Experimental Design Approach in the Optimization of Potentiometric Method for Lansoprazole Determination Using Lansoprazole-Tungstate Based Ion-Selective Electrode

High performance liquid chromatographic method optimized by Box-Behnken design model to determine caffeine in pharmaceutical preparations and urine samples

A UV-HPLC method optimized by Box-Behnken design model was developed to determine caffeine in pharmaceutical preparations and urine samples. The chromatographic conditions followed were mobile phase: methanol/water/ citrate buffer (pH 4.6) (40:25:35, v/v/v),AcclaimTMDionex C18 column (ODS 100A˚, 5 µm; 4.6 × 250 mm),flow rate (0.9 mL min-1), column temperature (30 °C) and UV-detection wavelength (204 nm). The chromatographic variables: pH (A), % methanol fraction (B), flow rate(C) and column temperature (D) were optimized at 50 μg mL-1caffeine using BBD model. The chromatogram resulted in the asymmetry factor (1.23), theoretical plate 13,786 and retention time (5.79 min). The proposed HPLC method's greenness point was assessed byAnalytical Eco-scale and found to be 78 (as per guidelines, ranked as excellent). The linearity was ranged from2.0 to 70 µg mL-1 with coefficient of correlation (r = 0.999) and detection limit of 0.19 µg mL-1. The proposedmethod was developed successfully and applied for the assay of active caffeine in pharmaceutical preparations and urine samples. The % recovery obtained by both (proposed and reference) methods ranged from 99.98 to 100.05 % followed the compliance (100 ± 2 %) with Canadian Health Protection regulatory guidelines. The performance of the proposed method was compared with published papers and found to be acceptable and superior. The proposed method was quite effective as the reference method, and hence can be used as an alternative method for the assay of active caffeine in pharmaceutical preparations and urine samples.

Development of Levo-Lansoprazole Chiral Molecularly Imprinted Polymer Sensor Based on the Polylysine-Phenylalanine Complex Framework Conformational Separation

The efficacies and toxicities of chiral drug enantiomers are often dissimilar, necessitating chiral recognition methods. Herein, a polylysine-phenylalanine complex framework was used to prepare molecularly imprinted polymers (MIPs) as sensors with enhanced specific recognition capabilities for levo-lansoprazole. The properties of the MIP sensor were investigated using Fourier-transform infrared spectroscopy and electrochemical methods. The optimal sensor performance was achieved by applying self-assembly times of 30.0 and 25.0 min for the complex framework and levo-lansoprazole, respectively, eight electropolymerization cycles with o-phenylenediamine as the functional monomer, an elution time of 5.0 min using an ethanol/acetic acid/H₂O mixture (2/3/8, V/V/V) as the eluent, and a rebound time of 10.0 min. A linear relationship was observed between the sensor response intensity (ΔI) and logarithm of the levo-lansoprazole concentration (l-g C) in the range of 1.0 × 10^-13-3.0 × 10^-11 mol/L. Compared with a conventional MIP sensor, the proposed sensor showed more efficient enantiomeric recognition, with high selectivity and specificity for levo-lansoprazole. The sensor was successfully applied to levo-lansoprazole detection in enteric-coated lansoprazole tablets, thus demonstrating its suitability for practical applications.

Synthesis of magnetic molecular imprinted polymer with a new functional monomer for dispersive micro solid phase extraction of captopril from wastewater and biological samples and determination by UV-Vis spectrophotometry

A magnetic molecularly imprinted polymer (MMIP) was fabricated for captopril by surface polymerization of Fe₃O₄@SiO₂ nanoparticles using a new functional monomer of N-(allylcarbamothioyl)-2-chlorobenzamide. It was then employed as a selective nanosorbent for dispersive magnetic micro solid phase extraction (DM-μ-SPE) of captopril from biological and wastewater samples. To characterize the physicochemical properties of the MMIP, different analytical methods such as the vibrating sample magnetometer, field emission scanning electron microscopy, Brunauer-Emmett-Teller, and Fourier transform infrared spectroscopy were utilized. To gain the maximum extraction recovery of captopril, the influence of various operating conditions was investigated and experimental settings optimized. After the extraction step, the concentration of captopril was measured by UV-Vis spectrophotometer at 245 nm. The assessments demonstrated that the MMIP provides higher extraction efficiency in comparison to magnetic non-imprinted polymer, suggesting the establishment of selective recognition binding sites at the MMIP surface. The method depicted desirable figures of merit of a low detection limit of 0.16 μg L^-1, a limit of quantification of 0.50 μg L^-1, a linear dynamic range of 0.50-22.0 μg L^-1, and an acceptable preconcentration factor of 333. The magnetic MIP was successfully employed for preconcentration and extraction of trace amounts of captopril in real samples, such as human blood serum, urine, and wastewater samples, with recoveries in the range 95.7 to 102.6% and relative standard deviations < 5%.

Box–Behnken Design Based Development of UV-Reversed Phase High Performance Liquid Chromatographic Method for Determination of Ascorbic Acid in Tablet Formulations

A simple, sensitive, accurate and inexpensive UV-reversed-phase high-performance liquid chromatographic method was developed for the determination of ascorbic acid in tablet formulations. The method was based on the separation of ascorbic acid using a mobile phase of an acetonitrile-NaH2PO4-H3PO4 buffer solution (pH = 3) (5:95 v/v) with a UV detection wavelength of 245 nm and a flow rate of 0.8 mL min−1 at ambient column temperature. The variables of the proposed method, such as acetonitrile fraction (%), flow rate (mL min−1) and column temperature (°C), were optimized on the peak area by response surface methodology via the Box–Behnken design. The mobile phase was passed isocratically, and the separation of ascorbic acid was performed at the retention time of 4.1 min. A calibration graph was obtained and found to be linear in the concentration range of 10–180 µg mL−1. The method suitability was assessed and an asymmetry factor of 1.15 was obtained. The proposed method was successfully applied for the determination of ascorbic acid in tablet formulations and statistically compared with the results of the reference method. The performance of the proposed method was excellent and in agreement with the reference method. The recovery percentage of the proposed and reference methods was in the range of 99.98–100.04% and showed compliance (100 ± 2%) with regulatory guidelines.

Determination of lansoprazole in pharmaceuticals using flow injection with rhodamine 6G-diperiodatoargentate (III)-chemiluminescence detection

A chemiluminescence (CL) method based on rhodamine 6G (R6G)-diperiodatoargentate (III) (silver (III) complex) reaction in acid solution is reported for the determination of lansoprazole (LNP) combined with flow injection (FI) technique. The most likely mechanism for CL reaction was elucidated considering reported data, spectrophotometric and spectrofluorimetric studies. The weak CL reaction between R6G and silver (III) complex could be magnanimously increased in the presence of LNP with a limit of detection (LOD) of 0.002 mg L^-1 (S/N = 3), the linear range of 0.01-10 mg L^-1 (R² = 0.9997, n = 7), relative standard deviations (RSD) of 1.2-3.2% (n = 4) and injection throughput of 140 h^-1 . No interference activity of commonly found excipients in LNP was detected. After LNP extraction from pharmaceutical samples, the recovery rate ranged from 93-110% (RSD, 1.4-3.3%, n = 4) was calculated. The results of proposed flow CL method were assessed with a spectrophotometric approach applying paired Student's t-test and the calculated value (0.178) was lower than the distributed value (2.20) at a 95% confidence limit.

Optimized Box-Behnken experimental design based response surface methodology and Youden's robustness test to develop and validate methods to determine nateglinide using kinetic spectrophotometry

Selective and straightforward kinetic spectrophotometric methods were developed to quantify nateglinide (NTG) in pharmaceutical dosage forms. Fixed time (ΔA) and the equilibrium methods utilized the reaction of NTG with 1-chloro-2,4-dinitrobenzene (CDNB) in dimethyl sulfoxide (DMSO) with heating at 80 °C for 25 min to form a stable yellow-coloured Meisenheimer complex, which absorbs maximally at 421 nm. The optimization was achieved by utilizing the Box-Behnken experimental design (BBD) combined with response surface methodology (RSM). In which three significant factors were studied, namely, CDNB volume (A), heating temperature (B) and heating time (C) against the absorbance as a response. Method validation presented the International Conference on Harmonisation (ICH) parameters such as specificity, selectivity, linearity, precision, accuracy, limit of detection (LOD), limit of quantitation (LOQ), robustness and solution stability. The LOD and LOQ values were 0.48, 1.46, and 0.21, 0.62 µg/ml, respectively, for a fixed time (ΔA) and equilibrium methods with the linear dynamic range of 1-15 µg/ml. Furthermore, Youden's robustness test using factorial combinations of the selected analytical parameters was performed and investigated its influence with alternative conditions. All results were reproducible and quickly adopted for routine analysis of NTG in pharmaceutical formulations and laboratory preparations.

Effective removal of doxycycline from aqueous solution using CuO nanoparticles decorated poly(2-acrylamido-2-methyl-1-propanesulfonic acid)/chitosan

The primary focus of the present study was to synthesize CuO nanoparticles decorated poly(2-acrylamido-2-methyl-1-propanesulfonic acid)/chitosan to explore its potential for uptake of doxycycline (DXN) from water. The composite material was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction and thermogravimetric analysis-differential thermal analysis. Central composite design under response surface methodology was opted to optimize the process variables (pH, adsorbent dosage, contact time and initial concentration of DXN) for obtaining the highest removal efficiency. The removal of DXN reached 98.84% at 303 K under the optimum conditions of pH 7.0, equilibrating time of 70 min, adsorbent dose of 20 mg/25 mL and initial concentration of 50 mg L-1. The Langmuir isotherm and pseudo-second-order kinetic models fitted best with the experimental data. The values of ΔG° (- 29.159 to - 31.997 kJ mol-1), ΔH° (56.768 kJ mol-1) and ΔS° (283.382 J mol-1 K-1) demonstrated the spontaneous and endothermic nature of adsorption process. The adsorption/desorption study revealed the reusability of the prepared composite material for DXN uptake up to six cycles.

Lansoprazole Determination in Pharmaceutical Formulations by Flow Injection Coupled with Acidic KMnO4-Quinine Chemiluminescence System

A simple and rapid flow injection chemiluminescence (FI-CL) method based on the reaction of potassium permanganate (KMnO₄) and quinine was established for the determination of lansoprazole in pharmaceutical formulations. A linear calibration curve was achieved over the range from 0.01 to 20.0 mg L^-1 LNP (R² = 0.9997 (n = 8); RSD = 1.1 - 3.7% (n = 4)) with a limit of detection of 3.0 × 10^-3 mg L^-1 (S/N = 3) and injection throughput of 150 h^-1. By applying the Student t-test (calculated t-test value: t = 1.059907664, and tabulated t-distributed (95%) = 2.200985) it was found that the proposed method and reported spectrophotometric method were not significantly different. The LNP was efficiently extracted and the recovery of LNP from the spiked pharmaceutical formulations was in the range of 91.0 - 105.9% (%RSD = 1.6 - 3.6, n = 4). No significant interference activity was detected from the excipients commonly found in the drug samples analyzed. The possible chemiluminescence emission mechanism is discussed briefly.

N-(((2-((2-Aminoethyl)amino)ethyl)amino)methyl)-4-sulfamoylbenzamide Impregnated Hydrous Zirconium Oxide as a Novel Adsorbent for Removal of Ni(II) from Aqueous Solutions: Optimization of Variables Using Central Composite Design

In this study, N-(((2-((2-aminoethyl)amino)ethyl)amino)methyl)-4-sulfamoylbenzamide was impregnated into the hydrous zirconium oxide matrix to yield N-(((2-((2-aminoethyl)amino)ethyl)amino)methyl)-4-sulfamoylbenzamide/hydrous zirconium oxide composite (AESB/HZO). The composite material was used to remove Ni(II) from aqueous environment. AESB/HZO was characterized using Fourier transform infrared, scanning electron microscopy with energy dispersive X-ray, and thermogravimetry-differential thermal analyses. An experimental design approach was utilized to model and optimize the variables of adsorption of Ni(II) onto the AESB/HZO composite. Four experimental parameters were selected as independent variables: contact time, pH, adsorbent dose, and initial Ni(II) concentration. A multivariable experimental design was used to establish quadratic model to describe the relationship between percent removal of Ni(II) and four independent variables. At the optimum conditions (contact time: 85 min, pH: 6, adsorbent dose: 10 mg/20 mL, and initial Ni(II) concentration: 20 mg L-1), high removal efficiency (99.35%) was achieved, which is reasonably well predicted by the quadratic model. The sorption of Ni(II) is dependent on pH and ionic strength at pH < 6.0. At low pH, -NH and -NH2 groups are protonated, whereas the -SO2- group is available for binding with Ni(II) and the sorption of Ni(II) is mainly governed by outer sphere surface complexation. In the pH range 6.0-7.5, -NH, -NH2, and -SO2- groups are available for binding with Ni(II) and the sorption is mainly governed by inner-sphere surface complexation. Adsorption isotherm data fitted well to the Langmuir model and the maximum adsorption capacity was found to be 96.03 mg g-1 at 303 K. The results of present investigation demonstrated that AESB/HZO has a good potential for Ni(II) removal from aqueous solution.