The use of hair strand drug tests has gained significant attention in clinical, environmental toxicology, and forensic applications. However, the accuracy of the test results requires the establishment of matrix reference materials (mRMs) products for internal use in laboratories. Immersion is a feasible method for preparing hair mRMs, but a lack of detailed preparation parameters often leads to unpredictable concentrations of target analytes. In this study, morphine (MOR), 6-acetylmorphine (6-AM), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), cocaine (COC), benzoylecgonine (BZE), and methamphetamine (MAMP) were selected as target analytes based on the Society of Hair Testing guidelines. The hair mRMs were prepared using the immersion method to investigate the influence of immersion time, washing protocol, and solution concentration on the resulting reference products. The preparation time should be limited to 30-45 days, which is the duration that hair analytes remain stable. The impregnated hair should be thoroughly cleansed, ideally using a combination of water and acetone, prior to hair sample testing. There is a positive correlation between the concentration of MAMP in the soaking solution and its presence in hair samples, which can be represented by the equation y = 0.2372 x - 0.347. This relationship suggests that adjusting the immersing concentration in accordance with the target hair concentration can enhance the efficiency of the preparation process, thus saving time and reducing costs. Stability results indicate that hair mRMs can be stored for at least six months under both cold storage and room temperature conditions. In the analysis of authentic hair drug samples, the application of hair mRMs significantly enhances the consistency and accuracy of the test results.
