Pharmaceutical Development of Green Innovations Group (PDGIG), Faculty of Pharmacy, Silpakorn University, Sanamchandra Palace Campus, Nakhon Pathom 73000, Thailand.
Newcharoen Pharmaceutical L.P., Pathumthani 12120, Thailand.
Int J Pharm. 2019 Mar 10;558:120-127. doi: 10.1016/j.ijpharm.2018.12.078. Epub 2019 Jan 9.
A new, smartphone-based colourimetric method for the assay of d-penicillamine formulations relying on the Ellman's reaction was developed by performing the colourimetric reaction in a microplate. Subsequently, the plate was positioned on a white illuminating screen of an iPad placed in a dark box in order to capture a top-view image using an iPhone 5s back camera. The intensity of yellow colour was converted to Red-Green-Blue pixels using a free mobile application. Under the optimal conditions for the reaction and photography, the intensity of blue colour, which was logarithmically transformed, showed an excellent linearity over the drug concentration range of 5-40 µg/mL. The assay was validated and successfully applied to the assay of drug content and the determination of drug amount released in the dissolution test in the capsule dosage forms. Apart from that, a smartphone was employed for the colour measurement as an alternative to a spectrophotometer in the currently used method for the quantitation of free sulfhydryl groups in polymers. Using cysteine-conjugated chitosan as a sample and l-cysteine as a standard, the smartphone method gave the results in agreement with those obtained from the absorbance measurement on a microplate reader. In conclusion, smartphone-based colourimetry has been proved to be a reliable, fast, simple and affordable alternative means for the analysis of d-penicillamine and cysteine-conjugated polymer and can be potentially applied to other thiol-containing drugs and excipients.
一种新的基于智能手机的比色法，用于测定二巯丁二酸制剂，该方法依赖于 Ellman 反应，通过在微孔板中进行比色反应来实现。随后，将平板放置在一个暗盒中的 iPad 的白色照明屏幕上，以便使用 iPhone 5s 后置摄像头拍摄顶视图图像。使用免费的移动应用程序将黄色强度转换为红-绿-蓝像素。在反应和摄影的最佳条件下，蓝色强度经过对数转换后，在 5-40μg/mL 的药物浓度范围内呈现出极好的线性关系。该测定方法经过验证，并成功应用于胶囊剂型中药物含量的测定和溶出试验中药物释放量的测定。此外，智能手机还被用于颜色测量，作为目前用于聚合物中游离巯基定量的分光光度法的替代方法。使用巯基化壳聚糖作为样品和 l-半胱氨酸作为标准，智能手机法得到的结果与在微孔板阅读器上进行吸光度测量得到的结果一致。总之，基于智能手机的比色法已被证明是一种可靠、快速、简单且经济实惠的替代方法，可用于分析二巯丁二酸和巯基化聚合物，并且可能适用于其他含硫醇的药物和赋形剂。
