罂粟碱的吸附伏安行为的研究

在ＮＨ３－ＮＨ４Ｃｌ底液中，罂粟碱在汞电极上有一一线性扫描还原峰，峰电位Ｅｐｃ＝－１．４４（ｖｓ．ｓａｔ．Ａｇ／ＡｇＣｌ）。该峰具有明显的吸附性。当ＰＡＰ浓度较小时，扫速较快，搅拌富集时间较长时，电极反应完全为吸附态的ＰＡＰ的还原所控制。

Adsorptive Stripping Voltammetry of Papaverine

In a supporting electrolyte containing NH3-NH4C1, a reduction peak of papaverine (PAP) was found by linear-sweep voltammetry at Hg electrode. The peak shows a potential of - 1. 44 V(vs. Ag/AgCl) and adsorptive characteristics. When the concentration of PAP is sufficiently low, the sweep rate is sufficiently rapid, and the accumulation time is sufficiently long, the peak current is totally contributed by the reduction of adsorbed PAP. The adsorbed species is most probably neutral molecule of PAP. The saturated adsorption amount of PAP at Hg electrode is 2. 78*10-10 mol/cm2 and every PAP molecule occupies 0. 60 nm2. On the surface of HMDE, the adsorption of PAP obeys Frumkin adsorption isotherm. The adsorption coefficient 3 is 1. 28*106,the attractive factor v is 0. 75. The number of electronstransferred per PAP molecule n is 2 and the transfer coefficient a of the irreversible adsorptive system of PAP is 0. 86. The mechanism of electrochemical reduction of PAP at Hg electrode is explored. The detection limit of the adsorptive stripping voltammetry of PAP is 1. 0 10-9 mol/L under optimized condition.