Mahmoud Reza Sohrabi - Department of Chemistry, Faculty of Chemistry, Azad University, North Tehran Branch, Tehran,Iran
Ali Niazi - Department of Chemistry, Faculty of Sciences, Arak Branch, Islamic Azad University, Arak,Iran
Mahdi Rahmani - Department of Chemistry, Faculty of Sciences, Arak Branch, Islamic Azad University, Arak,Iran

In this study a zero crossing technique based on continuous wavelet transform (CWT) aswell as classical derivative spectrophotometry (CDS) is presented for simultaneousdetermination of Methamphetamine (MA) and 3,4-methylendioxymethamphetamine(MDMA , ecstasy) in binary mixtures, without using prior chemical pre-treatment.Absorption spectra were recorded in the wavelength range 200–400 nm. Absorbancedata were subjected to various mother wavelets from continuous wavelet transform family to find the optimum point of the Wavelet signal processing (MATLAB 7.1) bior3.3, 3.7 and 1.5 with scaling factors a = 60, 40 and 15 while first derivative Δ was 10 nm. The validation of proposed methods was investigated by several synthetic mixtures and obtained results were successfully compared among each other. Mean recovery values were found 102.9% for CWT and 98.7% for DS, for the determination of MDMA and 97.4% and 99.9% for CWT and 101.6% for DS, for the determination of MA in synthetic mixtures..

3,4-methylendioxymethamphetamine, Methamphetamine, Continuous wavelet transforms, Simultaneous determination