The short version of Redox ratio fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-03-29. Anything still debated is marked as such rather than presented as settled.
Several techniques are used for quantification. Enzymatic recycling assays rely on glutathione reductase and a colorimetric or fluorescent readout, offering sensitivity for total glutathione. High-performance liquid chromatography can separate GSH from GSSG and other thiols, often with UV, fluorescence, or electrochemical detection. Mass spectrometry provides structural confirmation and can quantify low-abundance species when paired with separation. Each approach has trade-offs in specificity, throughput, and equipment requirements, so method selection depends on the research question and available instrumentation.
Stability depends on pH, temperature, oxygen exposure, and trace metals. Aqueous solutions of reduced glutathione are susceptible to oxidation, especially when neutral or alkaline and exposed to air. Transition metal ions can catalyze thiol oxidation, so chelators and inert atmospheres are sometimes used in research settings. Standards are typically stored cold and desiccated, with limited freeze-thaw cycles. Questions remain about how closely in vitro stability data reflect the behavior of glutathione within intact cells and tissues.
Measuring glutathione requires attention to oxidation during sample handling, because GSH in biological samples can convert to GSSG or form mixed disulfides with proteins after collection. Acidic extraction, rapid cooling, and chelating agents are commonly used to limit such changes. Analytical methods usually distinguish free reduced glutathione, total glutathione, and protein-bound forms. Because these forms have different stability and reactivity, reported values depend heavily on the preparation protocol. No single preparation is universally suitable for every biological matrix or analytical goal.
Quantification of glutathione in biological or food samples commonly uses liquid chromatography coupled to ultraviolet, fluorescence, electrochemical, or mass spectrometric detection. Because the thiol group oxidizes readily, samples are often acidified or derivatized immediately after collection to stabilize reduced glutathione. Enzymatic recycling assays and colorimetric kits offer higher throughput but generally lower specificity than chromatographic methods. Mass spectrometry can distinguish glutathione from related thiols and allow simultaneous measurement of oxidized forms. Reported concentrations depend strongly on sample type, extraction procedure, and analytical platform.
Glutathione reference materials are sensitive to oxygen, light, and elevated temperature. Solid material is typically stored desiccated at -20 °C or below, while solutions require tighter control because thiol oxidation proceeds faster in liquid form. Aqueous solutions are often prepared fresh, kept cold, and protected from air; some protocols add acid or chelating agents to slow metal-catalyzed oxidation. Repeated freeze-thaw cycles can accelerate degradation and should be avoided. Stability data vary by matrix, so laboratories usually verify performance with their own storage conditions.
| Property | Value | Notes |
|---|---|---|
| Reduced form | GSH | Main intracellular thiol |
| Oxidized form | GSSG | Disulfide dimer of two GSH molecules |
| Common separation method | Reversed-phase HPLC | Often with ion-pairing or derivatization |
| Typical detection | Fluorescence or mass spectrometry | UV detection is also used in some assays |
| Storage of standards | -20 °C or below, desiccated | Limit freeze-thaw and moisture exposure |
For solid glutathione, storage conditions affect shelf life. The reduced form is typically kept cool, dry, and protected from air and light. Moisture can promote oxidation, while elevated temperatures accelerate degradation. Suppliers often specify storage at or below freezing, sometimes under inert gas. Solutions are less stable than powders and may require preparation shortly before use. Buffers and chelating agents can slow oxidation, but they do not eliminate it. Published stability data vary with matrix, pH, and container.
Quality control for glutathione focuses on identity, purity, and oxidation state. Certificates of analysis may report assay value, water content, and the presence of GSSG or other impurities. Chromatographic purity is often expressed as a percentage of peak area. Reference standards help laboratories compare results across instruments and batches. Because glutathione is a small, polar molecule, separation from cysteine, gamma-glutamylcysteine, and related thiols can be challenging. Verification often combines more than one analytical technique.
Measuring glutathione requires attention to sample preparation because the molecule oxidizes readily. Blood, tissue, and cell samples are often treated with acid to precipitate proteins and stabilize the thiol. Without such steps, GSH can convert to GSSG or form mixed disulfides during storage. Analytical methods include spectrophotometric assays, high-performance liquid chromatography, and mass spectrometry. Each approach has different sensitivity, specificity, and susceptibility to interference from related compounds in complex matrices.
Storage conditions strongly influence glutathione stability. The solid reduced form is commonly kept desiccated at or below minus twenty degrees Celsius, protected from light and moisture. Aqueous solutions are less stable because the thiol group reacts with dissolved oxygen, and oxidation accelerates at neutral or alkaline pH. Acidic solutions and oxygen-free handling can slow degradation, but repeated freeze-thaw cycles should be avoided. Researchers often verify concentration before use, because apparent losses can arise from oxidation or water uptake.
Measuring glutathione in biological samples requires attention to oxidation and matrix effects. High-performance liquid chromatography with ultraviolet or fluorescence detection can separate reduced and oxidized forms after derivatization. Liquid chromatography with tandem mass spectrometry offers higher specificity and can quantify glutathione alongside related thiols. Because glutathione can oxidize during sample handling, many protocols use rapid acidification with metaphosphoric acid or sulfosalicylic acid. Internal standards help correct for losses during extraction and analysis.
Enzymatic recycling assays provide a complementary approach for total glutathione. In these methods, glutathione reductase reduces oxidized glutathione while a thiol-reactive reagent, such as 5,5'-dithiobis(2-nitrobenzoic acid), produces a colored product. The reaction cycles between reduced and oxidized forms, amplifying the signal. Spectrophotometric or fluorometric detection can then estimate concentration. Distinguishing reduced glutathione from glutathione disulfide often requires separate aliquots, masking agents, or chromatographic separation, and the choice affects reported values.
Glutathione is most stable as a dry powder stored cool and dry, but its thiol group is readily oxidized in solution. Aqueous preparations at neutral or alkaline pH lose GSH faster because the thiolate form reacts with dissolved oxygen and metal ions. Acidic conditions, chelating agents, and oxygen exclusion can slow oxidation, while repeated freeze-thaw cycles promote degradation. Light exposure and trace metals also contribute to loss. Laboratories typically validate stability for their own matrices because degradation rates depend on pH, temperature, concentration, and container materials.
Commercial glutathione is available in research-grade, food-grade, and supplement-grade forms, and purity specifications differ accordingly. Certificates of analysis commonly report identity by nuclear magnetic resonance or mass spectrometry, purity by HPLC, residual solvents, and heavy metals. Reference standards with assigned purity support calibration, while isotopically labeled glutathione can serve as an internal standard for mass spectrometry. For supplements, label claims may not be independently verified, and regulatory oversight varies by country. Verification often involves third-party testing for identity, potency, and contaminants.
Quality control for glutathione materials checks identity, assay, purity, water content, and disulfide content. Commercial products vary from research-grade powder to dietary supplements, and labels may not distinguish reduced from oxidized forms. In the United States, oral glutathione is commonly sold as a dietary supplement rather than an approved drug, while injectable forms fall under different rules and may require a prescription. Regulatory status differs by country. Analytical certificates, when available, help verify what a material contains, but independent testing remains important for interpretation.
Laboratory measurement of glutathione typically starts with rapid acid extraction to prevent oxidation and enzymatic degradation. Common methods include enzymatic recycling assays, high-performance liquid chromatography, and liquid chromatography coupled with mass spectrometry. The recycling assay uses glutathione reductase and a thiol-reactive colorimetric or fluorescent reagent, measuring total glutathione after converting disulfide forms. Chromatographic methods can separate reduced and oxidized forms, which helps when the redox ratio is the target. Choice of method affects sensitivity, specificity, and the amount of sample needed.
Picrorhiza kurroa is one of the major income generating non-timber forest products found in the Nepalese Himalayas. It is one of the oldest medicinal plants traded from the Karnali zone. Known as kutki or कुटकी in Nepali, it is a perennial herb and is used as a substitute for Indian gentian (Gentiana kurroo).
Patiromer, sold under the brand name Veltassa, is a medication used to treat high blood potassium. It is taken by mouth. It works by binding potassium in the GI tract. Common side effects include constipation, low blood magnesium, and abdominal pain. It was approved for medical use in the United States in October 2015, and in the European Union in July 2017.
Tsien, Osamu Shimomura, and Martin Chalfie were awarded the 2008 Nobel Prize in Chemistry on 10 October 2008 for their discovery and development of the green fluorescent protein. Most commercially available genes for GFP and similar fluorescent proteins are around 730 base-pairs long. The natural protein has 238 amino acids. Its molecular mass is 27 kD. Therefore, fusing the GFP gene to the gene of a protein of interest can significantly increase the protein's size and molecular mass, and can impair the protein's natural function or change its location or trajectory of transport within the cell.
Sources: en.wikipedia.org
Like most alchemical terms, the word "Sulfur" came to mean a lot of different things in alchemical works beyond its standard definition, representing concepts such as the active, masculine or fixing principle, combustion, or the soul. There were multiple "sulfurs", as the word was used as a Deckname, a secret codename for other substances.
In 1962, while a freshman history major at Harvard, Mark Granovetter became enamored of the concepts underlying the classic chemistry lecture in which "weak" hydrogen bonds hold huge numbers of water molecules together, which themselves are held together by "strong" covalent bonds. This model was the stimulus behind his famous 1973 paper The Strength of Weak Ties, which is now considered a classic paper in sociology. Weak social bonds are believed to be responsible for the majority of the embeddedness and structure of social networks in society as well as the transmission of information through these networks. Specifically, more novel information flows to individuals through weak than through strong ties. Because our close friends tend to move in the same circles that we do, the information they receive overlaps considerably with what we already know. Acquaintances, by contrast, know people that we do not, and thus receive more novel information. There are some demographic groups, such as alexithymics, who may find it very difficult to bond or share an emotional connection with others.
=== Continued unrest === Over Christmas, the UDF called for supporters to observe a "Black Christmas" – a form of consumer boycott, among other things – to mourn the casualties. This led to a fortnight of "comparative calm", excepting a large-scale confrontation on Christmas Day in Sharpeville, where a large crowd had clashed with police after returning from a Black Christmas event at the graves of those killed. Violence broke out again in PWV after Boxing Day. Morale was boosted by the successes of the Vaal uprising – the government had been forced to make certain concessions, removing local councillors to safety and suspending the rent increases – and militant vigour was piqued both by the severe state response and by the presence of troops in the townships, taken by some as a "declaration of war". The increased presence of state security forces in the townships led to a proliferation of opportunistic violence against the forces' members, who – if present in small enough numbers, or if they had run out of ammunition – became a frequent target for stone-throwing. One account describes young militants developing elaborate strategies to obstruct the security services' work: digging trenches to prevent armoured vehicles from moving around, blocking roads with burning tyres and rocks, painting over house numbers and other identifiers to stop police from identifying activists' houses, and staking out "liberated areas" where police and other state representatives could not go.
metabolome The complete set of small-molecule chemical compounds within a cell, organelle, or any other biological sample, including both endogenous molecules (e.g. individual amino acids and nucleotides, fatty acids, organic acids, amines, simple sugars, vitamins, antibiotics, etc.) and exogenous molecules (e.g. drugs, toxins, environmental contaminants, and other xenobiotics).
Sources: en.wikipedia.org
=== 18 May === Russia claimed to have taken the village of Starytsia in Kharkiv Oblast. Two people were killed in Russian attacks in Kherson Oblast. Lieutenant-colonel Denys Vasyliuk, chief of staff of the Ukrainian Air Force's 831st Tactical Aviation Brigade, was reported killed in action. Truckers partially blocked a section of the Kyiv-Odesa highway near Savran in protest over the revised mobilization law. A Russian court seized over 700 million euros ($700 million) worth of assets from UniCredit, Deutsche Bank and Commerzbank to counter western sanctions. Polish Prime Minister Donald Tusk announced a 10 billion zlotys ($2.55 billion) budget to secure Poland's borders with Russia, Belarus, and Ukraine. Tusk also announced he would speak with the European Investment Bank about financing 500 million zlotys ($127.7 million) for the European Sky Shield Initiative.
In 3+1 programs, the student attends classroom courses for three years and complete a clinical rotation their final year of study. In 2+2 programs, students have already completed their lower division coursework and return to complete their last two years of study in a CLS program. In 4+1 program, students who have already completed an undergraduate program return to complete a year of medical laboratory training. The training is typically completed at a clinical site rather than a college. The core curriculum in medical technology generally comprises 20 credits in clinical chemistry, 20 credits in hematology, and 20 credits in clinical microbiology. During clinical rotations, the student experiences hands-on learning in each discipline of the laboratory and performs diagnostic testing in a functioning laboratory under supervision. With limited or no compensation, a student in the clinical phase of training usually works 40 hours per week for 20 to 52 weeks. Some programs in the United States have halved the time students spend completing their clinical rotation reduced due to staffing shortages. For example, in 2015, the MLS program at the University of Minnesota reduced the clinical rotation portion of the program from 22 weeks to 12 weeks. In the United States, a two-year academic program (associate's degree) qualifies the graduate to work as a medical laboratory technician (MLT).
== Key applications == Toxicity assessment/toxicology by metabolic profiling (especially of urine or blood plasma samples) detects the physiological changes caused by toxic insult of a chemical (or mixture of chemicals). In many cases, the observed changes can be related to specific syndromes, e.g. a specific lesion in liver or kidney. This is of particular relevance to pharmaceutical companies wanting to test the toxicity of potential drug candidates: if a compound can be eliminated before it reaches clinical trials on the grounds of adverse toxicity, it saves the enormous expense of the trials. For functional genomics, metabolomics can be an excellent tool for determining the phenotype caused by a genetic manipulation, such as gene deletion or insertion. Sometimes this can be a sufficient goal in itself—for instance, to detect any phenotypic changes in a genetically modified plant intended for human or animal consumption. More exciting is the prospect of predicting the function of unknown genes by comparison with the metabolic perturbations caused by deletion/insertion of known genes. Such advances are most likely to come from model organisms such as Saccharomyces cerevisiae and Arabidopsis thaliana. The Cravatt laboratory at the Scripps Research Institute has recently applied this technology to mammalian systems, identifying the N-acyltaurines as previously uncharacterized endogenous substrates for the enzyme fatty acid amide hydrolase (FAAH) and the monoalkylglycerol ethers (MAGEs) as endogenous substrates for the uncharacterized hydrolase KIAA1363.
In 1953, changes in political leadership on both sides shifted the dynamic of the Cold War. Dwight D. Eisenhower was inaugurated president that January. During the last 18 months of the Truman administration, the American defense budget had quadrupled, and Eisenhower moved to reduce military spending by a third while continuing to fight the Cold War effectively. Joseph Stalin died in 1953. Nikita Khrushchev eventually won the ensuing power struggle by the mid-1950s. In 1956, he denounced Joseph Stalin and proceeded to ease controls over the party and society (de-Stalinization).
=== May === May 15, 2009: France, Austria, Belgium, Romania, Lithuania, Luxembourg, Portugal, Hungary The French Institute of Statistics and Economic Studies announced that French gross domestic product shrank 1.2% in the first quarter of 2009 after falling by 1.5% in the final quarter of 2008. The French economy had avoided narrowly a recession in 2008. The GDP is expected to keep shrinking in 2009. Eurostat also reported at this time that Austria, Belgium, and Romania had all entered recession in the first quarter of 2009, with two consecutive quarters of shrinking GDP, while Lithuania, Luxembourg, and Portugal had already done so in the last quarter of 2008 and Hungary in the quarter before that.
Sources: en.wikipedia.org
Common methods include enzymatic recycling assays, liquid chromatography, and mass spectrometry. Many protocols separate reduced glutathione from its oxidized disulfide form before detection.
The ratio compares reduced glutathione with its oxidized dimer. It is used as an indicator of redox status, although the value depends strongly on sample handling and analytical method.
Glutathione can oxidize quickly after a sample is collected. Acidification, cooling, and chelators are often used to reduce artifactual changes before analysis.
Acidification lowers pH and helps prevent oxidation of the thiol group during extraction and storage. It can also precipitate proteins and stabilize the reduced form before analysis.