Determination of d-limonene in adipose tissue by gas chromatography–mass spectrometry

We developed a novel method for analyzing d-limonene levels in adipose tissue. Fat samples were subjected to saponification followed by solvent extraction. d-Limonene in the sample extract was analyzed using gas chromatography–mass spectrometry (GC–MS) with selected ion monitoring. Linear calibration curves were established over the mass range of 79.0–2529 ng d-limonene per 0.1 g of adipose tissue. Satisfactory within-day precision (R.S.D. 6.7–9.6%) and accuracy (%difference of −2.7 to 3.8%) and between-day precision (R.S.D. 6.0–10.7%) and accuracy (%difference of 1.8–2.6%) were achieved. The assay was successfully applied to human fat biopsy samples from a d-limonene feeding trial.