If you have been reading about Moisture sorption and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-01-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
Residual moisture is a key quality attribute for lyophilized products. Water that remains after secondary drying can affect chemical stability, cake structure, and shelf life. Karl Fischer titration is a common method for measuring water content in the dried solid. The target range varies by product, but many biologics are dried to between 0.5% and 3% water by weight. Acceptable limits are set during development and confirmed by stability studies.
Stability studies examine how temperature, humidity, and time influence a lyophilized product. Accelerated conditions provide early information about degradation pathways, while long-term studies support shelf-life claims. The glass transition temperature of the dried formulation can indicate its physical stability, and storage above this temperature may increase molecular mobility and lead to collapse or aggregation. Container closure integrity also matters because moisture or oxygen ingress can degrade the product, so vial stoppers and seals are part of the quality system.
Handling and storage practices aim to keep the cake intact and dry. Vials are typically stored upright at controlled temperatures, often between 2 °C and 8 °C or at -20 °C for longer-term use. Reconstitution involves adding a suitable diluent and gently mixing until the solid dissolves. Shaking or rapid injection of diluent can create foam or damage sensitive molecules. Once reconstituted, the product may require refrigeration and use within a defined period.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
The process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
| Property | Value | Notes |
|---|---|---|
| Residual moisture | 0.5-3% w/w | Typical range for many biopharmaceuticals |
| Typical storage temperature | 2-8 °C | Some products require -20 °C or lower |
| Reconstitution time | Seconds to several minutes | Depends on cake porosity and diluent |
| Common moisture method | Karl Fischer titration | Measures water content in the solid |
| Container closure | Stoppered vial with seal | Protects against moisture and oxygen ingress |
Storage stability depends on water content, oxygen exposure, and temperature. Lyophilized solids are hygroscopic and can absorb water if exposed to humid air. Vials are usually sealed under vacuum or inert gas with rubber stoppers and aluminum crimps. Storage temperatures range from room temperature to refrigerated or frozen conditions depending on the material. Stability studies track potency, moisture, and physical form over time. Accelerated conditions can reveal sensitivity but may not predict long-term behavior.
Analytical methods for lyophilized materials include X-ray diffraction for crystallinity, differential scanning calorimetry for thermal transitions, and scanning electron microscopy for pore morphology. Moisture sorption analysis shows how the cake responds to humidity. These methods help distinguish amorphous from crystalline states and detect phase changes. Open questions remain about how pore structure changes during long-term storage and how best to predict collapse under varied conditions. Comparisons across studies are complicated by differences in formulation, cycle, and storage history.
Lyophilization, also known as freeze-drying, is a process that removes water from a material by freezing it and then reducing pressure to allow ice to sublimate directly into vapor. The method begins with a freezing step that solidifies the water content. Next, primary drying lowers the pressure below the triple point of water, enabling sublimation without passing through a liquid phase. A final secondary drying step removes bound water through desorption. This sequence produces a dry, porous cake that can be reconstituted later.
The process relies on the phase diagram of water, where the triple point marks the conditions at which ice, liquid water, and vapor coexist. By maintaining pressure below this point, typically around 0.01 to 0.1 millibar, sublimation becomes the dominant mechanism. Formulations often include excipients such as sugars or polymers that act as lyoprotectants and bulking agents. These additives help preserve the structure of the active ingredient and prevent collapse during drying. The choice of excipient and freezing rate influences the final cake morphology and stability.
Industries use lyophilization for pharmaceuticals, biological products, and food preservation. In the pharmaceutical sector, it extends the shelf life of injectable drugs, vaccines, and proteins that are unstable in aqueous solution. Food manufacturers apply freeze-drying to coffee, fruits, and ready meals to retain flavor and texture. The process is energy-intensive and requires specialized equipment, which limits its use to high-value products. Ongoing research examines how formulation and process parameters affect the quality of the final dried product.
Storage conditions depend on the formulation and the intended shelf life. Many pharmaceutical and biological freeze-dried products are kept at 2–8 °C, while some stable foods and reagents tolerate room temperature. Others require −20 °C or colder to slow chemical degradation or aggregation. Protection from light and oxygen is common because oxidation can continue in the dry state. Stability studies usually monitor potency, appearance, moisture, and reconstitution time over months or years. Predictions from accelerated studies are useful but may not fully capture real-time changes.
Quality control for freeze-dried lots combines visual inspection with instrumental tests. Cake appearance, color, and shrinkage are recorded against a reference, while residual moisture is measured by Karl Fischer titration or loss on drying. Thermal analysis can reveal phase transitions and crystallization events, and X-ray diffraction distinguishes amorphous from crystalline solids. Microbiological tests and container closure integrity checks are also routine for sterile products. Analytical methods must be validated for the matrix, because excipients and low moisture can affect accuracy. Open questions include how best to predict long-term stability from short-term data.
Lyophilized solids are often hygroscopic, so handling occurs in controlled low-humidity areas or glove boxes when the material is exposed. Vials remain sealed with elastomeric stoppers and aluminum crimps until use, because airborne moisture can raise residual water and shorten shelf life. The porous cake is fragile and may crack, shrink, or powder during transport. Personnel typically avoid repeated warming and cooling of sealed units, which can draw moisture through closures. These practices aim to preserve the low water content achieved during drying.
If the snake were really habitually aggressive records of its bite would be frequent; as it is they are extremely rare." Mortality rates vary sharply depending on many factors. In cases where envenomation is severe, death can be rapid.
==== PATH ==== Connections are also available to the PATH system at 33rd Street station, under Sixth Avenue on Herald Square. The JSQ-33 and HOB-33 services terminate at 33rd Street on weekdays, and are combined into the JSQ-33 (via HOB) service on late nights, weekends and holidays.
CH3OCH3 + SO3 → (CH3)2SO4 Sulfate esters are used as detergents, dyes, and pharmaceuticals. Sulfur trioxide is generated in situ from sulfuric acid or is used as a solution in the acid. B2O3 stabilized sulfur trioxide was traded by Baker & Adamson under the tradename "Sulfan" in the 20th century.
Sources: en.wikipedia.org
Market Place (formerly Market Place by Jasons, Jason's Food & Living, and Jasons ichiba) in Hong Kong is a high-end supermarket chain owned by DFI Retail Group. The chain also has a joint venture in mainland China with Beijing Hualian Group called BHG Market Place and formerly ran stores (Jasons Market Place) in Taiwan until they were sold to Carrefour. The Malaysian chain called Mercató (formerly Jasons Food Hall) is owned by Macrovalue Sdn Bhd. after its acquisition of DFI Malaysian food retailing business in 2023. Cold Storage Fresh (formerly Market Place, Jasons, and Jasons Deli) in Singapore is also owned by Macrovalue Sdn Bhd since 2025. The Marketplace (formerly Market Place by Rustan's) in the Philippines has been owned by Robinsons Retail Holdings since 2018, before which it was owned by Rustan Supercenters. DFI also operates further similar supermarkets under the 3hreeSixty and Oliver's The Delicatessen brands in Hong Kong and other supermarkets around Asia with Wellcome.
During the mid-19th century, canned food became a status symbol among middle-class households in Europe, being something of a frivolous novelty. Early methods of manufacture employed poisonous lead solder for sealing the cans. Studies in the 1980s attributed the lead from the cans as a factor in the disastrous outcome of the 1845 Franklin expedition to chart and navigate the Northwest Passage. However, studies in 2013 and 2016 suggested that lead poisoning was likely not a factor, and that the crew's ill health may, in fact, have been due to malnutrition—specifically zinc deficiency—possibly due to a lack of meat in their diet. Increasing mechanization of the canning process, coupled with a huge increase in urban populations across Europe, resulted in a rising demand for canned food. A number of inventions and improvements followed, and by the 1860s smaller machine-made steel cans were possible, and the time to cook food in sealed cans had been reduced from around six hours to thirty minutes.
The name "alkaloids" (German: Alkaloide) was introduced in 1819 by German chemist Carl Friedrich Wilhelm Meissner, and is derived from late Latin root alkali and the Greek-language suffix -οειδής -('like'). However, the term came into wide use only after the publication of a review article, by Oscar Jacobsen in the chemical dictionary of Albert Ladenburg in the 1880s. The name "alkaloid" was introduced, since at the time, chemists conceptualized the category of "alkaline" in such a way that plants cannot produce alkaline. For instance, potash, an alkaline substance that can be extracted from plants by burning, was thought to be either produced during burning, or extracted by plant from the soil. Subsequent research by chemists to extract the "principle" (what we nowadays call the active ingredient) of medicinal plants, led to the discovery of various substances that had properties resembling alkalines as understood at the time. These substances were variously named "salifiable vegetable bases", "vegetable organic compounds", "organic bases", etc. After enough such substances were discovered, these substances were classified as "alkaloid", a new chemical category. There is no unique method for naming alkaloids. Many individual names are formed by adding the suffix "ine" to the species or genus name. For example, atropine is isolated from the plant Atropa belladonna; strychnine is obtained from the seed of the Strychnine tree (Strychnos nux-vomica L.).
== External links == "Erythropoietin". Drug Information Portal. U.S. National Library of Medicine. Archived from the original on 7 April 2020. Overview of all the structural information available in the PDB for UniProt: P01588 (Erythropoietin) at the PDBe-KB.
Sources: en.wikipedia.org
Residual moisture can influence chemical degradation, cake collapse, and long-term stability. Low moisture levels usually improve stability, but each product has an optimal range.
Most lyophilized products are stored upright at controlled temperatures, often refrigerated or frozen. Protection from moisture and light helps maintain the dried cake.
A diluent is added to the dried cake, which dissolves to form a solution or suspension. Gentle mixing avoids foaming and preserves sensitive molecules.
The main change is sublimation, in which ice becomes water vapor without melting into liquid water. This occurs when the chamber pressure is held below the vapor pressure of ice while mild heat is supplied. The result is a dry, porous solid that retains much of its original shape.