A mixed-mode cationic exchange planar sorptive phase is presented.

The sorptive phase is affordable and simple.

It has been used for the isolation of two opioids from saliva samples.

The extraction procedure permits to process of several samples simultaneously.

The use of DI-MS provides a high sample throughput.

This article describes the synthesis of mixed-mode cationic exchange (MCX) tapes as sorptive phases in bioanalysis, and it faces the determination of methadone and tramadol in saliva as the model analytical problem. The tapes are synthesized using aluminum foil as substrate, which is subsequently covered with double-sided adhesive tape where the MCX particles (ca. 1.4 ± 0.2 mg) finally adhere. MCX particles allow the extraction of the analytes at the physiological pH, where both drugs are positively charged, minimizing the potential co-extraction of endogenous matrix compounds. The extraction conditions were studied considering the main variables (e.g. ionic strength, extraction time, sample dilution). Under the optimum conditions and using direct infusion mass spectrometry as the instrumental technique, detection limits as low as 3.3 μg·L−1 were obtained. The precision calculated at three different levels, and expressed as relative standard deviation, was better than 3.8%. The accuracy, expressed as relative recoveries, ranged from 83 to 113%. The method was finally applied to determine tramadol in saliva samples from patients under medical treatment. This approach opens the door to easily preparing sorptive tapes based on commercial (or ad-hoc synthesized) sorbent particles.

Sorptive tapes

Mixed-mode sorbent

Mass spectrometry

Opioids

Saliva

Data will be made available on request.

© 2023 The Author(s). Published by Elsevier B.V.