目的:建立一种快速、准确同时测定半枝莲药材中的原儿茶酸、p-香豆酸和木樨草素含量的高效液相色谱-电化学检测(HPLC—ECD)法。方法:采用 Gemini-C_(18)(250 mm×4.6 mm,5.0μm)色谱柱;以甲醇(A)-3%醋酸(B)为流动相,梯度洗脱[0 min 时 A-B(25∶75),5 min 时 A-B(25∶75),10 min 时 A-B(37.5∶62.5),15 min 时 A-B(25∶75),20 min 时 A-B(37.5∶62.5),30 min 时 A-B(60∶40)];流速为0.8 mL·min^(-1);柱温为30℃;电化学检测器的工作电位为0.9 V;采用标准曲线法对3种化合物进行定量。结果:原儿茶酸、p-香豆酸和木樨草素的线性范围分别为0.14～11.28μg·mL^(-1)(r=0.9990),0.29～9.25μg·mL^(-1)(r=0.9994),0.58～9.31μg·mL^(-1)(r=0.9993);3次加样的平均回收率分别为97.7%(RSD≤1.8%),100.1%(RSD≤5.6%),100.9%(RSD≤4.6%)。结论:与用于半枝莲约材中3种化合物测定的 HPLC—DAD 法相比较,HPLC—ECD 法不仅具有灵敏度高的特点,还可避免用 DAD 时由于不同物质的最大吸收波长不同而难以在同一波长下进行同时灵敏测定的问题。
An ionic liquid bulk-modified carbon paste electrode （M-CPE） has been fabricated by using 1-heptyl-3-methylimidazolium bromide as a modifier. Cyclic voltammetry （CV） and differential pulse voltammetry （DPV） were used to evaluate the electrocatalytic activity of the proposed electrode by choosing p-aminophenol （p-AP） as a model compound. Both at a bare carbon paste electrode （CPE） and the M-CPE, p-AP yielded a pair of redox peaks in 0.1 mol·L^-1 phosphate buffer solution （PBS, pH 7.0）. At the CPE, the peak-to-peak potential separation （AEp） was 0.233 V, while at the M-CPE the AEp was decreased to 0.105 V. Furthermore, the current response to p-AP at the M-CPE was 10.2 times of that at the CPE by DPV. The electron transfer rate constant （ks） ofp-AP at the M-CPE was 13.3 times of that at the CPE. Under the optimal condition, a linear dependence of the catalytic current versus p-AP concentration was obtained in the range of 2.0× 10^- 6 to 3.0× 10^- 4 mol·L^-1 with a detection limit of 6.0× 10^-7 mol·L^-1 by DPV. In addition, compared to other modified method the proposed electrode exhibited distinct advantages of simple prapartion, surface renewal, good reproducibility and good stability. It has been used to determine p-AP in simulated wastewater samples.
