Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand.
Anal Methods. 2021 Aug 14;13(30):3348-3358. doi: 10.1039/d1ay00719j. Epub 2021 Jul 20.
In this research, the pH differential method was explored for the first time using a mobile phone as a detector, replacing UV-Vis spectrophotometry. A smartphone digital image colorimetric (SDIC) system was developed for the determination of the total monomeric anthocyanin content in black rice grains using colour values. The change in colour of anthocyanin cyanidin-3-glucoside (C3G) at pH 1.0 and pH 4.5 was investigated and described through colour model systems (RGB and CIELAB). Under optimum conditions, the quantitative method based on the chroma difference, was able to quantify the total amount of monomeric anthocyanins with a linear correlation (R = 0.989) to that of UV-Vis spectrophotometry and high performance liquid chromatography (HPLC) (reference method). The SDIC system displayed good precision (≤1.88% RSD) and a low detection limit (2.2 ± 0.1 μg g). The validated results demonstrated that the developed method was a cost-effective alternative for the quantitation of anthocyanins. In addition, the effect of six mineral elements on black rice cultivation was investigated. The results showed that the addition of the Ca fertiliser resulted in black rice grains with an anthocyanin content 2-fold higher than that of the control with a significant difference (p < 0.05).
在这项研究中，首次探索了使用智能手机作为探测器的 pH 差示法，以取代紫外-可见分光光度法。开发了智能手机数字图像比色（SDIC）系统，用于通过颜色值测定黑米中总单体花色苷的含量。通过颜色模型系统（RGB 和 CIELAB）研究并描述了花色苷矢车菊素-3-葡萄糖苷（C3G）在 pH 1.0 和 pH 4.5 下的颜色变化。在最佳条件下，基于色差值的定量方法能够以与紫外-可见分光光度法和高效液相色谱法（参考方法）相当的线性相关性定量测定单体花色苷的总量（R = 0.989）。SDIC 系统显示出良好的精密度（≤1.88%RSD）和低检测限（2.2±0.1μg g）。验证结果表明，所开发的方法是定量花色苷的一种具有成本效益的替代方法。此外，还研究了六种矿物质元素对黑米栽培的影响。结果表明，与对照相比，添加钙肥可使黑米中的花色苷含量增加一倍，差异显著（p<0.05）。
