reference standard 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 2025-08-30. Numbers and descriptions here follow the published literature rather than marketing material.
Regulatory status varies by country and intended use. Major drug agencies have not granted marketing authorization for SR9009 as a medicine, and it is not listed as a controlled substance in many jurisdictions. It is often sold as a research chemical, a category that may fall outside pharmaceutical manufacturing rules. Buyers should verify local laws and supplier documentation, including certificates of analysis. The lack of standardized quality controls raises concerns about identity, purity, and actual content in products marketed online.
In laboratory settings, SR9009 is commonly identified by its molecular structure and its interaction with REV-ERB receptors. Vendors may list it under synonyms such as Stenabolic or REV-ERB agonist, but those names do not define purity or identity. Analytical confirmation typically uses high-performance liquid chromatography with ultraviolet detection or liquid chromatography–mass spectrometry. A reference standard is needed to compare retention time and mass spectrum, because the compound can be confused with related research chemicals.
SR9009 is generally described as poorly soluble in water and more soluble in organic solvents such as dimethyl sulfoxide and ethanol. Stock solutions are commonly prepared in an organic solvent before dilution into an aqueous buffer or vehicle. Precipitation can occur if the organic fraction is reduced too quickly or if the final concentration exceeds the compound's solubility limit. Sonication or gentle warming may aid dissolution in some protocols, but excessive heat can promote degradation. Container material and pH can also influence observed solubility.
For long-term storage, SR9009 is typically kept as a solid at low temperature, protected from moisture and light. Desiccated conditions limit hydrolysis, while opaque containers reduce photochemical breakdown. Solutions are less stable than solids and are often stored frozen in aliquots to avoid repeated freeze-thaw cycles. Stability data are not standardized across all suppliers, so users should rely on certificate-of-analysis information when available. Degradation may appear as color change, precipitate, or decreased chromatographic purity.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white solid | Visual inspection is not sufficient for identity. |
| Solubility | Soluble in DMSO and ethanol | Low solubility in water. |
| Typical storage | -20 °C, desiccated, dark | Protect from repeated temperature changes. |
| Common analytical method | LC-MS or HPLC-UV | Reference standard required for comparison. |
| Common synonyms | SR9009; Stenabolic; REV-ERB agonist | Vendor naming may vary. |
Pharmacokinetic data for SR9009 are limited in published literature. Some reports indicate low oral bioavailability and rapid clearance in animals, which complicates interpretation of exposure and effect. Researchers often use injected routes in preclinical work to achieve measurable systemic levels. Analytical studies rely on mass spectrometry to detect the parent compound and its metabolites. Questions about tissue distribution, active metabolites, and long-term consequences remain open. Species differences in metabolism can affect observed half-life and target engagement.
SR9009 is a synthetic small molecule studied as an agonist of the nuclear receptors REV-ERBα and REV-ERBβ. These receptors help regulate circadian rhythms and metabolic gene expression. In laboratory experiments, SR9009 binds these receptors and alters transcription of genes involved in lipid handling, glucose metabolism, and mitochondrial function. It is not a naturally occurring compound and has no approved therapeutic use. Research interest stems from its ability to modify energy metabolism in cells and animal models.
== Further reading == Johnson JE, Cornell RB (1999). "Amphitropic proteins: regulation by reversible membrane interactions (review)". Molecular Membrane Biology. 16 (3): 217–35. doi:10.1080/096876899294544. PMID 10503244. Alenghat FJ, Golan DE (2013). "Membrane protein dynamics and functional implications in mammalian cells". Current Topics in Membranes. 72: 89–120. doi:10.1016/b978-0-12-417027-8.00003-9. ISBN 9780124170278. PMC 4193470. PMID 24210428.{{cite journal}}: CS1 maint: periodical has ISBN (link)
These two are the heaviest isotopes of dubnium to date, and both were produced as a result of decay of the heavier nuclei 288Mc and 294Ts rather than directly, because the experiments that yielded them were originally designed in Dubna for 48Ca beams. For its mass, 48Ca has by far the greatest neutron excess of all practically stable nuclei, both quantitative and relative, which correspondingly helps synthesize superheavy nuclei with more neutrons, but this gain is compensated by the decreased likelihood of fusion for high atomic numbers.
==== Prokaryotic regulation ==== Because of the vital role rRNA plays in the cell physiology of prokaryotes, there is much overlap in rRNA regulation mechanisms. At the transcriptional level, there are both positive and negative effectors of rRNA transcription that facilitate a cell's maintenance of homeostasis:
== Sizes == While small-scale columns range from inner diameters of 0.5 cm and withstand pressures of up to 130 MPa, industrial large scale columns reach diameters of up to 2 m and operate at considerable lower pressures (below 1 MPa). While it is favorable to view the packed bed of a column large scale columns are manufactured from steel due to its superior resilience. Chromatography columns can be used as stand-alone devices or in combination with manual or automated chromatography systems. Medium to large columns are almost exclusively operated together with automated systems to decrease the risk of process failure and loss of product.
Sources: en.wikipedia.org
=== Common complications === Hemolytic crisis, with more pronounced jaundice due to accelerated hemolysis (may be precipitated by infection). Aplastic crisis with dramatic fall in hemoglobin level and (reticulocyte count)-decompensation, usually due to maturation arrest and often associated with megaloblastic changes; may be precipitated by infection, such as influenza, notably with parvovirus B19. Folate deficiency caused by increased bone marrow requirement. Pigmented gallstones occur in approximately half of untreated patients. Increased hemolysis of red blood cells leads to increased bilirubin levels, because bilirubin is a breakdown product of heme. The high levels of bilirubin must be excreted into the bile by the liver, which may cause the formation of a pigmented gallstone, which is composed of calcium bilirubinate. Since these stones contain high levels of calcium carbonates and phosphate, they are radiopaque and are visible on x-ray. Hyperglycemia with concomitant low hemoglobin A1C levels. Hemoglobin A1C (glycated hemoglobin) is a test for determining the average blood glucose levels over an extended period of time, and is often used to evaluate glucose control in diabetics. The hemoglobin A1C levels are abnormally low because the life span of the red blood cells is decreased - providing less time for the non-enzymatic glycosylation of hemoglobin. Thus, even with high overall blood sugar, the A1C will be lower than expected. Iron overload. Leg ulcer. Deep vein thrombosis (DVT). Cardiovascular disease.
Supelco is the chromatography products branch of Sigma-Aldrich. It provides chromatography columns and related tools for environmental, government, food and beverage, pharmaceutical, biotechnology, medical and chemical laboratories; sample preparation products and chemical reference standards.
=== Exposure in pregnancy === Antidepressant exposure (including citalopram) during pregnancy is associated with shorter duration of gestation (by three days), increased risk of preterm delivery (by 55%), lower birth weight (by 75 g), and lower Apgar scores (by <0.4 points). Antidepressant exposure is not associated with an increased risk of spontaneous abortion. It is uncertain whether there is an increased prevalence of septal heart defects among children whose mothers were prescribed an SSRI in early pregnancy.
According to the latest official projection, Brazil's estimated population was 214,211,951 on 1 July 2026—an increase from the figure of 203 million reported by the 2022 census. The population of Brazil, as recorded by the 2008 PNAD, was approximately 190 million (22.31 inhabitants per square kilometer or 57.8/sq mi), with a ratio of men to women of 0.95:1 and 83.75% of the population defined as urban. The population is heavily concentrated in the Southeast (89 million inhabitants) and Northeast (54.6 million inhabitants), while the two most extensive regions, the Center-West and the North, which together make up 64.12% of Brazilian territory, have a total of only 33.8 million inhabitants. The first census in Brazil was carried out in 1872 and recorded a population of 9,930,478. From 1880 to 1930, four million Europeans arrived. Brazil's population increased significantly between 1940 and 1970, because of a decline in the mortality rate, even though the birth rate underwent a slight decline. In the 1940s the annual population growth rate was 2.4%, rising to 3.0% in the 1950s and remaining at 2.9% in the 1960s, as life expectancy rose from 44 to 54 years, and to 72.6 years in 2007. It has been steadily falling since the 1960s, from 3.04% per year between 1950 and 1960 to 1.05% in 2008 and is expected to fall to a negative value of –0.29% by 2050, thus completing the demographic transition. In 2022, the illiteracy rate was roughly 7%, a significant decline from 11.48% in 2008. By comparison, in 1940, more than half the population (54%) was illiterate.
Since the onset of the 21st century, Australia has found that childhood obesity has followed trend with the United States. Information garnered has concluded that the increase has occurred in lower socioeconomic areas, where poor nutritional education has been blamed.
Sources: en.wikipedia.org
Liquid chromatography–mass spectrometry is common for identity and purity checks. High-performance liquid chromatography with ultraviolet detection can also be used. Both methods require a suitable reference standard.
The solid is usually kept desiccated at -20 °C or lower and protected from light. Stock solutions are aliquoted to limit freeze–thaw cycles. Aqueous solutions are not generally recommended for long-term storage.
Laws differ by country and by intended use. It is not an approved medicine, and many vendors sell it as a research chemical. Purchasers are responsible for confirming local restrictions.
Liquid chromatography with mass spectrometry is a common approach. Ultraviolet detection and nuclear magnetic resonance can support identification when suitable standards are available.