A portable solid-state potentiometric sensor based on a polymeric ion-exchanger for the assay of a controversial food colorant (sunset yellow).

Food additives are chemicals added to enhance the appearance, taste, or lifetime of food products. Authorities continuously update the lists of the allowed additives and their daily intake limits. Thus, authorities and food suppliers strictly monitor additives in food products to guarantee their safety and compliance with national laws and safety criteria. The daily intake of the food colorant sunset yellow is banned in some countries and strictly controlled in others. Herein, a chemically modified solid-state potentiometric sensor was fabricated and used for the direct, fast, sensitive and selective assay of sunset yellow in soft drink and pharmaceutical formulation samples. The study optimized the sensor composition and the optimized carbon paste included a novel polymeric ion-exchanger, dioctyl phthalate, chitosan, and calix-[8]-arene and produced a rapid and near-Nernstian response of -32.9 ± 0.821 mV per decade for sunset yellow in the concentration range 7.94 × 10-5 M to 1.0 × 10-2 M and in the pH range 5-10. The sensor revealed good selectivity toward sunset yellow in the presence of commonly encountered ionic species. The method was validated according to the International Council for Harmonization guidelines and the results were statistically comparable to those of a reported method. The solid-state sensor represents a tool for fast and direct assay of sunset yellow in food products without sample pretreatment.

Portable solid-state sensor for therapeutic monitoring of an antineoplastic drug; vinblastine in human plasma.

During cancer treatment, doses must be carefully administered and monitored to guarantee efficacy and minimize side-effects. A potentiometric sensor was developed for the direct real-time assay of a widely used antineoplastic drug (vinblastine (VB)) in plasma samples. Membrane cocktails were drop-casted over a glassy-carbon electrode coated with a lipophilic conducting polymer (polyaniline). The study investigated five cation exchangers, five plasticizers (of different polarities and dielectric constants), and four ionophores with different physicochemical characters on the sensor performance. The study substantiates a data-driven selection of the optimum membrane recipe. The latter included sodium tetraphenylborate as an ion exchanger, dioctylphthalate as a plasticizer, and hydroxypropyl-ß-cyclodextrin as ionophore. The membrane proved a near-Nernstian slope of 37.5 mV per decade, a LOQ of 2.99 × 10-6 M, and a stable fast response. The selectivity study proved poor responses to common physiological ions. The developed sensor was used for the determination of VB in its pure powder form, marketed formulation, and plasma samples. The fast and direct sensor response enables a wide range of applications in quality control laboratories and clinical studies.

Traditional versus advanced chemometric models for the impurity profiling of paracetamol and chlorzoxazone: Application to pure and pharmaceutical dosage forms.

Traditional Partial Least Squares (PLS) and Advanced Artificial Neural Network (ANN) models were applied for the quantitative determination of paracetamol (PAR) and chlorzoxazone (CZX) together with their process-related impurities namely; 4-aminophenol (AP), 4­chloroacetanilide (AC), 4­nitrophenol (NP), 4­chlorophenol (CP) and 2­amino-4-chlorophenol (ACP). Both models were applied first to full spectrum data then the results were compared to those obtained after wavelength selection using Genetic Algorithm (GA). A 5-level 7-factor experimental design was used giving rise to 25 mixtures containing different proportions of the seven compounds. The calibration set was composed of 15 mixtures while 9 mixtures were used in the validation set to test the predictive ability of the suggested models. The four models PLS, ANN, GA-PLS and GA-ANN were successfully applied for the determination of PAR and CZX in their pure and pharmaceutical dosage form. One way ANOVA was carried out between the developed methods and the official ones for PAR and CZX and no significant difference was found. The four models can be easily applied for the determination of the selected drugs in quality control laboratories lacking expensive HPLC instruments.

Study of Thermal Analysis Behavior of Fenbendazole and Rafoxanide.

Purpose: Thermal analysis techniques have been applied to study the thermal behavior of fenbendazole (Fen) and rafoxanide (Raf). Semi-empirical molecular orbital calculations were used to confirm these results. Methods: Thermogravimetric analysis, derivative thermogravimetry, differential thermal analysis and differential scanning calorimetry were used to determine the thermal behavior and purity of the drugs under investigation. Results: Thermal behavior of Fen and Raf were augmented using semi-empirical molecular orbital calculations. The purity values were found to be 99.17% and 99.60% for Fen and Raf, respectively. Conclusion: Thermal analysis techniques gave satisfactory results to obtain quality control parameters such as melting point and degree of purity at low cost, furthermore, its simplicity and sensitivity justifies its application in quality control laboratories.