Background: As the pharmacokinetics of methadone exhibit large inter-subject variability,
providing a simple and reliable analytical method for the monitoring of methadone levels in biological
samples during methadone maintenance therapy is necessary in order to determine an appropriate
Method: Determination of methadone in exhaled breath condensate (EBC) is performed using capillary electrophoresis in
stacking mode. EBC is obtained using a simple cooling lab-made system.
Results: The simplicity of the EBC matrix renders the sample analyzable without any pretreatment step. The LLOQ is 0.3
µg/mL across a linear range of 0.3–5 µg/mL. The developed method was validated according to US FDA guidelines and successfully
applied for the determination of methadone levels in four patients undergoing methadone maintenance therapy.
Conclusion: A simple and fast method was presented for determination of methadone in EBC with minimum required