Method development and validation for accurate and sensitive determination of terpenes in bio-based (citrus) oils by single quadrupole gas chromatography-mass spectrometry (GC/MS)

Studies for the utilize of valuable components such as terpenes in essential oils of citrus and similar valuable wastes to the environment have been progressively proceeding in recent years. This study presented the method development and validation studies for simple, accurate and sensitive determination of twenty-four terpenes in bio-based (citrus) oils by gas chromatography/mass spectrometry (GC/MS). The validation study covered the parameters of linearity of the matrix-matched calibration curve, sensitivity (the limit of detection (LOD) and the limit of quantification (LOQ)), accuracy (recovery), precision, matrix effect, and measurement uncertainty. In the method development, all terpenes had the best chromatographic conditions at 250 degrees C inlet temperature, 1:15 split ratio, and 2 & mu;L injection volume with a few exceptions. The measurement range had dynamic linearity between 0.50 mg/L and 100 mg/L in the calibration curves possessing a higher than 0.996 correlation coefficient for all terpenes. The LODs for all terpenes were obtained to be in the range of 0.08 mg/L and 0.16 mg/L, and the ranges of LOQ for terpenes were determined from 0.24 mg/L to 0.48 mg/L. Recoveries for accuracy ranged from 80.86% to 93.17% with relative standard deviations (RSDs) below 15% (3.28-10.19%). In precision, acceptable recovery (average: 86.13%, ranging from 79.84% to 97.29%) and RSD values (average: 7.14%, ranging from 1.70% to 13.90%) were obtained for all terpenes at three different concentrations. D-Limonene (58.56-78.08%), Myrcene (8.19-17.21%), Valencene (0.09-5.91%), Linalool (0.45-2.99%), Beta-Ocimene (0.36-2.86%), Nerol (0.19-7.98%), and Alpha-Pinene (0.38-1.47%)are the most abundant terpenes in real samples. These results indicate that this method represents an effective, reliable, and lower cost alternative to current-use analysis methods for terpenes in bio-based (citrus) oil samples.