是一种稳定的自由基，可用于测量抗氧化剂的自由基清除活性。DPPH 中氮原子的奇数电子通过从抗氧化剂吸收氢原子而还原为相应的肼。DPPH 方法可用于水性和非极性有机溶剂中，并可用于检查亲水性和亲脂性抗氧化剂。

使用本产品的应用案例（仅供参考）

DPPH scavenging activities （DPPH实验浓度：0.4mM；溶剂：乙醇）

The DPPH scavenging activities (%) of fresh MPN-GA samples (CON, A1, A2, F1 and F2) were evaluated via using the methods of Zhang et al. [17]. To be specific, fresh MPN-GAs (2.0 mL, 0, 0.01, 0.05, 0.25, 1 and 4 mg/mL), DPPH ethanol solution (0.8 mL, 0.4 mM) were incorporated into the water (4.0 mL). Then, obtained mixtures were centrifuged (6000 rpm, 15 min) after the reaction for 30 min (4 ◦C, in the darkness). Final DPPH scavenging activities were assessed through the transformation of measured absorbance (517 nm).

来源文献：Chen J, Chen X, Zhou G, Xu X. New insights into the ultrasound impact on covalent reactions of myofibrillar protein. Ultrason Sonochem. 2022 Mar;84:105973. doi: 10.1016/j.ultsonch.2022.105973. Epub 2022 Mar 3. PMID: 35272240; PMCID: PMC8913343.

Antioxidant capacity （DPPH实验浓度：0.2mM；溶剂：乙醇）

Film samples (4–20 mg) were added to 10 mL of distilled water and stirred until completely dissolved. DPPH solution (0.2 mmol/L) was prepared in anhydrous ethanol (≥ 99.7 %). Film solution (2 mL) was mixed with 2 mL of DPPH solution and the absorbance at 517 nm measured after reacting for 30 min at 25 ◦C in the dark. The DPPH radical scavenging rate of a Vit C solution at the same concentration as the film solution was determined as a positive control. The DPPH radical scavenging activity of film samples was calculated as follows: DPPH radical scavenging activity (%) = (A0 − A1 + A2)/ A0 × 100

where A0 is the absorbance of the mixture of distilled water and DPPH solution, A1 is the absorbance of the mixture of film or Vit C solution and DPPH solution, and A2 is the absorbance of the mixture of anhydrous alcohol and film or Vit C solution.

来源文献：Liu Z ,  Du M ,  Liu H , et al. Chitosan films incorporating litchi peel extract and titanium dioxide nanoparticles and their application as coatings on watercored apples[J]. Progress in Organic Coatings, 2021, 151:106103.