Improved Quality Control Method for Prescriptions of Polygonum capitatum through Simultaneous Determination of Nine Major Constituents by HPLC Coupled with Triple Quadruple Mass Spectrometry

As a traditional Miao-nationality medicinal plant, Polygonum capitatum has been used in clinical practice for several thousand years. Its prescriptions, including three dosage forms: granules, capsule and tablet are known by the brand name Relinqing® and have played an indispensable role in the treatment of urinary system infection, pyelonephritis and kidney stones. However, no study about the comprehensive quality evaluation of Relinqing® has been reported. In the present paper, a method for the simultaneous determination of nine major compounds in three dosage forms of Relinqing® using HPLC coupled with triple quadrupole mass spectrometry (HPLC-QQQ MS) was established to comprehensively evaluate their quality. The nine compounds, including four phenolic acids, four flavonoids and a lignin, were analyzed with acceptable linear regression relationship (r2, 0.9923–0.9992), precision (RSD, 1.25%–2.78%), repeatability (RSD, 2.05%%–3.47%), stability (RSD, 1.84%–3.72%) and recovery (93.60%–108.54%, RSD ≤ 3.67%). The present study fills the gap in the multivariate quality control of Relinqing® and provides a valuable reference for quality standards and dosage reforming of this traditional Chinese medicine.