3-Methylbutanol Molecular Biology Reagent

Product No. I9392

CAS RN 123-51-3
EC 204-633-5
Synonyms: 3-Methyl-1-butanol, Isoamyl alcohol, Isopentyl alcohol

Product Description

3-Methyl-1-butanol, commonly called isoamyl alcohol, is routinely used in molecular biology, notably in the purification of DNA. It is widely used in conjunction with phenol and chloroform, for the removal of proteins from the nucleic acid solutions by extraction. The addition of chloroform and isoamyl alcohol in the extraction protocol deals with two issues that the use of phenol alone does not completely address. First, iIsoamyl alcohol helps to inhibit RNase activity, which phenol does not completely inhibit. Second, isoamyl alcohol helps to prevent the solubilization in the phenol phase of long RNA molecules with long poly(A) portions. In addition, isoamyl alcohol reduces foaming during the extraction process.

Isoamyl alcohol may also be used in the extraction of ethidium bromide from DNA solutions and in the radiolabeling of RNA transcripts in nuclei that have been isolated from tissue.1

Isoamyl alcohol is often used in the HPLC analysis of various pharmaceuticals and metabolites.2,3,4 It has been used in the analysis of oxidized and reduced pyridine nucleotides and adenylates in organic phenol extracts from mitochondria.5

A phenol:chloroform:
isoamyl alcohol procedure for the extraction of chloroplast DNA that avoids density gradient differential centrifugation has been published.6 A protocol for the isolation of mRNA from a thermophilic cyanobacterium that incorporates a phenol:chloroform:isoamyl alcohol mixture has been described.7


Room Temperature

Precautions and Disclaimer

This product is for R&D use only, not for drug, household, or other uses. Please consult the Safety Data Sheet for information regarding hazards and safe handling practices. 

Preparation Instructions

This product is miscible in ethanol [0.1 ml/ml, 10% (v/v)], yielding a clear, colorless solution.

Product Profile

Molecular Formula: C5H12O
Molecular Weight: 88.15


This product is designated as molecular biology grade and is tested as suitable for use in the precipitation of nucleic acids.




  1. Molecular Cloning: A Laboratory Manual, 3rd ed., Sambrook, J. and Russell, D.W., CSHL Press (Cold Spring Harbor, NY: 2001), pp. 1.73, 6.24-6.27, 17.27-17.28, A1.23, A8.10.
  2. van de Merbel, N. C., et al., Validated liquid chromatographic method for the determination of bexarotene in human plasma. J. Chromatogr. B Analyt. Technol. Biomed. Life Sci., 775(2), 189-195 (2002).
  3. Dawson, M., et al., A rapid and sensitive highperformance liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry method for the quantitation of oxycodone in human plasma. J. Chromatogr. Sci., 40(1), 40-44 (2002).
  4. De Baere, S. M., et al., Identification and quantitation of despropionyl-bezitramide in postmortem samples by liquid chromatography coupled to electrospray ionization tandem mass spectrometry. Anal. Chem., 71(14), 2908-2914 (1999).


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