Sayyed Hossein Hashemi - Department of Marine Chemistry, Faculty of Marine Science, Chabahar Maritime University, P.O. Box ۹۸۶۱۷-۸۵۵۵۳, Chabahar, Iran.
Fateme Keykha - Department of Marine Chemistry, Faculty of Marine Science, Chabahar Maritime University, P.O. Box ۹۸۶۱۷-۸۵۵۵۳, Chabahar, Iran

In this research a graphene oxide/zinc oxide nanocomposite (GO/ZnO) was synthesized and employed for simple and sensitive pipette tip-based micro-solid phase extraction (PT-µSPE) of nalidixic acid (NA) from seawater and human blood plasma samples following by its determination by spectrophotometry. Several parameters affecting the suggested protocol were optimized, namely type and volume of eluent, amount of sorbent, sample volume, number of cycles of extraction and elution, pH of sample solution and type and amount of salt. The optimization performed by both response surface methodology (RSM) and one-variable-at-a-time techniques. Figures of merit were achieved as: detection limit; 0.30 µg L-1, enrichment factor 40 for NA, linear calibration curve in the range of 1.0-200.0 µg L-1; and reproducibility (as RSD %) better than 4.4%. Results for the application of the technique in seawater and human blood plasma showed that this analysis method can be applied for the determination of the analyte in complex real samples successfully. 

Nalidixic Acid, Seawater, Graphene Oxide/Zinc Oxide Nanocomposite, Pipette Tip Solid Phase Extraction, Response Surface Methodology