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Quantitative and Isomeric Determination of Amphetamine and Methamphetamine From Urine Using a Nonprotic Elution Solvent and R(-)-alpha-methoxy-alpha-trifluoromethylphenylacetic Acid Chloride Derivatization

Quantitative and Isomeric Determination of Amphetamine and Methamphetamine From Urine Using a Nonprotic Elution Solvent and R(-)-alpha-methoxy-alpha-trifluoromethylphenylacetic Acid Chloride Derivatization

Justin M Holler, Shawn P Vorce, Thomas Z Bosy, Aaron Jacobs

J Anal Toxicol. 2005 Oct;29(7):652-7.

PMID: 16419395

Abstract:

Forensic Urine Drug Testing Laboratories often requires two confirmatory methods for a methamphetamine positive screen. First, methamphetamine is identified and quantitated using gas chromatography-mass spectrometry. If the total methamphetamine concentration is above the administrative cutoff level, the isomeric composition must be determined. This eliminates a possible contribution by over-the-counter cold medications that contain l-methamphetamine (Vick's inhalers). Products that contain only the l-isomer of methamphetamine must be distinguishable from prescription or illicitly manufactured methamphetamine, which consists mainly of the d-isomer. Optically impure derivatizing reagents will produce an impure mixture from a pure isomeric compound. Therefore, methods utilizing impure reagents can prove problematic when interpreting results. Use of an optically pure chiral derivatizing reagent, such as R(-)-alpha-methoxy-alpha-trifluoromethylphenylacetic acid chloride, allows for the creation and measurement of chromatographically separable isomeric compounds. The novel method described here utilizes a polymer-based solid-phase column adapted to a positive pressure manifold extraction system and a one-step derivatization process that occurs directly in the elution solvent. This methodology eliminates an elution solvent dry-down step that may adversely affect recovery of volatile amphetamine compounds. Although the method was designed for the quantitative analysis of the isomers of amphetamine and methamphetamine, it can be adapted for use with a wide range of phenethylamines including methylenedioxyamphetamine, N-methylenedioxymethamphetamine, and possibly N-methylenedioxyethylamphetamine. The linear range for quantitation was 25-10,000 ng/mL for d,l-methamphetamine and d,l-amphetamine, and correlation coefficients were 0.997 or better. The coefficient of variation for all four analytes did not exceed 2.8%. Concentrations analyzed ranged from 500 to 4000 ng/mL (n=40). The method allows for a simple and accurate quantitation and isomeric determination of amphetamine and methamphetamine using a process that eliminates extraction and derivatization complications common in current methods.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP17257715	(S)-(−)-α-Methoxy-α-trifluoromethylphenylacetic acid		17257-71-5	Price

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