Method validation for determination of mitragynine in Kratom leaf extract by high performance liquid chromatography

Abstract

In this research, the method modified from the AOAC method (Mudge and Brown, 2017) and Limsuwanchote method (2017) for determination of mitragynine in Kratom leaf extract was optimized and validated.The method presented specificity and good linearity within a concentration range of 5 to 50 µg/mL, with a correlation coefficient (R²) of 0.9996. The accuracy studies were conducted as percent recovery, resulting in values ranging from 100.19 – 103.26%. The precision evaluated as a relative standard deviation of repeatability (%RSD) for intra-day and inter-day precision, which exhibited good repeatability of less than 3%. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.108 and 0.125 mg/g, respectively. The linearity, percent recovery, precision, LOD, and LOQ values were deemed acceptable and complied with the requirement of Standard Method Performance Requirements for Alkaloids of Mitragyna speciosa. Moreover, using this validated method, fifteen samples of Kratom leaves from the central and southern regions of Thailand were analyzed, revealing mitragynine concentrations ranging from 2.30 to 25.54 mg/g. The research results showed that the modified method is reliable and suitable for determining mitragynine in Kratom leaf extract samples.