The quantitation of procaine in equine plasma by liquid chromatography-linear ion trap mass spectrometry.

This research article presents a method for accurately determining amounts of procaine, a local anesthetic, in horse blood using a technique called liquid chromatography-mass spectrometry.

The Method

• The researchers have developed a technique to extract and quantify procaine from the plasma samples derived from horses.
• The extraction process involves a procedure called liquid-liquid extraction, which was performed at a pH value of 11 with a chemical named dichloromethane. A variant of procaine, procaine-d10, was used as an internal standard in this technique.
• Liquid Chromatography-Mass Spectrometry (LC-MS) is the technique used for quantification of the procaine. Here, a 3-micrometer (3µm) C-18 column, which is a device used in separation of chemical compounds, was used in combination with electrospray ionization (an approach to produce ions) installed on a linear ion-trap mass spectrometer (a device to isolate and measure ions).

Results and Comparisons

• The researchers were able to determine the limit of detection and the limit of quantitation of procaine to be 50 and 200 picograms per milliliter (pg/mL) respectively, using this method. These figures refer to the smallest amount of procaine that could be reliably detected and quantified in the plasma samples.
• The finding is remarkable as it indicates a significant improvement from previously reported methods, which had detection limits as high as 1 nanogram per milliliter (ng/mL).

Application in Determining Regulatory Limits

• The method was applied as part of a larger study aiming to determine a regulatory limit for procaine in racehorses. Procaine is a local anesthetic used in various medical and veterinary practices but can be misused in competitive horse racing for performance alteration.
• The precise quantification of procaine in the plasma samples was thus crucial in determining safe and regulatory limits for its usage in racehorses.