在0.2 mol·L-1 NaOH底液中,β-环糊精在二次微分简易示波伏安图上-0.38 V处产生一可逆峰,阴极支的峰高随L-苯丙氨酸与β-环糊精形成的包结物量的增加而降低.根据β-环糊精的示波特性,建立了L-苯丙氨酸含量测定的二次微分简易示波伏安法.试验结果表明:β-环糊精在二次微分简易示波伏安图上的峰高与L-苯丙氨酸浓度在2.5×10-6~4.5×10-5mol·L-1范围内呈线性关系,相关系数为0.999 6,检出限为1.0×10-6mol·L-1.对于8.0×10-5mol·L-1 L-苯丙氨酸5次测定的RSD为3.1%,平均回收率为100.0%.测得β-环糊精与L-苯丙氨酸形成包结物的包结比为1∶1,包结常数为1.9×106.

In the base solution of 0.2 mol·L-1 NaOH,a reversible peak produced by β-cyclodextrin (β-CD) was found in the 2nd derivative oscillovoltammogram at -0.38 V (vs.SCE);and the peak height of cathodic branch was found to decrease with the increase of concentration of the inclusive complex formed between β-CD and L-phenylalanine.A linear relationship between the peak height and concentration of L-phenylalanine was found in the range of 2.5×10-6-4.5×10-5mol·L-1 (r=0.999 6),with a detection limit of 1.0×10-6mol·L-1.Based on this feature,a method of 2nd derivative oscillovoltammetric determination of L-phenylalanine was proposed.Test of precision was made with 5 determinations of L-phenylalanine at the concentration level of 8.0×10-5mol·L-1,giving the value of RSD of 3.1%.Results of recovery test were obtained with an average of 100.0%.Molar ratio of the inclusive complex formed between β-CD and L-phenylalanine was found to be 1 to 1 and the complex formation constant was 1.9×106.