Application of flow injection analysis-solid phase extraction based on ion-pair formation for selective preconcentration of trace amount of anti-HIV drug

Abstract

In this study, a flow injection analysis (FIA) system combined with solid phase extraction (SPE) was designed for preconcentration and selective extraction of an HIV anti-virus drug (i.e. Nevirapine (NVP)). Molecularly imprinted polymer (MIP) nanostructures were used as the selective adsorbent in the extraction column. The synthesis of MIP was carried out, using methacrylic acid (MAA) as the functional monomer, ethyleneglycoldimetacrylate (EGDMA) as the cross-linking agent in methanol/acetonitrile as porogen solvent. Scanning electron microscopy (SEM) and differential thermal analysis (DTA) were used for the characterization of the as-synthesized NVP-MIP. In the SPE-FIA procedure, after analyte loading, the eluted NVP drug was treated with fast green (FCF) as a colorimetric reagent. After the formation of colored ion-pair between NVP and FCF in an acidic media, the quantitative determination was performed spectrophotometrically at 620 nm. The influence of experimental parameters on the NVP extraction, including adsorption and desorption flow rate, MIP amount, sampling time, and elution condition were studied and optimized. For the present method, two linear concentration ranges (0.0010–0.10 mg L-1 and 0.10–80 mg L-1), a low detection limit of 0.0005 mg L-1, and an acceptable preconcentration factor of 100 was obtained in optimum conditions. Meanwhile, a selective binding affinity of NVP toward MIP sorbent was observed against other drugs, in the selectivity study. Moreover, the applicability of the designed method was confirmed by successfully uptaking NVP from human urine real samples and artificial aqueous samples.