Water affects pharmaceutical materials in ways that extend far beyond simple moisture measurements. Hydration, hygroscopicity, solvent interactions, crystal stability, degradation, powder flow, and processing behavior can all change as environmental conditions change. Selecting the appropriate analytical approach requires understanding how water interacts with the material—not simply measuring how much water is present. Triclinic Labs applies Karl Fischer titration, Dynamic Vapor Sorption (DVS), thermal analysis, spectroscopy, and complementary techniques to characterize water interactions that influence product quality, stability, and manufacturability.
Karl Fischer (KF) titration measures water content selectively. DVS measures mass change as humidity changes, showing how quickly and how much water or solvent is absorbed or adsorbed. Low-relative-humidity (low-RH) and humidity-controlled handling protect samples whose physical state changes with water activity.
Use these methods for hygroscopicity, hydrate/anhydrate risk, amorphous-content and recrystallization studies, formulation water activity, packaging questions, low-RH sample handling, dissolution/disintegration support, and humidity-stability investigations.
KF can be complicated by insoluble samples, side reactions, volatile components, or non-water mass loss. DVS measures mass, not structure, so post-stress X-ray powder diffraction (XRPD), Raman/infrared (IR) spectroscopy, or microscopy is needed to prove hydrate formation, crystallization, or morphology change.
DVS typically uses milligram-scale material, but exact amounts depend on pan, sensitivity, inhomogeneity, and repeat requirements. KF amount depends on expected water level and method format: coulometric, volumetric, or oven KF.
Thermogravimetric analysis (TGA), loss on drying, XRPD, Raman and infrared (IR) spectroscopy, microscopy, differential scanning calorimetry (DSC), solid-state nuclear magnetic resonance (NMR) spectroscopy, and variable-temperature/variable-relative-humidity powder X-ray diffraction (VT/VRH-PXRD) all compete or complement water analysis depending on whether the question is quantity, phase identity, kinetics, or performance.
FDA cares that the water method distinguishes water from other volatiles, is specific and validated where used for release or stability, and is connected to form control, microbial risk, stability, packaging, or drug-product performance.
Common mistakes include treating TGA mass loss as water without confirmation, ignoring ambient humidity during sample transfer, using KF reagents incompatible with the sample, and running DVS without structural analysis of post-stress material.
Triclinic uses water-vapor and moisture analysis to evaluate real-world risks from hygroscopicity, hydrate formation, desolvation, sorption, desorption, and water-driven solid-form or performance changes. Applications include DVS and Karl Fischer support for stability, packaging, storage, process exposure, lot comparability, amorphous-material behavior, and investigations where water content or humidity history changes material performance.
Decision-quality DVS work goes beyond maximum percent mass change. The adsorption and desorption isotherms, equilibration rate, critical relative-humidity thresholds, step transitions, plateaus, hysteresis, and recovery after drying help distinguish weak reversible sorption from hydrate formation, amorphous plasticization, crystallization, or kinetically limited conversion. Because DVS measures mass rather than crystal structure, suspected phase changes should be confirmed on stressed material by XRPD, Raman or IR spectroscopy, TGA or Karl Fischer analysis, microscopy, or solid-state NMR as appropriate.
| DVS behavior | Possible interpretation | Development action |
|---|---|---|
| Minimal reversible uptake | Weak surface sorption and generally lower humidity sensitivity. | Confirm that the observed uptake is acceptable for the product, process, and dose. |
| Smooth increasing uptake | Progressive sorption or amorphous-phase plasticization. | Evaluate glass-transition depression, stability, flow, and packaging needs. |
| Uptake followed by mass loss | Water-assisted crystallization may have expelled previously absorbed water. | Identify the post-DVS phase and determine whether dissolution or stability changed. |
| Sharp step or plateau | A discrete hydrate or other phase transition may be occurring. | Define the RH boundary and confirm the resulting phase with an orthogonal method. |
| Adsorption/desorption hysteresis | The change may be kinetically limited or incompletely reversible. | Evaluate humidity excursions, recovery, and shelf-life risk. |
Decision output: Translate the DVS profile into a critical RH or water-activity boundary, allowable exposure, packaging requirement, storage or processing limit, drying endpoint, and any follow-up stability, dissolution, flow, or appearance testing. Record material history, prior drying, solvent exposure, and humidity exposure because these factors can change the result.
The table below lists the specific platforms, brands, models, software, detectors, and capability notes relevant to this service area.
| Instrument or platform | Brand, model, software, or detector | Additional capabilities and use |
|---|---|---|
| Karl Fischer water determination | Mettler Toledo V20 and C20 systems | Volumetric and coulometric KF water-content analysis for solids, liquids, and formulations. |
| Oven KF and insoluble-sample support | Mettler Toledo KF systems with drying-oven configuration | Water determination for insoluble materials or samples that react with conventional KF reagents. |
| Dynamic vapor sorption | TA Instruments Q5000 DVS systems with Thermal Advantage for Q Series v.5.4.0 | Sorption/desorption isotherms, kinetic water uptake, hygroscopicity, amorphous-content support, and moisture-induced change investigations. |
| Low-RH handling | Low-relative-humidity handling capability | Humidity-sensitive sample preparation, transfer, and analysis support where ambient water exposure may alter phase or performance. |
| Dissolution support | VanKel VF750D with ultraviolet/visible (UV/Vis) or high-performance liquid chromatography (HPLC) detection | Drug-release and dissolution profiles where water interaction and release behavior are linked. |
| Disintegration testing | Testerion DT2 | Tablet/capsule disintegration testing under standardized conditions. |
| Humidity-controlled XRPD support | Anton Paar CHCplus Cryo and Humidity Chamber on PXRD system | Structural confirmation of hydrate/anhydrate conversion, recrystallization, or phase changes under defined RH/temperature conditions. |
This example connects water analysis to solid-form risk. KF, DVS, low-relative-humidity handling, dissolution, and disintegration address questions involving water content, water uptake, and aqueous performance. A humidity-controlled XRPD example is useful because water does not just change mass; it can drive hydrate formation, dehydration, crystallization, or other phase changes that affect stability and performance.
DVS identifies the humidity at which mass changes; post-exposure XRPD, Raman, IR, microscopy, or solid-state NMR identifies what changed; and dissolution, flow, appearance, or stability testing determines whether the change matters. Together, the results support practical limits for handling, manufacturing, packaging, and storage.
These examples include technical resources, regulatory guidances, or literature relevant to the technique. Download buttons are placed at the bottom-left of each example.
Author: Triclinic Labs
Publication date: 2023
Abstract: Application note showing how VT/VRH-PXRD follows theophylline phase transitions under controlled humidity and temperature. The example supports using non-ambient diffraction to evaluate hydrates, anhydrates, stability boundaries, and process-relevant phase transformations.
Author: Triclinic Labs
Publication date: 2025
Abstract: This application note uses modulated DSC to quantify amorphous content in crystalline API by evaluating heat-capacity change at the glass transition, illustrating how thermal methods can support low-level amorphous-content control and stability interpretation.
Author: International Council for Harmonisation / FDA
Publication date: 2024
Abstract: FDA notes that ICH Q2(R2) and Q14 describe validation and development principles for analytical procedures used to assess drug substance and drug product quality. These guidances frame FDA expectations for specificity, accuracy, precision, range, robustness, lifecycle management, and fit-for-purpose method evidence.
Mass gain proves that the sample took up water or vapor. It does not by itself prove hydrate formation; structural confirmation is required.
Water can increase molecular mobility and trigger crystallization of an amorphous material. The resulting crystalline phase may retain less water.
Critical relative-humidity thresholds, uptake kinetics, and reversibility help define moisture-barrier needs, allowable exposure, and storage conditions.
Post-exposure phase identification is recommended when steps, hysteresis, mass loss, or performance changes suggest a structural transition.
Karl Fischer measures water content, TGA measures thermally driven mass loss, and DVS measures dynamic mass response as humidity changes.
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