Last updated
2-amino-2-(hydroxymethyl)propane-1,3-diol 200.svg
Preferred IUPAC name
Other names
TRIS, Tris, Tris base, Tris buffer, Trizma, Trisamine, THAM, Tromethamine, Trometamol, Tromethane, Trisaminol
3D model (JSmol)
ECHA InfoCard 100.000.969 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 201-064-4
PubChem CID
RTECS number
  • TY2900000
  • InChI=1S/C4H11NO3/c5-4(1-6,2-7)3-8/h6-8H,1-3,5H2 Yes check.svgY
  • InChI=1/C4H11NO3/c5-4(1-6,2-7)3-8/h6-8H,1-3,5H2
  • OCC(N)(CO)CO
Molar mass 121.136 g·mol−1
AppearanceWhite crystalline powder
Density 1.328g/cm3
Melting point >175-176 °C (448-449 K)
Boiling point 219 °C (426 °F; 492 K)
~50 g/100 mL (25 °C)
Acidity (pKa)8.07 (conjugate acid)
B05BB03 ( WHO ) B05XX02 ( WHO )
Hazards [1]
Occupational safety and health (OHS/OSH):
Main hazards
GHS labelling:
H315, H319, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P332+P313, P362, P403+P233, P405
NFPA 704 (fire diamond)
Flash point Non-flammable
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Tris, or tris(hydroxymethyl)aminomethane, or known during medical use as tromethamine or THAM, is an organic compound with the formula (HOCH2)3CNH2. It is extensively used in biochemistry and molecular biology as a component of buffer solutions [2] such as in TAE and TBE buffers, especially for solutions of nucleic acids. It contains a primary amine and thus undergoes the reactions associated with typical amines, e.g. condensations with aldehydes. Tris also complexes with metal ions in solution. [3] In medicine, tromethamine is occasionally used as a drug, given in intensive care for its properties as a buffer for the treatment of severe metabolic acidosis in specific circumstances. [4] [5] Some medications are formulated as the "tromethamine salt" including hemabate (carboprost as trometamol salt), and "ketorolac trometamol". [6]


Buffering features

The conjugate acid of tris has a pKa of 8.07 at 25 °C, which implies that the buffer has an effective pH range between 7.1 and 9.1 (pKa ± 1) at room temperature.

Buffer details

Buffer inhibition


Tris is prepared industrially by the exhaustive condensation of nitromethane with formaldehyde under basic conditions (i.e. repeated Henry reactions) to produce the intermediate (HOCH2)3CNO2, which is subsequently hydrogenated to give the final product. [10]


The useful buffer range for tris (pH 7–9) coincides with the physiological pH typical of most living organisms. This, and its low cost, make tris one of the most common buffers in the biology/biochemistry laboratory. Tris is also used as a primary standard to standardize acid solutions for chemical analysis.

Tris is used to increase permeability of cell membranes. [11] It is a component of the Moderna COVID-19 vaccine [12] and Pfizer-BioNTech COVID-19 Vaccine for use in children 5 through 11 years of age. [13]


Tris (usually known as THAM in this context) is used as alternative to sodium bicarbonate in the treatment of metabolic acidosis. [14] [15]

See also

Related Research Articles

A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. In nature, there are many systems that use buffering for pH regulation. For example, the bicarbonate buffering system is used to regulate the pH of blood, and bicarbonate also acts as a buffer in the ocean.

Citric acid Weak organic acid

Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms.

Sodium bicarbonate Chemical compound

Sodium bicarbonate (IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation (Na+) and a bicarbonate anion (HCO3). Sodium bicarbonate is a white solid that is crystalline, but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is nahcolite. It is a component of the mineral natron and is found dissolved in many mineral springs.

Lactic acidosis Metabolic medical condition

Lactic acidosis is a medical condition characterized by the buildup of lactate in the body, with formation of an excessively low pH in the bloodstream. It is a form of metabolic acidosis, in which excessive acid accumulates due to a problem with the body's oxidative metabolism.

Acidosis is a process causing increased acidity in the blood and other body tissues. If not further qualified, it usually refers to acidity of the blood plasma.

Hyperchloremia is an electrolyte disturbance in which there is an elevated level of chloride ions in the blood. The normal serum range for chloride is 96 to 106 mEq/L, therefore chloride levels at or above 110 mEq/L usually indicate kidney dysfunction as it is a regulator of chloride concentration. As of now there are no specific symptoms of hyperchloremia; however, it can be influenced by multiple abnormalities that cause a loss of electrolyte-free fluid, loss of hypotonic fluid, or increased administration of sodium chloride. These abnormalities are caused by diarrhea, vomiting, increased sodium chloride intake, renal dysfunction, diuretic use, and diabetes. Hyperchloremia should not be mistaken for hyperchloremic metabolic acidosis as hyperchloremic metabolic acidosis is characterized by two major changes: a decrease in blood pH and bicarbonate levels, as well as an increase in blood chloride levels. Instead those with hyperchloremic metabolic acidosis are usually predisposed to hyperchloremia.

Metabolic acidosis Medical condition

Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidneys to excrete excess acids. Metabolic acidosis can lead to acidemia, which is defined as arterial blood pH that is lower than 7.35. Acidemia and acidosis are not mutually exclusive – pH and hydrogen ion concentrations also depend on the coexistence of other acid-base disorders; therefore, pH levels in people with metabolic acidosis can range from low, normal, to high.

Ringers lactate solution

Ringer's lactate solution (RL), also known as sodium lactate solution,Lactated Ringer’s, and Hartmann's solution, is a mixture of sodium chloride, sodium lactate, potassium chloride, and calcium chloride in water. It is used for replacing fluids and electrolytes in those who have low blood volume or low blood pressure. It may also be used to treat metabolic acidosis and to wash the eye following a chemical burn. It is given by intravenous infusion or applied to the affected area.

The anion gap is a value calculated from the results of multiple individual medical lab tests. It may be reported with the results of an electrolyte panel, which is often performed as part of a comprehensive metabolic panel.

Bis-tris propane Chemical compound

Bis-tris propane, or 1,3-bis(tris methylamino)propane, also known as BTP, is a chemical substance that is used in buffer solutions. It is a white to off-white crystalline powder that is soluble in water. It has a wide buffering range, from 6 to 9.5 due to its two pKa values which are close in value. This buffer is primarily used in biochemistry and molecular biology.

Metabolic alkalosis Medical condition

Metabolic alkalosis is a metabolic condition in which the pH of tissue is elevated beyond the normal range (7.35–7.45). This is the result of decreased hydrogen ion concentration, leading to increased bicarbonate, or alternatively a direct result of increased bicarbonate concentrations. The condition typically cannot last long if the kidneys are functioning properly.

Renal tubular acidosis Medical condition

Renal tubular acidosis (RTA) is a medical condition that involves an accumulation of acid in the body due to a failure of the kidneys to appropriately acidify the urine. In renal physiology, when blood is filtered by the kidney, the filtrate passes through the tubules of the nephron, allowing for exchange of salts, acid equivalents, and other solutes before it drains into the bladder as urine. The metabolic acidosis that results from RTA may be caused either by insufficient secretion of hydrogen ions into the latter portions of the nephron or by failure to reabsorb sufficient bicarbonate ions from the filtrate in the early portion of the nephron. Although a metabolic acidosis also occurs in those with chronic kidney disease, the term RTA is reserved for individuals with poor urinary acidification in otherwise well-functioning kidneys. Several different types of RTA exist, which all have different syndromes and different causes. RTA is usually an incidental finding based on routine blood draws that show abnormal results. Clinically, patients may present with vague symptoms such as dehydration, mental status changes, or delayed growth in adolescents.

Carbonic anhydrase inhibitor Class of pharmaceuticals

Carbonic anhydrase inhibitors are a class of pharmaceuticals that suppress the activity of carbonic anhydrase. Their clinical use has been established as anti-glaucoma agents, diuretics, antiepileptics, in the management of mountain sickness, gastric and duodenal ulcers, idiopathic intracranial hypertension, neurological disorders, or osteoporosis.

Acid–base homeostasis is the homeostatic regulation of the pH of the body's extracellular fluid (ECF). The proper balance between the acids and bases in the ECF is crucial for the normal physiology of the body—and for cellular metabolism. The pH of the intracellular fluid and the extracellular fluid need to be maintained at a constant level.

In acid base physiology, the Davenport diagram is a graphical tool, developed by Horace W. Davenport, that allows a clinician or investigator to describe blood bicarbonate concentrations and blood pH following a respiratory and/or metabolic acid-base disturbance. The diagram depicts a three-dimensional surface describing all possible states of chemical equilibria between gaseous carbon dioxide, aqueous bicarbonate and aqueous protons at the physiologically complex interface of the alveoli of the lungs and the alveolar capillaries. Although the surface represented in the diagram is experimentally determined, the Davenport diagram is rarely used in the clinical setting, but allows the investigator to envision the effects of physiological changes on blood acid-base chemistry. For clinical use there are two recent innovations: an Acid-Base Diagram which provides Text Descriptions for the abnormalities and a High Altitude Version that provides text descriptions appropriate for the altitude.

Acid–base disorder Medical condition

Acid–base imbalance is an abnormality of the human body's normal balance of acids and bases that causes the plasma pH to deviate out of the normal range. In the fetus, the normal range differs based on which umbilical vessel is sampled. It can exist in varying levels of severity, some life-threatening.

Krebs–Henseleit solution, developed by Hans Krebs and Kurt Henseleit, is a solution containing sodium (Na), potassium (K), chloride (Cl), calcium (Ca), magnesium sulfate (MgSO4), bicarbonate (HCO3), phosphate (PO4), glucose, and sometimes supplemented with albumin, and tromethamine (THAM).

Intravenous sodium bicarbonate

Intravenous sodium bicarbonate, also known as sodium hydrogen carbonate, is a medication primarily used to treat severe metabolic acidosis. For this purpose it is generally only used when the pH is less than 7.1 and when the underlying cause is either diarrhea, vomiting, or the kidneys. Other uses include high blood potassium, tricyclic antidepressant overdose, and cocaine toxicity as well as a number of other poisonings. It is given by injection into a vein.

Methanol toxicity Medical condition

Methanol toxicity is poisoning from methanol, characteristically via ingestion. Symptoms may include a decreased level of consciousness, poor or no coordination, hypothermia, vomiting, abdominal pain, and a specific smell on the breath. Decreased vision may start as early as twelve hours after exposure. Long-term outcomes may include blindness and kidney failure. Toxicity and death may occur even after drinking a small amount.

SDS-PAGE Biochemical technique

SDS-PAGE is a discontinuous electrophoretic system developed by Ulrich K. Laemmli which is commonly used as a method to separate proteins with molecular masses between 5 and 250 kDa. The combined use of sodium dodecyl sulfate and polyacrylamide gel allows to eliminate the influence of structure and charge, and proteins are separated solely on the basis of differences in their molecular weight.


  1. "Tromethamine".
  2. Gomori, G., Preparation of Buffers for Use in Enzyme Studies. Methods Enzymology., 1, 138-146 (1955).
  3. 1 2 FISCHER, Beda E.; HARING, Ulrich K.; TRIBOLET, Roger; SIGEL, Helmut (1979). "Metal Ion/Buffer Interactions. Stability of Binary and Ternary Complexes Containing 2-Amino-2(hydroxymethyl)-1,3-propanediol (Tris) and Adenosine 5'-Triphosphate (ATP)". European Journal of Biochemistry. Wiley. 94 (2): 523–530. doi:10.1111/j.1432-1033.1979.tb12921.x. ISSN   0014-2956. PMID   428398.
  4. Stanley, David; Tunnicliffe, William (June 2008). "Management of life-threatening asthma in adults". Continuing Education in Anaesthesia, Critical Care & Pain. 8 (3): 95–99. doi:10.1093/bjaceaccp/mkn012 . Retrieved 21 July 2017.
  5. Hoste, Eric A.; Colpaert, Kirsten; Vanholder, Raymond C.; Lameire, Norbert H.; De Waele, Jan J.; Blot, Stijn I.; Colardyn, Francis A. (May 2005). "Sodium bicarbonate versus THAM in ICU patients with mild metabolic acidosis". Journal of Nephrology. 18 (3): 303–307. ISSN   1121-8428. PMID   16013019.
  6. BNF 73 March-September 2017. British Medical Association,, Royal Pharmaceutical Society of Great Britain. London. 21 March 2017. ISBN   978-0857112767. OCLC   988086079.{{cite book}}: CS1 maint: others (link)
  7. 1 2 "Sigma tris(hydroxymethyl)aminomethane; Tris Technical Bulletin No. 106B" (PDF). Sigma-Aldrich. Retrieved 2020-06-04.
  8. Desmarais, WT; et al. (2002). "The 1.20 Å resolution crystal structure of the aminopeptidase from Aeromonas proteolytica complexed with tris: A tale of buffer inhibition". Structure. 10 (8): 1063–1072. doi: 10.1016/S0969-2126(02)00810-9 . PMID   12176384.
  9. Ghalanbor, Z; et al. (2008). "Binding of tris to Bacillus licheniformis alpha-amylase can affect its starch hydrolysis activity". Protein Pept. Lett. 15 (2): 212–214. doi:10.2174/092986608783489616. PMID   18289113.
  10. Markofsky, Sheldon, B. (15 October 2011). "Nitro Compounds, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Vol. 24. p. 296. doi:10.1002/14356007.a17_401.pub2. ISBN   978-3527306732.{{cite book}}: Missing or empty |title= (help)
  11. Irvin, R.T.; MacAlister, T.J.; Costerton, J.W. (1981). "Tris(hydroxymethyl)aminomethane Buffer Modification of Escherichia coli Outer Membrane Permeability". J. Bacteriol. 145 (3): 1397–1403. doi:10.1128/JB.145.3.1397-1403.1981. PMC   217144 . PMID   7009585.
  12. [ bare URL PDF ]
  13. [ bare URL PDF ]
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  15. Hoste, EA; Colpaert, K; Vanholder, RC; Lameire, NH; De Waele, JJ; Blot, SI; Colardyn, FA (2005). "Sodium bicarbonate versus THAM in ICU patients with mild metabolic acidosis". Journal of Nephrology. 18 (3): 303–7. PMID   16013019.