Analysis of urinary aristolactams by on-line solid-phase extraction coupled with liquid chromatography–tandem mass spectrometry

Urinary biomarkers of oxidative and nitrosative stress and the risk for incident stroke: A nested case–control study from a community-based cohort

“…After diluted with 1 mM ammonium acetate and spiked with 1 μl of isotope-labeled standards (1 μg/ml), the urine supernatant was passed through a PVDF syringe filter (13 mm diameter, 0.22 μm pore size) for automatic online solid phase extraction (SPE) and LC-MS/MS analysis, as described previously [24].…”