A new analytical methodology for the detection of Methamphetamine using UV-Vis, FTIR, and GC-MS techniques

Abstract

Methamphetamine is one of the strongest and highly addictive stimulants of the central nervous system. It is a synthetic drug and belongs to the amphetamine-type stimulants but it is more potent as compared to amphetamines. It is illicitly manufactured in clandestine laboratories. The major precursors required for the manufacture of methamphetamine include ephedrine, pseudo-ephedrine, and phenyl-2-propanone. Its manufacturing, possession, trafficking, distribution, and sale have been restricted and controlled legally not only in Pakistan but internationally as well. The main objective is to develop and validate a new method for the detection and quantification of methamphetamine manufactured in Pakistan. The proposed method is quite easy, simple and cost-effective, and requires no complex methodology for sample preparation.A chemical spot test was used for the detection of methamphetamine as a presumptive test. The confirmation test for methamphetamine was performed using a Fourier transform infrared (FT-IR) spectrophotometer and gas chromatography-mass spectrometry (GC-MS). The quantification of methamphetamine was carried out on a UV-visible spectrophotometer.  All of the parameters, like accuracy, precision, linearity, reproducibility, detection limits, quantification limits, etc., were established and validated. The proposed method is easy, simple, and accurate, and the results are so reliable that they can be used for casework in forensics and clinical drug analysis. The quantitative linearity range was from 50 µg/mL to 1000 µg/mL and the observed λ_max was 259 nm. The calibrators were stable for 4 days. The limit of detection was 50 µg/mL and the lower limit of quantification was also 50 µg/mL. The absorbance of methamphetamine in the UV region is due to π to π* transition because of the presence of carbon-carbon double bonds in the methamphetamine structure.  FT-IR spectrum showed that the sample was 88 % pure and GC-MS results showed that the sample contained 85 % of methamphetamine.