Eman Y.Z. Frag

Potentiometric Determination of Ketotifen Fumarate in Pharmaceutical Preparations and Urine Using Carbon Paste and PVC Membrane Selective Electrodes

This study compares between unmodified carbon paste (CPE; the paste has no ion pair) and polyvinyl chloride (PVC) membrane selective electrodes that were used in potentiometric determination of ketotifen fumarate (KTF), where sodium tetraphenylborate (NaTPB) was used as titrant. The performance characteristics of these sensors were evaluated according to IUPAC recommendations which reveal a fast, stable, and linear response for KTF over the concentration range of 10−7 to 10−2 mol L−1. The electrodes show Nernstian slope value of 52.51 ± 0.20 and 51.51 ± 0.25 mV decade−1 for CPE and PVC membrane electrodes at 30°C, respectively. The potential is nearly stable over the pH range 3.0–6.0 and 2.0–7.0 for CPE and PVC membrane electrodes, respectively. Selectivity coefficient values towards different inorganic cations, sugars, and amino acids reflect high selectivity of the prepared electrodes. The electrodes responses at different temperatures were also studied, and long operational lifetime of 12 and 5 weeks for CPE and PVC membrane electrodes, respectively, were found. These are used for determination of ketotifen fumarate using potentiometric titration, calibration, and standard addition methods in pure samples, its pharmaceutical preparations (Zaditen tablets), and biological fluid (urine). The direct potentiometric determination of KTF using the proposed sensors gave recoveries % of 98.97 ± 0.53 and 98.62 ± 0.74 with RSD 1.42 and 0.63% for CPE and PVC membrane selective electrodes, respectively. Validation of the method shows suitability of the proposed sensors for use in quality control assessment of KTF. The obtained results were in a good agreement with those obtained using the reported spectrophotometric method.

Potentiometric determination of antihistaminic diphenhydramine hydrochloride in pharmaceutical preparations and biological fluids using screen-printed electrode

The performance characteristic of sensitive screen-printed (SPE) and carbon paste (CPE) electrodes was investigated for the determination of diphenhydramine hydrochloride (DPH) drug in pure, pharmaceutical preparations and biological fluids. Different experimental conditions namely types of materials used to prepare the working electrode (plasticizer), titrant, pH, temperature and life time were studied. Under these conditions, the SPE shows the best performance than CPE with respect to total potential change and potential break at the end point. The SPE and CPE exhibit suitable response to DPH in a concentration range of 1.0.10(-2) to 1.0.10(-6) mol/L with a limit of detection 9.70.10(-7) and 9.80.10(-7) mol/L, respectively. The slope of the system was 55.2±1.0 and 54.7±1.0 mV/decade over pH range 3.0-8.0 and 3-7 for SPE and CPE, respectively. Selectivity coefficients for DPH relative to a numbers of potential interfering substances were investigated. The SPE and CPE show a fast response time of 10 and 16s and were used over a period of 2 months with a good reproducibility. The sensors were applied successfully to determine DPH in pharmaceutical preparations and biological fluids. The results are compared with the official method.

Sensitive Extractive Spectrophotometric Method for the Determination of Some Statin Drugs in Pharmaceutical Preparations

The statins (or HMG-CoA reductase inhibitors) formed a class of hypolipidemic drugs used to lower cholesterol levels in people with or at risk of cardiovascular disease. They lower cholesterol by inhibiting the enzyme HMG-CoA reductase, which is the rate-limiting enzyme of the mevalonate pathway of chloestrol synethesis. The context and purpose: Simple, sensitive and rapid extractive spectrophotometric method has been developed for the assay of statin drugs, simvastatin, pravastatin sodium and atorvastatin calcium, in pure form and in tablets. The method involves the formation of coloured ion-pairs between the drugs and the Mo (V)-thiocyanate binary complex followed by their extraction with 1, 2dichloroethane and quantitative determination at 470 nm. The experimental conditions were optimized to obtain the maximum colour intensity. The method permits the determination of simvastatin, pravastatin and atorvastatin over a concentration range of 10-280, 10-150 and 10-180 μg mL, respectively, with the detection limit of 1.2, 0.26 and 0.642 μg mL, respectively. Results: The proposed methods are applicable for the assay of the investigated drug in different dosage forms and the results are in good agreement with those obtained by the official method that reported in the European pharmacopoeia and HPLC methods. The percentage recovery of 30-100 μg mL of the drugs under investigation are found to be 97.00-100.3 with a relative standard deviations (%) less than 1%. No interference was observed from common excipients present in pharmaceutical formulations. Conclusion: Simvastatin, pravastatin sodium and atorvastatin calcium drugs have been determined in pure form and in tablets using spectrophotometric method. Published In: Insight Pharmaceutical Sciences

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.

Utility of Ion-associate Formation Reactions for the SpectrophotometricDetermination of Sildenafil Citrate in Pure form and in Virecta Tablets

A simple, rapid and sensitive extractive spectrophotometric method has been developed for the assay of sildenafil citrate (SILC) in pure and pharmaceutical formulations (Virecta tablets). This method is based on the formation of chloroform soluble ion-pair of SILC with bromothymol blue (BTB) and methylene chloride soluble ion- pair of SILC with bromophenol blue (BPB) and eriochrome blue black R (EBBR) in borax buffer of pH 3 and volume 1mL for BTB while acetate buffer of pH 3 and volume 1mL for BPB and universal buffer of pH 2 and volume 1.5 mL for EBBR with absorption maximum at 415, 420 nm and 510 nm for BTB, BPB and EBBR reagents, respectively. Reaction conditions were optimized to obtain the maximum colour intensity. The absorbance was found to increase linearly with the increase in SILC concentration, which was corroborated by the calculated correlation coefficient values (0.9909, 0.9901 and 0.9917 for BTB, BPB and EBBR reagents, respectively). The systems obeyed Beer’s law over the concentration range of 1-40, 1-50 and 3-70 μg mL -1 for BTB, BPB and EBBR, respectively. Various analytical parameters have been evaluated and the results have been validated by statistical data. No interference was observed from common excipients present in pharmaceutical formulations.

Comparative Study of Different Modified Potentiometric Sensors for Determination of Moxifloxacin HCl in Dosage Forms

In situ modified carbon paste, screen-printed and PVC electrodes were fabricated for the determination of moxifloxacin hydrochloride (MOXHC). The electrodes under study revealed linear response over wide concentration range of 1.0×10-6 - 1.0×10-2 mol L-1 of MOXHC at 25oC with a monovalent cationic slope. It was found that the slope is 57.2 ± 2.6, 59.2 ± 4.6 and 57.7 ± 2.7 mV decade-1for IPVC electrodes modified with 7.5 mg NaTPB, PMA and PTA ion pairing agents, respectively, and 58.6 ± 1.7, 60.0 ± 2.0 and 59.0 ± 3.3 mV decade-1 for ISPE modified with 22, 16 and 30 mg NaTPB, RN and PTA ion pairing agents, respectively, but 60 ± 2.3 mV decade-1 for ICPE modified with 10 mg NaTPB. Moreover, the selectivity coefficient of the electrodes was determined by applying both matched potential and separate solution methods. The modified SPE sensor shows high selectivity and sensitivity for determination of MOXHC. The response of the electrodes was found to be pH independent in the range of 2-6 for ISPEs and IPVC electrodes and 3-7 for ICPE electrode. The electrodes under study have short response time. This potentiometric method can be used for determination of MOXHC in pharmaceutical preparation and the results obtained agreed with those obtained with HPLC official method. The proposed potentiometric method was validated according to the IUPAC recommendation.

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.

Fabrication of chemically and in situ modified carbon paste electrodes for the potentiometric determination of chlorpromazine HCl in pure pharmaceutical preparations, urine and serum

Newly developed modified and in situ modified carbon paste sensors were developed for the determination of chlorpromazine hydrochloride (CPZHC) in pharmaceutical formulations and biological fluids (urine and serum). The developed electrodes were characterized and optimized with respect to the main experimental parameters affecting the electrode performance including the composition, pH, temperature, response time, lifespan and interferences. The electrodes chemically modified with CPZ-TPB (electrode I) and CPZ-RN (electrode II) ion pairs exhibit a linear response over a concentration range of 1.0 × 10−6–1.0 × 10−2 mol L−1 with Nernstian slope values of 59.00 ± 1.75 and 55.50 ± 1.70 mV decade−1 at 25 °C over the pH range of 2–6 and 4–8, respectively. Meanwhile, in situ electrodes modified with NaTPB (electrode III), PTA (electrode IV) and RN (electrode V) ion pairing agents exhibited a linear response within the concentration ranges from 1.0 × 10−6 to 1.0 × 10−2, 1.0 × 10−6 to 1.0 × 10−2 and 1.0 × 10−7 to 1.0 × 10−2 mol L−1 with Nernstian slope values of 57.80 ± 0.37, 59.70 ± 0.88 and 59.57 ± 0.95 mV decade−1 at room temperature (25 °C) over the pH range of 2–6, 4–8 and 2–6, respectively. The dynamic response time of the modified electrodes was 7 s for a duration time of 53 and 35 days for electrodes (I) and (II), respectively. Meanwhile, the in situ modified electrodes had a fast dynamic response time of 11, 8 and 13 s for the duration time of 24, 42 and 58 days, respectively, for electrodes III, IV and V. The sensors were found to have good selectivity for CPZHC in the presence of some metal ions, sugars and glycine. Successfully, the developed sensors were used for the determination of CPZHC in neurazine tablets, urine and serum using calibration, potentiometric titration and standard addition methods. The obtained results were compared successfully with respect to those obtained using the official method. The proposed sensors showed significantly high selectivity, response time, accuracy, precision, limit of detection (LOD) and limit of quantification (LOQ) compared with other proposed methods, which confirmed the potential applicability of the developed method for the determination of CPZHC in real pharmaceutical tablets, serum and urine.

LIQUID CHROMATOGRAPHIC DETERMINATION OF SOLIFENACIN SUCCINATE, FLAVOXATE HYDROCHLORIDE AND TOLTERODINE TARTRATE IN BULK DRUGS AND THEIR PHARMACEUTICAL DOSAGE FORMS

A simple, precise, specific and accurate reversed phase HPLC (RP-HPLC) method has been developed for the determination of solifenacin succinate (SOLS), flavoxate HCl (FLXHC) and toltoridine tartarate (TOLT) in bulk and pharmaceutical dosage forms. The proposed RP-HPLC method was carried out using Xterra RP-18 column (5 μm practical size, 25 cm x 4.6 mm i.d.). The flow rate, the injection volume and the detection wavelength were 1.0 mL/min, 20 mL and 200 nm, respectively. The mobile phase consisted of 0.05 M pentane sulfonic acid sodium salt (SOLS: pH 3.0±0.05, FLXHC and TOLT: pH 5.5±0.05) and acetonitrile (50:50 v/v). The retention times for SOLS, FLXHC and TOLT drugs were found to be 4.1±0.1 min, 4.3±0.0 min and 5.8±0.1 min, respectively. The calibration was linear over the concentration range of 0.1-100 μg/mL. The mean recoveries for SOLS, FLXHC and TOLT drugs were about 99.80%, 100.43% and 100.00%, respectively. The method was validated according to the ICH guidelines with respect to specificity, linearity, accuracy, precision and robustness.