CAJ | 학술논문

采用二苯碳酰二肼分光光度法，测定了食品中15种常见有机物在不同pH值、不同温度下还原Cr(VI)的动力学数据，结果表明：L-抗坏血酸、L-半胱氨酸盐酸盐、L-甲硫氨酸表现出较强的还原Cr(VI)能力，其余12种有机物在5 h内基本未还原Cr(VI)。L-抗坏血酸在短时可将Cr(VI)全部还原，L-半胱氨酸盐酸盐在60 min内可将Cr(VI)全部还原，L-甲硫氨酸在5 h内能将Cr(VI)还原23%，其还原能力次序为：L-抗坏血酸>L-半胱氨酸盐酸盐>L-甲硫氨酸。pH值对还原反应动力学影响较大，L-半胱氨酸盐酸盐对Cr(VI)的还原作用随pH的升高而增强，而L-甲硫氨酸对Cr(VI)的还原作用则随pH的升高而减弱直至不反应。以零级反应动力学方程拟合了pH=3.0时L-甲硫氨酸还原Cr(VI)的动力学数据，得到L-甲硫氨酸还原Cr(VI)的表观活化能为35.5 kJ×mol-1；以一级反应动力学方程拟合了L-半胱氨酸盐酸盐还原Cr(VI)动力学数据，得到pH=3.0、5.0和7.0时，L-半胱氨酸盐酸盐还原Cr(VI)的表观活化能分别为34.4,45.3,34.9 kJ×mol-1。
채용이분탄선이정분광광도법，측정료식품중15충상견유궤물재불동pH치、불동온도하환원Cr(VI)적동역학수거，결과표명：L-항배혈산、L-반광안산염산염、L-갑류안산표현출교강적환원Cr(VI)능력，기여12충유궤물재5 h내기본미환원Cr(VI)。L-항배혈산재단시가장Cr(VI)전부환원，L-반광안산염산염재60 min내가장Cr(VI)전부환원，L-갑류안산재5 h내능장Cr(VI)환원23%，기환원능력차서위：L-항배혈산>L-반광안산염산염>L-갑류안산。pH치대환원반응동역학영향교대，L-반광안산염산염대Cr(VI)적환원작용수pH적승고이증강，이L-갑류안산대Cr(VI)적환원작용칙수pH적승고이감약직지불반응。이령급반응동역학방정의합료pH=3.0시L-갑류안산환원Cr(VI)적동역학수거，득도L-갑류안산환원Cr(VI)적표관활화능위35.5 kJ×mol-1；이일급반응동역학방정의합료L-반광안산염산염환원Cr(VI)동역학수거，득도pH=3.0、5.0화7.0시，L-반광안산염산염환원Cr(VI)적표관활화능분별위34.4,45.3,34.9 kJ×mol-1。
The data of Cr(VI) reduction kinetics with 15 kinds of common organic compounds in food were determined by the diphenylcarbazide spectrophotometry at different pH values and temperatures. The results indicate that the L-Ascorbic acid, L-Cysteine hydrochloride and L-Methionine have relatively strong reduction activities for Cr(VI), while Cr(VI) hardly undergoes the reduction with other 12 kinds of organics within 5 hours. Cr(VI) is completely reduced by L-Ascorbic acid in a short period of time, and completely reduced by L-Cysteine hydrochloride within 60 minutes, but reduced for 23%by L-Methionine after 5 hours. Therefore, the sequence of the reduction activity of the three organic compounds is L-Ascorbic acid >L-Cysteine hydrochloride>L-Methionine. The values of pH have a great effect on the reduction kinetics. As the pH value increases, the reduction with L-Cysteine hydrochloride salt is enhanced, while the reduction with L-Methionine is decreased, and even decreased to none. The kinetics data of Cr(VI) reduction with L-Methionine were fitted by a zero-order kinetics equation at the pH of 3.0, and the apparent activation energy was obtained as 35.5 kJ×mol-1. In addition, the kinetics data of Cr(VI) reduction with L-Cysteine hydrochloride at the pH of 3.0, 5.0 and 7.0 were fitted by a first-order kinetics equation, and the apparent activation energies of the reduction were obtained as 34.4, 45.3, 34.9 kJ×mol-1, respectively.