An environmentally friendly method based on micro-cloud point extraction for determination of trace amount of quercetin in food and fruit juice samples.

This study was conducted for quantitative determination of quercetin in food and fruit juice samples based on a green, fast, and accurate method namely, micro-cloud point extraction (MCPE). The proposed MCPE is essentially a miniaturized form of traditional cloud point extraction (CPE) in which only a few microliters of micellar extracting phase is sufficient for determination. Factors influencing the extraction efficiency, such as amount of Triton X-114 (5%, v/v), effect of pH, amount of NaSO salt (5%, w/v) and time of centrifugation were investigated and optimized by experimental design. Under the optimized condition, the calibration range was found to be linear over 10-100 ng mL with the limit of detection of 2.2 ng mL. The relative standard deviation of 2.8%, was obtained on a 30 ng mLquercetin standard solution (n = 3). Finally, the proposed method was successfully applied for the determination of quercetin in onion, tomato, apple and orange juice samples.