Determination of flunixin in equine plasma by reversed-phase liquid chromatography.

This research presents an efficient method for determining the drug flunixin in horse blood plasma using reversed-phase liquid chromatography, a technique that separates compounds in a solution. The study highlights the level of flunixin that can be detected, indicating the method’s usefulness for tracking the drug’s presence in horses.

Methodology

• The research uses a specific type of liquid chromatography known as reversed-phase chromatography. This technique is beneficial for its high resolution and the wide range of substances that it can be applied to.
• The substance used for chromatography is a solution of 70% methanol in a phosphate buffer of pH 3.1, using LiChrosorb RP-18 as the adsorbent. This solution, known as eluent, aids in the separation of different substances within the plasma.
• The plasma is first deproteinized with methanol; this process helps to remove potential contaminants that might hinder the detection of flunixin.
• The supernatant, or the liquid part left after sedimentation or centrifugation, is then directly injected into the chromatography system for analysis.

Analysis and Findings

• A small pre-column within the chromatography system is used for the procedure. After every 25-40 sample injections, this pre-column is replaced to maintain the integrity of the analysis.
• Through this method, up to 420 plasma samples can be analyzed on a single analytical column, showcasing the method’s efficiency.
• The detection limit of flunixin in plasma is 0.30 micromol/l, or 89 ng/ml. This reflects the sensitivity of the method, indicating that even low concentrations of the drug can be detected.

Implications

• This method can be applied in studies investigating the pharmacokinetics of flunixin in horses. Pharmacokinetics focuses on how drugs are absorbed, distributed, metabolized, and excreted in the body, and is crucial for understanding how drugs work and how they can be used safely and effectively.