.4. Analysis of Yaba samples
Five seized Yaba samples were extracted and analyzed using GC-FID (Fig. 7). The GC-FID was calibrated and demonstrated good linearity in the range of 0.0025–1.0 mg mL−1 of methamphetamine in methanol (y = 408.85x − 2.78; R2 = 0.9996; %RSD < 4.4). The results displayed in Table 2, clearly demonstrated a very good correlation between the accurately determined concentration of methamphetamine in the samples using GC-FID and the real-time mobile quantitative method. This also indicated that the color tests applied were not influenced by any color ingredient within the sample being analyzed.