Programmable flow heart cutting solid phase extraction using polydopamine coated microfibrous sorbent as a front-end to UHPLC for direct determination of xenobiotic residues in surface water.

Automation and hyphenation of multiple steps were used for the sensitive determination of xenobiotic residues in surface waters. The online hyphenated sequential injection analysis instrumentation used surface-modified microfibrous sorbent for the effective solid phase extraction of 1.0 mL of sample into 100 μL zone, then subjected to the reversed-phase ultra-high performance liquid chromatography (SIA-SPE-UHPLC). The SPE column was packed with polypropylene microfibers and coated with polydopamine by rinsing with the dopamine solution. The freshly prepared column was used for highly reproducible extraction of more than 200 samples in the SIA-SPE-UHPLC method. The matrix calibration covered the expected range with limits of detection in the range 0.1-0.9 μg/L. The method precision was <13 % RSD (at 3 concentration levels), and the method accuracy was in the range 86.5-114.8 %. The sample throughput of the method was 5 samples/hour when the separation took 12 min, including a 5 min SPE step of the next sample run in parallel. The performance of the developed method was demonstrated with the analysis of fifteen river water samples spiked with eleven residues of xenobiotics (ivermectin, fenbendazole, praziquantel, ibuprofen, diclofenac, 17α-ethynylestradiol, androstenedione, carbamazepine, omeprazole, sotalol, and caffeine) at the levels typical for such monitoring. Initial sample treatment prior to the automated analysis consisted only of methanol addition, pH adjustment, and centrifugation. The innovations in the manifold and process that contribute to the modern and effective analysis of environmental samples are discussed.