This is a working overview of Karl Fischer, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-07-24. Anything still debated is marked as such rather than presented as settled.
The physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilisation is the British spelling; the process is not simple evaporation. |
| Primary drying pressure | 0.05–0.3 mbar | Pressure must remain below the vapor pressure of ice at the product temperature. |
| Sublimation temperature | Below 0 °C | Ice changes directly to vapor while the product remains frozen. |
| Typical shelf temperature | −40 to −10 °C | Exact setting depends on formulation critical temperature and equipment. |
| Cycle duration | 12–72 hours | Time varies with fill volume, formulation, and dryer performance. |
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.
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.
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.
Freezing is the first stage and sets the ice structure that later becomes the pore network. The formulation is cooled below its freezing point, often with a controlled ramp, and solutes concentrate as ice forms. Primary drying then lowers chamber pressure and supplies heat to sublime the ice. The product temperature must stay below its collapse or eutectic temperature to prevent structural loss. Secondary drying raises the temperature modestly to remove bound water and achieve a low residual moisture.
A freeze-dryer consists of a vacuum chamber, temperature-controlled shelves, a condenser, and a vacuum pump. Vials, ampoules, or bulk trays hold the product during the cycle. The condenser traps water vapor as ice at a temperature lower than the product. Cycle development balances shelf temperature, chamber pressure, and time. Scale-up can be difficult because heat and mass transfer change with equipment size, so process analytical tools and conservative validation are often used.
Lyophilization is a dehydration technique in which a product is frozen and the solvent is removed under reduced pressure. The low pressure allows ice to sublimate directly into vapor without passing through a bulk liquid phase. This differs from conventional drying, where heat drives evaporation and can damage heat-sensitive structures. The process is used for biological materials, pharmaceutical formulations, and some foods. Its main advantage is preservation of porous structure and rapid reconstitution.
After lyophilization, the dried product is often sealed under vacuum or an inert gas to limit moisture and oxygen exposure. Vials, stoppers, and seals must maintain their barrier throughout shelf life. Storage temperature depends on product sensitivity: some cakes tolerate controlled room temperature, while labile biologics require refrigeration. Humidity is a critical variable because dried cakes are hygroscopic and can absorb water when exposed to air. Handling procedures therefore limit open-vial time and use desiccated environments for sampling.
Quality control for lyophilized materials examines appearance, reconstitution time, residual moisture, and mechanical integrity. An acceptable cake is usually uniform and porous, though appearance alone does not prove stability. Karl Fischer titration is a common method for water content, while differential scanning calorimetry can reveal glass transition events. Stability studies track potency, aggregation, and moisture over time under defined temperature and humidity conditions. Specifications are product-specific and may include sterility and endotoxin tests for sterile preparations.
5 and Savings) Order 1993 (S.I. 1993/1186) Friendly Societies Act 1992 (Consequential Provisions) (No. 2) Regulations 1993 (S.I. 1993/1187) Serbia and Montenegro (United Nations Sanctions) Order 1993 (S.I. 1993/1188) Export of Goods (Control) (Croatian and Bosnian Territories) Order 1993 (S.I. 1993/1189) Education (Schools) Act 1992 (Commencement No. 2 and Transitional Provision) Order 1993 (S.I. 1993/1190) Lothian Region (Electoral Arrangements) Order 1993 (S.I. 1993/1191) Injuries in War (Shore Employments) Compensation (Amendment) Scheme 1993 (S.I. 1993/1192) Electricity (Standards of Performance) Regulations 1993 (S.I. 1993/1193) Diseases of Animals (Approved Disinfectants) (Amendment) Order 1993 (S.I. 1993/1194) Serbia and Montenegro (United Nations Sanctions) (Dependent Territories) Order 1993 (S.I. 1993/1195) Sea Fish Licensing (Time at Sea) (Principles) Order 1993 (S.I. 1993/1196) Third Country Fishing (Enforcement) Order 1993 (S.I. 1993/1197) Police (Amendment) (No. 2) Regulations 1993 (S.I. 1993/1198) Lincolnshire County Council (Tattershall Bridge Reconstruction) Scheme 1991 Confirmation Instrument 1993 (S.I. 1993/1199)
Some Australian elapids and most viper envenomations will cause coagulopathy, sometimes so severe that a person may bleed spontaneously from the mouth, nose, and even old, seemingly healed wounds. Internal organs may bleed, including the brain and intestines, and ecchymosis (bruising) of the skin is often seen. The venom of elapids, including sea snakes, kraits, cobras, king cobra, mambas, and many Australian species, contains toxins which attack the nervous system, causing neurotoxicity. The person may present with strange disturbances to their vision, including blurriness. Paresthesia throughout the body, as well as difficulty in speaking and breathing, may be reported. Nervous system problems will cause a huge array of symptoms, and those provided here are not exhaustive. If not treated immediately they may die from respiratory failure. Venom emitted from some types of cobras, almost all vipers, and some sea snakes cause necrosis of muscle tissue. Muscle tissue will begin to die throughout the body, a condition known as rhabdomyolysis. Rhabdomyolysis can result in damage to the kidneys as a result of myoglobin accumulation in the renal tubules. This, coupled with hypotension, can lead to acute kidney injury, and, if left untreated, eventually death. Snakebite is also known to cause depression and post-traumatic stress disorder in a high proportion of people who survive.
=== Available forms === Ciclosporin exhibits very poor solubility in water, and, as a consequence, suspension and emulsion forms of the medication have been developed for oral administration and for injection. Ciclosporin was originally brought to market by Sandoz (now Novartis), under the brand name Sandimmune, which is available as soft gelatin capsules, an oral solution, and a formulation for intravenous administration. These are all nonaqueous compositions. A newer microemulsion, orally-administered formulation, Neoral, is available as a solution and as soft gelatin capsules. Compositions of Neoral are designed to form microemulsions in contact with water. Generic ciclosporin preparations have been marketed under various brand names, including Cicloral (by Sandoz/Hexal), Gengraf (by Abbott) and Deximune (by Dexcel Pharma). Since 2002, a topical emulsion of ciclosporin for treating inflammation caused by keratoconjunctivitis sicca (dry eye syndrome) has been marketed under the brand name Restasis. Ikervis is a similar formulation with a concentration of 0.1%. Inhaled ciclosporin formulations are in clinical development, and include a solution in propylene glycol and liposome dispersions.
Diethyl maleate is an organic compound with the CAS Registry number 141-05-9. It is chemically a maleate ester with the formula C8H12O4. It is a colorless liquid at room temperature. It has the IUPAC name of diethyl (Z)-but-2-enedioate.
Sources: en.wikipedia.org
Polypeptide directionality is similarly based on identifying the functional groups of amino acids, specifically the amino group, which forms the N-terminus, and the carboxyl group, which forms the C-terminus; amino acid sequences are assembled in the N-to-C direction during translation, and by convention are written in the same direction.
Genome analysis reveal rifampicin resistant strains have a mutation in rpoA and rpoC. A similar study investigated the bacterial fitness associated with compensatory mutations in rifampin resistant Escherichia coli. Results obtained from this study demonstrate that drug resistance is linked to bacterial fitness as higher fitness costs are linked to greater transcription errors.
Unlike atomic absorption spectroscopy, which can only measure a single element at a time, ICP-MS has the capability to scan for all elements simultaneously. This allows rapid sample processing. A simultaneous ICP-MS that can record the entire analytical spectrum from lithium to uranium in every analysis won the Silver Award at the 2010 Pittcon Editors' Awards. An ICP-MS may use multiple scan modes, each one striking a different balance between speed and precision. Using the magnet alone to scan is slow due to hysteresis but is precise. Electrostatic plates can be used in addition to the magnet to increase the speed, and with multiple collectors can allow a scan of every element from Lithium 6 to Uranium Oxide 256 in less than a quarter of a second. For low detection limits, interfering species and high precision, the counting time can increase substantially. The rapid scanning, large dynamic range and large mass range of ICP-MS is ideally suited to measuring multiple unknown concentrations and isotope ratios in samples that have had minimal preparation (an advantage over TIMS). The analysis of seawater, urine, and digested whole rock samples are examples of industry applications. These properties also lend well to laser-ablated rock samples, where the scanning rate is fast enough to enable a real-time plot of any number of isotopes. This also allows easy spatial mapping of mineral grains.
==== Diagnosis of disease ==== TSH concentrations are measured as part of a thyroid function test in patients suspected of having an excess (hyperthyroidism) or deficiency (hypothyroidism) of thyroid hormones. Interpretation of the results depends on both the TSH and T4 concentrations. In some situations measurement of T3 may also be useful.
La Familia Michoacana was a drug cartel based in Michoacán between at least 2006 and 2011. It was formerly allied with the Gulf Cartel and Los Zetas, but split off to become an independent organization. La Familia Michoacana was the first cartel targeted by President Calderón's security strategy, beginning with Operation Michoacán in December 2006. Between 2009 and 2010, joint U.S.–Mexican operations led to the arrest of hundreds of La Familia members and the reported death of founder Nazario Moreno González ("El Más Loco"). The group soon split between the Knights Templar Cartel and a faction led by José de Jesús Méndez Vargas ("El Chango"), who was arrested in 2011, after which authorities declared La Familia dismantled, leaving the Knights Templar as its de facto successor. In February 2010, La Familia allied with the Gulf Cartel against Los Zetas and the Beltrán-Leyva Cartel. La Nueva Familia Michoacana emerged from splinters of La Familia in the early 2010s, rebranding while continuing operations in Michoacán and Guerrero, and clashing with the Jalisco New Generation Cartel.
Sources: en.wikipedia.org
of the electron was first measured by J. J. Thomson. By doing this he showed that the electron, which was postulated before in order to explain electricity, was in fact a particle with a mass and a charge and that its mass-to-charge ratio was much smaller than the one for the hydrogen ion H+. In 1913 he measured the mass-to-charge ratio of ions with an instrument he called a parabola spectrograph. Although this data was not represented as a modern mass spectrum, it was similar in meaning. Eventually there was a change to the notation as m/e giving way to the current standard of m/z. Early in mass spectrometry research the resolution of mass spectrometers did not allow for accurate mass determination. Francis William Aston won the Nobel prize in Chemistry in 1922. "For his discovery, by means of his mass spectrograph, of isotopes, in a large number of non-radioactive elements, and for his enunciation of the Whole Number Rule." In which he stated that all atoms (including isotopes) follow a whole-number rule This implied that the masses of atoms were not on a scale but could be expressed as integers (in fact multiple charged ions were rare, so for the most part the ratio was whole as well). There have been several suggestions (e.g. the unit thomson) to change the official mass spectrometry nomenclature
=== Pharmacodynamics === Pinoline shows affinity for serotonin receptors, including the serotonin 5-HT1A, 5-HT2A, 5-HT2B, 5-HT2C, and 5-HT7 receptors (Ki = 156–4,335 nM). It is a high-efficacy partial agonist of the serotonin 5-HT2A receptor, an antagonist of the serotonin 5-HT2B receptor, and a full agonist of the serotonin 5-HT2C receptor, with EC50Tooltip half-maximal effective concentration (EmaxTooltip maximal efficacy) values of 2,140 nM (75%) at the serotonin 5-HT2A receptor and 33 nM (95%) at the serotonin 5-HT2C receptor and an IC50Tooltip half-maximal inhibitory concentration of 1,120 nM at the serotonin 5-HT2B receptor. Hence, pinoline appears to act as a potent and selective serotonin 5-HT2C receptor agonist. The drug shows affinity for the serotonin transporter (SERT) (Ki = 172–572 nM). It is a serotonin reuptake inhibitor, with an IC50 value of 1,100 nM. Pinoline shows affinity for the imidazoline I2 receptor (Ki = 1,640 nM) and for the α2-adrenergic receptor (Ki = 7,830 nM). Conversely, it shows no affinity for the dopamine D2 receptor (Ki = >10,000 nM). The drug is a weak monoamine oxidase inhibitor (MAOI), with an IC50 value for inhibition of MAO-ATooltip monoamine oxidase A of 41,500 nM. Both pinoline and tryptoline partially substitute for the psychedelic drug LSD in rodent drug discrimination tests. The substitution by tryptoline was further assessed and was found to be blocked by the serotonin receptor antagonist pizotifen and by the serotonin synthesis inhibitor para-chlorophenylalanine (PCPA).
The stability of nuclei quickly decreases with the increase in atomic number after curium, element 96, whose half-life is over ten thousand times longer than that of any subsequent element. All isotopes with an atomic number above 101 undergo radioactive decay with half-lives of less than 30 hours: this is because of the ever-increasing Coulomb repulsion of protons, so that the strong nuclear force cannot hold the nucleus together against spontaneous fission for long. Calculations suggest that in the absence of other stabilising factors, elements with more than 103 protons should not exist. Researchers in the 1960s suggested that the closed nuclear shells around 114 protons and 184 neutrons should counteract this instability, and create an "island of stability" containing nuclides with half-lives reaching thousands or millions of years. The existence of the island is still unproven, but the existence of the superheavy elements (including nihonium) confirms that the stabilising effect is real, and in general the known superheavy nuclides become longer-lived as they approach the predicted location of the island. All nihonium isotopes are unstable and radioactive; the heavier nihonium isotopes are more stable than the lighter ones, as they are closer to the centre of the island. The most stable known nihonium isotope, 286Nh, is also the heaviest; it has a half-life of 8 seconds. The isotope 285Nh, as well as the unconfirmed 287Nh and 290Nh, have also been reported to have half-lives of over a second.
== Hematopoietic == Acute biphenotypic leukemia Acute eosinophilic leukemia Acute lymphoblastic leukemia Acute myeloid leukemia Acute myeloid dendritic cell leukemia AIDS-related lymphoma Anaplastic large cell lymphoma Angioimmunoblastic T-cell lymphoma B-cell prolymphocytic leukemia Burkitt's lymphoma Chronic lymphocytic leukemia Chronic myelogenous leukemia Cutaneous T-cell lymphoma Diffuse large B-cell lymphoma Follicular lymphoma Hairy cell leukemia Hepatosplenic T-cell lymphoma Hodgkin's lymphoma Intravascular large B-cell lymphoma Large granular lymphocytic leukemia Lymphoplasmacytic lymphoma Lymphomatoid granulomatosis Mantle cell lymphoma Marginal zone B-cell lymphoma Mast cell leukemia Mediastinal large B cell lymphoma Multiple myeloma/plasma cell neoplasm Myelodysplastic syndromes Mucosa-associated lymphoid tissue lymphoma Mycosis fungoides Nodal marginal zone B cell lymphoma Non-Hodgkin lymphoma Precursor B lymphoblastic leukemia Primary central nervous system lymphoma Primary cutaneous follicular lymphoma Primary cutaneous immunocytoma Primary effusion lymphoma Plasmablastic lymphoma Sézary syndrome Splenic marginal zone lymphoma T-cell prolymphocytic leukemia
Thomas Edison began serious research into developing a practical incandescent lamp in 1878. Edison filed his first patent application for "Improvement in Electric Lights" on 14 October 1878. After many experiments, first with carbon in the early 1880s and then with platinum and other metals, in the end Edison returned to a carbon filament. The first successful test was on 22 October 1879, and lasted 13.5 hours. Edison continued to improve this design and by 4 November 1879, filed for a US patent for an electric lamp using "a carbon filament or strip coiled and connected ... to platina contact wires." Although the patent described several ways of creating the carbon filament including using "cotton and linen thread, wood splints, papers coiled in various ways," Edison and his team later discovered that a carbonized Japanese bamboo filament could last more than 1200 hours. In 1880, the Oregon Railroad and Navigation Company steamer, Columbia, became the first application for Edison's incandescent electric lamps (it was also the first ship to use a dynamo). Albon Man, a New York lawyer, started Electro-Dynamic Light Company in 1878 to exploit his patents and those of William Sawyer. Weeks later the United States Electric Lighting Company was organized. This company made their first commercial installation of incandescent lamps in the fall of 1880, at the Mercantile Safe Deposit Company in New York City, about six months after the Edison incandescent lamps had been installed on the Columbia. Hiram S. Maxim was the chief engineer at the United States Electric Lighting Company.
Sources: en.wikipedia.org
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.
Freezing determines ice crystal size, solute distribution, and the pore network left after drying. A slow or fast freezing rate can produce different cake structures and affect reconstitution. It also sets whether the formulation follows an amorphous or crystalline drying path.
It removes most free water during primary drying and part of the bound water during secondary drying. A small residual moisture content often remains and is specified for each product. Complete removal is generally neither practical nor desirable for stability.
Karl Fischer titration is a common method, using coulometric or volumetric detection. Thermogravimetric analysis can also measure weight loss on heating. Results depend on sample handling because the dried solid can absorb moisture quickly.