Hydroxyl-functionalized multi-walled carbon nanotube-coated pipette tips for extraction and determination of illegally adulterated androgenic steroids

The illegal addition of androgenic steroids, such as testosterone and methyltestosterone, to herbal oral liquids poses a significant threat to consumer health. This study presents a novel method for the extraction and determination of these steroids in herbal products using pipette tip solid-phase microextraction combined with liquid chromatography-tandem mass spectrometry. The pipette tips are coated with hydroxyl-functionalized multi-walled carbon nanotubes, ensuring efficient analyte extraction while reducing sample handling and contamination risks. The method was optimized for parameters such as solvent volume, extraction time, and pH, and demonstrated excellent analytical performance. It demonstrated linearity over the range of 5–5000 ng/mL (R 2  > 0.99), with detection limits of 0.96 ng/mL for testosterone and 1.44 ng/mL for methyltestosterone, and limits of quantification of 3.20 ng/mL for testosterone and 4.80 ng/mL for methyltestosterone. Recovery experiments across multiple matrices and concentration levels showed recoveries ranging from 93.8 % to 108.1 %, with relative standard deviations between 1.1 % and 4.5 %. This approach offers a cost-effective, high-throughput solution for the routine detection of illegal steroid additives in herbal and functional food products, providing a valuable tool for regulatory monitoring and consumer safety.