Rapid microwave-assisted Porter method for determination of proanthocyanidins.

Abstract

Proanthocyanidins have been widely developed and utilised in food, medicine, health care products and cosmetics. Porter-high-performance liquid chromatography (HPLC) is a quantitative method often utilised in many fields. This method uses a water bath to reflux the proanthocyanidins, but the process is cumbersome, the reagent consumption is large, and multiple batches of simultaneous treatments cannot be evaluated. To establish a more convenient, rapid and high-batch processing method for determining the content of proanthocyanidins in functional food by HPLC. N-Butanol-hydrochloric acid and iron salt are used as the reaction medium in the Porter method. After investigating the optimal conditions, the hydrolysis of proanthocyanidins can be performed in a microwave reactor at a power of 640W for 75s in the Porter reaction system. The content of proanthocyanidins was determined by HPLC with external standards. After the rapid pretreatment of samples, proanthocyanidins were determined by HPLC with a diode array detector at a detection wavelength of 525nm with 0.53μg/mL and 1.61μg/mL limits of detection and quantification, respectively, for proanthocyanidin ions, and the linearity was 0.9999. Intra- and inter-day relative standard deviation values were between 1.5% and 3.1%, and the recovery was between 91.40% and 107.43% for the determination of different products, such as capsules, tablets and tea, which were similar to the values obtained with the conventional Porter method. This method is a time-saving and low cost approach for quantitative analysis of various proanthocyanidin health products that offers the advantages of high-batch processing and environmental friendliness.