Deep eutectic solvent-doped graphite as an efficient adsorbent for pipette tip micro-solid phase extraction of mitoxantrone from seawater, drug, urine and blood samples prior to its spectrophotometric determination

In this study, a novel adsorbent was prepared by modification of graphite with deep eutectic solvent based on camphor–thymol (by the mole ratio of 1:1) and was utilized as a separation phase for pipette tip micro-solid phase extraction of mitoxantrone from seawater, drug, urine and blood samples. After extraction, mitoxantrone content of samples was determined by spectrophotometry at 260 nm wavelength. Various variables which could affect the extraction, including pH, amount of extracting phase, volumes of sample and eluent, type of eluent, and number of the extraction/ejection cycles of solution and eluent, were evaluated and optimized by both one-variable-at-a-time and response surface methodology methods. Observations indicated that the highest extraction achieved when 200 mg of the adsorbent was employed for 100 µL of sample solution with 7 extraction cycles at pH 7.0. Analyte was desorbed from the adsorbent by 200 µL of methanol (as eluent) after 3 ejection cycles. The linear dynamic range of the technique was between 1 and 1000 µg L−1, and the limit of detection and quantification were 0.2 µg L−1 and 0.7 µg L−1, respectively. Finally, the proposed extraction was successfully employed for the determination of mitoxantrone in various real samples with complicated matrices.