyanin extracted from red cabbage and stored in dark and low-temperature conditions, urease extracted into water₅₅ + glycerol₄₅ (Aq₅₅ + G₄₅), and urea hydrolysis time of 40 min and temperature of 45°C offer the best detection condition. The fabricated sensor showed exceptional sensitivity of 0.018 pixel/mg urea-N/L with a very low limit of detection (2.01 mg urea-N/L) and a limit of quantification (6.71 mg urea-N/L). Moreover, the sensor reaction zone is optically visible for urea concentration as low as 5 mg urea-N/L, making it a promising tool for urea screening in diverse applications. The unique analytical features and accuracy of the sensor compared to the spectrophotometry method also suggest that it can be used as a replacement for environmentally unfriendly spectrophotometry methods for on-site urea determination.

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用于比色尿素测定的简单且高灵敏度的基于花青素的传感装置的设计与开发

我们介绍了一种基于花青素的快速纸传感器，具有非常高的灵敏度和光学可见度，可用于尿素的比色检测。工作原理基于传感器暴露于尿素酶作为催化剂存在下尿素水解产生的氨时，颜色从紫色变为蓝色。为了提高传感器灵敏度和光学可见度，研究了花青素储存、脲酶溶剂、尿素水解时间和温度。结果表明，从紫甘蓝中提取的花青素在黑暗和低温条件下储存，脲酶提取到水₅₅  + 甘油₄₅ (Aq ₅₅  + G ₄₅), 尿素水解时间为 40 分钟, 温度为 45°C 提供了最佳检测条件。制造的传感器显示出 0.018 像素/mg 尿素-N/L 的卓越灵敏度，具有非常低的检测限（2.01 mg 尿素-N/L）和定量限（6.71 mg 尿素-N/L）。此外，对于低至 5 mg urea-N/L 的尿素浓度，传感器反应区是光学可见的，这使其成为在各种应用中进行尿素筛选的有前途的工具。与分光光度法相比，该传感器独特的分析特性和准确性也表明它可以替代环境不友好的分光光度法，用于现场尿素测定。