Pisoschi Aurelia Magdalena, Cheregi Mihaela Carmen, Danet Andrei Florin
Chemistry and Biochemistry Department, Faculty of Veterinary Medicine, University of Agronomic Sciences and Veterinary Medicine, bulevardul Marasti, no 59, Bucharest, Romania.
Molecules. 2009 Jan 20;14(1):480-93. doi: 10.3390/molecules14010480.
The aim of this paper was to assess the total antioxidant capacity of some commercial fruit juices (namely citrus), spectrophotometrically and by the biamperometric method, using the redox couple DPPH. (2,2-diphenyl-1-picrylhydrazyl)/DPPH (2,2-diphenyl-1-picrylhydrazine). Trolox was chosen as a standard antioxidant. In the case of the spectrophometric method, the absorbance decrease of the DPPH. solution was followed. For the biamperometric method, the influence of some parameters like the potential difference, DeltaE, DPPH. concentration, and Trolox concentration was investigated. The calibration graph obtained for Trolox presents linearity between 5 and 30 microM, (y=0.059 x + 0.0564, where y represents the value of current intensity, expressed as microA and x the value of Trolox concentration, expressed as muM; r(2)=0.9944). The R.S.D. value for the biamperometric method was 1.29% (n=10, c=15 microM Trolox). In the case of the spectrophotometric method, the calibration graph obtained for Trolox presents linearity between 0.01 and 0.125 mM (y= -9.5789 x+1.4533, where y represents the value of absorbance and x, the value of Trolox concentration, expressed as mM; r(2)=0.9963). The R.S.D. value for the spectrophotometric method was 2.05%. Both methods were applied to total antioxidant activity determination in real samples (natural juices and soft drinks) and the results were in good agreement.
本文旨在通过分光光度法和双安培法，使用氧化还原对DPPH·（2,2-二苯基-1-苦基肼基）/DPPH（2,2-二苯基-1-苦基肼）来评估一些市售果汁（即柑橘类果汁）的总抗氧化能力。选择Trolox作为标准抗氧化剂。在分光光度法中，跟踪DPPH·溶液的吸光度下降情况。对于双安培法，研究了一些参数的影响，如电位差ΔE、DPPH·浓度和Trolox浓度。得到的Trolox校准曲线在5至30μM之间呈线性（y = 0.059x + 0.0564，其中y表示电流强度值，单位为μA，x表示Trolox浓度值，单位为μM；r² = 0.9944）。双安培法的相对标准偏差（R.S.D.）值为1.29%（n = 10，c = 15μM Trolox）。在分光光度法中，得到的Trolox校准曲线在0.01至0.125 mM之间呈线性（y = -9.5789x + 1.4533，其中y表示吸光度值，x表示Trolox浓度值，单位为mM；r² = 0.9963）。分光光度法的R.S.D.值为2.05%。两种方法都应用于实际样品（天然果汁和软饮料）中总抗氧化活性的测定，结果吻合良好。
