A fast, sensitive, and high‐throughput method for the simultaneous quantitation of three ellagitannins from Euphorbiae pekinensis R adix in rat plasma by ultra‐ HPLC – MS / MS

A fast, sensitive, and high‐throughput ultra‐ HPLC – MS / MS method has been developed and validated for the simultaneous determination of three main active constituents of E uphorbiae pekinensis R adix in rat plasma. After addition of the internal standard, plasma samples were extracted by liquid–liquid extraction with ethyl acetate/isopropanol (1:1, v/v) and separated on a CAPCELL PAK C 18 column (100 × 2.0 mm, 2 μm, S hiseido, J apan), using a gradient mobile phase system of methanol/water. The detection of the analytes was performed on a 4000 Q UHPLC – MS / MS system with turbo ion spray source in the negative ion and multiple reaction‐monitoring mode. The linear range was 1.0–1000 ng/mL for 3,3′‐di‐ O ‐methyl ellagic acid‐4′‐ O ‐ β ‐d ‐glucopyranoside (i), 1.5–1500 ng/mL for 3,3′‐di‐ O ‐methyl ellagic acid‐4′‐ O ‐ β ‐d ‐xylopyranoside (ii), and 5.0–5000 ng/mL for 3,3′‐di‐ O ‐methyl ellagic acid (iii). The intra‐ and interday precision and accuracy of all the analytes were within 15%. The extraction recoveries of the three analytes and internal standard from plasma were all more than 80%. The validated method was first successfully applied to the evaluation of pharmacokinetic parameters of compounds 1 , 2 , and 3 in rat plasma after intragastric administration of the E uphorbiae pekinensis R adix extract.