We described a simple and rapid method to quantify simultaneously chlorhexidine (CHD) and its major metabolite, para Chloroaniline (pCA) by HPLC with UV detection without the additional need of mobile-phase amine modi...We described a simple and rapid method to quantify simultaneously chlorhexidine (CHD) and its major metabolite, para Chloroaniline (pCA) by HPLC with UV detection without the additional need of mobile-phase amine modifiers or ion-pairing reagents, with good resolution between pCA and CHD, symmetry peak of the compound and short run time. HPLC-UV analyses were performed using a Dionex? Summit liquid chromatograph (Dionex Corp, Sunnyvale, CA, USA). Chromatographic separations were carried out on a Luna? 150 mm×3 mm i.d. column packed with 3 μm CN (cyano) particles (Phenomenex?), guarded by an on-line filter. Mobile phase consist of methanol:water with sodium chloride with 0.02% of formic acid (55:45). Wavelengths for pCA and for CHD are 238 and 255 nm respectively. Influence of methanol and of sodium chloride content in the eluant has been studied. Linearity of CHD is very good, from 0.5 up to 21.2 μg/l while linearity of pCA is in the range of 0.05 to 10 μg/l with correlation coefficients above 0.999. Resolution between the components is above 4, asymmetry is about 1.3 and 1.7 for pCA and CHD respectively and the run time is less than 5 minutes. This method has been applied to CHD solution of different medical devices. No interference has been reported, and the analysis of direct injection of solution, without any treatment is achieved in less than five minutes.In conclusion, we present a validated method for dosage of CHD and its major impurity pCA, known to be carcinogen, available into medical products or medicinal device for in-vitro diagnostic.展开更多
The effects of palladium addition and the reduction methods on Au/TiO2 were investigated. Pd was loaded on TiO2 firstly by incipient-wetness impregnation, Au was then loaded by deposition-precipitation method. The nom...The effects of palladium addition and the reduction methods on Au/TiO2 were investigated. Pd was loaded on TiO2 firstly by incipient-wetness impregnation, Au was then loaded by deposition-precipitation method. The nominal loadings of Au and Pd were 1 wt% and 0.01 wt%. The bimetallic catalysts were reduced by heating at 453 K, by flowing H2 at 423 K, or by NaBH4 at 298 K. The catalysts were characterized by ICP, XRD, TEM, HRTEM, TPR and XPS. Hydrogenation of p-chloronitrobenzene was carried out at 1.2 MPa H2 pressure and 353 K. The results showed that even adding very small amount of Pd could enhance activity and selectivity of p-chloroaniline significantly. Pd and Au formed alloy and Pd could donate partial electron to Au. Pd metal on the surface of alloy could adsorb hydrogen and enhanced the activity. The pretreatment methods did not change particle size significantly, all were below 4 nm. The sample reduced by NaBH4 could have higher concentration of Au0 and sustain small Au particle size, resulting in high activity.展开更多
文摘We described a simple and rapid method to quantify simultaneously chlorhexidine (CHD) and its major metabolite, para Chloroaniline (pCA) by HPLC with UV detection without the additional need of mobile-phase amine modifiers or ion-pairing reagents, with good resolution between pCA and CHD, symmetry peak of the compound and short run time. HPLC-UV analyses were performed using a Dionex? Summit liquid chromatograph (Dionex Corp, Sunnyvale, CA, USA). Chromatographic separations were carried out on a Luna? 150 mm×3 mm i.d. column packed with 3 μm CN (cyano) particles (Phenomenex?), guarded by an on-line filter. Mobile phase consist of methanol:water with sodium chloride with 0.02% of formic acid (55:45). Wavelengths for pCA and for CHD are 238 and 255 nm respectively. Influence of methanol and of sodium chloride content in the eluant has been studied. Linearity of CHD is very good, from 0.5 up to 21.2 μg/l while linearity of pCA is in the range of 0.05 to 10 μg/l with correlation coefficients above 0.999. Resolution between the components is above 4, asymmetry is about 1.3 and 1.7 for pCA and CHD respectively and the run time is less than 5 minutes. This method has been applied to CHD solution of different medical devices. No interference has been reported, and the analysis of direct injection of solution, without any treatment is achieved in less than five minutes.In conclusion, we present a validated method for dosage of CHD and its major impurity pCA, known to be carcinogen, available into medical products or medicinal device for in-vitro diagnostic.
文摘The effects of palladium addition and the reduction methods on Au/TiO2 were investigated. Pd was loaded on TiO2 firstly by incipient-wetness impregnation, Au was then loaded by deposition-precipitation method. The nominal loadings of Au and Pd were 1 wt% and 0.01 wt%. The bimetallic catalysts were reduced by heating at 453 K, by flowing H2 at 423 K, or by NaBH4 at 298 K. The catalysts were characterized by ICP, XRD, TEM, HRTEM, TPR and XPS. Hydrogenation of p-chloronitrobenzene was carried out at 1.2 MPa H2 pressure and 353 K. The results showed that even adding very small amount of Pd could enhance activity and selectivity of p-chloroaniline significantly. Pd and Au formed alloy and Pd could donate partial electron to Au. Pd metal on the surface of alloy could adsorb hydrogen and enhanced the activity. The pretreatment methods did not change particle size significantly, all were below 4 nm. The sample reduced by NaBH4 could have higher concentration of Au0 and sustain small Au particle size, resulting in high activity.
