Salicylic acid as a switchable hydrophilicity solvent for the microextraction of the antibiotic amphotericin B from human urine followed by HPLC-UV analysis

Abstract

Monitoring the concentration levels of amphotericin B in the human organism is of utmost importance to evaluate the efficacy of the therapy. However, the reported sample preparation protocols for the extraction of this compound are very limited. In this work, salicylic acid is utilized as a switchable hydrophilicity solvent for the microextraction of amphotericin B from human urine samples before the HPLC analysis. The method is based on the phase transition of salicylic acid by changing the pH of the sample enabling efficient dispersion and phase separation in one step. A high contact area of the solidified solvent with the sample solution provided effective extraction of the target analyte. Among others, critical experimental parameters affecting the extraction performance of the drug were systematically investigated. The separation of the drug was carried out on a C8 stationary phase using mixtures of citric acid and methanol as mobile phases. Excellent linearity was observed in the range of 0.1 – 2.0 μg mL−1, while the precision (%RSD) was less than 14.5 % in all cases. The lower limit of quantification was 0.1 μg mL−1, and the limit of detection was 0.03 μg mL−1. The intra-day and inter-day accuracy were satisfactory, being in the range of 85.2 – 109.1 %. The robustness of the microextraction protocol was evaluated using DoE. The green potential and the practicality of the proposed analytical scheme were examined based on Green Analytical Procedure Index (GAPI) and Blue Applicability Grade Index (BAGI), respectively. A BAGI score of 65 was attained, demonstrating good applicability in terms of practicality, while the novel protocol was found to show green merits. The developed method can be used for the analysis of the drug in human urine.