Determination of non-steroidal anti-inflammatory drugs residues in animal muscles by liquid chromatography-tandem mass spectrometry.

This research presents a method to detect residues of nine non-steroidal anti-inflammatory drugs and a metabolite in animal muscles. The method, employing liquid chromatography-tandem mass spectrometry, was validated on bovine muscles and its effectiveness also checked on swine, horse, and chicken muscles.

Method Development and Implementation

• The research focus was the determination of residues from nine different non-steroidal anti-inflammatory drugs and one metabolite in animal muscles.
• An enzymatic hydrolysis was performed first. This biological process uses enzymes to break down larger molecules into smaller ones, in this case potentially to expose the drug residues.
• Then, the samples were extracted using acetonitrile. Acetonitrile is often used as a solvent in analytical chemistry, allowing for the isolation of certain compounds.
• The samples are then cleaned up via alumina and C(18) Solid Phase Extraction (SPE) cartridges, a technique used to purify samples of unwanted compounds and potentially concentrate the desired trace residues.
• Finally, Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) was deployed. LC-MS/MS is a two-stage technique used to separate and identify complex mixtures. Liquid chromatography separates the samples’ compounds, whilst mass spectrometry can identify and quantify them.

Method Validation and Applicability

• The method was validated according to the Commission Decision 2002/657/EC criteria, an European Commission rule setting out the criteria for analytical methods used in the context of residue control, ensuring quality of results.
• Bovine muscles were the primary focus of the method’s validation.

Extending the Method to Other Animals

• The method’s applicability was tested for swine, horse, and chicken muscles, extending its use beyond bovine muscles.
• This extension was measured by precision and recovery experiments. Precision refers to the reproducibility of the method, and recovery assesses how well the method can extract and measure the analytes.

Exploring Matrix Effect

• The influence of the matrix effect on the quantification of the noted drug residues was studied. Matrix effect refers to any impact that non-analyte constituents of the sample have on the response of the analyte in mass spectrometry detection. By studying these effects, the accuracy of results can be better ensured.
• The developed method was applied to confirm the presence of specific drugs, phenylbutazone and oxyphenbutazone, in a horse muscle sample, demonstrating the method’s practical implementation.