Development of Highly Sensitive Analytical Method for Evaluation of Evening Primrose Oil’s Enhancing Effect in Prostaglandin E 1 (OP 1206) Biosynthesis

This study aimed to develop and validate highly sensitive determination method of a prostaglandin (PGE 1 , OP 1206) in human plasma by LC-MS/MS using column switching. Plasma stored at ­30℃ and treated with methanol effectively inhibited interferences synthesized post-sampling. Samples were added with internal standard and were separated by reversed-phase HPLC with a cycle time of 30min. The method was selective for OP 1206 and the regression models, based on internal standard, were linear across the concentration range 0.5-50 pg/mL with the limit of quantification of 0.5 pg/mL (limit of quantitation, LOQ) for OP 1206. The calibration curve of OP 1206 standards spiked in five individual plasma samples was linear (r 2 =0.9999). Accuracy and precision at the concentrations of 0.5, 1.5, 5.0 and 40 pg/mL, and at the lower LOQ of 0.5 pg/mL were excellent at ＜20%. OP1206 was stable in plasma samples for at least 24 hours at room temperature, 24 hours frozen at ­70℃, 24 hours in an auto sampler at 6℃, and for two freeze/unfreezing cycles. The validated determination method successfully quantified the concentrations of OP 1206 in plasma samples from simulated administrating a single 5 µg OP 1206 formulation. Thus, this novel LC-MS/MS technique for drug separation, detection and quantitation is expected to become the standard highly-sensitive detection method in bioanalysis and to be applied to many low dose pharmaceutical products.