Saad, A. S., A. M. Abou Al-Alamein, M. M. Galal, and H. E. Zaazaa, "Voltammetric determination of lidocaine and its toxic metabolite using C18 silica modified carbon paste electrode", Journal of the Electrochemical Society, vol. 166, issue 2, pp. B103-B109, 2019. Abstract

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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

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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

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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

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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.

Abdalla, O. M., A. M. Abdel-Megied, A. S. Saad, and S. S. Soliman, "Simultaneous spectrophotometric determination of compounds having relatively disparate absorbance and concentration ranges; application to antidiabetic formulation of linagliptin and metformin.", Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, vol. 203, pp. 112-117, 2018. Abstract

The limited linear range of UV-Visible spectrophotometry may be insufficient to occupy multiple components with wide variations in their concentrations or absorptivities that will hinder the simultaneous spectrophotometric determination and may require spiking or measurements in subsequent dilution steps. The current work introduces the absorptivity target concentration (ATC) values, a simple way for the proper choice of the working spectral region to execute accurate and linear spectrophotometric measurements. Simultaneous spectrophotometric determination of linagliptin (LNG) and metformin (MET) that are present in a ratio of 1:400 was carried out using traditional spectrophotometric techniques such as third derivative and derivative ratio as well as recently developed techniques such as ratio difference and factorized dual wavelength. The proposed methods were able to determine MET in the concentration range of 50-1200 μg mL. On the other hand, LNG was successfully determined from its zero-order absorption UV-spectrum at λ (296 nm) in the concentration range 2.5-25 μg mL. The mentioned methods were successfully applied for the determination of the LNG and MET in their combined dosage form. The methods were validated according to the ICH guidelines. The proposed ATC value can be employed as a novel concept for the proper choice of the working spectral region where spectrophotometric measurements can be deployed accurately and precisely.

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.

Saad, A. S., M. R. El-Ghobashy, N. S. Ayish, and B. A. El-Zeany, "ISE-potentiometric sensor for the determination of zolmitriptan: applications in plasma, pharmaceutical formulation and in vitro release profile", New Journal of Chemistry, vol. 42, issue 18, pp. 15263 - 15269, 2018///. AbstractWebsite

Six different sensors were fabricated and compared for the potentiometric determination of a widely used serotonin receptor agonist zolmitriptan (ZT), which is mainly used for the treatment of acute migraine attacks.

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