Development and validation of a GC-fid technique for detecting methamphetamine in illicit drugs samples in Sri Lanka

Methamphetamine, commonly known as "ICE" in Sri Lanka, is a potent drug classified within the amphetamine group, functioning as a stimulant for the central nervous system. Data from the Government Analyst’s Department (GAD) indicates a notable increase in received methamphetamine cases. As the authorized institute for analyzing and providing reports on illicit drugs to the courts, it is crucial for the Government Analyst’s Department to develop and validate a rapid GC-FID method for accurately quantifying methamphetamine. This study involves the qualitative and quantitative analysis of forty samples received by the Government Analyst's Department (GAD) between 2019 and 2021. Presumptive tests, TLC, FTIR, and GCMS methods were primarily used for qualitative analysis, whereas quantitative analysis was carried out using GC-FID. Chromatographic separation was performed on HP-5MS column (30 m x 250 μm x 0.25 μm) with a temperature program of 110°C for 4 min, followed by a ramp up at 10°C/min to 280°C, with nitrogen as the carrier gas at a flow rate of 1.0 ml/min. The method was found to be satisfactory and successfully applied in the quantification of methamphetamine. In the validation of GC-FID method parameters, linearity, precision, LOD, and LOQ were considered. Calibration curves ranged between 50-400 mg/L and 10-50 mg/L, representing correlation coefficients of 0.9978 and 0.9985, respectively. The precision was expressed as Relative Standard Deviation below 2%. The limit of detection and the limit of quantification were 5.32 mg/L and 5.98 mg/L, respectively.