V. Madhavi

Application of phytogenic zerovalent iron nanoparticles in the adsorption of hexavalent chromium

Zerovalent iron nanoparticles (ZVNI) were synthesized using a rapid, single step and completely green synthetic method from the leaf extracts of Eucalyptus globules and were characterized using the techniques Scanning Electron Microscopy (SEM), UV-Vis Spectroscopy, Fourier Transform-Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD) and Zeta potential measurement. The FT-IR analysis reveals that the polyphenolic compounds present in the leaf extract may be responsible for the reduction and stabilization of the ZVNI. These nanoparticles were utilized for the adsorption of hexavalent chromium (Cr (VI)) and the concentration of Cr (VI) was determined using UV-Vis spectrometer after treating with ZVNI. Response and surface contour plots were drawn with the help of Mini-tab software to explain the adsorption of Cr (VI). The adsorption efficiency of Cr (VI) reaches to the highest value (98.1%) when the reaction time was about 30 min. and the ZVNI dosage was 0.8 g/L. The effective parameters such as adsorbent (ZVNI) dosage, initial Cr (VI) concentration and the kinetics were also examined.

A selective and sensitive UPLC–MS/MS approach for trace level quantification of four potential genotoxic impurities in zolmitriptan drug substance

The pivotal task of pharmaceutical industry is to separate and quantify the potential genotoxic impurities (PGIs) rising from the process of drug production. For trace level quantification of these PGIs we need to develop sensitive and selective analytical methods. APP, NPA, NPP and MNA have been highlighted as PGIs in zolmitriptan. A sensitive and selective UPLC-MS/MS method has developed for identification and quantification of four PGIs viz. APP, NPA, NPP and MNA in zolmitriptan. The method utilizes Hypersil BDS C8 column (50 mm × 4.6 mm, 3.0 μm) with electrospray ionization in selected ion recording (SIR) mode for quantitation of four PGIs. The method was validated as per International Conference on Harmonization (ICH) guidelines and is able to quantitate APP at 0.1 ppm and NPA, NPP and MNA at 0.15 ppm with respect to 5.0mg/mL of zolmitriptan. The proposed method is specific, linear, accurate and precise. The method is linear in the range of 0.1-2.0 ppm for APP and 0.15-2.0 ppm for NPA, NPP and MNA, which matches the range of LOQ-200% of estimated permitted level (1.0 ppm). The correlation coefficient obtained was >0.999 in each case. The impurities were not present in the studied three pure and formulation batches of zolmitriptan. The accuracy of the method was ranged between 98.1 and 102.8% for four PGIs. This method is a good quality control tool for quantitation of four APP, NPA, NPP and MNA PGIs at very low levels in zolmitriptan.

Remediation of Chlorpyrifos-Contaminated Soils by Laboratory-Synthesized Zero-Valent Nano Iron Particles: Effect of pH and Aluminium Salts

Degradation of the insecticide chlorpyrifos in contaminated soils was investigated using laboratory synthesized zero-valent nano iron (ZVNI) particles. The synthesized ZVNI particles were characterized as nanoscale sized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The zero-valent state (Fe0) of iron was confirmed by EDAX analysis and the morphology of the ZVNI particles was studied by XRD. Batch experiments were conducted by treating the chlorpyrifos contaminated soil with ZVNI, our results indicate that 90% of chlorpyrifos was degraded after 10 days of incubation. Only 32% degradation was observed with micro zero-valent iron (mZVI) and no considerable degradation was attained without ZVNI. The degradation of chlorpyrifos followed the first-order kinetics with a rate constant and a half-life of 0.245 day−1 and 2.82 days, respectively. Degradation was monitored at two different pH values, that is, pH 10 and pH 4. Chlorpyrifos degradation rate constant increased as the pH decreases from 10 to 4. The corresponding rate constant and half-lives were 0.43 day−1 and 1.57days for pH 4, 0.18 day−1 and 3.65 days for pH 10. In addition, an attempt was made by augmenting Al2(SO4)3 with ZVNI and it was found that the degradation rate of chlorpyrifos was greatly enhanced and the rate constant was rapidly increased from 0.245 day−1 to 0.60 day−1. Hydrolysis and stepwise dechlorination pathway of chlorpyrifos with ZVNI was the dominant reaction.

Method development and validation study for quantitative determination of 2-chloromethyl-3,4-dimethoxy pyridine hydrochloride a genotoxic impurity in pantoprazole active pharmaceutical ingredient (API) by LC/MS/MS.

A sensitive and selective liquid chromatographic-tandem mass spectrometric (LC/MS/MS) method was developed and validated for the trace analysis (>1 ppm level) of 2-chloromethyl-3,4-dimethoxy pyridine hydrochloride a genotoxic impurity in pantoprazole sodium drug substances. LC/MS/MS analysis of 2-chloromethyl-3,4-dimethoxy pyridine hydrochloride was done on Hypersil BDS C18 (50 mm × 4.6 mm) 3 μm column and 10 mM ammonium acetate in 1000 mL of water was used as buffer. The mobile phase used was in the ratio of buffer-acetonitrile (79:21, v/v). The flow rate was 1.0 mL/min and elution was monitored at 210 nm. The method was validated as per International Conference on Harmonization (ICH) guidelines. LC/MS/MS is able to quantitate up to 0.3 ppm of 2-chloromethyl-3,4-dimethoxy pyridine hydrochloride.

Systematic approach for trace level quantification of 2-n-butyl-4-spirocyclopentane-2-imidazole-5-one genotoxic impurity in irbesartan using lc-ms/ms

2-N-butyl-4-spirocyclopentane-2-imidazoline-5-one has been highlighted as a potential genotoxic impurity in irbesartan. A sensitive LC-MS/MS method was developed and validated for the determination of 2-N-butyl-4-spirocyclopentane-2-imidazoline-5-one in irbesartan. Good separation between 2-N-butyl-4-spirocyclopentane-2-imidazoline-5-one and irbesartan was achieved with Symmetry C18 (100×4.6 mm, 3.5 μm) column using 65:35 v/v mixture of 0.1% formic acid and acetonitrile as mobile phase with a flow rate of 0.7 ml/min. The proposed method was specific, linear, accurate, and precise. The calibration curve shows good linearity over the concentration range of 0.1-2.0 μg/ml, which matches the range of limit of quantitation-20×limit of quantitation of estimated permitted level (1.0 μg/ml) of 2-N-butyl-4-spirocyclopentane-2-imidazoline-5-one. The method was validated as per International Conference on Harmonization guidelines and was able to quantitate 2-N-butyl-4-spirocyclopentane-2-imidazoline-5-one impurity at 1.0 μg/ml with respect to 2 mg/ml of irbesartan. 2-N-butyl-4-spirocyclopentane-2-imidazoline-5-one was not present in the three studied pure and formulation batches of irbesartan and the developed method was a good quality control tool for quantitation of 2-N-butyl-4-spirocyclopentane-2-imidazole-5-one at very low levels in irbesartan.