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 254 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 f 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.

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According to FDA guidance, a biowaiver concept declares that dissolution testing could be approved as a replacement strategy for bioequivalence studies and/or in vivo bioavailability. From the analytical chemistry standpoint, the shift from the classically developed offline methods to the highly integrated miniaturized inline analyzers is one of the pioneering ways that would modernize future of in-vitro - in-vivo correlation (IVIVC). The emergence of screen-printed electrodes (SPE) is now making the move from successive sampling steps and off-line measurements to real-time and in-line monitoring. Recently, “SPE” potentiometric sensor was presented as real-time analyzer that can offer similar analytical results as separation-based chromatographic techniques. Thus, the main objective of this paper is to design a real-time SPE for in-situ monitoring of the dissolution of trospium chloride in neutral media. Validation of the proposed sensor was performed according to the IUPAC commendations. The measurements performed with this sensor showed an accuracy of average recovery 100.50 % and standard deviation of less than 1.0%, also the repeatability and intermediate electrode variabilities were less than 1.0 and 1.3%, respectively. The developed sensor was successfully used for direct observation of the dissolution profile without any need for an extraction step or sample preparation.

A simple electrochemical procedure was developed for the electrochemical determination of Loperamide hydrochloride (LOP). A square wave voltammetric method was applied to determine LOP in its pure form, pharmaceutical formulation, in presence of co-administered drugs omeprazole, trimebutine, and naproxen and in human plasma. In the applied method, a newly fabricated carbon paste electrode chemically modified with silver sulfadiazine and zinc oxide was used. Experimental parameters such as pH of Britton-Robinson buffer, scan rate and applied current potential of the electrode surface were optimized. The morphological structure of the newly fabricated electrode was illustrated using transmission electron microscopy. Using Britton–Robinson buffer of pH 8.00, LOP showed an irreversible anodic peak of 0.827 V. The manufactured sensor displayed high sensitivity and optimum charge/electrode kinetic transmission. Linear calibration curve was obtained between the peak current and the corresponding concentration of LOP over the range (14.00 × 10−12 − 1.00 × 10−4 M) with low detection limit of about (4.00 × 10−12 M) indicating good sensitivity. The proposed method was validated according to the ICH guidelines. The proposed sensor was also applied to determine LOP in human plasma after successfully validating the method according to the FDA bioanalytical methods guidelines. The greenness of the method was assessed using the Analytical Eco-Scale approach and the results reveal that the developed method is not only greener and uses non-hazardous chemicals than the previously reported HPLC methods for LOP determination in biological fluid but also can be used in the quality control laboratories for LOP determination in pharmaceutical formulation and in human plasma.