Marwa El-Badry Mohamed

In situ modified screen printed and carbon paste ion selective electrodes for potentiometric determination of naphazoline hydrochloride in its formulation

The construction and performance characteristics of new sensitive and selective in situ modified screen printed (ISPE) and carbon paste (ICPE) electrodes for determination of naphazoline hydrochloride (NPZ-HCl) have been developed. The electrodes under investigation show potentiometric response for NPZ-HCl in the concentration range from 7.0×10–7 to 1.0×10–2 M at 25 °C and the electrode response is independent of pH in the range of 3.1–7.9. These sensors have slope values of 59.7±0.6 and 59.2±0.2 mV decade−1 with detection limit values of 5.6×10–7 and 5.9×10–7 M NPZ-HCl using ISPE and ICPE, respectively. These electrodes show fast response time of 4–7 s and 5–8 s and exhibits lifetimes of 28 and 30 days for ISPE and ICPE, respectively. Selectivity for NPZ-HCl with respect to a number of interfering materials was also investigated. It was found that there is no interference from the investigated inorganic cations, anions, sugars and other pharmaceutical excipients. The proposed sensors were applied for the determination of NPZ-HCl in pharmaceutical formulation using the direct potentiometric method. It showed a mean average recovery of 100.2% and 102.6% for ISPE and ICPE, respectively. The obtained results using the proposed sensors were in good agreement with those obtained using the official method. The proposed sensors show significantly high selectivity, response time, accuracy, precision, limit of detection (LOD) and limit of quantification (LOQ) compared with other proposed methods.

Melatonin charge transfer complex with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone: Molecular structure, DFT studies, thermal analyses, evaluation of biological activity and utility for determination of melatonin in pure and dosage forms

A simple, accurate and fast spectrophotometric method for the quantitative determination of melatonin (ML) drug in its pure and pharmaceutical forms was developed based on the formation of its charge transfer complex with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an electron acceptor. The different conditions for this method were optimized accurately. The Lambert-Beers law was found to be valid over the concentration range of 4-100μgmL-1 ML. The solid form of the CT complex was structurally characterized by means of different spectral methods. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were carried out. The different quantum chemical parameters of the CT complex were calculated. Thermal properties of the CT complex and its kinetic thermodynamic parameters were studied, as well as its antimicrobial and antifungal activities were investigated. Molecular docking studies were performed to predict the binding modes of the CT complex components towards E. coli bacterial RNA and the receptor of breast cancer mutant oxidoreductase.

The Use of Integrated Analytical Tools for Determination of Cyclopentolate and Naphazoline Hydrochlolrides in Pure and Pharmaceutical Preparations

Simple and sensitive spectrophotometric methods were described for the determination of cyclopentolate (CPH) and naphazoline hydrochlorides (NPZ) drugs in pure form and in pharmaceutical preparations based on ion pair and charge transfer complexation reactions, respectively. The first method is based on the reaction of the CPH drug with Mo(V)-thiocyanate in hydrochloric acid medium and dyestuff reagents namely bromophenol blue (BPB), bromocresol green (BCG) and bromocresol purple (BCP). The ion pair complexes formed were quantitatively extracted into dichloroethane, chloroform and methylene chloride in case of Mo(V)-thiocyanate, BPB, and BCP reagents, respectively. The second method is based on charge transfer complex formation between NPZ (electron donor) and TCNQ (π-acceptor reagent). All the experimental variables were optimized. The calibration graphs are rectilinear in the concentration ranges 5.00-250.0, 0.93-56.07, 0.93-56.07 and 1.86-56.07 μg mL -1 for CPH using Mo(V)-thiocyanate, BPB, BCG and BCP reagents, respectively, and 2.00-240.0 μg mL -1 for NPZ using TCNQ reagent. The Sandell sensitivity (S), molar absorptivity, correlation coefficient and regression equations were calculated. The limits of detection (LOD =5.54, 0.51, 0.32, 0.54 and 3.19 using Mo(V)-thiocyanate, BPB, BCG ,BCP and TCNQ reagents, respectively) and limits of quantification (LOQ = 7.55, 1.70, 1.05, 1.80 and 5.60 using Mo(V)-thiocyanate, BPB, BCG , BCP and TCNQ reagents, respectively) are calculated. The law values of standard deviation and relative standard deviation reflect the accuracy and precision of the proposed methods. The two methods can be applied to the analysis of the two drugs in eye drops, with no evidence of interference from excipients. There was no significant difference between each of the two methods and the official one.

A newly validated and characterized spectrophotometric method for determination of a three water pollutants metal ions

A simple, fast and accurate spectrophotometric method had been developed to determine lead (II), chromium (III) and barium (II) ions in pure forms and in spiked water samples using thoron (THO) as a reagent forming colored complexes. It was found that the formed complexes absorbed maximally at 539, 540 and 538nm for Pb(II)-THO, Cr(III)-THO and Ba(II)-THO complexes, respectively. The optimum experimental conditions for these complexes had been studied carefully. Beers law was obeyed in the range 1-35, 1-70, and 1-45μgmL-1 for Pb (II), Cr(III) and Ba(II) ions with THO reagent, respectively. Different parameters such as linearity, selectivity, recovery, limits of quantification and detection, precision and accuracy were also evaluated in order to validate the proposed method. The results showed that, THO was effective in simultaneous determination of Pb(II), Cr(III) and Ba(III) ions in pure forms and in spiked water samples. Also, the results of the proposed method were compared with that obtained from atomic absorption spectrometry. The isolated solid complexes had been characterized using elemental analysis, X-ray powder diffraction (XRD), IR, mass spectrometry and TD-DFT calculations. Their biological activities were investigated against different types of bacteria and fungi organisms.

Spectrophotometric determination of fenoprofen calcium drug in pure and pharmaceutical preparations. Spectroscopic characterization of the charge transfer solid complexes

Simple, accurate and robust spectrophotometric method was developed for determination of fenoprofen calcium drug (FPC). The proposed method was based on the charge transfer (CT) reaction of FPC drug (as n-electron donor) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,4,6-trinitrophenol (picric acid, PA) or 1,2,5,8-tetrahydroxyanthraquinone (Quinalizarin, QZ) (as π-acceptors) to give highly colored charge transfer complexes. Different variables affecting the reaction such as reagent concentration, temperature and time have been carefully optimized to achieve the highest sensitivity. Beers law was obeyed over the concentration ranges of 2-60, 0.6-90 and 4-30μgmL-1 using DDQ, PA and QZ CT reagents, respectively, with correlation coefficients of 0.9986, 0.9989 and 0.997 and detection limits of 1.78, 0.48 and 2.6μgmL-1 for the CT reagents in the same order. Elucidation of the chemical structure of the solid CT complexes formed via reaction between the drug under study and π-acceptors was done using elemental, thermal analyses, IR, 1H NMR and mass spectrometry. X-ray diffraction was used to estimate the crystallinity of the CT complexes. Their biological activities were screened against different bacterial and fungal organisms. The method was applied successfully with satisfactory results for the determination of FPC drug in fenoprofen capsules. The method was validated with respect to linearity, limit of detection and quantification, inter- and intra-days precision and accuracy. The proposed method gave comparable results with the official method.

Application of carbon sensors for potentiometric determination of copper(II) in water and biological fluids of Wilson disease patients. Studying the surface reaction using SEM, EDX, IR and DFT

The performance characteristics of a new selective and sensitive modified screen printed electrode (MSPE; electrode I) and carbon paste electrode (MCPE; electrode II) based on 2-N, N-dimethylcarbamimidoyl (metformin) as modifier for the potentiometric determination of copper (II) in water sample, serum and urine samples of Wilson disease patients have been optimized. The chemical reaction which happens between Cu (II) and the modifier on the surface of the sensors was investigated with scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX), IR spectra measurement and computational calculations at DFT/B3LYP. The sensors showed perfect potentiometric response for Cu (II) over concentration range of 1.0 × 10-6 - 1.0 × 10-2 and 1.0 × 10-6 - 5.0 × 10-2 mol L-1 with a detection limit of 1.0 × 10-6 mol L-1with divalent slope value 30.2 and 31.8 mV decade-1 over the pH range of 2-6 for MCPE and MSPE, respectively. MSPE was stable with repeatable potential over period of 37 days and exhibits fast response time of 6 and 10 s for MSPE and MCPE, respectively. Also, these sensors exhibited good selectivity towards Cu(II) with respect to other metal ions and have higher antibacterial activity against Staphylococcus aureus as Gram-positive bacteria and Escherichia coli as Gram-negative bacteria. The obtained results using the sensors were in agreement with those obtained using the reported method.

Modified carbon paste electrode for potentiometric determination of aluminium ion in spiked real water sample

The present paper describes the development of a new chemically modified carbon paste electrode based on azithromycin (AMC) that considered as a selective aluminium recognition agent in the carbon paste electrode (CPE). This electrode was fully characterized in terms of composition, response time, usable pH range and temperature. The electrode exhibited a Nernstian response for Al3+ ion over a concentration range from 7.0 × 10–6 to 1.0 × 10–2 mol L–1 with a slope of 21.3 ± 0.18 mV decade–1 and the limit of detection was 6.0 × 10–6 mol L−1. It had a response time of about 6 s. The proposed sensor possesses a very good selectivity with respect to a variety of other cations. Finally this modified electrode was applied for the determination of the concentration of Al3+ ion in different water samples and the obtained results were comparable with those obtained with atomic absorption spectrometer (AAS).

Flowcytometric analysis of aldehyde dehydrogenase activity in mononuclear cells from umbilical cord blood

Aldehyde dehydrogenase (ALDH) is a cytosolic enzyme that is responsible for the oxidation of intracellular aldehydes. Elevated levels of ALDH have been demonstrated in murine and human progenitor cells compared with other hematopoietic cells, and this is thought to be important in chemoresistance and purification techniques and an indication of the proper function of the cell. A Flowcytometric method for the assessment of ALDH activity in viable cells recently has been developed. Forty six cord blood samples from mothers which underwent normal delivery of full term infants were obtained, after informed consent. Mononuclear cells were obtained by Ficoll-Paque density centrifugation and ammonium chloride red cell lysis. Percentage of viable cells was determined by trypan blue exclusion dye. Cells were labeled with Aldefluor reagent (Vancouver Canada) as described by the manufacturer. Cells were then stained with phycoerythrin (PE)–conjugated anti-CD34 (Miltenyi Biotec, Cologne, Germany) antibodies for 30 min at 4°C. Cells were washed and re-suspended in phosphate-buffered saline (PBS) with 2% fetal calf serum. Cells were then analyzed on coulter epics flow cytometer. The mean percentage of ALDH enzyme expression among the CD34+ cells in the cord blood samples was 61.3% with a minimum of 28% and a maximum of 94.6%. Significant correlations were found between the white blood cell (WBCS) count in the cord blood samples and both the CD34+ cell count and the count of ALDH expressing cells, while no correlation was found between the CD34+ cells count or the ALDH expressing cells count in the cord blood samples and either the sex or the weight of the newborn. Identification and isolation of cells on the basis of ALDH activity provides a tool for their isolation and further analysis. In summary, a high ALDH-1 activity identifies CD34+ cells in cord blood. Key words: Umbilical cord blood, stem cells, aldehyde dehydrogenase (ALDH), CD34.