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Objective: To establish an electrochemical method for the determination of phenol. Methods: An electrochemical workstation with three electrodes system was used with glassy carbon electrode as working electrode, Ag/AgCl as reference electrode and Pt as counter electrode. Cyclic voltammetry and differential pulse voltammetry were used for the determination of phenol. Results:Under the condition of 4% Na2SO4as the supporting electrolyte, phenol showed an obvious oxidation peak on the glassy carbon elec-trode. The peak current increased linearly with the concentration of phenol within the range of 0. 8 μg·ml-1-10. 2 μg·ml-1( r=0. 997 5). The lower limit of detection was 0. 20 μg·ml-1. The average recovery was 101. 2% (RSD=2. 2% , n=6). Conclusion:The method is simple and accurate, and can be used for the determination of phenol.
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Objective To investigate effect of hydroxypropyl methyl cellulose (HPMC) to in vitro release characteristics of cefaclor sustained-release tablets.Methods Collected 10 batches of HPMC from different manufacturers.Determined the viscosity, molecular weight and the distribution of molecular weight of HPMC.HPMC from different manufacturers was used as blocking agent for the preparation of cefaclor sustained-release tablets according to the same prescription.Results The molecular weight was positively related to the viscosity of HPMC.The more molecular weight was, the slower the drugs release rate was,the better controlled released.Conclusion HPMC from different manufacturers show different quality stability and effect in vitro release of cefacor sustained-release tablets.
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Objective To investigate the effect of angiotensin Ⅱ (AngⅡ) type 1 receptor block irbesartan on the expression of renal cyclooxygenase-2 ( COX-2 ) in rats with type 2 diabetes mellitus.Methods 18 rats were divided into control group, diabetes mellitus group and treating group.Immunohistochemistry was used to measure the expression of COX-2, matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1).The urinary TXB2,6-Ket-PGF1 αconcentration was determined by radioimmunoassay at the 6th week .Results There was an increasing expression of COX-2,TIMP-1 and decreasing M MP-9 ( COX-2:0.39 ± 0.02 vs 0.24 ± 0.04, TIMP :0.41 ± 0.03 vs 0.24 ± 0.02,MMP-9:0.24 ± 0.02 vs 0.32 ± 0.02, P ＜ 0.05 ) expression in the diabetes mellitus group ( P ＜ 0.05 ).Irbesartan could increase MMP-9 (0.29 ± 0.03 ) and depress TIMP-1 (0.34 ± 0.02) expression through inhibiting the expression of COX-2(0.31 ± 0.03) in renal tissue.Conclusions COX-2 was involved in the pathogenesis of the injury of type 2 diabetic nephropathy.Irbesartan might exert its renoprotective effects through inhibiting COX-2 activity, modulating the expression of MMP-9 and TIMP-1.