Real time quantitative colourimetric test for methamphetamine detection using digital and mobile phone technology

The Simon presumptive color test was used in combination with the built-in digital camera on a mobile phone to detect methamphetamine. The real-time Red-Green-Blue (RGB) basic color data was obtained using an application installed on the mobile phone and the relationship profile between RGB intensity, including other calculated values, and the colourimetric product was investigated. A wide linear range (0.1–2.5 mg mL−1) and a low detection limit (0.0110 ± 0.0001–0.044 ± 0.002 mg mL−1) were achieved. The method also required a small sample size (20 μL). The results obtained from the analysis of illicit methamphetamine tablets were comparable to values obtained from gas chromatograph-flame ionization detector (GC-FID) analysis. Method validation indicated good intra- and inter-day precision (2.27–4.49%RSD and 2.65–5.62%RSD, respectively). The results suggest that this is a powerful real-time mobile method with the potential to be applied in field tests.