Development and validation of a method for determining D-limonene and its oxidation products in vegetables and soil using GC-MS

A simple, rapid and effective gas chromatography-mass spectrometry method was developed for the simultaneous determination of d-limonene and its oxidation products in some vegetables and soils. Using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method, the sample was extracted with n-hexane, purified with octadecylsilane (C18) and graphitized carbon black (GCB), and detected using gas chromatography-quadrupole mass spectrometry. The linear correlation coefficients of all analytes in the nine matrices were good (R2 > 0.995). At levels of 50, 100, and 1000 mu g kg(-1), the average recoveries ranged from 71.2 to 114.5%, while intra-day and inter-day precision were below 13.4%. The limits of detection (LODs) and the limits of quantification (LOQs) in all matrices for d-limonene and its five oxidation products were 1-16 and 4-48 mu g kg (1), respectively. The residual levels of d-limonene can be well described by first-order kinetics. Dissipation in soil was microbially dominated, with half-lives of 1.95-2.84 days in the three soils and no residue in tomatoes. Its oxidation products were converted in soil mainly by microorganisms, with more trans-isomer production compared to cis-isomer. Moreover, no d-limonene residue was detected in tomatoes, and the persistence of d-limonene in soil was limited. The results of this study can provide data to understand the fate of d-limonene in tomato and soil and for further study its suitability as an environmentally friendly agrochemical.

Automated summary

A simple and effective method using gas chromatography-mass spectrometry was developed to simultaneously determine d-limonene and its oxidation products in vegetables and soils. The results showed that d-limonene did not persist in tomatoes, but had limited persistence in soil.