Analytical Cannabis Testing and the Importance of High-Quality Water

As state and federal regulations for cannabis testing continue to evolve, the robustness of testing services must grow to keep pace

High-performance water filtration systems, such as the arium® Series water purification system from Sartorius, provide long-term practical and economical advantages to cannabis testing laboratories and address the needs of this changing industry.

Cannabis Quality Testing

The cannabis industry is witnessing tremendous growth. More companies and start-ups are looking to offer cannabis products to their customers. Accordingly, the demand for lab consumables and testing equipment will continue to expand and flourish in the coming years.

As the industry matures, processing and testing labs will see increasing pressure to offer reliable testing services to ensure high-quality cannabis production and processing. The instruments and methods behind these testing services must perform with the highest level of sensitivity, accuracy, and precision to meet or exceed market and regulatory demands.

Pure, high-quality water and solvents used in analytical testing systems is the basis for safe and economical analytics. Ultrapure water reduces interference and ensures accurate measurements when analyzing cannabis products for purity.

Steps in Cannabis Testing

An initial step in the testing process includes identification of target analyte(s) in the source material. Some examples of testing for target analytes include potency determination of a distinct cannabinoid or a panel of cannabinoids, presence of pesticides, heavy metals, mycotoxins or other contaminants, and terpenes profiling.

Identification is typically followed by testing to determine the concentrations of detected compounds and if these concentrations either meet the desired levels or adhere to regulatory limits. This quantitative information can be critical when making the choice to invest further resources for downstream cannabis processing.

Methods for Cannabis Testing

The required performance balanced by the complexity and cost considerations determine the choice of testing technique and system. A common method for both identification and quantification of compounds in cannabis extraction material is high-performance liquid chromatography (HPLC) with ultraviolet (UV) or photodiode array detection. The benefit of HPLC as a stand-alone method is that it can provide fast measurements of target compounds. HPLC may be coupled with mass spectrometry (LC-MS or LC-MS/MS) as necessary to improve sensitivity, resolution, and depth of profiling. Another method for identification of volatile organic compounds is gas chromatography (GC) with or without MS detection (GC-MS).

Regardless of the approach used for cannabis testing, the quality and purity of the solvents and water have significant impact on the accuracy of any analytical system.

Importance of Water Quality in HPLC Performance

Initial steps in HPLC analysis include filtration of the source material and dilution of the samples in water or solvent. Filtration removes particles that can introduce background interference and negatively impact HPLC column performance. Dilutions of filtered samples are often needed to accurately measure peaks at the high and low ends of the concentration range.

The use of ultrapure water minimizes impurities, preventing interference with sample preparation and inaccurate peak detection in diluted samples.

Contaminating aromatic organic compounds can adversely affect UV detection and solvent chemistries, for instance, by introducing “ghost peaks,” arising from carryover or build-up of column impurities.

Ultrapure water helps minimize ghost peaks and column impurities, providing reliable baselines for precise HPLC measurements.

Reference standards are necessary to establish detection linearity for sample concentration measurements and quantification. Factors such as imprecise solvent additions or temperature or density fluctuations of the sample, can negatively affect standards preparation and influence concentration determinations. These factors can particularly affect testing precision between column runs or over several days of testing.

Careful and consistent standards preparation depends on the purity of the water used as a solvent and may also be impacted by temperature, density, and other sample inconsistencies.

Key Features of High-Performance Water Filtration Systems

Water Quality

To ensure high-performance HPLC analysis, a water filtration system must have consistent and reliable water conductivity measurements and monitoring. Another important feature to look for is the ability to measure total organic carbon (TOC) content in the filtered water.

The Sartorius arium® comfort Series and pro Series ultrapure water purification systems provide ASTM Type 1 (18.2 MΩ) water, optimal for HPLC, LC-MS, GC-MS, and other analytical techniques. These systems also ensure minimal microorganisms (<1 cfu/1 mL), TOC content (≤ 2 ppb), and particulates (< 1/mL) by continuously checking and displaying levels for real-time verification.

Consistency and Reliability

Run-to-run precision is an absolute necessity to ensure reliable and trustworthy testing methods. Contamination and inconsistency in water delivery can have serious impacts on run-to-run precision.

Most of the problems occurring during HPLC runs are attributable to inadequate water quality. Even purchased HPLC-grade water is frequently found to have a high TOC level. The Sartorius arium® comfort Series and pro Series provide excellent retention rates of TOCs. This makes them highly suitable for analytical applications, such as chromatography.

The graphic and acoustic signals indicating maintenance cycles, alerts and alarms if any limits are exceeded, as well as cartridge change-out intervals of the arium® water filtration systems ensure a reliable source of high-quality, analytical-grade water.

Ease-of-Use

An ideal water filtration device should be easy to use and the methods should be accessible to everyone in the testing lab. This enables adherence to sample preparation procedures, improves standards performance, and enhances run-to-run precision.

Sartorius’s arium® Series of water filtration systems uses a clearly organized user interface, featuring intuitive navigation, continuous display of measurement data, and graphic and acoustic signals for limit alerts and maintenance prompts. The “Favorites” function allows quick access to pre-programmed volume dispensing.

Flexible Performance

Each testing facility is different, and high-quality water filtration systems should be designed with adaptability in mind so they can be ready to meet your demands as your operation changes and grows.

A variety of hardware and operating configurations, such as flexibly positioned dispensers, enable easy and space-spacing integration of the arium® Series water filtration system into your lab. Up to 70 different system varieties offer tailor-made solutions, without compromises.

View more information on the Sartorius arium® line of water purification systems:

https://www.sartorius.com/en/products/water-purification/lab-water-systems

View Sartorius solutions for analytical cannabis testing:

https://www.sartorius.com/en/applications/applied-industries/cannabis-testing

This article was written by LabX and published in partnership with Sartorius.

Updated October 2022