Moisture content determination is the process of quantifying the amount of moisture (e.g., water, oils, solvents, fragrances, volatile substances) present in a material or substance, expressed as a percentage of the total weight. Dry content, on the other hand, is the portion of the material remaining after all moisture has been removed, also expressed as a percentage of the total weight.
Moisture content is a critical quality parameter in many industries, impacting product consistency, safety, and overall process efficiency. METTLER TOLEDO offers advanced moisture analyzers designed for fast, precise, and reliable moisture determination, helping you maintain optimal product quality and streamline your production processes.
Moisture content directly dictates a material’s chemical stability, rheological properties, and microbial resistance. Precise determination ensures compliance with regulatory standards (e.g., USP <731>), prevents batch degradation, and optimizes manufacturing energy efficiency by refining drying cycle parameters.
Moisture levels affect the compressibility of powders, the viscosity of polymers, and the flowability of granular materials.
Excess water activity (aW) accelerates oxidative rancidity and microbial proliferation, leading to premature product spoilage.
Accurate quantification prevents "selling water" (over-moisturizing) or excessive energy expenditure during over-drying processes.
Essential for meeting ISO and specific industry standards (AOAC, ASTM, Pharmacopeia).
Moisture and water content are related, but they are not the same. “Moisture content” encompasses all volatile substances that evaporate when heated to a defined temperature, including water, alcohol, solvents, and other compounds. “Water content”, however, specifically measures the proportion of water within the material.
represents the whole sample
represents solid content
represents moisture content
represents water content
Moisture content measures the total amount of water and volatile substances in a material, expressed as a percentage of its weight. Water activity, on the other hand, indicates the availability of free water in the material that can support microbial growth and chemical reactions. While moisture content shows how much moisture and volatile substances are present, water activity reveals how that water affects product stability and shelf life. To measure water activity, a dedicated water activity meter is required. However, knowing the moisture content can help in understanding and controlling water activity because moisture levels influence water availability.
Moisture content is commonly measured using several reliable techniques tailored to the sample type and accuracy needs. Popular methods include loss on drying (using moisture analyzers or drying ovens), Karl Fischer titration, and near-infrared spectroscopy. Each technique offers precise moisture quantification to ensure product quality and compliance.
Selected METTLER TOLEDO instruments can integrate with Lab 4.0 ecosystems to ensure data integrity and process automation.
Loss on Drying (LOD) is a common technique for measuring moisture by weighing a sample before and after heating to evaporate moisture. As a direct measurement, it’s widely accepted as a reference standard.
Accurate sample prep is essential for reliable results. LOD works well with liquids, solids, powders, and even inhomogeneous samples. LOD equipment generally costs less than methods like Near-Infrared (NIR) spectroscopy.
Karl Fischer (KF) titration is a highly accurate method for measuring water content in liquids and solids, even at very low levels. It uses a specific chemical reaction to selectively quantify water with exceptional sensitivity, detecting moisture down to parts per million (ppm).
KF titration offers precise results across various sample types and excels at low moisture detection. However, it requires specialized reagents, careful sample prep, and skilled operators, leading to higher costs and lab-based use. Chemical interferences may affect accuracy, and it measures only water, not total moisture.
Despite these limitations, Karl Fischer titration remains the gold standard for accurate low-level water analysis.
Near-Infrared (NIR) spectroscopy is a rapid and non-destructive method for measuring moisture by using near-infrared light on a sample and analyzing the absorbed, reflected, or transmitted light, which correlates to moisture levels. It requires minimal or no sample preparation depending on the sample type, provides fast results, and can simultaneously analyze multiple components.
While NIR measures moisture indirectly through calibration models tailored to each sample type, these calibrations help ensure accurate and reliable results. Calibration involves developing reference datasets using dedicated instruments such as moisture analyzers or Karl Fischer titrators and should be periodically updated to maintain accuracy. Some further limitations include dependency on sample type, uniformity, reduced accuracy at very low moisture levels, and reliance on the quality of reference methods.
A moisture analyzer combines a heating unit with a weighing unit. The heating unit rapidly evaporates the moisture. The integrated balance continuously monitors the sample’s weight loss during the drying process. This real-time weight measurement during drying allows the analyzer to accurately calculate the moisture content, delivering fast and reliable results.
Robust and user-friendly, moisture analyzers are ideal for quality and in-process control across industries—from pharma labs to food and plastics production.
Our instrumentation is engineered for Lab 4.0 integration, ensuring that precision metrology translates into actionable data and seamless compliance.
Thanks to halogen heating technology
Results in just a few minutes
Built to last with quality materials
User-friendly interface and intuitive controls for easy operation
Easy data management and full connectivity
Based on our Good Moisture Analysis Practice (GMAP™)
Switching from a traditional drying oven to a moisture analyzer can significantly improve your testing efficiency while maintaining the same accuracy. Transitioning to a moisture analyzer streamlines your quality control processes, reduces operator errors, and helps maintain consistent product standards.
To help you with your switch, we created a comprehensive white paper. The white paper explains the best practices for moving from drying ovens to moisture analyzers. Download it to learn everything that you need to know.
As experts in all things measuring in the laboratory, we know the challenges of the different industries. Learn about how we address these challenges and offer specific solutions and support for the following industries:
➤ Product: HC103
GMAP is a scientific, risk-based guideline to ensure your moisture analyzer is fit for your specific application. It helps with:
The unique GMAP Recommendation helps you find the right solution based on your specific process requirements. The service is free of charge, takes only a few minutes, and is based on your sample type, process tolerances, environmental conditions, and regulatory requirements.
Achieving reliable and repeatable moisture analysis results hinges on meticulous sample preparation and handling techniques. From ensuring precise samples in the sample pan to enhancing ergonomic operation, our comprehensive suite of consumables empowers you to adhere to rigorous sample preparation protocols.
Expert service ensures optimal instrument performance through installation, calibration, maintenance, and qualification.
Ensure consistent and accurate results by following our clear and easy-to-use SOPs for moisture analyzer testing. Our SOPs guide you through proper steps for temperature calibration, SmartCal testing, and sensitivity testing of the weighing unit.
Are you switching technology, changing instruments, or moving between brands? We can make transferring your moisture analysis methods simple and efficient. With expert guidance, tailored support, and an extensive library of proven moisture methods we can ensure a smooth transition.
The drying oven method is a thermogravimetric method (loss on drying) in which the sample is dried for a defined period of time at constant temperature. The moisture content is determined by weighing the sample before and after drying and determining the difference.
In the drying oven, samples are heated by convection. This means the samples are at the same temperature as the drying oven. When using a moisture analyzer, the sample heats up and dries by absorbing infrared radiation from the heating element. The sample's temperature and drying time depends on its absorption characteristics.
This is a common misconception. Everything which evaporates upon heating is named moisture. Water may be a part of this but there may be other substances which also evaporate, such as alcohol or solvents.
Moisture affects the processability, shelf life, usability and quality of many products such as pharmaceutical substances, plastics and foods. Information about and monitoring of moisture content is therefore very important. Most substances have an optimum moisture content for obtaining the best possible processing results and therefore attaining maximum quality. Furthermore, moisture content impacts on price and there are statutory rules for some products governing the maximum permissible moisture content (e.g. as defined by national food regulations).
In general, all kinds of samples are suitable for both the drying oven and the halogen moisture analyzer. Which method is best for you, depends on how fast you need the result or if you need the result using an official method. Sometimes, for example, in goods-in or final product quality control, moisture analyzers are used in parallel with a drying oven. Fast analysis with the moisture analyzer is done to optimize processes and the drying oven is used for official documentation purposes.
Many industry regulations require manufacturers to follow a standard method. However, it is acceptable to use a moisture analyzer if you can prove its results are the same as those from the drying oven procedure and are of the same level of accuracy. This requires developing a drying method for the moisture analyzer and cross-validating it against the drying oven through a series of analyses. METTLER TOLEDO's application database contains over 100 free ready-to-use cross-validated drying methods. Contact us if you don't find what you need.
You can do this either through the ID management functionality on our moisture analyzers or in the differential weighing application on our balances. If your batch number is a barcode, you can even connect a barcode reader to scan it, or any other ID.
Manual processes are more prone to error so it's best to use the built-in balance application or a software solution (LabX™) with a balance to capture all the results and do the calculations automatically. It's not only much faster but it's error-free too. Results can be printed out for your lab journal or saved on a USB stick to be saved electronically. LabX saves everything in a secure database so you can be sure your data is safe. The LabX report generator enables you to create elegant reports with charts which can be printed out or saved electronically.
Good labelling is key. Using barcode labels uniquely identifies each sample. A barcode reader attached to the balance ensures that no mix-ups occur and weighing results are correctly logged against each sample. Use of a barcode reader is fully supported by the differential weighing application on the balance and by LabX.
Moisture content is the amount of moisture in the sample given as a percentage of the sample's original (wet) weight. Dry content is the amount of solids which are left after drying given as a percentage of the sample's original (wet) weight. ATRO moisture (AM) is the amount of moisture in the sample given as a percentage of the sample's final (dry) weight. Different industries use different units e.g. in wood or pulp, ATRO is commonly used.
The loss on drying procedure can be used to determine moisture content (MC) or, alternatively, dry content (DC). A sample may undergo extensive drying to remove all the moisture. The dry content remaining may be termed the total solids (TS).
Dry content and total solids mean the same thing. They describe the amount of material remaining after all the moisture has been evaporated.
Moisture content measures the total amount of water and volatile compounds present before drying. Dry content, by contrast, refers to the portion of a material remaining after all moisture and volatile substances have been removed through heating. It represents the solid, nonvolatile matter in the sample. In summary: The total sample weight minus the moisture content equals the dry content.
