Determination of six effective components in Rheum by cyclodextrin modified micellar electrokinetic chromatography / 药学学报

<p><b>AIM</b>To determine six effective components (aloe-emodin, rhein, emodin, rhaponticin, physcion and chrysophanol) in Rheum.</p><p><b>METHODS</b>Using buffer solution containing 20 mmol.L-1 borax, 20 mmol.L-1 sodium deoxycholate (SDC), 20 mmol.L-1 sodium taurocholate (STC), 15 mmol.L-1 beta-cyclodextrin (beta-CD) and O-phthalic acid as the internal standard, the six components were determined by cyclodextrin modified micellar electrokinetic chromatography.</p><p><b>RESULTS</b>In less than 25 min, aloe-emodin, rhein, emodin, rhaponticin, physion and chrysophanol were separated. The separation conditions were optimized by adjusting buffer pH, concentrations of SDC, STC and beta-CD. The linearity ranges of aloe-emodin, rhein, emodin, rhaponticin, physcion and chrysophanol were 4-34, 5-40, 4-60, 5-80, 6-90 and 5-85 micrograms.mL-1 respectively. Relative standard deviation (RSD) of the method was less than 2.2%. The recoveries of aloe-emodin, rhein, emodin, rhaponticin, physcion and chrysophanol were 100.0%, 98.3%, 100.4%, 94.6%. 95.2% and 93.8% respectively. Raw Rheum, Mongolian Rheum and Rheum tanguticum samples were analyzed.</p><p><b>CONCLUSION</b>This method can be an effective one for identification of Rhubarb.</p>

Electrochemical behavior of dopamine at the poly (isonicotinic acid) modified glassy carbon electrode / 药学学报

<p><b>AIM</b>To study the determination of dopamine (DA) in the presence of ascorbic acid (AA) using poly (isonicotinic acid) film modified electrode.</p><p><b>METHODS</b>The cyclic voltammetry and differential pulse voltammetry were used to study the electrochemical behavior of DA at the poly (isonicotinic acid) film modified electrode.</p><p><b>RESULTS</b>The poly (isonicotinic acid) film modified electrode showed an electrocatalytic effect on DA, and shifted the oxidation of AA to negative potential. The difference between the oxidation potentials of DA and AA was 204 mV, thus, AA did not interfere with the determination of DA. The linear range between the anodic currents and DA concentration was: 1.0 x 10(-7)-2.0 x 10(-5) and 2.0 x 10(-5)-1.0 x 10(-4) mol.L-1. The detection limit was 8.0 x 10(-9) mol.L-1.</p><p><b>CONCLUSION</b>The useful life period of the modified electrode is three weeks at least. The modified electrode can be used to the determination of DA in the sample.</p>