Quercetin is a naturally occurring and valuable bioactive compound found in various vegetables and fruits. The determination of quercetin concentrations in foodstuffs is of great importance; however, it is challenging due to matrix interference. A new sorbent, an aliphatic polyester, polybutylene dodecanedioate was synthesized for extraction of quercetin. It was characterized by NMR, FTIR, XPS, and DSC spectroscopy. A dispersive solid-phase microextraction method for spectrophotometric determination of quercetin in foodstuffs was developed using synthesized adsorbent. Under the optimized conditions, the proposed method showed a linear working range of 15-900 ng/mL, a limit of detection of 4.5 ng/mL, and an enrichment factor of 175 determined using matrixcompatible aqueous model solutions. Quercetin concentrations in vegetables, fruits, and beverages were determined to range from 1.20 to 42.0 mg per 100 g, with spike-test recovery values ranging from 91 to 99%. Determination of quercetin in the real samples was completed within only 10 min by the proposed methodology.