Use of modified henequen fibers for the analysis of malachite green and leuco-malachite green in fish muscle by d-SPE followed by capillary electrophoresis.

• A method for the determination of malachite green and its leuco form was proposed. • The methodology consists on the use of modified henequen fibers as adsorbent in d-SPE. • The work proposes the use of copper phthalocyanine to modify the henequen fibers. • The methodology allowed the determination of both analytes using d-SPE-CE-DAD. • The methodology was applied in the analysis of fish samples with satisfactory results. A novel and simple procedure for the determination of malachite green (MG) and leuco-malachite green (LMG) in fish muscle was designed and validated. The method involved the use of henequen fibers modified with copper phthalocyanine as an efficient adsorbent in a dispersive-solid phase extraction technique. Following the extraction and pre-concentration process, CE-DAD was employed to quantify MG and LMG. The structural similarity of MG and LMG and the presence of the cationic forms under acidic conditions are the main drawbacks to determine these analytes in capillary electrophoresis. The proposed methodology allowed for the effective extraction and separation of both analytes using d-SPE-CE-DAD. The experimental parameters of the d-SPE technique were evaluated in order to get the highest pre-concentration efficiency. Under optimum conditions, the methodology achieves a limit of detection of 12.5 μg kg−1 for malachite green and 5.0 μg kg−1 for leuco-malachite green. Repeatability and reproducibility (%RSD n = 3) were less than 5.0% RSD in all cases, indicating that the method shows good precision for the analysis of real samples. In order to evaluate the accuracy of the method, the recovery was evaluated in tilapia samples at three concentration levels, recoveries varied from 88.7% to 109.5% for MG and from 65.3% to 88.8% for LMG. The method was validated and successfully applied to determine MG and LMG in fish samples. [ABSTRACT FROM AUTHOR]