β-环糊精增敏荧光猝灭法对粮食样品中L-色氨酸的分析研究

Determination of L-Tryptophan in Grain by β-Cyclodextrin Sensitized Fluorescence Quenching Method

研究了Se(Ⅳ)-丁基罗丹明B与L-色氨酸结合物在β-环糊精(β-CD)介质中的荧光光谱行为。加入L-色氨酸可使Se(Ⅳ)-丁基罗丹明B体系发生荧光猝灭,β-CD的加入导致溶液中荧光猝灭值ΔIF增加,且L-色氨酸的质量浓度与ΔIF呈良好的线性关系,据此建立了荧光猝灭测定L-色氨酸的新方法。优化了实验条件,结果表明:β-CD对测定具有增敏作用,色氨酸的质量浓度在1.0～30.0mg/L范围内与荧光强度呈线性关系,回归方程为ΔIF=399.1ρ(mg/L)+258.9,相关系数r=0.9993,检出限为0.21mg/L。将方法用于粮食样品中L-色氨酸的测定,结果令人满意。

The fluorescence spectral characteristic of interaction between Se （ Ⅳ ） - butylrhodamine B and L-tryptophan（L-Trp） was studied in β-cyclodextrin（β-CD） medium. The result indicated that the addition of L-Trp would resulted in the decrease of fluorescence intensity of Se（ Ⅳ ）-butylrhodam- ine B, and fluorescence quenching value（AIF） was increased in the presence of β-CD. A good line- arity was obtained between fluorescence quenching intensity of the system and concentration of L-Trp. Based on this, a novel fluorescence quenching method for the determination of L-Trp was established. The results showed that under the optimal conditions, β-eyclodextrin could sensitize on determina- tion, the calibration curve was linear for L-Trp concentration in the range of 1.0 -30. 0 mg/L with a detection limit of 0. 21 mg/L. The linear regression equation was AIF = 399. lp （mg/L） ＋ 258.9 with a correlation coefficient（r） of 0. 999 3. The method was simple and rapid, and was applied in the determination of L-tryptophan in real sample with satisfactory result.