Opiorphin analysis in equine plasma and urine using hydrophilic interaction LC-MS.

The research presents a new method for detecting opiorphin (a substance with pain-killing and mood-enhancing properties) in horse plasma and urine, which is a concern in racing jurisdictions due to its potential misusage.

Overview of Opiorphin and Study Aim

• Opiorphin has gained attention due to its analgesic (pain-relieving) and antidepressant functions, raising potential concerns about its illicit use, notably in horse racing jurisdictions.
• However, opiorphin is challenging to track. This difficulty stems from its hydrophilic (water-attracted) property, which enables it to dissolve quickly in body fluids. Moreover, opiorphin rapidly degrades in plasma and urine samples, further complicating its detection.
• This study aims to develop a dependable and sensitive method to detect and confirm the presence of opiorphin in horse plasma and urine samples.

New Detection Method

• The proposed method uses a compound, ethylenediaminetetraacetic acid (EDTA), to prevent opiorphin from degrading between the sample collection and analysis phases.
• Then, opiorphin is extracted from the samples using a process called weak cation exchange. This method separates and purifies opiorphin using its electrostatic properties.
• Afterward, opiorphin is analyzed using Hydrophilic Interaction Liquid Chromatography – Mass Spectrometry/Mass Spectrometry (HILIC-MS/MS). This technique allows scientists to separate, identify, and quantify opiorphin in the samples.

Validation and Results

• The research team validated the new detection method and determined the Limit of Detection (LOD), the smallest quantity of opiorphin that can be reliably measured, to be 50 picograms per milliliter in horse plasma and urine.
• The method showed good selectivity (accurately identifying opiorphin from other substances) and precision (consistently producing the same result under the same conditions).
• This method is the first reported method for the detection of opiorphin in equine plasma and urine, marking a significant step forward in preventing the potential misuse of opiorphin in equine sports.