Gas Chromatography-Flame Ionization Technique for the Determination of Mitragynine, Caffeine, Diphenhydramine, Promethazine, and Tramadol in Kratom Drinks.

The determination of mitragynine and psychoactive substances in kratom drinks is essential for forensic investigation and medical treatment. In this study, gas chromatography coupled with flame ionization was used to identify mitragynine, caffeine, diphenhydramine, promethazine, and tramadol in various kratom drinks. The analysis was conducted using the HP‑5 column with a nitrogen gas flowing at a rate of 1.8 mL/min. The oven temperature was held at 220°C for 1 min and then increased to 270°C at a rate of 5°C/min. It was further ramped to 300°C at a rate of 30°C/min and held for 13 min. The injector and detector temperatures were set at 280°C. Samples were injected using the split mode (50 : 1) and the total run time was 25 min. Alkalinized samples were extracted with an 80 : 20 (v/v) mixture of ethyl acetate and n-hexane. Method validation revealed acceptable linearity for all analytes (r > 0.990), good precision (0.7–4.2% RSD), accuracy (–11.0–15.2% RE), lower limit of quantification (3–15 µg/mL), and extraction recoveries (81.8–105.8%, except caffeine). The developed method successfully detected and quantified the target analytes. [ABSTRACT FROM AUTHOR]