DEVELOPMENT AND VALIDATION OF RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF PIPERAQUINE PHOSPHATE AND DIHYDROARTEMISININ IN BULK

High Performance Liquid Chromatography (HPLC) methods are described for determination of drugs as a single or in combination in bulk or pharmaceutical formulation. The objective of the present study was to develop and validate novel, accurate, sensitive, precise, rapid and isocratic reverse Phase HPLC (RP-HPLC) method for the simultaneous determination of Piperaquine phosphate and Dihydroartemisinin in bulk because no method is available for simultaneous estimation of these drugs. The separation was achieved on GRACESMART RP-18 column (250 mm × 4.6 mm, 5μm) with mobile phase consisting of 10 mM Ammonium acetate (pH4.6, adjusted with Acetic acid): Methanol (15:85 % v/v) at a flow rate of 1.2 ml/min. UV detection at 220 nm. PQP and DHA obeyed linearity in the concentration range of 5-25 μg/ml (r2 = 0.9993) and 5-25 μg/ml (r2 = 0.9987) respectively. The asymmetric factors were found to be 1.17 for PQP and 1.2 for DHA. The developed method was validated as per ICH guidelines fulfill all the acceptance criteria and can be use for routine analysis

A novel approach towards selective bulk synthesis of delaminated graphenes in an electric arc

Here we demonstrate the selective bulk scale synthesis of delaminated graphene sheets by a proper choice of magnetic field modulating an electric-arc. An ultra-high purity glassy graphite anode was sublimated in an argon atmosphere. Carbon nanotubes, as well as graphene sheets were found inside the deposit formed on the cathode. Both the high purity carbon nanotubes as well as graphene sheets, with minimal structural defects, were synthesized separately by varying the strength and orientation of the external magnetic field generated by arrays of permanent magnets. The as-synthesized carbonaceous samples were characterized with the help of transmission electron microscopy, selected area electron diffraction, Raman spectroscopy and thermogravimetry for optimizing the highest selective production of delaminated graphenes. This optimization was done by varying the strength and orientation of the external magnetic field. The as-synthesized graphene sheets exhibited relatively high degree of graphitization and low structural defect density as confirmed by RS. They were found to exhibit higher oxidation temperature than that of the carbon nanocrystalline particles as inferred from the thermogravimatric analysis. Moreover, they were found to form scroll-like carbon nanotubes at their edges on account of their surface energy minimization. This was confirmed by the selected area electron diffraction analysis. With this new technique, we could successfully synthesize delaminated graphenes at a rate of few grams per hour.Comment: 21 pages, 14 figures, 2 table

Investigation of structural and magnetic properties of thermal plasma-synthesized Fe_1-xNi_x alloy nanoparticles

Structural and magnetic properties of thermal plasma synthesized Fe1-xNix (x = 0.25, 0.33, 0.50, 0.67 and 0.75) alloy nanoparticles have been investigated using x-ray diffraction, neutron diffraction, transmission electron microscopy, scanning electron microscopy, dc magnetization, and Mössbauer spectroscopy techniques. High temperature gas phase nucleation and growth environment inside thermal plasma reactor facilitate stabilization of the disordered γ-FeNi (fcc) phase throughout (except for x = 0.25) the composition range under investigation. For x = 0.25 composition, a small (∼8%) amount of the disordered bcc phase along with prominent fcc (∼92%) phase is present, as inferred from the neutron diffraction data analysis. The spherical shaped nanoparticles possess high crystallinity. The average crystallite size (in 30–40 nm range) as well as particle size distribution show insignificant change as a function of composition. The observed value of the saturation magnetic moment for these nanoparticles are very close to that for their bulk counterparts, indicate highly crystalline nature of the thermal plasma synthesized nanoparticles. Room temperature Mössbauer spectroscopic data reveals that the alloy nanoparticles contain two different sites for Fe corresponding to high moment/low moment states. The neutron diffraction data indicates ferromagnetic ordering for all the compositions of the series. The average magnetic moments/f.u., derived from neutron diffraction and dc magnetization, are found to match with each other as well as with the values reported in the literature for bulk Fe1-xNix alloys. The highest ordered magnetic moment was found to be 1.4 μB per f.u. for Fe0.50Ni0.50 composition. Overall, thermal plasma based synthesis is found to be an excellent route to produce high-quality nanoparticles of the binary metallic alloys