The Challenge of Standard Stability in LC-MS Based Multi-Analyte Approaches for Veterinary Drugs

摘要

The short-and long-term stability of multi-component mixtures and intermediate mixtures of analytical standards of veterinary drugs,which can potentially occur in food and feed chains,was examined by an isochronous measurement approach.Short-term stability testing of calibrants included storage for 1,2,4,and 7 days at-20℃(as a baseline)4℃,and 23℃(with and without exposure to sunlight),respectively.Long-term stability testing conditions of intermediate mixes were-20℃,4℃,23℃(with and without exposure to sunlight),and control temperature at-80℃while the testing period was 2,4,8,and 12 weeks,respectively.Results indicated that calibration standards should ideally be stored at 4℃for only 1~2 days,without the presence of acid.Neutral storage conditions were acceptable even at room temperature.Storage of intermediate mixtures containingß-lactams and cephalosporins for longer than 1 month under 4℃ and room temperature resulted in a loss of almost 90%.When it comes to the intermediate mixtures with penicillin V and G,acceptable storage conditions were 2 weeks at-20℃,without the presence of acid.Other classes of veterinary drugs were less critical as considers long-term stability.Overall,storage conditions at-20℃were considered optimal for long-term storage of intermediate mixes of veterinary drug standards.