RESUMO
The utility of hydrogen stable isotope ratio measurement by IR-MS for establishing the origin of ephedrine and pseudoephedrine (ephedrines), precursors of methamphetamine, was evaluated. There are two kinds of commercial semisynthetic ephedrines, one produced from molasses and the other from pyruvic acid. While the semisynthetic ephedrines derived from pyruvic acid cannot be discriminated from biosynthetic ephedrines and synthetic ephedrines based on delta(13)C and delta(15)N values, they could be identified from the delta(2)H values. The low deuterium content of biosynthetic ephedrines (delta(2)H: -193 to -151 per thousand) allows a clear distinction from synthetic ephedrines (delta(2)H: -73 to -30 per thousand), semisynthetic ephedrines derived from pyruvic acid (delta(2)H: +75 to +148 per thousand) and semisynthetic ephedrines derived from molasses (delta(2)H: -74 to +243 per thousand). The wide range of delta(2)H values of semisynthetic ephedrines is therefore very useful for the detailed classification of ephedrines, in combination with the measurement of delta(13)C and delta(15)N values as described in our previous work. This study was carried out on a limited number of samples reflecting the various routes of ephedrines manufacture. But it has become apparent that this stable-isotope analysis is an appropriate means by which to screen for manufacturing process of ephedrines. This approach should be useful for worldwide precursor control of methamphetamine.
