罗丹明6G缔合微粒光度法检测羟自由基及其在离体筛选抗氧化剂中的应用

在HCl-NaAc缓冲溶液中，Fenton反应产生的羟自由基被过量的KI捕获;生成的I-₃分别与罗丹明B(λ_max=554 nm)、罗丹明6G(λ_max=526 nm)、罗丹明S(λ_max=526 nm)和丁基罗丹明B(λ_max=556 nm)形成缔合微粒，导致其吸收峰降低。羟自由基浓度(以H₂O₂浓度计)分别在0.136～0.68 μg·mL-1,0.064～0.680 μg·mL-1,0.064～0.680 μg·mL-1和0.064～0.680 μg·mL-1范围内与罗丹明B、罗丹明6G、罗丹明S和丁基罗丹明B体系的吸光度降低值成正比。据此建立了一种测定抗氧化剂对羟自由基的清除率的新方法。测试了抗坏血酸等4种抗氧化剂以及6种茶叶提取液的抗氧化活性，所得到的结果较为满意。

Rhodamine 6G Association Particle Based Spectrophotometric Determination of Hydroxy Free Radical and Its Application to the Selection of Antioxidant

In HCl-NaAc buffer solution, the hydroxy free radical from the Fenton reaction is captured by excess KI and releases I3-. The I3- combines with Rhodamine B (RhB, lamdamax=554 nm), Rhodamine 6G(Rh6G, lamdamax=526 nm), Rhodamine S (RhS, lamdamax=526 nm), and butyl Rhodamine B(b -RhB, A,lamdamax56 nm) to form association particles, so the absorbance at max wavelength decreases. The concentration of hydroxy free radical (calculated by the concentration of hydrogen peroxide) is proportional to the decreased absorbance of the systems of RhB, Rh6G, RhS, b-RhB in the range of 0.136-0.680 microg x L(-1), 0.34-0.680 microg x mL(-1), 0.034-0.680 microg x mL(-1), 0.034-0.680 microg c mL(-1), espectively. Based on this fact, a new method for the determination of scavenging percentage of hydroxy free radical with antioxidant was developed. The resistance to oxidation of four substances and six kinds of tea extract were measured with satisfactory results.