Simultaneous method development and Validation by HPLC for Capecitabine and Oxaliplatin in mucoadhesive microspheres containing capsules

A simple, specific and accurate reversed-phase high performance liquid chromatographic method was developed for the simultaneous determination of Capecitabine and Oxaliplatin, using a Hypersil BDS C18, 150x4.6 mm, 5μ column and a mobile phase composed of 10mM dipotassium hydrogen phosphate+0.1% TEA pH 5.0: Acetonitrile (50:50%v/v). The flow rate was 1.0 ml/min, and the detection wavelength was 245 nm. The injection volume was 20 μL. The retention times of Capecitabine and Oxaliplatin found 4.29 min and 5.52 min, respectively. Linearity was established for Capecitabine and Oxaliplatin in the range of 60-210μg/ml and 20-70 μg/ml, respectively. The percentage recoveries of Capecitabine and Oxaliplatin found to be in the range of 99.1-101.5% and 97.9-99.7 %, respectively. The proposed method validated for precision, accuracy, linearity range, and robustness. This method can successfully be employed for simultaneous quantitative analysis of Capecitabine and Oxaliplatin in the capsule.

Novel RP-HPLC-PDA Approach for Efficient Simultaneous Quantification of Imipenem, Cilastatin and Relebactum in Bulk Drug and Injection Dose Forms

In this investigation, a highly reliable, precise, stability indicating, specific and selective RP-HPLC approach with photodiode array detection (RP-HPLC-PDA) was established to determine simultaneously imipenem, cilastatin and relebactum in bulk drug and injection dose forms. Chromatographic separation of imipenem, cilastatin and relebactum was achieved via using C18 XTerra column and a mobile phase poised of acetonitrile and 0.1 M dipotassium hydrogen phosphate buffer (4.5 pH, set with 0.1% orthophosphoric acid) at 45:55 (v/v) ratio with a flow stream of 1 mL/min. The photodiode array detector was fixed at wavelength 245 nm and quantifications of imipenem, cilastatin and relebactum were based on assessing their peak response areas. Good linearity was detected in target range concentrations of 250-750 μg/mL (imipenem and cilastatin) and 125-375 μg/mL (relebactum). The precision (standard variation percentage) was between 0.141% and 0.257%. Accuracy (%assay nominal) determined was between 99.144% and 99.638%. The validated RP-HPLC approach was applied to Recarbio injection dose evaluating imipenem, cilastatin and relebactum content with no interference encountered from the injection dose inactive ingredients. Imipenem, cilastatin and relebactum were subjected to forced conditions like 30% peroxide, 0.1 N NaOH, sunlight, 0.1 N HCl and 60 ºC. Imipenem, cilastatin and relebactum were effectively separated, quantified and resolved from the degradants generated in forced conditions.

Stability Indicating Method to Analyze Benidipine and Chlorthalidone Using HPLC Technique: Establishment, Validation and Application to Tablets

Background : The combination of chlorthalidone and benidipine was used to manage hypertension. The mixture of chlorthalidone and benidipine in tablet dosage form has not been previously determined by any method. A stability indicating HPLC method was developed for the simultaneous determination of benidipine and chlorthalidone in bulk and tablets. Methods: Chromatographic separation was accomplished in a reverse phase system using an isocratic elution with a mobile phase composed of methanol-0.1M dipotassium hydrogen phosphate buffer (40:60, v/v), at 1 ml/min flow rate. The photodiode array (PDA) detector set at 260 nm was used to detect and quantify benidipine and chlorthalidone. Benidipine and chlorthalidone tablet samples were subjected to degradation under acid, neutral, alkali, thermal, photo and oxidative. The proposed method was effectively adapted to quantify benidipine and chlorthalidone in the combined tablet formulation. Results: The elution times for benidipine and chlorthalidone were approximately 4.573 min and 6.422 min, respectively. The method was validated within a concentration range of 2 - 6 μg/ml (R2 = 0.9997) for benidipine and 6.25 - 18.75 μg/ml (R2 = 0.9998) for chlorthalidone. Adequate results were obtained for precision (RSD% = 0.106% for benidipine and RSD% = 0.031% for chlorthalidone) and accuracy (99.95 - 100.25 % mean recovery for benidipine and 99.60 - 99.63% mean recovery for chlorthalidone). Robustness has also been found to be acceptable. During the degradation study, interference was not noticed in the analysis of studied drugs. Conclusion: The findings demonstrated that the method could be useful for determination of the selected drug combination in routine analysis.

Effect of Dipotassium Hydrogen Phosphate and Calcium Nitrate on Strength and Microstructural Properties of Geopolymer Mortar

Adoption of coal fly ash (Class C) as the main source material for geopolymers would cause rapid setting to the fresh geopolymer mortar or concrete. This behaviour explained the limited application of this material in the construction industry. On the other hand, calcium nitrate (Ca (NO3)2) and dipotassium hydrogen phosphate (K2HPO4) are alternative admixtures that known to extend the setting time of fresh geopolymers. However, their effect on the strength and microstructural properties remain unclear due to the limitation of relevant literature from previous studies. Therefore, this study aims to investigate the effect of these admixtures in fly ash based geopolymer system, particularly to its strength performance. The effects of adding Ca (NO3)2 and K2HPO4 were evaluated at dosages of 0.5%, 1.5%, and 2.5% (by fly ash weight) in the geopolymer mixture, and samples were cured at room temperature. Hardened geopolymer specimens were measured for their compressive strength, porosity, and microstructural characteristic. The inclusion of 0.5% of alternative chemical reagents was found as the optimum proportion and able to enhance the compressive strength of the geopolymer mixtures. However, efflorescence was detected on the surface of the hardened specimen when K2HPO4 was included in its mixture. This phenomenon is influenced by the presence of monovalent and trivalent anions in the system namely nitrates and phosphates. In this study, each anion had a particular role in each stage of geopolymerisation, and determined the quality via crystal growth control and influenced the development of aluminosilicate structures.

Potential Sustainable Slow-Release Fertilizers Obtained by Mechanochemical Activation of MgAl and MgFe Layered Double Hydroxides and K2HPO4

This study describes the behavior of potential slow-release fertilizers (SRF), prepared by the mechanochemical activation of calcined Mg2Al-CO3 or Mg2Fe-CO3 layered double hydroxides (LDH) mixed with dipotassium hydrogen phosphate (K2HPO4). The effects of LDH thermal treatment on P/K release behavior were investigated. Characterizations of the inorganic composites before and after release experiments combined X-Ray diffraction (XRD), Fourier-transform infra-red spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The best release profile (<75% in 28 days and at least 75% release) was obtained for MgAl/K2HPO4 (9 h milling, 2:1 molar ratio, MR). Compared to readily used K2HPO4, milling orthophosphate into LDH matrices decreases its solubility and slows down its release, with 60% and 5.4% release after 168 h for MgAl/K2HPO4 and MgFe/K2HPO4 composites, respectively. Mechanochemical addition of carboxymethylcellulose to the LDH/K2HPO4 composites leads to a noticeable improvement of P release properties.

Degree of Reaction and Alkali-Leaching of Geopolymer Containing Ca-Rich Source Material and Dipotassium Hydrogen Phosphate

Disparity of anion and cation in geopolymer framework may result in the formation of efflorescence on the surface of hardened geopolymer specimen. The existence of efflorescence would be intensified with the use of dipotassium hydrogen phosphate (K2HPO4) as a chemical retarder for geopolymer mixture. In this study, paper mill sludge ash (PMSA) was used as a Ca-rich aluminosilicate source to reduce the development of efflorescence crystals. PMSA was utilized to partially replace fly ash at 5% and 10% (by weight of fly ash). Meanwhile, K2HPO4 was used as the external agent with various proportions, which were 0.1%, 0.3%, and 0.5% (by weight of fly ash). The external agent in this study was purposed to extend the setting time and enhance the mechanical properties of geopolymer. Fly ash and PMSA (if any) were activated by reacting them with 6M sodium hydroxide and sodium silicate solution. Freshly cast specimens were cured for 24 hours in electronic oven with the temperature setting of 30°C and 90°C. They were demoulded after 24 h and kept at room temperature (28±2 °C) until the testing day. Evaluation on the setting time characteristic of fresh geopolymer mortar was conducted with Vicat test while degree of reaction was performed on the hardened specimens to measure the reaction of fly ash during geopolymerization. Based on the experimental result, the inclusion of 5% PMSA shows the greatest effect in reducing the development of efflorescence crystal and increase the degree of reaction of geopolymer system. It is presumed that PMSA has altered the geopolymerization process by activating calcium oxide precursors to form three tetrahedral structures in the framework.