关键词: 青霉素V钾；鸡蛋；药物残留；休药期

Abstract: This experiment aimed to investigate the elimination profile of phenoxymethylpenicillin（penicillin V potassium）soluble powder in eggs. Ten healthy laying hens meeting the required egg production criteria. They were administered the drug orally via drinking water at the maximum recommended clinical dose of 20 mg/kg B.W./d for 5 consecutive days. Freshly prepared medicated water was provided daily and ensured to be fully consumed by the flock.Eggs were collected daily at fixed time points from the start of administration until 14 days after the last dose，with detailed records maintained. Quantitative analysis was performed using an internal standard method. After sample pretreatment，penicillin V residues in eggs were determined by LC?MS/MS. The method demonstrated good linearity within the concentration range of 5－200 ng/mL，with a limit of detection of 5 μg/kg. Recoveries ranged from 96% to 101.4%，with RSD≤3.5%. Penicillin V residues were rapidly eliminated from eggs，falling below the detection limit by the first day post?treatment. Based on the maximum residue limit（MRL）regulations for penicillin V，a withdrawal period of zero days is recommended for phenoxymethylpenicillin soluble powder in laying hens.

Key words: Phenoxymethylpenicillin；Eggs；Drug residue；Withdrawal