Accelerating Cannabis Testing: How Filter Plates Increase Throughput and Productivity

States that legalize cannabis sales require that all cannabis products undergo analytical testing before purchase by the public. This trend has driven cannabis testing services to become a $1.1 billion industry in the US. In addition, the market is expected to grow at a compound annual rate of 15.4% from 2020 to 2027. The leading factor propelling market growth was a rise in contamination cases. As the sale of medical and recreational cannabis products became increasingly popular, it was essential that products were properly tested for safe consumption. Regulatory agencies established maximum quantity limits for residual solvents, insecticides, pesticides, heavy metals, microbes, and mycotoxins found in cannabis plants. In recent years, laboratories have adapted a multitude of analytical testing techniques to protect consumers from these dangerous contaminants. As the demand for testing services grows, in-house and independent laboratories are searching for new technologies that offer significant throughput advantages in cannabis testing workflows. In response, this article explores five common cannabis tests, incorporating filter plates into sample preparation workflows, and the benefits of incorporating filter plates in cannabis testing workflows.

States that legalize cannabis sales require that all cannabis products undergo analytical testing before purchase by the public. This trend has driven cannabis testing services to become a $1.1 billion industry in the US—and the market is expected to grow at a compound annual rate of 15.4% from 2020 to 2027 (1).

The leading factor propelling market growth was a rise in contamination cases. As the sale of medical and recreational cannabis products became increasingly popular, it was essential that products were properly tested for safe for consumption. Regulatory agencies established maximum quantity limits for residual solvents, insecticides, pesticides, heavy metals, microbes, and mycotoxins found in cannabis plants. In recent years, laboratories have adapted a multitude of analytical testing techniques to protect consumers from these dangerous contaminants. As the demand for testing services grows, in-house and independent laboratories are searching for new technologies that offer significant throughput advantages in cannabis testing workflows. Here, we review five common cannabis tests and discuss how adding filter plates into sample preparation workflows can be beneficial.

Five Common Cannabis Tests

There are five common tests that most laboratories perform to ensure cannabis products are safe for consumption:

1. Potency testing: This test determines the amount of cannabidiol (CBD) and tetrahydrocannabinol (THC) in a given product. Full cannabinoid profiling requires a filtration step followed by ultrahigh-pressure liquid chromatography with diode array detection (UHPLC-DAD). This workflow allows analysts to directly measure the amount of cannabidiolic acid in a sample.
2. Pesticide testing: This testing workflow typically requires extraction and cleanup steps to remove elements that may affect testing results. Then, the sample is analyzed using either liquid or gas chromatography with tandem mass spectrometry (LC–MS/MS or GC–MS/MS) for the qualification and quantification of chemical residues.

1. Heavy metal testing: Cannabis plants may extract heavy metals from surrounding soil. Larger laboratories use inductively coupled plasma mass spectrometry (ICP-MS) analysis, which is capable of detecting metals at sub-ppb levels. ICP-MS offers fast runtimes, high throughput, and superior sensitivity while yielding accurate and reliable results.
2. Microbial testing: With medical cannabis growing in popularity, it’s critical that the product is free from harmful bacteria that might harm immunocompromised patients. Most laboratories use quantitative polymerase chain reaction (qPCR) analysis to detect microbial contamination. A filtration step removes plant debris from the sample. A second filtration step isolates the nucleic acid. The process uses polymerase chain reactions to amplify the DNA or RNA characteristic to the target microbes to detect their presence.
3. Mycotoxin testing: Molds and fungi can release mycotoxins that are harmful to human health.
   After performing a sample filtration step, laboratories will use UHPLC–MS/MS analysis to detect mycotoxin presence.

Incorporating Filter
Plates into Sample Preparation Workflows

The quality of your cannabis testing results will largely depend on the quality of the samples. Filtration is essential in preparing diluted cannabis samples for high performance liquid chromatography (HPLC) and LC–MS analysis. The filter removes particulates and buffers that can sub-optimize results.

In a typical cannabis sample preparation workflow, the plant is ground up and washed with a solvent or organic solution. The solution is then filtered through individual membrane filters. To speed up this workflow, samples can be placed in a 24-well filter plate. While a 24-well plate is ideal due to its larger well, a 96-well filter plate also can be used. This filtration step screens out the plant material to provide a clean sample. At this point, specific buffers or extraction agents are added to the sample, depending upon the testing protocol. A final filtration step is required to clarify the sample for analysis by the HPLC or LC–MS instrument. Here, 96-well filter plates with wwPTFE membranes can enable significantly faster processing. The wwPTFE is a universal membrane that is well suited for identifying chemical residues. The membrane has broad chemical compatibility, resists harsh organics, and processes a variety of extraction buffers. This filtration is the final step before the sample enters the analytical instrument.

For laboratories performing microbial testing, sample preparation plays an important role in the quality of results. The goal in these tests is to identify yeast or bacteria that would be a microbial contaminant. After grinding or washing the plant, a 30–40 µm PP-PE filter would screen out plant debris. As in the analytical sample preparation workflow, a 24-well filter plate could be substituted to accelerate processing. Following this step, buffer or extraction agents are added to the sample. The solution is then filtered again to isolate the nucleic acid (RNA). For higher throughput, a 96-well nucleic acid binding plate could be used to separate the RNA. An rt-PCR test follows to identify a specific PCR set that represents a microbial contaminant.

The Benefits of Incorporating Filter Plates in Cannabis Testing Workflows

In conventional cannabis testing, laboratories would use syringe filters or spin devices to perform sample filtration steps. However, as the demand for testing skyrockets, new processes are needed to achieve higher throughput. Filter plates offer an attractive opportunity to accelerate and optimize processing. From grind to find, totally automated workflows can be created that process both 24-well and 96-well plate formats on the same line. Automated systems using filter plates offer the following benefits:

• Higher throughput: Filter plates and automation enable much faster processing. For example, a syringe filter processes one sample at a time, a spin device filters up to 24 samples at a time, while a filter plate can process 96 samples at a time.
• Greater tracking accuracy: When testing products from different customers and lots, barcoded filter plates allow precise, error-free sample tracking.
• Lower hold-up volume: Small sample volumes require a filter with a small effective filtration area (EFA) to reduce sample loss. The 96-well filter plate’s low hold-up volume minimizes sample loss—an important benefit when laboratories are testing precious samples in triplicate for downstream processing.
• Common plate footprint: 24-well and 96-well filter plates have the same dimensions, facilitating the implementation of automated workflows that can handle both plate formats.

Conclusion

The cannabis testing industry is experiencing extreme growth as more states legalize the sale of cannabis products for medicinal and recreational use. This dramatic growth is driving laboratories to develop testing workflows with significantly greater throughput and productivity. The application of 24-well and 96-well filter plates in automated workflows is producing exciting advances in cannabis testing processes. The new filter plates enable faster processing, greater tracking accuracy, and minimized hold-up volumes offering laboratories new approaches to fulfill the growing demand for their services. 

Reference

1. Cannabis Testing Services Market Size, Share & Trends Analysis Report By Service Type, By End User, By Region (North America, Europe, Asia Pacific, Latin America, MEA), and Segment Forecasts, 2020 – 2027, Grand View Research, May 2020.

About the Author

LORI EULER has over 20 years of experience working in research and development labs in the areas of microbiology and molecular biology. She received her Bachelor of Science degree in microbiology and a Master of Science degree in biomedical chemistry. Most of her career was spent as a senior research scientist at the DuPont Company engineering bacterial strains to produce a variety of compounds as part of their “green chemistry” initiative. Ms. Euler has extensive publications, presentations, and patents in her name, detailing her protocol and process development in the areas of metabolic engineering and bacterial strain analysis. Since joining Pall, she has held positions as regional sales area manager and is currently the product manager for the Molecular portfolio. Direct correspondence to:
lori_euler@pall.com

How to Cite:

How to Cite this Article

L. Euler, Cannabis Science and Technology 4(8), 58-60 (2021).