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.　©　2023