Analysis of micro-encapsulated d-limonene dimercaptan, a possible herbicide marker for Cannabis sprayed with paraquat, using gas chromatography.

A method for the determination of encapsulated d-limonene dimercaptan (d-LDM), a possible marker for Cannabis sativa L. sprayed with herbicide, has been developed. The methodology includes a single-step extraction, followed by gas chromatography with flame photometric detector (FDP) using n-octadecyl mercaptan (n-octadecylthiol) as an internal standard. A liner relationship was obtained from spiked samples with an average coefficient of variation of 9.0 per cent. The method has been used to determine part-per-million levels of LDM in actual field experiments in Mexico. The FDP limit was found to be 7 ng for d-LDM.