LC-MS comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-01-29. Numbers and descriptions here follow the published literature rather than marketing material.
Laboratory measurement of NAD+ usually begins with rapid sample quenching because the molecule can change form after collection. Enzymatic cycling assays amplify signal through coupled reactions and are suited to small samples. High-performance liquid chromatography with ultraviolet detection separates NAD+ from related nucleotides. Liquid chromatography-mass spectrometry offers higher specificity and can distinguish NAD+ from close analogs. Each method has trade-offs in sensitivity, throughput, and equipment needs, so reported values depend heavily on extraction and detection choices.
Stability of NAD+ depends on form, temperature, pH, and water content. The solid is generally more stable than solutions, and it should be kept dry and cold. In solution, hydrolysis can cleave the dinucleotide, especially under alkaline conditions or at elevated temperature. Light exposure may also contribute to degradation. Buffers, chelating agents, and sterile handling can reduce losses, but no single condition preserves all preparations indefinitely. Researchers often prepare working solutions shortly before use and verify activity or purity after storage.
Quality control for NAD+ relies on identity, purity, and functional tests. A certificate of analysis may report high-performance liquid chromatography purity, ultraviolet spectrum, water content, and residual solvents. Because NAD+ is hygroscopic, gravimetric values can shift as material absorbs water, so purity should be interpreted alongside storage history. Mass spectrometry confirms molecular identity, while enzymatic assays show whether the material supports dehydrogenase activity. Commercial material is available as the free acid and as salts, and the counterion affects molecular weight, solubility, and how concentrations are calculated.
Nicotinamide adenine dinucleotide, abbreviated NAD+, is a dinucleotide composed of two nucleotides joined by phosphate groups. One nucleotide contains adenine; the other contains nicotinamide. The molecule exists in oxidized (NAD+) and reduced (NADH) forms, and the reversible hydride transfer between them underlies many metabolic oxidation-reduction reactions. In cells, NAD+ serves as an electron acceptor in pathways such as glycolysis, the citric acid cycle, and oxidative phosphorylation. Its concentration and redox ratio vary by compartment, tissue, and metabolic state.
Beyond redox chemistry, NAD+ is consumed as a substrate by enzymes that transfer ADP-ribose or remove acetyl groups. Sirtuins use NAD+ in deacylation reactions, poly(ADP-ribose) polymerases use it in DNA damage responses, and CD38 hydrolases convert it to signaling metabolites. Because these enzymes compete for the same pool, changes in NAD+ availability can influence multiple cellular processes. The relative contribution of each consumption route differs by cell type and condition, and precise quantitative links remain an active area of study.
| Property | Value | Notes |
|---|---|---|
| CAS number | 53-84-9 | Refers to the free acid form of NAD+. |
| Molecular formula | C21H27N7O14P2 | Free acid; salts include additional counterions. |
| UV absorbance maximum | 259-260 nm | Used for detection and concentration estimation. |
| Typical storage | -20 °C or below, desiccated | Protect from light and moisture; avoid repeated freeze-thaw. |
| Common analytical method | HPLC-UV or LC-MS | Enzymatic cycling is an alternative for low-abundance samples. |
In glycolysis, NAD+ accepts electrons during the oxidation of glyceraldehyde-3-phosphate, forming NADH. The tricarboxylic acid cycle and fatty acid oxidation also generate NADH, which donates electrons to the mitochondrial electron transport chain. This flow supports ATP synthesis and helps maintain the redox balance of the cell. Other dehydrogenases use NAD+ as a cofactor for biosynthetic reductions and detoxification reactions. NADH is later reoxidized to sustain continued flux through these pathways.
Beyond electron transfer, NAD+ serves as a substrate for enzymes that cleave the molecule and transfer ADP-ribose units. Sirtuins, poly(ADP-ribose) polymerases, and CD38 consume NAD+ in regulatory reactions. These activities link NAD+ availability to DNA repair, chromatin modification, calcium signaling, and metabolic stress responses. Because consumption can exceed biosynthesis under some conditions, cellular NAD+ levels are dynamic rather than fixed. Enzyme affinity and local synthesis also influence how much NAD+ is available for signaling.
In humans, NAD+ can be synthesized from nicotinic acid, nicotinamide, nicotinamide riboside, and tryptophan through overlapping pathways. The salvage pathway recycles nicotinamide back to NAD+ and is often considered a major route in many tissues. Dietary precursors and intracellular recycling both contribute to the pool, but the quantitative importance of each source remains an active research question. NAD+ levels are not uniform across organs or cell compartments. Measurements in blood do not necessarily reflect concentrations inside tissues.
NAD+ is a dinucleotide composed of nicotinamide, ribose, and adenine linked by phosphate groups. Its full name is nicotinamide adenine dinucleotide, with "+" denoting the oxidized form. The molecule acts as a coenzyme in redox reactions, cycling between NAD+ and NADH. In cells, it participates in electron transfer during glycolysis, the citric acid cycle, and oxidative phosphorylation. It is distinct from NADP+, which carries an additional phosphate group and supports different biosynthetic reactions.
Beyond redox chemistry, NAD+ serves as a substrate for enzymes that transfer ADP-ribose or remove acetyl groups. Sirtuins, PARPs, and CD38-family enzymes consume NAD+ and produce nicotinamide and ADP-ribose-related products. These reactions link NAD+ availability to DNA repair, chromatin modification, and cellular signaling. Because the molecule is central to energy metabolism and regulation, changes in its concentration are studied in aging, immunity, and metabolic research. The balance between synthesis and consumption varies by tissue, developmental stage, and physiological state.
Commercial NAD+ is available at research grade, often with purity specifications determined by high-performance liquid chromatography. Certificates of analysis may report water content, residual solvents, and counterion identity. Identity can be confirmed by ultraviolet absorbance near 260 nm, mass spectrometry, or enzymatic activity. Because different salt forms and hydration states exist, researchers should verify that the product matches the intended molecular form. Lot-to-lot variation in purity can affect quantitative assays and should be documented.
Solid NAD+ is usually supplied as a white to off-white powder or lyophilized preparation. It is hygroscopic and should be kept desiccated at low temperature, commonly -20 °C or below for long-term storage. Aqueous solutions are less stable than dry material and are often prepared fresh or stored frozen in aliquots. Light exposure and repeated freeze-thaw cycles can promote degradation, so amber containers and single-use aliquots are preferred. Buffered solutions near neutral pH are generally less stable than acidic or frozen preparations.
==== Cardiomyopathies ==== Cardiomyopathies are diseases affecting the muscle of the heart. Some cause abnormal thickening of the heart muscle (hypertrophic cardiomyopathy), some cause the heart to abnormally expand and weaken (dilated cardiomyopathy), some cause the heart muscle to become stiff and unable to fully relax between contractions (restrictive cardiomyopathy) and some make the heart prone to abnormal heart rhythms (arrhythmogenic cardiomyopathy). These conditions are often genetic and can be inherited, but some such as dilated cardiomyopathy may be caused by damage from toxins such as alcohol. Some cardiomyopathies such as hypertrophic cardiomopathy are linked to a higher risk of sudden cardiac death, particularly in athletes. Many cardiomyopathies can lead to heart failure in the later stages of the disease.
Another recent phosphoproteomic study included large-scale identification and quantification of phosphorylation events triggered by the anti-diuretic hormone vasopressin in kidney collecting duct. A total of 714 phosphorylation sites on 223 unique phosphoproteins were identified, including three novel phosphorylation sites in the vasopressin-sensitive water channel aquaporin-2 (AQP2).
The primary use of saffron is in food and drink preparation. Saffron has a long history of use in traditional medicine. Saffron has also been used as a fabric dye, particularly in China and India, and in perfumery. It is used for religious purposes in India. In the European E number categorisation for food elements and additives, Saffron is coded as E164.
Sources: en.wikipedia.org
Washington (Hb Lepore Washington, also known as Hb Lepore Boston or Hb Lepore Washington-Boston); most common in Italians from Southern Italy Baltimore (Hb Lepore Baltimore); first described in a family with African ancestry; most common in people from the Balkan countries, Albanians Croats, Serbs, Slovenes and Romanians. It has also been described in Turks and in regions of Spain and Portugal. A rare case of the Baltimore variety was discovered in an African American woman in the Bronx, New York and dubbed Hn Lepore-Bronx and another variety was discovered in the city of Saskatoon, Saskatchewan, Canada and dubbed Hb E-Lepore Saskatoon Hollandia (Hb Lepore Hollandia); identified in Papua New Guinea and Bangladesh.
Didanosine (ddI), sold under the brand name Videx among others, is a medication used to treat HIV/AIDS. It is used in combination with other medications as part of highly active antiretroviral therapy (HAART). It is of the reverse-transcriptase inhibitor class. Didanosine was first described in 1975 and approved for use in the United States in 1991.
The American Journal of Respiratory Cell and Molecular Biology is a monthly peer-reviewed medical journal and an official publication of the American Thoracic Society. It covers research on the structure and function of the respiratory system under physiologic and pathophysiologic conditions. It was established in July 1989. The founding editors-in-chief were Jerome S. Brody, Robert M. Senior, and Mary C. Williams. John A. Mcdonald served as editor from 1993 to 1998. Kenneth B. Adler (North Carolina State University) served as editor from 2009 to 2016. Paul Schumacker (Northwestern University) served as editor from October 1, 2016, to October 21, 2023. Andrew Halayko (University of Manitoba) assumed the editorship on November 1, 2023. The journal is abstracted and indexed in BIOSIS Previews, Current Contents/Life Sciences, Current Contents/Critical Care Medicine, Embase, Index Medicus/MEDLINE/PubMed, Science Citation Index Expanded, and Scopus. According to the Journal Citation Reports, the journal has a 2024 impact factor of 5.3. Official website
Lactobacillales (order) as the most abundant; primarily upstream of pnuC, and sometimes pncB or pnuC–nadR operons. Notable organisms include species of Fructobacillus and many other lactic acid bacteria. Planctomycetota (phylum), commonly upstream of nadA. Pseudomonadota, found in Pseudomonas laurylsulfatiphila and related species, upstream of an annotated nucleoside transporter. Actinobacteriota, in isolated instances from metagenome-assembled genomes. The prevalence of mini-NAD⁺-II riboswitches in lactic acid bacteria is thought to be functionally significant, as these organisms rely on various anaerobic fermentation strategies (e.g., lactic acid or ethanol production) to maintain a balanced NAD⁺/NADH ratio. The prevalence of mini-NAD⁺-II riboswitches in lactic acid bacteria is thought to be functionally significant, as these organisms rely on various anaerobic fermentation strategies (e.g., lactic acid or ethanol production) to maintain a balanced NAD⁺/NADH ratio.
Sources: en.wikipedia.org
Uranium-233 (233U or U-233) is a fissile isotope of uranium that is bred from thorium-232 as part of the thorium fuel cycle. Uranium-233 was investigated for use in nuclear weapons and as a reactor fuel. It has been used successfully in experimental nuclear reactors and has been proposed for much wider use as a nuclear fuel. It decays primarily by alpha emission, with a half-life of about 159,200 years, and is part of the neptunium decay chain. Uranium-233 is produced by the neutron irradiation of thorium-232. When thorium-232 absorbs a neutron, it becomes thorium-233, which has a half-life of about 22 minutes. Thorium-233 decays into protactinium-233 through beta decay. Protactinium-233 has a longer half-life of about 27 days to further decay into uranium-233; some proposed molten salt reactor designs attempt to physically isolate the protactinium from further neutron capture before beta decay can occur, to maintain the neutron economy. 233U usually fissions on neutron absorption, but sometimes retains the neutron, becoming uranium-234. At a neutron energy of 0.0253 eV, JENDL-4.0 data give capture-to-fission ratios of about 0.085 for uranium-233, 0.169 for uranium-235 and 0.363 for plutonium-239.
Dasiglucagon, sold under the brand name Zegalogue, is a medication used to treat severe hypoglycemia in people with diabetes. The most common side effects include nausea, vomiting, headache, diarrhea, and injection site pain. Dasiglucagon was approved for medical use in the United States in March 2021.
==== Monoamine releasing agent ==== Phenethylamine, being similar to amphetamine in its action at their common biomolecular targets, is a releasing agent of norepinephrine and dopamine. It is roughly equipotent to amphetamine in this regard in vitro. Phenethylamine is inactive as a psychostimulant under normal circumstances due to rapid metabolism by monoamine oxidase (MAO), but can become active in the presence of a monoamine oxidase inhibitor (MAOI).
The Digico Micro 16V had a standard memory of 4k words with 950 nano second cycle time, expandable to 64k words, and able to support up to 64 external interfaces. It had an optional microprogrammed floating-point unit. The Micro 16V was supported by a simple and flexibly sized executive that could optionally support multiprogramming, disc files and teletypes. The Micro 16V used semiconductor memory, rather than magnetic-core memory as in the previous models. The instruction set architecture is single accumulator based with instructions generally having a consistent 12-bit address field. A direct address thus limits memory size to 4k (4096) words in the current selected memory region, named a "stack". Three instructions (load, store, add) permit indirect addressing where the direct address contains the 16-bit address of the operand. A carry register supports multi-word arithmetic; there is no integer multiply or divide instruction. One instruction uses the address field to specify a variety of non-addressing sub-instructions such as shift, carry manipulation and input-output. Floating-point arithmetic is handled by software or an optional floating-point unit with its own registers that can work in 32, 48 or 80-bit modes. The Micro 16 sold primarily into the data logging market until 1969, when it expanded into areas like process control, stock control and front-end processors for the ICL 1900 mainframe. In 1978 the Digico Micro 16E stackable minicomputer, which was well suited to an office environment, won a Design Council Award for Engineering Products.
== Match records == Highest score: 32.16 (208) v Footscray 9.8 (62) – Round 22, 1982, at Western Oval Lowest score: 0.9 (9) v Fitzroy 6.11 (47) – Round 1, 1899, at Brunswick Street Oval Lowest score since 1919: 1.12 (18) v St Kilda 5.5 (35) – Round 10, 1923, at Junction Oval Highest losing score: Essendon 21.13 (139) v Collingwood 23.6 (144), Round 22, 1987, M.C.G. Lowest winning score: Essendon 1.8 (14) v Melbourne 0.8 (8), Finals Week 3, 1897, Lake Oval (League record) Lowest winning score since 1919: Essendon 3.10 (28) v Footscray 3.5 (23), Round 13, 1989, Windy Hill Greatest winning margin: 165 points – Essendon 28.16 (184) v South Melbourne 2.7 (19), Round 18, 1964, Windy Hill Greatest losing margin: 163 points – Essendon 11.7 (73) v Sydney Swans 36.20 (236), Round 17, 1987, S.C.G. Record attendance (home-and-away game): 94,825 – 25 April 1995 at MCG v Collingwood (inaugural Anzac Day match) Record attendance (finals match): 116,828 – 1968 VFL Grand Final v Carlton
Sources: en.wikipedia.org
Common methods include enzymatic cycling assays, HPLC with UV detection, and LC-MS. The choice depends on sample size, specificity needs, and available equipment. Rapid quenching before analysis is important because NAD+ and NADH can interconvert.
Water promotes hydrolysis, and heat accelerates degradation. Cold, dry storage slows these processes. Repeated warming and cooling can introduce moisture and condensation, so aliquoting is often used.
Yes. They may be free acid or salts, with different counterions and purity grades. The counterion changes molecular weight, so concentration calculations should account for the actual form. Certificates of analysis provide batch-specific information.
NAD+ is a coenzyme found in all living cells. It carries electrons in metabolic reactions and also serves as a substrate for enzymes involved in signaling and DNA repair. Its oxidized and reduced forms are central to energy metabolism.