Carrier-mediated solvent bar microextraction coupled with HPLC-DAD for the quantitative analysis of the hydrophilic antihypertensive peptide VLPVPR in human plasma

Abstract

The aim of this study was to develop a method for the determination of the Val-Leu-Pro-Val-Pro-Arg (VLPVPR) antihypertensive peptide in human plasma based on a carrier-mediated three-phase solvent bar microextraction (SBME) coupled with a high performance liquid chromatography diode array detector (HPLC-DAD). For this purpose, the SBME was performed under various operating conditions to optimize the parameters including the pH of the donor and receiving phases, sodium chloride (NaCl) concentration in the receiving phase, carrier concentration, agitation rate, and extraction time. A high enrichment effect was achieved when the pH of the donor phase (i.e., sample solution) was 12, the pH of the receiving phase was 2, the NaCl concentration in the receiving phase was 2 mol L⁻¹, the carrier concentration was 15% (w/v), the agitation rate was 700 rpm, and the extraction time was 60 min. Furthermore, the analytical characteristics of the SBME-HPLC method including the linear range (0.2–20 μg mL⁻¹), the detection limit (68.5 ng mL⁻¹), the precision (RSD = 1.1%, n = 5), and the enrichment factor (27.5 ± 0.65) were evaluated in human plasma. The results showed that the method was suitable for the determination of VLPVPR antihypertensive peptide in bio-fluid samples.