Low-cost and convenient ballpoint tip-protected liquid-phase microextraction for sensitive analysis of organic molecules in water samples

Simplification and miniaturization in analytical procedures are highly preferred by analysts and other researchers. In this study, a low-cost, convenient and efficient liquid-phase microextraction method, termed ballpoint tip-protected liquid-phase microextraction (BT-LPME), was established. The bullet-shaped BT possessed a hollow cavity of several microliters for solvent storage and an opening tail for solute extraction. Magnetic field-induced BT spinning significantly accelerated the extraction process. By virtue of the adhesion between a stainless steel sheath and an organic solvent, along with cave protection, finely stable storage of extractant was achieved even under high spinning speeds (>1000 rpm). The BT-LPME performance was evaluated by extracting five polycyclic aromatic hydrocarbons (PAHs) from aqueous solution, followed by gas chromatography-mass spectrometry (GCMS) analysis. Compared to static single drop microextraction (SDME), the BT-LPME method provided higher enrichments (128–173-fold) for the five PAHs. Good linearities (from 0.01∼0.05 μg L−1 to 50 μg L−1) with a regression coefficient (r2) ≥0.9993, as well as low limits of detection (LODs, 0.002–0.011 μg L−1) and limits of quantification (LOQs, 0.007–0.023 μg L−1), were obtained. Relative recoveries varied from 92.3% to 103.4% at three spiked levels of 0.1, 1 and 10 μg L−1. The BT-LPME technique was also successfully applied to the enrichment of other organic compounds, such as organophosphorus compounds, organochlorines and triazines.