Three sensitive,selective and reproducible stability-indicating methods are presented for determination of nitazoxanide (NTZ),a new anti-protozoal drug,in presence of its degradation products.Method A utilizes the fir...Three sensitive,selective and reproducible stability-indicating methods are presented for determination of nitazoxanide (NTZ),a new anti-protozoal drug,in presence of its degradation products.Method A utilizes the first derivative of ratio spectra spectrophotometry by measurement of the amplitude at 364.4 nm using one of the degradation products as a divisor.Method B is a chemometric-assisted spectrophotometry,where principal component regression (PCR) and partial least squares (PLS) were applied.These two approaches were successfully applied to quantify NTZ in presence of degradation products using the information included in the absorption spectra in the range 260-360 nm.Method C is based on the separation of NTZ from its degradation products followed by densitometric measurement of the bands at 254 nm.The separation was carried out on silica gel 60F 254,using chloroform-methanol-ammonia solution-glacial acetic acid (95:5:1:1 by volume,pH=5.80) as a developing system.These methods are suitable as stability-indicating methods for the determination of NTZ in presence of its degradation products either in bulk powder or in pharmaceutical formulations.Statistical analysis of the results has been carried out revealing high accuracy and good precision.展开更多
Tadalafil(TAD)and dapoxetine HCl(DAP)are recently co-formulated and both show native fluorescence.Therefore,a novel,accurate,specific and sensitive reversed-phase high performance liquid chromatographic method with fl...Tadalafil(TAD)and dapoxetine HCl(DAP)are recently co-formulated and both show native fluorescence.Therefore,a novel,accurate,specific and sensitive reversed-phase high performance liquid chromatographic method with fluorescence detection was developed and validated for their separation and quantitation in dosage form and human plasma using avanafil as an internal standard(IS).Separation was achieved using isocratic elution within 7.0 min on C18column and acetonitrile-0.15%triethylamine(40∶60,v/v;pH 4)as a mobile phase.The flow rate was 1.0 mL/min and the detection was time-programmed at 330,410 and 370 nm for TAD,DAP and IS,respectively,after excitation at 236 nm.The linear ranges from 0.01 to 30.00μg/mL for each drug with the limits of detection of 4.20 and 7.20 ng/mL for TAD and DAP,respectively.The method was validated in accordance to the International Conference on Harmonization(ICH)guidelines and was successfully applied to spiked human plasma with mean recoveries of 98.17%and 98.83%for TAD and DAP respectively.展开更多
Two different Ti alloys were cast in a graphite mould using vacuum induction skull melting furnace. The first alloy was Ti-6Al-4V and the second was Ti-6Al-4V 0.5Si. Silicon as a grain refiner was added into Ti-6Al-4V...Two different Ti alloys were cast in a graphite mould using vacuum induction skull melting furnace. The first alloy was Ti-6Al-4V and the second was Ti-6Al-4V 0.5Si. Silicon as a grain refiner was added into Ti-6Al-4V alloy, and the effects of Si-addition on the microstructure and properties of the as-cast and swaged alloys were investigated. Hot swaging at 900 °C was performed on the cast samples and then two different thermal treatments were applied. The first treatment was done by heating the swaged samples at 1050 °C to produce fine lamella structure, while the second treatment was carried out at 1050 °C and then decreased the temperature to 800 °C for getting coarse lamella structure. An addition of 0.5% Si to Ti-6Al-4V alloy decreased the grain size of the as-cast sample from 627 to 337 μm. There was an increase in ultimate tensile strength of about 25 MPa for the as-cast Ti-6Al-4V 0.5Si alloy compared to Ti-6Al-4V due to the refinement effect caused by Si addition. A maximum ultimate tensile strength of 1380 MPa and a minimum corrosion rate （1.35×10 6 mm/a in Hank’s solution and 5.78×10 4 mm/a in NaCl solution） were reported for the heat treated fine lamella structure of Ti-6Al-4V 0.5Si alloy. The wear rate was decreased to about 50% by adding 0.5% Si at low sliding speeds and to about 73% at high sliding speeds.展开更多
文摘Three sensitive,selective and reproducible stability-indicating methods are presented for determination of nitazoxanide (NTZ),a new anti-protozoal drug,in presence of its degradation products.Method A utilizes the first derivative of ratio spectra spectrophotometry by measurement of the amplitude at 364.4 nm using one of the degradation products as a divisor.Method B is a chemometric-assisted spectrophotometry,where principal component regression (PCR) and partial least squares (PLS) were applied.These two approaches were successfully applied to quantify NTZ in presence of degradation products using the information included in the absorption spectra in the range 260-360 nm.Method C is based on the separation of NTZ from its degradation products followed by densitometric measurement of the bands at 254 nm.The separation was carried out on silica gel 60F 254,using chloroform-methanol-ammonia solution-glacial acetic acid (95:5:1:1 by volume,pH=5.80) as a developing system.These methods are suitable as stability-indicating methods for the determination of NTZ in presence of its degradation products either in bulk powder or in pharmaceutical formulations.Statistical analysis of the results has been carried out revealing high accuracy and good precision.
文摘Tadalafil(TAD)and dapoxetine HCl(DAP)are recently co-formulated and both show native fluorescence.Therefore,a novel,accurate,specific and sensitive reversed-phase high performance liquid chromatographic method with fluorescence detection was developed and validated for their separation and quantitation in dosage form and human plasma using avanafil as an internal standard(IS).Separation was achieved using isocratic elution within 7.0 min on C18column and acetonitrile-0.15%triethylamine(40∶60,v/v;pH 4)as a mobile phase.The flow rate was 1.0 mL/min and the detection was time-programmed at 330,410 and 370 nm for TAD,DAP and IS,respectively,after excitation at 236 nm.The linear ranges from 0.01 to 30.00μg/mL for each drug with the limits of detection of 4.20 and 7.20 ng/mL for TAD and DAP,respectively.The method was validated in accordance to the International Conference on Harmonization(ICH)guidelines and was successfully applied to spiked human plasma with mean recoveries of 98.17%and 98.83%for TAD and DAP respectively.
文摘Two different Ti alloys were cast in a graphite mould using vacuum induction skull melting furnace. The first alloy was Ti-6Al-4V and the second was Ti-6Al-4V 0.5Si. Silicon as a grain refiner was added into Ti-6Al-4V alloy, and the effects of Si-addition on the microstructure and properties of the as-cast and swaged alloys were investigated. Hot swaging at 900 °C was performed on the cast samples and then two different thermal treatments were applied. The first treatment was done by heating the swaged samples at 1050 °C to produce fine lamella structure, while the second treatment was carried out at 1050 °C and then decreased the temperature to 800 °C for getting coarse lamella structure. An addition of 0.5% Si to Ti-6Al-4V alloy decreased the grain size of the as-cast sample from 627 to 337 μm. There was an increase in ultimate tensile strength of about 25 MPa for the as-cast Ti-6Al-4V 0.5Si alloy compared to Ti-6Al-4V due to the refinement effect caused by Si addition. A maximum ultimate tensile strength of 1380 MPa and a minimum corrosion rate （1.35×10 6 mm/a in Hank’s solution and 5.78×10 4 mm/a in NaCl solution） were reported for the heat treated fine lamella structure of Ti-6Al-4V 0.5Si alloy. The wear rate was decreased to about 50% by adding 0.5% Si at low sliding speeds and to about 73% at high sliding speeds.
