Tantawy, M. A., H. Y. Aboul-Enein, and A. M. Yehia, "Resolving phenylephrine HCl and guaifenesin enantiomers on cellulose-based chiral stationary phases: Separation of four enantiomers on 50-mm column", ChiralityChirality, vol. 35, issue 12: John Wiley & Sons, Ltd, pp. 1019 - 1028, 2023. AbstractWebsite

Abstract Chiral high performance liquid chromatographic technique usually employs polysaccharide-based stationary phases in a normal phase mode. This frequently generates large waste of organic solvents. Using shorter columns of 50?mm length as well as a mobile phase with a high water percentage are common approaches for greening this analytical technique. In this context, a new chiral chromatographic technique was developed for simultaneous enantio-separation of phenylephrine HCl and guaifenesin racemates. Four 50?mm cellulose-based columns were experimented to separate the four enantiomers in a reversed phase mode. A face centered design was then employed to optimize the mobile phase acetonitrile% and flow rate on Lux Cellulose-1 (50???4.6?mm, 5??m). The simultaneous resolution of the cited drugs enantiomers was achieved using acetonitrile?water (30:70, by volume), with a flow rate of 0.5?ml?min?1. These optimized chromatographic conditions separate the enantiomers in 7?min running time, generating about 1.0?ml acetonitrile per run. The proposed method was favorably compared with other reported chiral ones in terms of waste volume generated and analysis time required.

Kelani, K. M., M. A. Hegazy, A. M. Hassan, and M. A. Tantawy, Application of multivariate chemometrics tools for spectrophotometric determination of naphazoline HCl, pheniramine maleate and three official impurities in their eye drops, , vol. 13, issue 1, pp. 19678, 2023. AbstractWebsite

This work is concerned with exploiting the power of chemometrics in the assay and purity determination of naphazoline HCl (NZ) and pheniramine maleate (PN) in their combined eye drops. Partial least squares (PLS) and artificial neural network (ANN) were the chosen models for that purpose where three selected official impurities, namely; NZ impurity B and PN impurities A and B, were successfully determined. The quantitative determinations of studied components were assessed by percentage recoveries, standard errors of prediction as well as root mean square errors of prediction. The developed models were constructed in the ranges of 5.0–13.0 μg mL−1 for NZ, 10.0–60.0 μg mL−1 for PN, 1.0–5.0 μg mL−1 for NZ impurity B and 2.0–14.0 μg mL−1 for two PN impurities. The proposed models could determine NZ and PN with respective detection limits of 0.447 and 1.750 μg mL−1 for PLS, and 0.494 and 2.093 μg mL−1 for ANN. The two established models were compared favorably with official methods where no significant difference observed.

Hassan, A. M., K. M. Kelani, M. A. Hegazy, and M. A. Tantawy, Molecular imprinted polymer-based potentiometric approach for the assay of the co-formulated tetracycline HCl, metronidazole and bismuth subcitrate in capsules and spiked human plasma, , vol. 1278, pp. 341707, 2023. AbstractWebsite

BackgroundAn anti-H-pylori co-formulated mixture of tetracycline HCl (TET), metronidazole (MET), and bismuth subcitrate (BSC) is recently available. Only two chromatographic and spectrophotometric methods are reported for determining those drugs simultaneously where the effect of impurities that could be present as well as the biological fluids matrix influence do not be taken into consideration. There is a need to develop an easy-to-use potentiometric technique for analysis of TET, MET, and BSC in their co-formulated capsules, in presence of some official impurities and in spiked human plasma.
Results
Three carbon paste electrodes (CPEs) were fabricated for this purpose. Being a solid contact ion-selective electrode, CPE suffers from the creation of a water layer affecting its stability and reproducibility. Besides, it has a common problem in differentiation between two drugs carrying the same charge (positively charged TET and MET). Water layer formation was prevented through inserting polyaniline nanoparticles (≈10.0 nm diameter) between solid contact and ion-sensing membrane in the three proposed sensors. TET and MET interference was overcome by synthesizing a corresponding molecular imprinted polymer (MIP) for each drug. The synthesized MIPs were inserted in equivalent sensing membranes and characterized using several techniques. The suggested MIPs have a noticeable enhanced sensitivity in potentiometric determination. The obtained LODs were 5.88 × 10−8, 5.19 × 10−7, and 1.73 × 10−6 M for TET, MET and BSC proposed CPEs, respectively, with corresponding slopes of 57.37, 56.20, and −57.40 mV decade−1.
Significance
The proposed potentiometric method makes the detection of the three cited drugs simple, fast, and feasible. This approach is the first for determining three drugs potentiometrically in one combined formulation. The obtained results were compared favorably with previously reported potentiometric methods.

Tantawy, M. A., A. M. Yehia, and H. T. Elbalkiny, All-solid-state chip utilizing molecular imprinted polymer for erythromycin detection in milk samples: Printed circuit board-based potentiometric system, , vol. 190, issue 10, pp. 408, 2023. AbstractWebsite

Detection of erythromycin (ERY) residues in commercial milk samples is crucial for the safety assessment. Herein, a printed circuit board was patterned as a feasible miniaturized potentiometric sensor for ERY determination in dairy samples. The proposed chip design fits to a 3.5-mm female audio plug to facilitate the potential measurements of working electrode versus reference one in this all-solid-state system. The sensor utilizes molecular imprinted polymer (MIP) for the selective recognition of the studied drug in such challenging matrix. The electrode stability is achieved through the addition of poly (3,4-ethylenedioxythiophene) nano-dispersion on its surface. The proposed device detects down to 6.6 × 10−8 M ERY with a slope of 51 mV/decade in the 1 × 10−7–1 × 10−3 M range. The results display high accuracy (99.9% ± 2.6) with satisfactory relative standard deviation for repeatability (1.6%) and reproducibility (5.0%). The effect of common antibiotic classes, namely, amphenicols, beta-lactams, fluoroquinolones, sulfonamides, and tetracyclines, can be neglected as evidenced by their calculated binding capacities towards the proposed MIP. The calculated selectivity coefficients also show a good electrode performance in the presence of naturally present inorganic ions allowing its application to different milk samples.

Tantawy, M. A., S. A. Abdulla, O. Y. Mohamed, and A. M. Abou Al-Alamein, Normal-Phase TLC and Gradient Reversed-Phase HPLC for the Simultaneous Determination of Enrofloxacin and Bromhexine HCl in Presence of Two of Their Official Impurities, , vol. 61, issue 6, pp. 546 - 551, 2023/07/01. AbstractWebsite

In this work, two chromatographic methods are developed and validated for the determination of enrofloxacin and bromhexine (BRM) HCl in the presence of two of their specified impurities, ciprofloxacin and BRM impurity C. The suggested chromatographic methods included the use of thin layer chromatography (TLC-densitometry) and high-performance liquid chromatography (HPLC). In case of TLC-densitometry, good separation was achieved by using mobile phase of n.butanol:acetone:water:glacial acetic acid:triethylamine (10:3:1:0.5:0.5, by volume) on silica gel stationary phase at 254-nm detection. The developed HPLC method used BDS HYPERSIL C18 column with a mobile phase of water:acetonitrile:methanol:triflouroacetic acid. A linear gradient elution of 75–10%, 20–50% and 5–40% for water, acetonitrile and methanol, respectively, was applied in 13 min at a flow rate of 1.5 mL min−1. These methods were sufficient to separate the four substances simultaneously, and they are validated as per International Conference on Harmonization guidelines.

Tantawy, M. A., I. A. Wahba, Samah S Saad, and N. K. Ramadan, Classical versus chemometrics tools for spectrophotometric determination of fluocinolone acetonide, ciprofloxacin HCl and ciprofloxacin impurity-A in their ternary mixture, , vol. 17, issue 1, pp. 49, 2023. AbstractWebsite

Green, simple, accurate and robust univariate and chemometrics assisted UV spectrophotometric approaches have been adopted and validated for concurrent quantification of fluocinolone acetonide (FLU), ciprofloxacin HCl (CIP) together with ciprofloxacin impurity-A (CIP imp-A) in their ternary mixture. Double-divisor ratio spectra derivative (DDRD) method has been used for determination of FLU. On the other hand, the first (D1) and second (D2) derivative approaches have been applied for the quantification of CIP and CIP imp-A, respectively. For the ratio difference (RD), derivative ratio (DR), and mean centering of ratio spectra (MC) methods, CIP and its impurity A have been simultaneously determined. The acquired calibration plots were linear over the concentration range of 0.6–20.0 μg/mL, 1.0–40.0 μg/mL and 1.0–40.0 μg/mL for fluocinolone acetonide, ciprofloxacin HCl, and ciprofloxacin impurity-A, respectively. The chemometrics methods namely; partial least squares (PLS) and artificial neural networks (ANN) were used for the concurrent determination of the three adopted components via using twenty-five mixtures as calibration set and fifteen mixtures as validation one. The investigated approaches were validated in accordance with International Council for Harmonisation (ICH) guidelines, and statistically compared with the official ones. The proposed methods were acceptably applied to the examination of FLU and CIP in their pure powders and pharmaceutical ear drops.

Mohamed, H. M., H. E. Zaazaa, M. Abdelkawy, and M. A. Tantawy, Exploiting the power of UPLC in separation and simultaneous determination of pholcodine, guaiacol along with three specified guaiacol impurities, , vol. 17, issue 1, pp. 35, 2023. AbstractWebsite

Pholcodine and guaiacol are widely used together in pharmaceutical syrups for cough treatment. On the other hand, the Ultra Performance Liquid Chromatographic technique is characterized by having the power of increasing chromatographic efficiency and decreasing run time compared to the traditional High Performance Liquid Chromatographic one. In this work, this power was exploited for the simultaneous determination of pholcodine, guaiacol along with three guaiacol impurities, namely; guaiacol impurity A, guaiacol impurity B, and guaiacol impurity E. Good separation was achieved by employing Agilent Zorbax C8 column (50 × 2.1 mm) as the stationary phase, and acetonitrile: phosphate buffer pH 3.5 (40: 60, by volume) as a mobile phase. The proposed method was validated as per International Council for Harmonisation guidelines. Linear relationships, at ranges of 50–1000 µg mL−1 for pholcodine and 5–100 µg mL−1 for guaiacol and the three related impurities, were established. Finally, the proposed method was applied for pholcodine and guaiacol determination in Coughpent® syrup and compared favorably to the reported one.

Elbalkiny, H. T., A. M. Yehia, and M. A. Tantawy, "A trimodal detection paper chip for undisclosed drug “sibutramine” in nutraceuticals", Analytical Methods, vol. 15, issue 28: The Royal Society of Chemistry, pp. 3439 - 3448, 2023. AbstractWebsite

Nutraceuticals are promoted and marketed with the stated label of being natural as well as safe herbal products. In order to enhance their effectiveness, nutraceuticals are usually adulterated with undeclared constituents. Slimming herbs may contain sibutramine (SBT) which is an FDA-banned ingredient due to its fatal outcomes. This current work's aim is to design a trimodal sensor for SBT detection in different herbal slimming formulations. Screen-printed silver and multi-walled carbon nanotube inks were employed for the potentiometric sensor. The sensor was designed to fill a reaction well in which a carbon dot–silver nanoparticle pair was applied for fluorimetric and colorimetric purposes. The trimodal sensor was designed to fit an 8 mm 2-pin LED strip connector. Potentiometric measurement took place upon application of one sample aliquot then the optical reaction proceeded next in a specified zone for optical detection. These multiple detection mechanisms achieved the required selectivity for SBT determination in the presence of other slimming products' additives. This trimodal sensor satisfied World Health Organization standards for point-of-care devices demonstrating the suggested device as a dynamic part for rapid on-site detection of undisclosed SBT.

Kelani, K. M., M. A. Hegazy, A. M. Hassan, and M. A. Tantawy, "A New Comparative Potentiometric Method for Analysis of Omarigliptin Using Three Different Sensors", ElectroanalysisElectroanalysis, vol. 35, issue 1: John Wiley & Sons, Ltd, pp. e202100653, 2023. AbstractWebsite

Abstract This work represents first attempt for potentiometric determination of the most recent antidiabetic; omarigliptin. Three sensors, employing potassium tetrakis (p-chlorophenyl) borate as a lipophilic cation exchanger, were developed and compared. One liquid contact ion-selective electrode and two carbon paste-based solid contact ones, plain one and another one modified with polyaniline nanoparticles, were employed. Performances of fabricated sensors were assessed as per IUPAC recommendations. Incorporation of hydrophobic polyaniline nanoparticles as ion-to-electron transducer layer at solid contact/ion-sensitive membrane interface enhanced sensitivity and stability of the third sensor showing LOD of 2.5?10?7?mol?L?1 and slope of 58.57?mV decade?1. The three sensors were applied for omarigliptin determination in presence of its degradation products, in dosage form and spiked human plasma.

Tantawy, M. A., I. A. Wahba, Samah S Saad, and N. K. Ramadan, Two fabricated carbon paste electrodes for novel potentiometric determination of probenecid in dosage form and human plasma, , vol. 12, issue 1, pp. 20418, 2022. AbstractWebsite

Solid contact ion selective electrodes are extensively utilized owing to their marvelous performance over traditional liquid contact ones. The main drawback of those solid contact electrodes is aqueous layer formation which affects their constancy. Herein and to overcome this common drawback, a carbon paste electrode containing poly(3,4-ethylenedioxythiophene) was constructed and used for determination of probenecid at variant pH values. This modification decreased the potential drift down to 0.8 mV/h and improved its stability over 30 days. A Nernstian slope of − 57.8 mV/decade associated with a linear range of 1.0 × 10−6–1.0 × 10−2 mol/L was obtained. The modified carbon paste electrode successfully detected up to 8.0 × 10−7 mol/L probenecid. Results of this modified carbon paste electrode were also compared to unmodified one.

Tourism