Measuring Moisture Content– Slow/Simple v. Fast/Accurate

Moisture Content

Measuring Moisture Content – Slow/Simple vs Fast/Accurate

Measuring moisture content is a necessary, often mandated requirement in many industries like pharmaceutical, aerospace, food, and cannabis.  From meeting testing requirements, ensuring moisture content accuracy, identifying potential presence of unsafe microbial contamination, determining bio-mass buy/sell weights, there are many critical reasons to effectively measure biomass moisture content.  In this article we will touch on two of the most common methodologies.

Safety & Compliance

Freshly harvested biomass has a moisture content of about 70 to 80 percent by weight. and then dried further to a moisture content dictated by its intended end use. Most commercial growers dry their plants to 15 percent or less to comply with the different testing requirements of each state.

Determining the moisture content in biomass is one of the most vital measurements to controlling the safety of the product in the marketplace.  Moisture control and effective drying practices are critical to keeping product safe and at the highest quality. Moisture analyzing equipment should be routinely calibrated to an ISO:17025 traceable standard to ensure accuracy and compliance with best quality practices and state mandates.

Optimizing Extraction Efficiencies

Particularly in the case of CO2 Extractions, target moisture ranges are typically less than 10 percent for the highest extraction yields, most efficient run times, and ease of post-extraction refinement.  It’s much easier to remove water prior to a CO2 extraction than once it has become embedded in the extracted crude oil.  In R&D, using a moisture analyzer helps to pin-point the ideal moisture content for maximum extraction efficiency.  Post extraction, moisture analysis is often done after a bio-mass decarb to ensure the batch can move onto the next step.

Method 1:  Slow But Simple
The simplest method used to determine the moisture content of a sample is by weighing the sample then completely drying it out and measuring the difference.

Processors can use a low temperature oven and an accurate scientific balance to determine the weight of the sample. A small amount would be weighed and recorded on a scientific balance, then placed in the low-temperature oven to slowly dry out.  This can take many hours until the sample visually crisps up, at which point it is re-weighed. The oven-dried weight divided by the weight of the original sample would then give the moisture content of the biomass as a percentage.  The size and temperature uniformity of the low temp oven can introduce variables into the readings, as well as the tendency to use a large sample size, which can skew results.  The temperature uniformity of most lab ovens lessens at low temperatures.  Ovens simply want to get hot.  Although this time-consuming process is susceptible to human error, it can be improved somewhat by making sure the oven temperature control is performing within temperature uniformity specifications and is calibrated to an ISO:17025 traceable standard.

Method 2: Benchtop Moisture Analyzers: Fast and Highly Accurate

The fastest and most accurate method is to use benchtop moisture analyzers, like the Cascade Sciences CM-Series, that provide quick, reliable moisture content results and save processors time and money.

Fast, Repeatable Results Throughout Each Processing Step

They are portable! Benchtop moisture analyzers can be used almost anywhere in the process:

  • At the grow, ensuring identifying potential presence of unsafe microbial contamination and determining bio-mass buy/sell weights
  • Post decarb, to determine ideal low moisture percentages for optimal extraction
  • As a redundant, test result comparison, when dealing with outside labs

Benchtop moisture analyzers come in various capacities and are essentially a highly accurate scale and oven in a small, portable unit.  They use an IR (infrared) emitter to generate a heat source.  Generally, samples used in moisture testing will be discarded.  Depending on the process recipe executed, the samples can see temperatures as high as 160°C (320°F). 

Features to Demand

When selecting a moisture analyzer, look for the following important features:

  • Accuracy. Require a readability in the range of 0.1mg/0.0001% for 50g samples and 1mg/0.001% for larger ~210g samples.
  • Repeatability. Require a repeatability in the range of 0.05% (~2g sample), 0.01% (~10g sample)
  • Calibration.  Look for units that come pre calibrated to an ISO: 17025 standard.  You should receive a certificate and the unit will be labeled as such.  This will save time and money getting you in business faster – without waiting for a calibration tech to show up and perform the calibration.
  • Warranty.  At least 3 years.

Investing in a portable, benchtop moisture analyzer pays off with the ability to quickly and accurately measure the moisture content during every stage of processing. Learn more at https://www.youtube.com/watch?v=IZMf9Hwk3Qo