Analysis of an Expanded Panel of Sympathomimetic Amines in Urine Using Single Quadrupole GC–MS

Matthew Lambing and Jason Cole, Thermo Fisher Scientific, Inc.

The United States Substance Abuse and Mental Health Services Administration (SAMHSA) released a revision to the Mandatory Guidelines for Federal Workplace Drug Testing Programs, scheduled to become effective May 1, 2010. As part of the new guidelines, multiple changes were made for the confirmation of amphetamine-class urine analysis. In addition to SAMHSA's previously published guidelines for amphetamine and methamphetamine, three amphetamine-analogue drugs will be added to the panel: 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyethylamphetamine (MDEA). The confirmatory cutoff concentration level for the regulated amphetamines will be lowered from 500 ng/mL to 250 ng/mL.

Method

A method for the confirmation and quantification of these sympathomimetic amines in human urine was developed using the Thermo Scientific ISQ Single Quadrupole GC–MS system. The method developed adheres to guidelines published by SAMHSA, the College of American Pathologists (CAP), the Society of Forensic Toxicologists (SOFT,) and the European Workplace Drug Testing Society (EWDTS).

Figure 1

Thermo Scientific HyperSep Verify-CX solid phase extraction columns (200 mg, 10 mL, P/N: 60108-742) were used for sample extraction, and extracts were derivatized with trifluoroacetic acid anhydride (TFAA). Selected ion monitoring (SIM) conditions used on the ISQ are shown in Table I.

Table I: Retention times and ions monitored for the five amphetamine class analytes and their deuterated internal standards

Results

• Assay linearity ranged from 25 ng/mL to 25,000 ng/mL, with correlation coefficients (R²) of 0.9990 or better for all compounds

• Limits of detection and quantification of 25 ng/mL using a 2 mL sample size for all compounds

• Intra- and inter- day precision of < 4% CV (coefficient of variation) at the quality control levels of 100 ng/mL and 312.5 ng/mL

• No interference seen from coeluting matrix compounds, including spiked ephedrine and pseudoephedrine

Conclusions

A method was developed to demonstrate the performance of the ISQ GC–MS system for the analysis of five amphetamines in a urine matrix. The extended amphetamines assay described offers broad linearity to cover a wide range of analyte concentrations, with R² values of 0.9990 or higher for all analytes over the range of 25–25,000 ng/mL in sample. Excellent precision was also demonstrated near the 250 ng/mL cutoff, with CV measurements of 4% or less over multiple batches. Limits of detection and quantification at 25 ng/mL ensure sensitive performance for retest and directed assay samples. And with the final analyte, MDEA, eluting at a retention time of less than 5 min, the methodology described offers a productive means for a high-throughput toxicology laboratory to confirm the five amphetamine panel.

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