Development and Validation of an Analytical Method for Quantitation of Alpha-Pinene Oxide in Rodent Blood and Mammary Glands by GC–MS

Alpha-pinene is a monoterpene found in the oil of coniferous trees and has a wide variety of applications. Alpha-pinene oxide (APO) is a potential reactive metabolite of alpha-pinene in rodents. The objective of this work is to validate a gas chromatography–mass spectrometry method to quantitate APO in rat and mouse blood and mammary glands in support of studies investigating the toxicity and toxicokinetic behavior of alpha-pinene. The method was validated in male Sprague Dawley rat blood over the concentration range of 5–250 ng/mL. Matrix standard curves were linear (r ≥ 0.99), and accuracy (percent relative error, %RE) was ≤±15% for standards at all levels. Intra- and interday precision (percent relative standard deviation, %RSD) and accuracy (%RE) were evaluated at three concentration levels (10, 50 and 200 ng/mL) and were ≤6.3% and ≤±5.4%, respectively. The limit of detection, determined from the SD of the limit of quantitation (5 ng/mL), was 1.06 ng/mL. Standards as high as 25,000 ng/mL could be accurately quantified after diluting to the validated range (%RE ≤ ±7.1%; %RSD ≤ 5.8%). APO was stable in rat blood for at least 70 days in frozen storage (−80°C). APO could accurately be quantified in male and female Hsd:Sprague Dawley® SD® rat and B6C3F1 mouse blood (mean %RE ≤ ±5.3%; %RSD ≤ 7.8%) and female B6C3F1 and Sprague Dawley rat mammary glands (mean %RE ≤ ±14.6%; %RSD ≤ 8.1%) using a primary matrix standard curve. These results demonstrate that the method is suitable for the analysis of APO in rodent blood and mammary glands generated from toxicokinetic and toxicology studies.