AOAC 2011

Medical marijuana, long recognized for therapeutic benefits like pain relief, nausea and vomiting control, appetite stimulation, and muscle relaxation, is currently legal in 15 US states and the District of Columbia. Unlike other prescription drugs, medical cannabis is still considered a Schedule 1 drug and is illegal according to US federal laws. Consequently, patients have no assurance of product quality or safety and desire potency, microbiological, and pesticide residue testing. Currently, there are no USDA guidelines for pesticide residues in marijuana.

The Quick-Easy-Cheap-Effective-Rugged-Safe (QuEChERS) extraction approach was applied to marijuana. The complexity of the sample required cartridge solid phase extraction cleanup and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-TOFMS) for pesticide residue analysis. In addition, the sample extracts were diluted and analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS) for comparison and for determination of pesticides such as bifenazate and abamectin that are not amenable to gas chromatography.

Polycyclic aromatic hydrocarbons (PAHs) were determined in various sugarcane products using QuEChERS sample preparation, GC/MS with selected ion monitoring (SIM), and comprehensive two-dimensional GC with time-of-flight MS (GCxGC-TOFMS). In sugarcane production, it is common to set fields on fire to make harvesting easier by burning the leaves while leaving the sugarcane stalks intact. Unfortunately, sugarcane burning can produce toxic PAHs. Although a variety of sugarcane products (e.g., juice and liquors) have been tested for the presence of PAHs, often the number of PAHs investigated has been limited.

We tested sugarcane products, including cachaça, other sugarcane liquors, and sugarcane, for the presence of PAHs. QuEChERS-based sample preparation and separations on an Rxi^®-17Sil MS column were investigated with attention to extraction recoveries and chromatographic resolution of isobaric PAH compounds from EPA and EU lists as well as others.

On April 20, 2010, the offshore drilling rig Deepwater Horizon exploded and caught fire in the Gulf of Mexico near the Louisiana coast. Although chemical dispersants and containment booms were used to mitigate the leak, oil spread over a large area and the event could be one of the biggest environmental and economical disasters ever in the United States. As regards commercial fishing, a large area of the Gulf was closed because of possible contamination of seafood from the oil.

FDA has issued a protocol to reopen closed fishing waters that includes sensory and chemical testing of seafood (for polycyclic aromatic hydrocarbons, or PAHs, and their alkylated congeners). Unfortunately, the NOAA sample preparation method that the FDA proposes to use for chemical testing is extremely tedious and time-consuming, requires expensive pressurized fluid extraction and gel permeation chromatography equipment, and uses large volumes of environmentally unfriendly methylene chloride. Turnaround time for 30 samples is estimated to be 5 to 7 days employing up to 5 lab staff.

An alternate approach is to use QuEChERS, the Quick-Easy-Cheap-Effective-Rugged-Safe extraction method that was invented for pesticides in fruits and vegetables. In this work, a QuEChERS approach was used to generate seafood sample extracts for GC/MS determination of PAHs, PCBs, and organochlorine pesticides. Numerous samples can be prepared in batch fashion for analysis in a very short period of time (approximately 2 hours) to allow increased throughput. Good recoveries were achieved for spiked fresh seafood, including shrimp, oysters, scallops, and crabs. A NIST SRM (Standard Reference Materials®) of mussel tissue also showed high recoveries with the QuEChERS approach.

Currently, the United States Department of Agriculture (USDA) regulates only infestation and disease on imported cut flowers, representing approximately 70% of the rose market. This regulatory situation unintentionally encourages heavy use of pesticides, which are not regulated by USDA for cut flowers. Heavy pesticide use can have serious consequences for the health of workers in the flower industry and their local environment. To address those issues, an organic flower industry exists that advertises agricultural sustainability practices, including limited pesticide use.

In this contribution, the Quick-Easy-Cheap-Effective-Rugged-Safe (QuEChERS) sample preparation method was used with gas chromatography/mass spectrometry (GC/MS) and comprehensive two-dimensional GC with time-of-flight MS (GCxGC-TOFMS) to analyze pesticides on cut roses. Pesticide classes selected for investigation include organochlorine, organophosphorus, carbamate, pyrethroid, and triazole compounds that are routinely used by the flower industry. Development and optimization of sample preparation, including extraction and cleanup, will be highlighted. Baseline residue levels for organic certified roses and non-certified roses will be estimated in hopes of determining whether “a rose is a rose is a rose.”