Amanda Rigdon | Authors

While systems for growing, production and sale of cannabis and cannabis related products are well established, regulation and enforcement of quality and safety testing have lagged behind. However, state governments and private labs are focusing on product safety testing with special emphasis on pesticide analysis. This is partially the result of various product recalls, media attention and concern from patient advocacy groups. We evaluated a modified QuEChERS LC-MS/MS method for analysis of multiresidue pesticides. The AOAC QuEChERS method was used for a reduced 1.5 g amount of plant material and processed with a universal dSPE formulation. LC-MS/MS analysis used constant polarity switching ESI and monitored at least two transitions per analyte. Matrix-matched calibration was used for quantitation and both method and instrument internal standards were used. Analyte recovery validation was performed according to FDA guidelines by testing three matrices at three fortification levels in triplicate for over 200 pesticides. For the large majority of pesticides, in all three matrices and at all three fortification levels, recovery was between 70-120%.

Following sampling, tubes were transferred to a Markes UNITY™ thermal desorption system paired with an Agilent 7890B GC that was coupled to an Agilent 5977A MS detector. The UNITY™ system and GC–MS parameters are presented in Table I and Table II, respectively.

Pharmaceutical actives and impurities often contain sulfur in the form of a sulfone or sulfoxide group. Both groups have dipole moments, adding a hydrophilic character to compounds containing these functional groups. The analysis of hydrophilic compounds on traditional alkyl columns (e.g. C18) can be problematic, since alkyl columns depend on hydrophobic interactions for retention. Since the sulfone and sulfoxide groups contain π-π bonds, the biphenyl column's ability to undergo π-π interactions makes it an excellent choice when increased retention or selectivity of compounds containing these groups is desired. To demonstrate the selectivity of the biphenyl phase towards aromatic compounds containing sulfur groups, a set of target compounds was selected and analyzed on C18, phenyl, and biphenyl columns.