The short version of mass spectrometry fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-09-17. Anything still debated is marked as such rather than presented as settled.
Mass spectrometry provides complementary information by measuring molecular mass. Electrospray ionization or matrix-assisted laser desorption/ionization can confirm the expected peptide mass and reveal related impurities with different masses. It does not directly quantify all species because ionization efficiency varies. When coupled to liquid chromatography, LC-MS can assign masses to chromatographic peaks. This helps distinguish target peptide from truncation, oxidation, or deletion products. Mass accuracy and resolution determine how confidently a mass can be matched to a proposed structure.
Other methods address specific purity concerns. Amino acid analysis gives compositional data after hydrolysis, while capillary electrophoresis separates by charge-to-mass ratio. Karl Fischer titration measures residual water, and gas chromatography can detect residual solvents. Nuclear magnetic resonance can identify organic impurities but is less sensitive for trace levels. No single test covers all possible impurities, so purity testing usually combines orthogonal methods and reports the conditions used. The choice of methods is guided by the impurity classes of interest.
Purity results are only meaningful when linked to a defined sample and method. A certificate of analysis typically lists the analytical technique, column type, gradient, detection wavelength, and integration parameters. It may also report mass confirmation, water content, and counterion composition. For research peptides, laboratories often request the raw chromatogram rather than only a summary percentage. This allows independent review of baseline, peak shape, and any unresolved shoulders that might be missed by a single number.
Stability testing examines how purity changes under controlled conditions. Samples are stored at defined temperatures, such as -20 °C or -80 °C, and analyzed at intervals. Lyophilized powders are generally more stable than solutions because water promotes hydrolysis and aggregation. Repeated freeze-thaw cycles can also degrade peptides, especially those with oxidation-prone residues. Accelerated studies at elevated temperature provide useful comparisons, but they do not always predict long-term behavior at lower temperatures.
| Property | Value | Notes |
|---|---|---|
| Typical analytical method | RP-HPLC with UV detection | Separates by hydrophobicity; purity is method-dependent |
| Confirmatory method | LC-MS or MALDI-TOF MS | Provides molecular mass and impurity mass information |
| Common detection wavelength | 214 nm or 220 nm | Peptide bond absorbance; also 280 nm for aromatic residues |
| Typical purity specification | 95% or greater by HPLC area | Common research grade; exact threshold depends on application |
| Sample preparation | Dissolve in water/acetonitrile with acid | Formic acid or trifluoroacetic acid often used |
Chromatographic separation resolves truncated, oxidized, deamidated, and epimerized peptide variants when their retention times differ from the target. Mass spectrometry confirms molecular mass and can reveal modifications that UV detection misses. Liquid chromatography coupled to mass spectrometry combines separation with identity information, which helps distinguish a pure target from a co-eluting impurity. UV-based area percent can overestimate purity if an impurity lacks a chromophore or if the target and impurity have similar response factors. Researchers often report both chromatographic purity and mass confirmation to give a fuller picture.
Additional techniques address components that reversed-phase chromatography may not resolve. Ion-exchange chromatography separates by charge, size-exclusion chromatography detects aggregates, and capillary electrophoresis offers high separation efficiency. Water content is measured by Karl Fischer titration, residual solvents by gas chromatography, and elemental impurities by inductively coupled plasma mass spectrometry. Amino acid analysis or nitrogen determination can estimate peptide content on a mass basis. Purity is frequently reported as area percent, yet standardized comparison across laboratories remains an open question because methods and reporting practices differ.
Peptide purity testing measures how much of a sample consists of the intended peptide sequence compared with related substances, water, counterions, and residual solvents. No single analytical method captures all of these components at once. Reversed-phase high-performance liquid chromatography with ultraviolet detection is widely used because it separates peptides by hydrophobicity. The reported purity value therefore depends on the chosen method, column, mobile phase, and detection wavelength. Established practice treats purity as method-dependent rather than an absolute property of the material.
Regulatory and accreditation expectations depend on the peptide's intended use. Research reagents may be tested with in-house methods, while pharmaceutical development follows validated procedures and pharmacopeial chapters where applicable. Method validation commonly examines accuracy, precision, specificity, linearity, range, and limits of detection and quantitation. Laboratories accredited to ISO/IEC 17025 must document competence, equipment calibration, and uncertainty. Comparing purity results across laboratories remains difficult because different columns, gradients, detection wavelengths, and integration rules can change reported values; open questions include how best to standardize impurity identification and reporting for diverse peptide products.
Quality control for peptides places purity testing within a documented system that includes specifications, test methods, and acceptance criteria. A certificate of analysis typically reports appearance, chromatographic purity, mass confirmation, and storage conditions. System suitability checks, blank injections, and reference standards help ensure that an analytical run is valid. Traceability requires records of sample preparation, instrument settings, and data processing. No single purity threshold applies to all peptides or uses, so specifications are set according to the intended application and risk assessment.
Sampling and sample preparation influence measured purity. Peptides are often hygroscopic, so weighing should occur quickly under controlled humidity to avoid water uptake. Complete dissolution in a suitable solvent is necessary before injection; undissolved material can block columns or distort results. Filtration removes particulates but may also remove aggregates if the filter pore size is too small. Impurities can originate from synthesis, cleavage, purification, or storage, and forced degradation under heat, light, oxidation, or pH extremes can help identify degradation pathways.
Quality control includes system suitability, blank injections, and reference standards. System suitability checks column performance and retention time reproducibility, while blank runs detect carryover or mobile-phase contaminants. Reference standards help calibrate retention time and detector response. Without these controls, a purity value is difficult to compare across laboratories or over time. Documentation of instrument settings and integration parameters is also part of quality control, and acceptance criteria should be set before samples are analyzed.
Impurity profiles can include deletion peptides, oxidized forms, truncated sequences, and residual solvents. Some impurities arise during synthesis, cleavage, or purification, while others form during storage. Purity testing often focuses on peptide-related impurities, whereas residual solvents and counterions require separate assays. The significance of a given impurity depends on its amount and properties, which may not be established for a research peptide. Reporting an impurity profile is more informative than reporting a single purity number.
Although Moderna has stated that it will not seek enforcement of its patents during the pandemic, a patent waiver (voluntary or involuntary) would not force a vaccine manufacturer to disclose the complete knowledge (i.e., know-how) for making a vaccine, which is not found in patents. The World Health Organization (WHO) has promoted the COVID-19 Technology Access Pool to facilitate disclosures, but participation is voluntary and none of the vaccine manufacturers have joined. Without access to the original vaccine manufacturer's know-how, reverse engineering the manufacturing process is difficult and expensive with no guarantee of success. Even if a third party succeeds, they must prove that fact to the satisfaction of regulatory authorities. For small molecule drugs, proving bioequivalence of a generic drug to the original drug costs only about US$1 to $2 million; but for biologics, proving biosimilarity of a third-party product to the original product requires clinical trials, with costs ranging from US$100 to $250 million. One financial analyst specializing in pharmaceuticals estimated that it would take a minimum of two years after patent waiver for the first independent reproductions of a COVID-19 vaccine to reach the market, which may be too long to have any net impact on global public health. While discussing the idea of "open source" COVID-19 vaccine manufacturing, Bill Gates said: "There's not a single additional vaccine that would have come out of that ....
=== How they were built and why they were effective === Studies have indicated that when terraces like the ones in the Colca Valley were being constructed, the first step was excavating into the slope, and then a subsequent infilling of the slope. A retaining wall was built to hold the fill material. This wall had many uses, including absorbing heat from the sun during the day and radiating it back out at night, often keeping crops from freezing in the chilling nighttime temperatures, and holding back the different layers of sediment. After the wall is built, the larger rocks would be placed on the bottom, then smaller rocks, then sand, then soil. Since the soil was now level, the water did not rush down the side of the mountain, which is what causes erosion. Previously, this erosion was so powerful that it had potential to wipe out major areas of the Inca road, as well as wash away all of the nutrients and fertile soil. Not only was it serving a purpose in crops it also was able to support canals due to the high altitude which would accumulate water and further transport it to other sections. Since the soil never washed away, nutrients would always be added from previously grown crops year after year. The Inca even grew specific crops together, to balance out the optimal amount of nutrients for all plants. For example, a planting method is known as "three sisters" incorporated the growth of corn, beans, and squash in the same terrace.
On 3 November, a South African unit advancing towards Benguela, Angola paused to attack a FAPLA base which housed a substantial training contingent of Cuban advisers. When reports reached Cuban President Fidel Castro that the advisers had been engaged by what appeared to be SADF regulars, he decided to approve a request from the MPLA leadership for direct military assistance. Castro declared that he would send all "the men and weapons necessary to win that struggle", in the spirit of proletarian internationalism and solidarity with the MPLA. Castro named this mission Operation Carlota after an African woman who had organised a slave revolt on Cuba. The first Cuban combat troops began departing for Angola on 7 November, and were drawn from a special paramilitary battalion of the Cuban Ministry of Interior. These were followed closely by one mechanised and one artillery battalion of the Cuban Revolutionary Armed Forces, which set off by ship and would not reach Luanda until 27 November. They were kept supplied by a massive airlift carried out with Soviet aircraft. The Soviet Union also deployed a small naval contingent and about 400 military advisers to Luanda. Heavy weapons were flown and transported by sea directly from various Warsaw Pact member states to Angola for the arriving Cubans, including tanks, helicopters, armoured cars, and even 10 Mikoyan-Gurevich MiG-21 fighter aircraft, which were assembled by Cuban and Soviet technicians in Luanda.
Sources: en.wikipedia.org
=== 30 April === Three people were killed in a Russian missile attack on Odesa. Russia subsequently claimed that it had struck the headquarters of the Ukrainian Operational Command South in the city. One person was killed in a Russian airstrike in Kharkiv. Russian-installed officials in southern Ukraine claimed that several Ukrainian missiles were shot down by air defenses over Crimea. The SBU arrested two people in Kyiv on suspicion of impersonating security officials on social media and establishing a bot farm as part of a Russian disinformation campaign. Germany announced a new military aid package for Ukraine, including a Skynex air defense system, missiles for the IRIS-T launchers, ammunition for Leopard 2 tanks, Gepard ammunition, 155 mm shells, small arms ammunition, grenade launchers, mine clearing equipment, bridge laying and first aid supplies. Latvia also pledged another military aid package that included anti-aircraft guns and tactical unmanned surveillance systems. Lithuania announced its support for repatriating Ukrainian military-aged men to be mobilised. Andriy Demchenko, head of the State Border Guard Service of Ukraine, said that 30 Ukrainians had died trying to leave the country since the invasion began.
Pathologist: A physician who specializes in diagnosing disease through the examination of human tissues and bodily fluids. Pathologists' Assistant: A master's level, certified professional with specialized training in human anatomy. These professionals perform autopsies, screen histopathology slides, and create physical descriptions of surgical specimen. Scientists/Technologists: Certified laboratory professionals with at least a Bachelor's degree level of education. Scientists in the fields of Blood Banking, Microbiology, Cytogenetics, Chemistry, Hematology, Molecular Biology, Andrology, etc. Medical Technologist, Medical Laboratory Scientist, Clinical Laboratory Scientist (MT, MLS or CLS). Histotechnologist: Scientists who specialize in the analysis of human tissues. Cytotechnologist: Scientists who specialize in the analysis of human cells. Technicians: Certified laboratory professionals with an Associate's level of education. Medical Laboratory Technician or Clinical Laboratory Technician (MLT or CLT) Histotechnicians Grossing Technician Phlebotomist (PBT): A certified healthcare professional who performs venipuncture. Medical Laboratory Assistant or Laboratory Assistant (MLA, LA): Medical laboratory assistants play a critical role in assisting with laboratory operations. They are often responsible for interacting with interdisciplinary healthcare professionals and maintaining specimen integrity Transcriptionist
==== Sweden ==== Sveriges riksdags health ministry Statens folkhälsoinstitut classified salvinorin A (and Salvia divinorum) as "health hazard" under the act Lagen om förbud mot vissa hälsofarliga varor (translated Act on the Prohibition of Certain Goods Dangerous to Health) as of April 1, 2006, in their regulation SFS 2006:167 listed as "salvinorin A", making it illegal to sell or possess. Salvinorin A has been screened for its possible use as a structural "scaffold" in medicinal chemistry in developing new drugs for treating psychiatric diseases such as cocaine dependence.
==== Cisplatin-resistance ==== The drug paclitaxel may be useful in the treatment of cisplatin-resistant cancer. About 68.1% of cisplatin-resistant cells appear to be sensitive to paclitaxel and 66.7% of paclitaxel-resistant cells to cisplatin. The mechanism for this activity is unknown. Paclitaxel-based chemotherapy showed modest activity in SCLC patients refractory to both etoposide- and camptothecin-based chemotherapy. The newer agent lurbinectedin is active in relapsed SCLC and was approved for medical use in the United States in June 2020.
Sources: en.wikipedia.org
The chloroplasts of plants have a number of biochemical, structural and genetic similarities to cyanobacteria, (commonly but incorrectly known as "blue-green algae") and are thought to be derived from an ancient endosymbiotic relationship between an ancestral eukaryotic cell and a cyanobacterial resident. The algae are a polyphyletic group and are placed in various divisions, some more closely related to plants than others. There are many differences between them in features such as cell wall composition, biochemistry, pigmentation, chloroplast structure and nutrient reserves. The algal division Charophyta, sister to the green algal division Chlorophyta, is considered to contain the ancestor of true plants. The Charophyte class Charophyceae and the land plant sub-kingdom Embryophyta together form the monophyletic group or clade Streptophytina. Nonvascular land plants are embryophytes that lack the vascular tissues xylem and phloem. They include mosses, liverworts and hornworts. Pteridophytic vascular plants with true xylem and phloem that reproduced by spores germinating into free-living gametophytes evolved during the Silurian period and diversified into several lineages during the late Silurian and early Devonian. Representatives of the lycopods have survived to the present day. By the end of the Devonian period, several groups, including the lycopods, sphenophylls and progymnosperms, had independently evolved "megaspory" – their spores were of two distinct sizes, larger megaspores and smaller microspores.
== Tetanus vaccine conspiracy theory == Catholic Bishops in Kenya are among those who have spread a conspiracy theory asserting that HCG forms part of a covert sterilization program, forcing denials from the Kenyan government. In order to induce a stronger immune response, some versions of human chorionic gonadotropin-based anti-fertility vaccines were designed as conjugates of the β subunit of HCG covalently linked to tetanus toxoid. It was alleged that a non-conjugated tetanus vaccine used in developing countries was laced with a human chorionic gonadotropin-based anti-fertility drug and was distributed as a means of mass sterilization. This charge has been vigorously denied by the World Health Organization (WHO) and UNICEF. Others have argued that an hCG-laced vaccine could not possibly be used for sterilization, since the effects of the anti-fertility vaccines are reversible (requiring booster doses to maintain infertility) and a non-conjugated vaccine is likely to be ineffective. Finally, independent testing of the tetanus vaccine by Kenya's health authorities revealed no traces of the human chorionic gonadotropin hormone.
QT prolongation is a measure of delayed ventricular repolarisation, which means the heart muscle takes longer than normal to recharge between beats. It is an electrical disturbance which can be seen on an electrocardiogram (EKG). Excessive QT prolongation can trigger tachycardias such as torsades de pointes (TdP). QT prolongation is an established side effect of antiarrhythmics, but can also be caused by a wide range of non-cardiac medicines, including antibiotics, antidepressants, antipsychotics, antihistamines, opioids, and complementary medicines. On an EKG, the QT interval represents the summation of action potentials in cardiac muscle cells, which can be caused by an increase in inward current through sodium or calcium channels, or a decrease in outward current through potassium channels. By binding to and inhibiting the "rapid" delayed rectifier potassium current protein, certain drugs are able to decrease the outward flow of potassium ions and extend the length of phase 3 myocardial repolarization, resulting in QT prolongation.
Miguel Angel Ondetti (May 14, 1930 – August 23, 2004) was an Argentine-born American chemist who first synthesized captopril, the first ACE inhibitor that was used to treat heart disease. With his co-worker, David Cushman, he won the 1999 Lasker Award, with David Cushman, for: "developing an innovative approach to drug design based on protein structure and using it to create the ACE inhibitors, powerful oral agents for the treatment of high blood pressure, heart failure, and diabetic kidney disease". Ondetti was born and raised in Buenos Aires and received a PhD in chemistry from the University of Buenos Aires, in his hometown, in 1957. In 1960 he moved to The Squibb Institute for Medical Research in New Jersey where he researched and developed Captopril in 1975.
=== 2018–2021: Dancing on Ice and Diva === In January 2018, Collins appeared on Celebrity 100% Hotter in an attempt to change her style. Collins admitted she was "terrified" about having a makeover but said she was keen to try out some different trends. In February 2018, she took part in the fourth series of Celebs Go Dating. During her time on the show, Collins walked out on one of her dates within the first few minutes after he branded her a "diva" due to her being late, whilst she was also reprimanded by the dating experts after she failed to turn up to her date with Laurence, who was planning to take her to Paris. In June 2018, she released her second book, titled The GC: How to Be a Diva, in which she provides advice and self help for women to gain confidence. In an interview on Loose Women, she admitted to using a ghostwriter. She also guest starred in a promotional advert for Netflix's Orange Is the New Black. Collins went on to appear in Gemma Collins: Diva España, a one-off reality television special which aired in August 2018. In September 2018, Collins took part in the thirteenth series of Celebrity MasterChef. She was eliminated in the second round of the third heat after her sea bass served in greaseproof paper failed to impress the judges. In November 2018, Collins was the subject of a song released by Tallia Storm, titled "It's the GC (Diva Forever)". The song was featured in one of Collins' clothing advertisements for Boohoo.com and later became the theme song of her television franchise Gemma Collins: Diva.
Sources: en.wikipedia.org
It usually refers to the relative area of the main peak in a chromatographic separation, such as RP-HPLC. It estimates the proportion of UV-absorbing material in that peak, not the absolute mass fraction of the target peptide. Different methods can give different percentages.
HPLC separates and quantifies components, while mass spectrometry identifies molecular masses. Together they can show whether a main peak has the expected mass and whether other peaks correspond to related peptide variants. This combination is more informative than either method alone.
Higher purity reduces the proportion of detectable related impurities, which can matter for research reproducibility. However, purity value alone does not establish identity, biological activity, or safety. The appropriate purity depends on the intended use and the sensitivity of the assay.
It typically includes the peptide sequence, molecular mass, purity method and result, storage recommendations, and date of analysis. Raw chromatograms and mass spectra may be provided on request. The absence of method details makes a purity value difficult to interpret.