Tag Archives: QuEChERS analysis

Automated Solutions for Cannabis Laboratories: Part I

By Danielle Mackowsky
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Using well plates for dSPE sorbents can help expedite sample clean up.

Sample volume remains to be the primary influence on whether an automated solution is a logical investment for a cannabis testing facility. Due to both the complexity of the material being tested and the extraction approach at hand, it may be difficult to find an automated platform that can fully accommodate your laboratory’s needs. Hamilton Robotics in collaboration with United Chemical Technologies (UCT) has developed a solution that allows for automation of specific sample clean up steps commonly utilized in cannabis pesticide testing schemes. The MPE2 Positive Pressure Extraction/Evaporation Module is a standalone manifold that can also be incorporated into a number of automated liquid handling decks. Used in tandem with dispersive solid phase extraction (dSPE) salts/sorbents packed into a 96 well plate, this combination provides laboratories with high throughput extraction convenience with comparable results to traditional dSPE for the analysis of over forty pesticides.

As states continue to expand testing requirements for pesticides, it is vital that your laboratory is equipped with a method that allows versatility for the addition of new compounds without burdening your extraction team. There are a variety of dSPE salt and sorbent blends readily available that have been optimized for cannabis extractions. This allows for the use of a reliable extraction technique that can be adapted for the automation age. Hamilton is widely recognized throughout both clinical and forensic laboratory settings and the MPE2 platform is an excellent first system for laboratories beginning to automate/semi-automate their processes.

MPE2 Positive Pressure Extraction/Evaporation Module
MPE2 Positive Pressure Extraction/Evaporation Module

Following an initial QuEChERS extraction, additional cleanup is typically recommended for extracts that are being analyzed for pesticide content due to the low detection limits often required. dSPE provides the necessary sample clean up to obtain those thresholds, but often burdens a laboratory staff with additional time consuming preparation steps. Traditionally, dSPE salts are packed into 2 mL centrifugation tubes that require a cumbersome supernatant pipetting step followed by additional vortex, spin and transfer steps. By packing the dSPE sorbents into a well plate format, the user is able to completely automate this above described clean up ultimately saving time and adding convenience without jeopardizing any recovery data.

For most compounds, the recovery was greater than 65% for both methods of dSPE. The mean recoveries for traditional dSPE were 98.0%, 99.2% and 97.9% at pesticide concentrations of 50 ng/mL, 100 ng/mL and 200 ng/mL, respectively. For comparison, the mean recoveries at the same concentrations for well plate dSPE were 85.0%, 88.9% and 89.1%. Therefore, there was typically about a 10-11% absolute difference in recovery between the two methods, which can be corrected for by implementing the use of internal standards. When comparing the recovery differences between the two methods, there are six compounds with noticeably larger discrepancies across all three concentrations, namely: chlorpyrifos, cyprodinil, diazinon, spinetoram, spiromesifen 278 and trifloxystrobin. If these data sets are excluded, then the average absolute differences in recovery between the two methods decrease to 8.8%, 6.4% and 5.8% for concentrations of 50 ng/mL, 100 ng/mL and 200 ng/mL, respectively.rsz_1shutterstock_226135945-1

Overall, laboratories can estimate on saving 40-60 minutes per 96 samples processed using the Hamilton MPE2 in conjunction with a UCT dSPE plate. When a liquid handling robot is also available, this time saving estimation is potentially doubled. Time spent per sample, including the training of laboratory scientists, is an important factor to consider when setting up your laboratory. Automation is in an investment that can greatly reduce a laboratory’s overall labor costs in the long run.


How Potent is Your Product: Getting Educated on Edibles Analysis

By Danielle Mackowsky
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As a result of the rapidly developing cannabis industry, many forensic toxicology labs are looking for fast, reliable and cost-effective methods to determine cannabis potency and pesticide residue in edibles. Although the pros and cons of legalization are still heavily debated throughout the country, all scientists agree that uniform testing policies and procedures need to be established as soon as possible.

Within environmental and food testing laboratories, the use of QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) has been practiced widely for the past 15 years. In 2003, Dr.’s Michelangelo Anastassiades and Steven Lehotay published the first QuEChERS application, which detailed the determination of pesticide residues in produce. Since then, QuEChERS has become the gold standard for the testing and analysis of a wide variety of edible matrices. United Chemical Technologies (UCT) was the first company to commercialize the product and it became apparent that the application of this technology to cannabis edibles was a natural solution to pesticide residue testing. All of the data from the QuEChERS cannabis edibles pesticide and potency analyses can be found here.

Sample preparation

Hard candy before freezer mill grinding

Preparation of a sample for QuEChERS analysis varies depending on the type of edible product being tested. Baked goods, chocolate bars and hard candies should be ground into a fine powder prior to analysis. Although this can be achieved using a product such as a SPEX 6770 freezer mill, a blender can suffice when analyzing typical plant-based samples. Liquid samples, such as sodas or teas, should be degassed prior to analysis, whereas any gummy-based candies should be cut into fine pieces. With the exception of the liquid samples, all other matrices should then be hydrated for one hour within a QuEChERS extraction tube.

Hard candy after freezer mill grinding

Following sample preparation, acetonitrile is added to all samples along with a proprietary blend of QuEChERS extraction salts. These salts remove water from the organic phase, help to facilitate solvent partitioning and protect base-sensitive analytes from degradation. After shaking and centrifuging the sample, three distinct layers are formed. The top layer, which is the organic phase, can then be aliquoted off for further sample clean-up or dilution.

A mint milk chocolate sample after QuEChERS extraction

For pesticide analysis, an aliquot of the organic layer was subjected to dispersive solid phase extraction (dSPE). This process utilizes an additional blend of proprietary sorbents that remove chlorophyll, sugars, organic acids and fatty compounds from the sample. The resulting extract is free of pigmentation and is ready for analysis on the LC-MS/MS. All samples that were analyzed for cannabinoids did not undergo dSPE; rather, a serial dilution was carried out due to the high concentration of cannabinoids in the original organic layer. The original QuEChERS extract required a dilution of 100-200x in order to have a sample that was ultimately suitable for analysis on LC-MS/MS. A UCT Selectra Aqueous C18 HPLC Column and Guard Column were used in a Thermo Scientific Dionex UltiMate 3000 LC System. An aqueous C18 column was selected due to the extreme polarity of the pesticides being analyzed.

Comparison of QuEChERS extracts before and after dSPE cleanup (gummy sample)


This application utilizes the advantages of  UCT’s proprietary QuEChERS combination to extract 35 pesticides and 3 cannabinoids, including tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN) in edibles, followed by either serial dilutions for cannabis potency analysis, or a dSPE cleanup for pesticide residue analysis. This hybrid method allows QuEChERs, which are extensively used in the food testing industry, to be utilized in a forensic setting.