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Saad, A. S., M. E. Draz, I. A. Naguib, H. E. Zaazaa, A. S. Lashien, and F. F. Abdallah, "Adoption of Advanced Chemometric Methods for Determination of Pyridoxine HCl, Cyclizine HCl, and Meclizine HCl in the Presence of Related Impurities: A Comparative Study", Journal of AOAC International, vol. 105, issue 2, pp. 630-640, 2022.
Rahman, M. A. A., A. S. Saad, S. S. El-Mosallamy, M. R. Elghobashy, H. E. Zaazaa, and S. A. Atty, "Economical Voltammetric Sensor for Sensitive Rapid Determination of Ondansetron in the Presence of Opioid Antagonist Naltrexone", Electrocatalysis, 2022.
Soliman, S. S., A. E. El-Haddad, G. A. Sedik, M. R. Elghobashy, H. E. Zaazaa, and A. S. Saad, "Experimentally designed chemometric models for the assay of toxic adulterants in turmeric powder", RSC advances, vol. 12, issue 15, pp. 9087-9094, 2022.
Saad, A. S., M. E. Draz, I. A. Naguib, H. E. Zaazaa, A. S. Lashien, and F. F. Abdallah, "Impurity‐profiling UPLC methods for quantitative analysis of some antiemetics formulated with pyridoxine", Biomedical Chromatography, vol. 36, issue 6, pp. e5353, 2022.
Draz, M. E., H. W. Darwish, I. A. Darwish, and A. S. Saad, "Solid-state potentiometric sensor for the rapid assay of the biologically active biogenic amine (tyramine) as a marker of food spoilage", Food Chemistry, vol. 346, pp. 128911 - 128911, 2021/12//. AbstractWebsite
Draz, M. E., I. A. Naguib, and A. S. Saad, "Computational ionophore selection during optimization of a portable calixarene based sensor for direct assay of levamisole residues in livestock products", Journal of Electroanalytical Chemistry, vol. 897, pp. 115546 - 115546, 2021/09//. AbstractWebsite
Saad, A. S., N. S. Ismail, N. S. Gaber, and E. S. Elzanfaly, "Introducing a Polymeric Ion Exchanger as a Modifier for Carbon-Paste Potentiometric Sensors", Journal of The Electrochemical Society, vol. 168, issue 1, pp. 017504 - 017504, 2021/01//. AbstractWebsite
Ibrahim, H., A. M. Hamdy, H. A. Merey, and A. S. Saad, "Simultaneous Determination of Paracetamol, Propyphenazone and Caffeine in Presence of Paracetamol Impurities Using Dual-Mode Gradient HPLC and TLC Densitometry Methods", Journal of Chromatographic Science, vol. 59, issue 2, pp. 140 - 147, 2021/01//. AbstractWebsite

Two chromatographic methods were validated for the determination of the widely prescribed analgesic and antipyretic drug combination of paracetamol (PC) (recently integrated into the supportive treatment of COVID-19), propyphenazone (PZ) and caffeine (CF) in the presence of two PC impurities, namely 4-aminophenol and 4-nitrophenol. A “dual-mode” gradient high-performance liquid chromatography method was developed, where the separation was achieved via “dual-mode” gradient by changing both the ternary mobile phase composition (acetonitrile: methanol: water) and the flow rate. This enables a good resolution within a relatively shorter analysis time. The analysis was realized using Zorbax Eclipse XDB column C18, 5 μm (250 × 4.6 mm) and the UV detector was set at 220 nm. The other method is a thin-layer chromatography densitometry method, where the separation was achieved using a mobile phase composed of chloroform: toluene: ethyl acetate: methanol: acetic acid (6: 6: 1: 2: 0.1, by volume). Densitometric detection was performed at 220 nm on silica gel 60 F254 plates. The developed methods were fully validated as per the ICH guidelines and proved to be accurate, robust, specific and suitable for application as purity indicating methods for routine analysis of PC in pure form or in pharmaceuticals with PZ and CF in quality control laboratories.

Wahba, M. E., D. El Wasseef, A. S. Saad, and M. E. Draz, "Calixarene based portable sensor for the direct assay of indiscriminate ephedrine content of weight loss herbal preparations", RSC Advances, vol. 11, issue 21: Royal Society of Chemistry, pp. 12833 - 12844, 2021///. AbstractWebsite

A novel potentiometric sensor was developed and optimized for the quantitative analysis of ephedrine in non-prescribed herbal supplements used as adjunctive therapy for weight loss. An initial optimization study aimed to reach the optimum membrane composition, sensor assembly, and experimental conditions. The study evaluated the effect of several factors on the sensor performance including different ion-exchangers, plasticizers, ionophores, membrane thicknesses, soaking solution concentrations, soaking time intervals, and pH. The optimized polyvinyl chloride membrane included tungstophosphoric acid hydrate as a cation exchanger, tricresyl phosphate as a plasticizer, and calix[8]arene as an ionophore to enhance the sensitivity and selectivity of the developed sensor. The polyvinyl chloride membrane was drop-casted over a polyaniline modified glassy carbon electrode surface to form a solid-state sensor. The proposed membrane succeeded to quantify ephedrine over a linear range of 6 × 10−6to 1 × 10−2M with a LOD of 3.60 × 10−6M, acceptable selectivity, and fast response time. The IUPAC characterization of sensor response and International Conference on Harmonization validation parameters were calculated. The method successfully determined ephedrine concentration in spiked herbal mixtures and determined labeled and undeclared ephedrine content of weight loss herbal preparations.

Edrees, F. H., A. S. Saad, M. T. Alsaadi, N. H. Amin, and N. S. Abdelwahab, "Experimentally designed chromatographic method for the simultaneous analysis of dimenhydrinate, cinnarizine and their toxic impurities", RSC Advances, vol. 11, issue 3, pp. 1450 - 1460, 2021///. AbstractWebsite

Experimentally designed HPLC method for simultaneous analysis of dimenhydrinate, cinnarizine and their toxic impurities.

Soliman, M., A. S. Saad, N. S. Ismail, and H. E. - S. Zaazaa, "A validated RP-HPLC method for determination of nitroxinil and investigation of its intrinsic stability", Journal of the Iranian Chemical Society, vol. 18, issue 2, pp. 351 - 361, 2021. AbstractWebsite

A fast, sensitive and selective RP-HPLC method was developed for extensive investigation of nitroxinil’s stability. The stability of the studied drug was tested under different stress conditions, namely hydrolytic, oxidative, photolytic and thermal. Separation of nitroxinil and its degradation products was achieved in less than 5 min using Venusil XBP C18 (150 × 2.1 mm id, 5 um particle size) column and isocratic mobile phase composed of 0.1% triethylamine pH 2.5 (adjusted with phosphoric acid) and acetonitrile mixture in a ratio of (70:30; v/v). UV detection at 270 nm was employed for monitoring nitroxinil degradation behavior over a linearity range of 1–75 µg/mL. Plackett–Burman experimental design was adopted for robustness testing of the developed chromatographic method. LC-mass identification of nitroxinil’s hydrolytic and oxidative degradations was attempted, and the suggested mechanism was deduced. The proposed method was successfully applied in determination of the drug in raw material and pharmaceutical dosage form.

Heragy, M. O., A. A. M. Moustafa, E. S. ElZanfaly, and A. S. Saad, "A portable solid-state potentiometric sensor based on a polymeric ion-exchanger for the assay of a controversial food colorant (sunset yellow)", Analytical Methods, vol. 13, issue 41, pp. 4896-4903, 2021.
Yehia, A. M., A. S. Saad, and M. A. Tantawy, "USB multiplex analyzer employing screen-printed silver electrodes on paper substrate; A developed design for dissolution testing", Journal of Pharmaceutical and Biomedical Analysis, vol. 186: Elsevier, pp. 113272, 2020. Abstract


Saad, A. S., F. H. Edrees, M. T. Alsaadi, N. H. Amin, and N. S. Abdelwahab, "Experimentally Designed Sensor for Direct Determination of the Environmentally Hazardous Compound and Occupational Exposure Biomarker (p-aminophenol) in Different Sampling Matrices", Journal of The Electrochemical Society, vol. 167, issue 14, pp. 147504, 2020.
Galal, M. M., and A. S. Saad, "Portable solid-state sensor for therapeutic monitoring of an antineoplastic drug; vinblastine in human plasma", RSC Advances, vol. 10, issue 42699, pp. 42705, 2020.
Abdelwahab, N. S., F. H. Edrees, M. T. Alsaadi, N. H. Amin, and A. S. Saad, "Simultaneous estimation of dimenhydrinate, cinnarizine and their toxic impurities benzophenone and diphenylmethylpiperazine; in silico toxicity profiling of impurities", RSC Advances, vol. 10, pp. 37439-37448, 2020.
Saad, A. S., and H. A. M. Essam, "Evaluating the Effect of four Hosting Ionophores on the Performance of Anion Selective Potentiometric Sensor", Electroanalysis, vol. 31, issue 11: Wiley Online Library, pp. 2224 - 2231, 2019. Abstract


Saad, A. S., M. R. El-Ghobashy, N. S. Ayish, and B. A. El-Zeany, "Greenness assessment as per Eco ‑ scale and AMVI metrics for the chromatographic assay of selected drugs in a semisolid dosage form and in tissues", Chemical Papers, vol. 73, issue 3: Springer International Publishing, pp. 683-691, 2018///, 2019. AbstractWebsite


Saad, A. S., E. S. Elzanfaly, M. K. Halim, and K. M. Kelani, "Comparing the predictability of different chemometric models over UV-spectral data of isoxsuprine and its toxic photothermal degradation products.", Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, vol. 219, pp. 444-449, 2019. Abstract

Isoxsuprine (ISX) is widely used for cerebral and peripheral vascular diseases. A comparative study was held among different multivariate calibration models for selective determination of a complex mixture of Isoxsuprine and four of its toxic photothermal degradation products that impair kidney and liver functions. The Partial Least Squares (PLS) and Artificial Neural Network (ANN) models were applied on the specific spectrum and on selected wavelengths using genetic algorithm (GA) technique as an efficient variable selection tool. The effect of GA on the model construction and performance was evaluated. The multilevel multifactor experimental design was adopted for the construction of the calibration set. Optimized parameters were used for the development of the different models. The performances of the developed models were assessed by predicting the concentration of eight different mixtures composing the validation set. Results were compared to one another and to the official method using one-way ANOVA statistical test to assure the validity of the constructed models. The lower chance of overfitting offered by ANN minimized the RMSEP relative to the PLS. On the other hand, the application of GA prior to model implementation affected the number of latent variables the prediction ability of both PLS and ANN models. The validated models were successfully applied as stability indicating assay methods for the selective determination of ISX and its photothermal degradation products in ISX raw material and market formulations.

Saad, A. S., N. S. Ismail, M. Soliman, and H. E. Zaazaa, "Study of Oxyclozanide's Innate Stability Coupled with the Assessment of its Aquatic Photo-Transformation Using a Validated Isocratic HPLC Method.", Journal of AOAC International, vol. 102, issue 2, pp. 480-489, 2019. Abstract

Oxyclozanide (OXY) is a veterinary medicine used for control of fascioliasis in farm animals. Literature review shows absence of sufficient information regarding its stability. Such information is important as it affects many stages of a drug's life cycle, from pharmaceutical manufacturing to its environmental fate understanding of the degradation of the drug once it is placed in the environment. An HPLC method was developed to address the impact of different stress conditions on OXY's stability. OXY's stability was investigated by exposure to forced acid and alkaline hydrolysis, thermal, oxidative and photolytic degradation, which are different stress conditions applied to the forced degradation study. Separation was performed on Eurosphere C18 analytical column (125 × 4.6 mm, 5 μm particle size) using 50 mM sodium acetate trihydrate (pH 4.5) and acetonitrile (50:50, v/v) as mobile phase and UV detection at 254 nm. A photolytic kinetics study was conducted by monitoring OXY photolysis under monochromatic and polychromatic light sources (UV lamp at 366 nm and natural sunlight) in aqueous buffers of different pHs (5, 7, and 9). LC-MS was used to identify the major photolytic degradate. OXY was quantified over a concentration range of 1-80 μg/mL with mean recovery of 99.32 ± 1.80%. The drug was susceptible to oxidative and photolytic degradation. The photolytic kinetics were pH dependent. The LC-MS result supported photo-dehalogenation degradation mechanism. The developed method could be used in OXY stability testing. The results of the photolytic kinetics study can address OXY aquatic photo-transformation, thereby predicting its environmental fate and risks imposed on the ecosystem. An HPLC method was developed for monitoring OXY degradation behavior and studying its photolytic kinetics with identification of its photodegradate.