科研之友
微信
新浪微博
Facebook
分享链接
摘要
Among the analytical methods used to assess total flavonoid content in food products, the aluminum chloride method is widely used for routine/screening purposes. This method relies on the spectrophotometric detection of colored complexes formed between Al(III) and the carbonyl and hydroxyl groups of flavonoids in alkaline medium. However, during the last decade, different analytical conditions have been applied, which hinder the production of reliable and comparable data for nutritional studies. In this context, the aim of the present work was to standardize the analytical protocol regarding the standard compound, reaction time after addition of each reagent, and reagents concentration. According to the results obtained, the use of (+)-catechin as the standard compound is proposed due to its higher sensitivity and reaction times of 1, 2, and 1 min were fixed for time interval between sequential additions of reagents. The concentration of Al(III) was reduced about three times. Using the improved analytical conditions, the colorimetric assay was adapted to flow injection analysis (FIA) in order to obtain an automatic procedure with controlled features, namely reaction time, sample to reagent concentration ratio, and sample dilution. The proposed FIA method was applied to food products (n = 18), including red wines, teas, and herbal infusions, providing results that were in agreement with those obtained by the classical batch method, here performed under a microplate format. This automatic method allowed the reduction of analysis time from the original 12 to 4 min, with high repeatability [relative standard deviation (RSD) %26lt; 1.1%] and high reproducibility (RSD %26lt; 2.0%).
- 出版日期2012-6
