Systematic analysis of acid, neutral and basic drugs in horse plasma by combination of solid-phase extraction, non-aqueous partitioning and gas chromatography-mass spectrometry.

The research article details a method for preparing horse plasma samples for the detection of doping drugs using mass chromatography. This method uses a combination of solid-phase extraction, non-aqueous partitioning and gas chromatography-mass spectrometry, showing that it can effectively detect nanogram per milliliter levels of drugs in horse plasma.

Methodology

• The sample preparation begins with the use of Bond Elut Certify (1 g/6 ml) to extract 4 ml of horse plasma. Bond Elut Certify is a type of mixed-mode solid phase extraction that isolates drugs from plasma by a procedure of washing and elution. It is often used for the extraction of drugs and metabolites in biological fluids.
• Fractionation is then performed using 6 ml of CHCl3-Me2CO (8:2) and 5 ml of 1% TEA-MeOH, allowing the various components in the plasma to be separated according to their physical or chemical properties. CHCl3 or Chloroform is often used for extraction, while Me2CO or Acetone and TEA-MeOH (triethylamine-methanol) are used for pH adjustments.
• A step of non-aqueous partitioning is utilized to clean the sample, removing any co-eluting contaminants in both acid and basic fractions. Co-elution occurs when two or more compounds travel down the column at almost the same speed, resulting in overlap between analytes of interest and interfering compounds.
• To calculate the retention index, a parameter used in chromatography to help identify compounds, two varieties of 1-(N,N-diisopropylamino)-n-alkanes are co-injected with the sample into the gas chromatography-mass spectrometry (GC-MS) system.

Results and Implications

• The researchers examine the total recoveries of 107 drugs, although the specific results are not provided in the abstract. Total recovery in this context refers to the amount of the analytes of interest that are successfully isolated and collected after the extraction and purification processes.
• It is noted that the overall procedure yields clean extracts and sufficient recoveries for GC-MS analysis, showing the effectiveness of this sample preparation method.
• The method can detect drugs at the level of nanograms per milliliter in horse plasma, indicating high sensitivity and therefore suitability for detecting even small amounts of doping drugs.
• The research could be important for equine sports where doping is a concern, as it provides a highly sensitive and reliable method for testing the presence of doping drugs in horses.