Proceeding2562

1259 การประชุมวิชาการระดับชาติมหาวิทยาลัยทักษิณ ครั้งที่ 29 ประจ�ำปี 2562 วิจัยและนวัตกรรมเพื่อการพัฒนาที่ยั่งยืน Portable colorimetric test kit for the determination of promethazine abuse in lean cocktails Areena Lantam 1 and Apichai Phonchai 2* Abstract Introduction : The lean cocktail is a dangerous hallucinogenic drink which is prepared by mixing promethazine syrup with soft drinks to be used as a drug of abuse by Thai teenagers. The information of a possible death resulting from an over dose of a promethazine in lean cocktail evidence is needed in the forensic investigation. Objective : To investigate the development of a portable colorimetric test kit using a portable photometer for promethazine detection in lean cocktails. Methods : The colorimetric test kit is based on the oxidation of promethazine with potassium persulfate to from pinkish color complex. The colored product were quantified using a portable photometer. The method development, analytical characteristic and lean cocktail evidences analysis were conducted. Results : The method development was investigated such as reagent concentrations, sample and reagent ratio and reaction time. Under the optimization condition, calibration curve was linear over the concentration range of 25–400 mg L -1 with good coefficient of determination (r 2 = 0.995). Limit of detection (LOD) and limit of quan- tification (LOQ) were 5 mg L -1 and 35.6 mg L -1 , respectively. The intra-day and inter-day precisions were 0.8-4.8 %RSD and 0.2-1.9 %RSD (n=5), respectively. The percentage recovery of promethazine detection ranged from 86.6–99.9 % (n=5). Conclusion : A simple, low-cost, precise and accurate, selective and portable method was successfully applied for the determination of promethazine abuse in lean cocktail samples. Keywords : Colorimetric, test kit, Portable photometer, Promethazine, Lean cocktail