A sensitive and accurate method, employing high-resolution continuum source atomic absorption spectrometry, for the determination of antimony (Sb) was developed. Conditions such as pyrolysis and atomization temperatures, the use of chemical modifiers, and sample pretreatment were optimized for the determination of Sb in pharmaceutical preparations and beverages stored in polyethylene terephthalate (PET) containers. In addition to container analysis, the influence of time of contact, temperature, and content composition on the migration of Sb was investigated. Twenty-six samples were periodically analyzed until finalize 1 year bottling. Eight mineral water samples were analyzed after storage at temperatures from 40 to 80°C for 48 h. Five different-colored PET samples were stored at 80°C for 20 days and periodically analyzed. Bottles, containing from 46.4 mg/kg Sb (amber PET) to 91.6 mg/kg Sb (colorless PET), leached Sb depending on the content ingredients, time of contact, and temperature. Although drinking water itself did not promote Sb migration at room temperature, juices and medicines did. After 1 year of storage, the Sb level in the samples ranged from 5 to 50 μg/L. The rate of leaching depended on the temperature, which was slow below 60°C, but rapidly increased at 60-80°C. The higher the Sb content in the bottle, the higher the amount of migration. Because Sb is a possible carcinogen to humans, containers for pharmaceutical use should be better controlled, and factors that increase Sb leaching in products that are widely consumed should be avoided.