If you have been reading about HPLC 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 2026-01-08. Where a claim depends on a specific study, the study is described rather than over-claimed.
Measuring glutathione in biological samples requires attention to oxidation, because GSH can convert to GSSG after sample collection. Blood and plasma samples are often treated with acid or alkylating agents to preserve the reduced form. Without stabilization, apparent GSH concentrations can fall while GSSG rises. Differences in sample type, handling delay, and deproteinization method can produce results that are not comparable across studies. Reporting preanalytical details is therefore important for interpreting findings.
Common analytical approaches include enzymatic recycling assays, high-performance liquid chromatography, and mass spectrometry. Enzymatic recycling measures total glutathione after converting GSSG back to GSH, while separation methods can quantify GSH and GSSG separately. Derivatization may be used to improve detection or stability during analysis. LC-MS/MS offers high specificity and can distinguish glutathione from related thiols and adducts. Each method has different sensitivity, throughput, and susceptibility to interference, so method selection depends on the study question and sample matrix.
For solid glutathione reagents, storage at low temperature and protection from moisture and light are typical precautions. Aqueous solutions can oxidize over time, and pH affects stability; alkaline conditions generally promote thiol oxidation. Some protocols prepare fresh solutions, while others use antioxidants or chelators to limit metal-catalyzed oxidation. Purity and counterion content can vary among commercial preparations, affecting concentration calculations. Certificates of analysis and validated assays help verify identity and purity.
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.
Samples for glutathione analysis require careful handling because the compound oxidizes readily and can be consumed by enzymes after collection. Blood is often treated with acid or thiol-blocking agents soon after draw, and plasma should be separated quickly from red blood cells. Tissues are usually snap-frozen or extracted immediately. Aqueous solutions of glutathione are less stable than dry powder and degrade faster at neutral or alkaline pH, in light, or with dissolved oxygen. Repeated freeze-thaw cycles also reduce reliability.
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.
| Property | Value | Notes |
|---|---|---|
| Typical analytical method | LC-MS/MS, HPLC, or enzymatic recycling | Choice depends on whether total, reduced, or oxidized glutathione is measured. |
| Sample stabilization | Acidification or thiol alkylation | Helps limit conversion of GSH to GSSG after collection. |
| Solution stability | Limited at room temperature | Oxidation and pH-dependent degradation can occur. |
| Storage of solid | -20 °C, desiccated, protected from light | Common for research reagents; follow supplier instructions. |
| Common interference | Other thiols and metal ions | Can affect separation or enzymatic detection. |
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.
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.
Thymus is a preferred tissue for viral replication of feline immunodeficiency virus, which results in lesions and dysfunction. In 1983 scientists succeeded in cloning epithelial cell lines from the thymus of various species and began to biochemically and biologically characterize these thymus derived regulatory factors. A protein with a molecular weight of about 50,000 daltons was subsequently described and shown to augment the immune responses of both immature and mature T-cells. This protein came to be known as lymphocyte T-cell immunomodulator.
Swiss chemist Albert Hofmann first synthesized LSD in 1938 and discovered its potent psychedelic effects in 1943 after accidental ingestion. It became widely studied in the 1950s and 1960s. The drug was initially explored for psychiatric use due to its structural similarity to serotonin and safety profile. It was used experimentally in psychiatry for treating alcoholism and schizophrenia. By the mid-1960s, LSD became central to the youth counterculture in places like San Francisco and London, influencing art, music, and social movements through events like Acid Tests and figures such as Timothy Leary, Owsley Stanley and Michael Hollingshead. Its psychedelic effects inspired distinct visual art styles and musical innovations, and caused a lasting cultural impact. However, its association with the counterculture movement of the 1960s led to its classification as a Schedule I drug in the United States in 1970. It was also listed as a Schedule I controlled substance by the United Nations in 1971 and remains without approved medical uses. Despite its legal restrictions, LSD remains influential in scientific and cultural contexts. Research on LSD declined due to cultural controversies by the 1960s, but has resurged since 2009. In 2024, the United States Food and Drug Administration designated LSD (code name MM120 or DT120) as a breakthrough therapy for generalized anxiety disorder. As of 2017, about 10% of people in the United States had used LSD at some point, with 0.7% having used it in the past year.
== Geography == According to the United States Census Bureau, the borough had a total area of 2.07 square miles (5.36 km2), including 2.07 square miles (5.35 km2) of land and 0.01 square miles (0.01 km2) of water (0.24%). It rests on land originally inhabited by the Munsee-Delaware. The borough, a suburb of New York City, borders the Bergen County municipalities of Alpine, Bergenfield, Demarest, Dumont and Tenafly.
Sources: en.wikipedia.org
== Adverse effects == Most common side-effects are gastrointestinal, including diarrhea, nausea, abdominal pain and vomiting. Headache and disturbances in taste also occur. Less common side-effects include palpitations, blurred vision, and rashes. Prolonged QTc intervals may also be caused by telithromycin. Rare but severe side-effects were initially reported in March 2006, involving damage to the liver. Three different incidents were reported: one case of temporary drug-induced hepatitis, one ending in a liver transplant, and one ending in death. In the United States, the FDA's Office of Epidemiology and Surveillance identified 12 cases of acute liver failure, resulting in four deaths, and an additional 23 cases of acute, serious liver injury, among 5.2 million patients taking telithromycin through April 2006. In 2010, a published report described the likely mechanism of action underlying not only the cases of liver failure but also cases of visual disturbances and exacerbations of myasthenia gravis. The study showed that a pyridine moiety that is part of the telithromycin molecule acts as an antagonist on cholinergic receptors located in the neuromuscular junction, the ciliary ganglion of the eye and the vagus nerve innervating the liver. Other macrolides, such as azithromycin and clarithromycin and the fluoroketolide, solithromycin, do not contain the pyridine moiety and do not antagonize these cholinergic receptors significantly.
== History == In 1925, construction began on the current infectious diseases hospital building (the old pavilion) and the annex building (which now houses the hospital pharmacy). On 21 September 1932, the newly completed pavilion was designated for the treatment of patients with communicable diseases, including tuberculosis (TB). Prior to the opening of the new TB pavilion in 1942, the epidemic hospital operated with 50 beds for infectious diseases and 20 beds for TB patients. These 70 beds were attended to by four nurses, a sanitary officer, a disinfectant, and two maids. The doctors who served the newly established unit were: Dimitrie Preda (1932–1959), Alfred Metz (1932–1936 and 1947–1949), Tiberiu Micle (1939–1942), Dumitru Hortopan (1940–1947), Oliver Pop (1946–1962), and Laurențiu Cucuruz (1946–1989). Alfred Metz, as a secondary physician, laid the foundations of the clinical laboratory of the newly built hospital. From 1949 to 1969, Hans Röhrich served as the head of the infectious diseases hospital, where he established the first department of thoracic and lung surgery in Timișoara. The first lung segmentectomy was performed in 1958. Starting in 1961, thoracic surgery made significant progress in areas such as thoracic plastic surgery, pneumothorax, mediastinum, rib resection, and pericardium. Virgil Ene succeeded Hans Röhrich, taking over as head of the clinic in 1970. The growing demand for hospital space prompted the construction of a new pavilion. Construction started in 1971, and the pavilion was inaugurated on 1 July 1973.
=== Autumn 2007: Deaths across north Texas === The spread of the drug to the outlying suburbs of Dallas was confirmed in September by the return of toxicology reports from the July 13 death of an 18-year-old student from McKinney, located northeast of Dallas in Collin County, and from two July deaths in nearby Tarrant County, one involving a 17-year-old male and the other, a 26-year-old male. Additional suburban deaths in September — in Irving to the west and Rockwall to the east — were believed to be linked to cheese heroin, though police cautioned toxicology reports would not likely be complete until November. The Tarrant County medical examiner's office announced on September 24 that a review of deaths in Tarrant County (west) and Denton County (north) showed an additional 15 deaths between 2004 and 2007 that appeared to be linked to "cheese," and Collin and Rockwall counties had reported one death each. These new figures brought the total number of deaths associated with cheese heroin in northern Texas to 40, a figure that included many older adults along with those age 18 and under.
== Chemistry == 1,2-Diarylethylamines contain the substructure ArCH2CH(Ar')NRR', where Ar, Ar' = aryl and R, R' = H or organyl. A chiral center exists at the ethylamine carbon atom bearing the two aryl groups. The enantiomers often have a large difference in pharmacological activity. For example, (+)-(S)-diphenidine has 40 times higher affinity than (−)-(R)-form for the NMDA receptor. According to a review by Jason Wallach and Simon Brandt (2018), most psychoactive 1,2-diarylethylamines reported in the scientific literature contain non-heteroaromatic aryl groups (i.e., both rings are carbocyclic). Some exceptions include lanicemine and an analogue N-ethyl-lanicemine, which feature a heteroaromatic pyridyl ring. Additional heteroaromatic analogues have been disclosed in the patent literature.
Sources: en.wikipedia.org
Preanalytical factors such as sample type, time to processing, and stabilization method can change GSH and GSSG amounts. Analytical method and calibration also contribute to variation. Comparing absolute values across studies requires caution.
These assays typically measure total glutathione after oxidizing or reducing steps convert GSSG to GSH. A colorimetric or fluorometric signal is proportional to the recycling reaction. They generally do not report GSH and GSSG separately unless additional steps are used.
Solutions are often prepared fresh and kept cold, with protection from light and oxygen exposure. Chelating agents may reduce metal-catalyzed oxidation. Storage recommendations vary by buffer, pH, and concentration, so protocol-specific guidance should be followed.
Common approaches include enzymatic recycling assays, HPLC, and LC-MS/MS. Acid extraction and rapid processing limit oxidation before analysis.