Online measurement of tetraethyllead in aqueous samples utilizing monolith-based magnetism-enhanced in-tube solid...

A new procedure that utilizing a preconcentration system based on magnetism-enhanced in-tube solid phase microextraction (ME/IT-SPME) and detection by HPLC with diode array detector (DAD) after liquid desorption from the microextraction column has been developed for the online measurement of tetraethyllead (TEL) in various aqueous samples. In this connection, according to the chemical features of TEL, porous monolith mingled with Fe₃O₄ nanoparticles were designed and synthesized in a silica capillary, and used as the microextraction column of ME/IT-SPME. To favor the implement of variable magnetic fields during extraction procedure, the as-prepared microextraction column was twined a magnetic coil. Results revealed that the exertion of magnetic field during the adsorption and eluting procedures assisted the extraction of TEL with an enhancement by 52% in extraction efficiency. Under the most beneficial conditions, the developed ME/IT-SPME was online hyphenated with HPLC/DAD to measure trace TEL in various aqueous samples. The limit of detection was 0.082 μg/L and the RSDs for precision were in the range of 6.3-8.5%. The recoveries with low, medium and high fortified levels varied from 80.6% to 95.0% with good repeatability. To the best of knowledge, this is the first study that using IT-SPME to extract TEL and then online quantification with HPLC/DAD.