An online field-amplification sample stacking method for the determination of β2-agonists in human urine by CE-ESI/MS

► We presented a CE-ESI-MS method for four β2-agonists detection. ► CE-ESI-MS method was introduced in this system. ► The FASS method achieved a low detection limit of ng/mL concentration range. ► This method could be applied to determination of β2-agonists in the urine.