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In the present study, initially Aspergillus niger was tested for biosorption of Pb(II) ions and then studied the effect of pretreatment for enhanced biosorption. It was found that the maximum biosorption potential was achieved with citric acid treatment (70.56 %) in comparison with the biomass without treatment (65.46 %) at a biosorbent dose of 20 mg/L, pH 4, 100 rpm, 37 ºC for 8 h. The optimized conditions for treated Aspergillus niger were determined by optimizing the biosorption parameters such as pH, temperature, biomass dose, incubation time and agitation speed. This study indicates that the citric acid treated Aspergillus niger is an effective biosorbent for removal of lead (II) at optimized conditions with the maximum biosorption potential of 83.6 % as compared to previous reported work. SEM-EDX and FTIR analysis showed the structural variations and the functional groups involved in lead biosorption, respectively. Biosorption kinetics showed that pseudo second order kinetic model as the better fit.

Objectives Leflunomide (LFNM) is a drug that belongs to isoxazole derivatives and has immunosuppressive and anti-inflammatory activities. A literature search confirms that there is no method reported for the simultaneous estimation of LFNM and its related impurities A and B in pharmaceutical dosage forms or in bulk drug. Hence the present work aimed to develop a simple stability indicating RP-HPLC method for the separation and quantification of LFNM and its impurities A and B. Materials and methods Systematic trials of method conditions like mobile phase ratio, pH, flow rate, stationary phase, and detector wavelength were performed for the simultaneous analysis of LFNM and its related impurities A and B. The developed method was validated as per the ICH guidelines including forced degradation studies in different stress conditions. Results Optimized separation was achieved on a Thermo Scientific Hypersil ODS C18 column (250 mm×4.6 mm; 5 μm id) using mobile phase composition of acetonitrile, methanol, and 0.1 M sodium perchlorate in the ratio of 40:30:30 (v/v), pH 4.6, at a flow rate of 1.0 mL/min in isocratic elution. UV detection was carried out at a wavelength of 246 nm. Well-resolved peaks were observed with high numbers of theoretical plates, lower tailing factor, and reproducible relative retention time and response factor. The method was validated and all the validation parameters were found to be within the acceptance limits. Stability tests were done through exposure of the analyte solution to five different stress conditions, i.e. 1 N HCl, 1 N NaOH, 3% H2O2, thermal degradation of powder, and exposure to UV radiation. The method can successfully separate the degradation products along with both the impurities studied. The % degradation was also found to be less. Conclusion The method developed for LFNM is simple and precise and can be applied for the separation and quantification of LFNM and its related impurities in bulk drug and pharmaceutical formulations.

Objective of the present research work is to develop a sensitive, selective and accurate new RPHPLC method with UV detection and determination for estimation of Nevirapine (NVP)and its impurities in bulk drug. The separation and quantification was achieved with Kromosil C18 isocratic column, (150 mm × 4.6 mm i.d., particle size 3.5 µm, maintained at ambient temperature), HPLC system (Peak LC P7000), a mixture of 20% acetonitrile, 80% buffer (sodium per chlorate) (v/v), at pH of 4.8 and the flow rate was set at 1.0 ml/min. and UV detection at 220 nm. The retention time for NVP, Impurity-A and Impurity-B were found to be 5.5, 7.8, 3.4 min respectively. The method was validated for Linearity, Accuracy, and Precision. The Limit of detection of NVP, Impurity-A and Impurity-B were found to be 0.03, 0.03, 0.03(µg/ml) respectively.

Decitabine is an anti-cancer chemotherapy drug. This article describes method development and method validation of related substances of Decitabine (a- decitabine, a-isomer, methyl 4-chlorobenzoate, s-isomer, O-Acetyl and unknown impurities) in decitabine drug substance and finished dosage forms by using a high Performance liquid chromatography. In this high performance liquid chromatography, the resolution was achieved on Inertsil ODS 3V, 250×4.6 mm, 5µm column with a gradient elution at a flow rate of 1.2 mL/min using a mobile phase A as Ammonium acetate buffer solution and mobile phase B as water: acetonitrile (10:90% v/v) at wavelength 254 nm by an UV detector. The method was validated in the concentration range of 0.7 ppm to 7.1 ppm, 1.2 ppm to 11.0 ppm, 1.2 ppm to 10.9 ppm, 1.2 ppm to 11.0 ppm, 1.2 ppm to 10.9 ppm and 0.8 ppm to 7.7 ppm for related substances of a- decitabine, a-isomer, methyl 4-chlorobenzoate, s-isomer, O-Acetyl and Decitabine respectively. The obtained recovery was in between 90.0 % to 110.0 % and the % RSD was not more than 10.0. The HPLC method is suitable, specific, linear, accurate, precise, stability indicating and robust which may be useful for the routine and stability analysis for determination of related substances in Decitabine drug substance and finished dosages.

A novel high speed, high resolution Reverse phase-UPLC method was developed for the quantification of related substances in Febuxostat drug substance. The separation of drug from the possible impurities was achieved on a Halo C18 column. The innovative approach of using stationary phase with sub 2 μ particles provides a comprehensive combination of selectivity and speed. 10 mM mono basic potassium phosphate buffer at pH 2.7 and acetonitrile mixture was selected as mobile phase. Flow rate and detection were kept at 0.8 mL/min and 320 nm respectively. The developed UPLC method was subjected to validation parameters. System precision, accuracy, specificity, limit of detection, limit of quantification and linearity were established as per the guidelines recommended by ICH. Stability indicating nature of the method was also performed by exposing the sample under various conditions like acid, base, peroxide and photo stability exposures. Total analysis run time 7.0 minutes indicates the speed and cost saving initiation of the developed method. Using the method one can carry out the quantitative estimation of related substances in Febuxostat drug substance, further the same method can be adopted for determination of drug substance assay also.

A simple, sensitive and accurate analytical method for related substances of Voriconazole has been developed and validated by using RP-UPLC technique. The developed analytical procedure was validated as per ICH recommendations. Analysis was performed on a HALO C18 (100 × 2.1 2.7 μ) column. 20 mM ammonium formate adjusted the pH to 4.5 with formic acid was selected as buffer. Acetonitrile was used as organic modifier in the mobile phase composition. A simple gradient was applied in the method. Flow rate of mobile phase was kept at 0.4 ml per min. Column compartment temperature was maintained at 45°C. Injection volume was set at 1 μL with an auto sampler maintained the temperature at 10°C. Detection of all the components was monitored at 254 nm by photodiode array detector. Developed method satisfies the system suitability criteria, peak integrity, and resolution for the parent drug and its related substances. The proposed method was validated for Specificity, precision, accuracy, linearity, limit of detection and quantification. Forced degradation studies were conducted to assess stability indicating nature of the method under acidic, basic, oxidative and photolytic conditions. Run time less than 7.0 minutes indicating that the method is cost effective and productive; it can be successfully applied for testing of related substances in drug substance and assay of drug substance in routine quality control analysis and stability testing.

New High-performance liquid chromatographic bio-analytical method has been developed and validated for the simultaneous analysis of Trifluridine (TFD) and Tipiracil (TPC) in human plasma. The combination of TFD and TPC are used in the treatment of unresectable advanced or recurrent colorectal cancer. The method was developed with UV detector (at 260 nm wave length), Intersil ODSC 18 column (250 mm × 4.6 mm×5μ), at flow rate of 1.0mL/min. The mobile phase consisted of 15% NaClO4 buffer (PH 4.5 v/v), 85% Methanol. The retention times of TFD and TPC are 3.4 min and 7.4 min respectively. The method was developed and validated in terms of selectivity, precision, linearity, accuracy, LOQ, LOD and stability study. The proposed method can be applicable for pharmacokinetic studies using HPLC or LC-MS.