Sirivibulkovit Kitima, Nouanthavong Souksanh, Sameenoi Yupaporn
Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Burapha University.
Savannakhet Teacher Training College.
Anal Sci. 2018;34(7):795-800. doi: 10.2116/analsci.18P014.
We report on a paper-based 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) assay for a simple, inexpensive, low reagent and sample consumption and high throughput analysis of antioxidant activity. The paper-based device was fabricated using a lamination method to create a 5-mm in diameter circular test zone that was embedded with a DPPH reagent. The analysis was carried out in one-step by dropping an antioxidant/sample onto the test zone. After reduction by the antioxidant, the DPPH radicals become stable DPPH molecules, resulting in a change in color from deep violet to pale yellow. The violet color intensity of DPPH was inversely proportional to the antioxidant activity of the samples, and was measured using imaging software. A high precision and a low limit of detection were found in the analysis of six standard antioxidants including gallic acid, trolox, ascorbic acid, caffeic acid, vanilliic acid and quercetin. The device was then validated against the traditional spectrophotometric DPPH assay by analyzing the antioxidant activity of 7 tea samples. The results showed no significant difference for gallic acid equivalent for all 7 samples obtained from the two methods at the 95% confidence level, indicating that the developed method was reliable for antioxidant activity analysis of real samples. Finally, the paper-based DPPH device was found to be stable over 10 days when stored in a refrigerator (2 - 4°C), making it an easy-to-use device for end-users.
我们报道了一种基于纸的2,2-二苯基-1-(2,4,6-三硝基苯基)肼(DPPH)分析法，用于对抗氧化活性进行简单、廉价、低试剂和样品消耗以及高通量分析。该基于纸的装置采用层压方法制造，形成一个直径为5毫米的圆形测试区，其中嵌入了DPPH试剂。通过将抗氧化剂/样品滴到测试区进行一步分析。在被抗氧化剂还原后，DPPH自由基变成稳定的DPPH分子，导致颜色从深紫色变为浅黄色。DPPH的紫色强度与样品的抗氧化活性成反比，并使用成像软件进行测量。在对包括没食子酸、Trolox、抗坏血酸、咖啡酸、香草酸和槲皮素在内的六种标准抗氧化剂的分析中发现了高精度和低检测限。然后通过分析7个茶叶样品的抗氧化活性，将该装置与传统的分光光度法DPPH分析进行了验证。结果表明，在95%置信水平下，两种方法对所有7个样品的没食子酸当量无显著差异，表明所开发的方法对实际样品的抗氧化活性分析是可靠的。最后，发现基于纸的DPPH装置在冰箱(2-4°C)中储存10天仍保持稳定，使其成为终端用户易于使用的装置。
