Sol-gel Carbowax 20M-zwitterionic ionic liquid composite sorbent-based capsule phase microextraction device combined with HPLC/post-column derivatization for the determination of lanreotide, a human somatostatin analogue in urine.

ABSTRACT

In this research, a sol-gel Carbowax 20M-zwitterionic ionic liquid composite sorbent-based capsule phase microextraction (CPME) device was developed in combination with liquid chromatography-post column derivatization for the first ever reported determination of a somatostatin analogue - lanreotide in human urine. The sol-gel Carbowax 20M-zwitterionic ionic liquid composite sorbent was encapsulated in the lumen of a polypropylene capillary tube and characterized by FT-IR spectroscopy and SEM with energy dispersive X-ray spectroscopy (EDS). The main steps of the CPME workflow were optimized to obtain high extraction efficiency for the target analyte. After the separation of the analyte on a C8 stationary phase, the peptide was derivatized online with o-phthalaldehyde before the fluorescence detection. The main experimental parameters of CPME and the post-column procedures were systematically investigated and optimized. The method was validated in terms of selectivity, linearity, accuracy, precision, limits of detection (LOD), and limits of quantification (LOQ). The relative bias ranged between 88.8 and 115.6 % for the peptide, while the RSD values for repeatability and intermediate precision were less than 14.3 %. The achieved limit of detection (LOD) was 0.2 µΜ while the limit of quantitation (LOQ) was established as 0.9 µΜ. Finally, the sol-gel Carbowax 20M-zwitterionic ionic liquid composite sorbent-based microextraction capsules were found to be reusable for at least 20 extractions. The developed method presented adequate overall performance, and it could be applied in the analysis of selected peptide in human urine samples.