Determination of Paraquat in Marijuana by Reversed-Phase Paired-Ion High Performance Liquid Chromatography

Abstract

A sensitive and selective method is described for the quantitative determination of paraquat in marijuana. Paraquat is extracted from finely ground plant material with hydrochloric acid with sonification, and the resulting acidic solution is extracted with chloroform:isopropanol (9:1) and evaporated to dryness. The residue is reconstituted with aqueous phosphate buffer pH 7.0; the solution is passed through a C-18 SEP-PAK TM and is analyzed with high performance liquid chromatography, using a reversed-phase column and an "ion pairing" reagent in the mobile phase. The recovery of paraquat in laboratory-spiked material varied from 90-97%. Results obtained with confiscated, field-sprayed marijuana by the procedure described were in excellent agreement with those obtained with a well-established ultraviolet procedure. The calculated limit of detection with this method is 2 ng of paraquat.

The use of pesticides in Belgian illicit indoor cannabis plantations

“…They comprise the fungicides promocarb, tebuconazole, propiconazole and tolylfluanid, the neonicotinoid insecticides imidacloprid, bifenthrin and hexythiazox. In the late 1970s and early 1980s, paraquat residues were found on confiscated cannabis samples [7][8][9][10][11][12][13]. Recently paraquat, together with other herbicides such as glyphosate and aminomethylphosphonic acid were detected on illicit cannabis samples from unknown origin in Brazil [14].…”

Enzyme-linked immunosorbent assay for paraquat and its application to exposure analysis

“…For analysis by GC, samples are prepared similarly to the spectrophotometric procedure and then either fully reduced (27) or reduced to the mono-and diunsaturated derivatives (28). Both ion pair (29) and cation-exchange (30) HPLC procedures have also been developed for prepared samples yielding sensitivities in the nanogram range. Procedures such as these are relatively cumbersome, which limits the scope of studies conducted to assess human exposure.…”

Determination of Herbicides Paraquat, Glyphosate, and Aminomethylphosphonic Acid in Marijuana Samples by Capillary Electrophoresis

“…A broad range of concentration was evaluated for the linearity study. Shown inside the dynamic interval of the methods, this range was established by the method for paraquat determination based on the concentrations found in marijuana samples contaminated in the 70's . Meanwhile, these concentrations were found when the purpose of application was culture eradication.…”