Ibrahim Maha Mahmoud, Kelani Khadiga Mohamed, Ramadan Nesreen Khamis, Elzanfaly Eman Saad
Analytical Chemistry Department, Faculty of Pharmacy, Modern University for Technology and Information, 12055 Cairo, Egypt.
Analytical Chemistry Department, Faculty of Pharmacy, Cairo University, 11562 Cairo, Egypt.
ACS Omega. 2022 Jun 24;7(27):23815-23820. doi: 10.1021/acsomega.2c02482. eCollection 2022 Jul 12.
Thin-layer chromatography (TLC) is an effective and simple technique for screening, evaluating, and quantifying low-quality and counterfeit pharmaceutical products. Smartphones have recently been used as accessible, cheap, and portable detectors that can replace more complicated analytical detectors. In this work, we have developed a simple and sensitive TLC method utilizing a smartphone charged-coupled device (CCD) camera not only to verify and quantify some gastrointestinal tract drugs, namely, loperamide hydrochloride (LOP) and bisacodyl (BIS), but also to detect acetaminophen (ACT) as a counterfeit drug. Both drugs (LOP and BIS) were chromatographed separately on a silica gel 60 F plate as a stationary phase under previously reported chromatographic conditions, using ethyl acetate:methanol:ammonium hydroxide (24:3:1, by volume) and ethyl acetate:methanol:glacial acetic acid (85:10:5, by volume) as developing systems to determine LOP and BIS, respectively. Universal stains, namely, iodine vapors and vanillin, were used to visualize the spots on the TLC plates to get a visual image using the smartphone camera and a spotlight as an illumination source with no need for a UV illumination source. The spot intensity was calculated using a commercially available smartphone application for quantitative analysis of the studied drugs utilizing ″acetaminophen″ as an example of a counterfeit substance. R values were calculated using the recorded images and found to be 0.77, 0.79, and 0.74 for LOP, BIS, and ACT, respectively, providing drug identity. Linear calibration curves using the smartphone-TLC method were obtained between the luminance and the corresponding concentrations over the ranges of 2.00-10.00 μg/mL and 1.00-10.00 μg/mL with limits of detection of 0.57 and 0.10 μg/mL for LOP and BIS, respectively. The suggested method was validated according to the International Conference of Harmonization (ICH) guidelines. The method was then successfully applied for the qualitative and quantitative determination of LOP or BIS as an example for gastrointestinal tract drugs in pure form and in their pharmaceutical dosage formulations. The proposed method is considered as a perfect alternative to traditional reported densitometric methods due to its simplicity, easy application, and inexpensiveness. No previously reported methods utilizing smartphones have been published for the determination of the studied drugs. The developed approach is considered the first TLC method using smartphones for the determination of some gastrointestinal tract drugs in their pure form and in pharmaceutical formulations.
薄层色谱法（TLC）是一种用于筛查、评估和定量低质量及假冒药品的有效且简单的技术。近年来，智能手机被用作便捷、廉价且便携式的检测器，可替代更为复杂的分析检测器。在本研究中，我们开发了一种简单且灵敏的TLC方法，利用智能手机的电荷耦合器件（CCD）相机，不仅用于验证和定量某些胃肠道药物，即盐酸洛哌丁胺（LOP）和比沙可啶（BIS），还用于检测对乙酰氨基酚（ACT）这一假冒药物。在先前报道的色谱条件下，将两种药物（LOP和BIS）分别在硅胶60 F板上作为固定相进行色谱分离，分别使用乙酸乙酯：甲醇：氢氧化铵（24:3:1，体积比）和乙酸乙酯：甲醇：冰醋酸（85:10:5，体积比）作为展开系统来测定LOP和BIS。使用通用显色剂，即碘蒸气和香草醛，使TLC板上的斑点显色，通过智能手机相机和聚光灯作为照明源获取可视图像，无需紫外线照明源。以“对乙酰氨基酚”作为假冒物质的示例，使用市售的智能手机应用程序计算斑点强度，对所研究的药物进行定量分析。利用记录的图像计算Rf值，发现LOP、BIS和ACT的Rf值分别为0.77、0.79和0.74，从而确定药物的身份。使用智能手机-TLC方法在2.00 - 10.00 μg/mL和1.00 - 10.00 μg/mL范围内获得了亮度与相应浓度之间的线性校准曲线，LOP和BIS的检测限分别为0.57和0.10 μg/mL。所建议的方法根据国际协调会议（ICH）指南进行了验证。然后，该方法成功应用于以纯形式及其药物剂型存在的胃肠道药物LOP或BIS的定性和定量测定。由于其简单性、易于应用和低成本，所提出的方法被认为是传统报道的密度测定方法的完美替代方法。此前尚未有利用智能手机测定所研究药物的报道方法。所开发的方法被认为是第一种使用智能手机测定纯形式及其药物制剂中某些胃肠道药物的TLC方法。
