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Chemical Sampling Information (CSI)
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General Description

Synonyms: Isopentane; Ethyldimethylethane; Isoamylhydride

OSHA IMIS Code Number: R228

Chemical Abstracts Service (CAS) Registry Number: 78-78-4

Other Chemical Abstracts Service (CAS) Registry Numbers: 109-66-0 (Pentane)

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: EK4430000

Chemical Description and Physical Properties:

colorless liquid, with characteristic odor
molecular weight: 72.17
vapor pressure: 79 kPa at 20°C
molecular formula: C5H12
boiling point: 28°C
melting point: -160°C

Exposure Limits

There is no specific OSHA PEL or NIOSH REL for this compound.

OSHA Permissible Exposure Limit (PEL) (for Pentane):

General Industry: 29 CFR 1910.1000 Table Z-1 - 1000 ppm, 2950 mg/m3 TWA

Construction Industry: 29 CFR 1926.55 Appendix A - 500 ppm, 1500 mg/m3 TWA

Maritime: 29 CFR 1915.1000 Table Z-Shipyards - 500 ppm, 1500 mg/m3 TWA

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) (for Pentane): 120 ppm; 350 mg/m3 TWA; 610 ppm, 1800 mg/m3 Ceiling (15 Minutes)

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 600 ppm, 1770 mg/m3 TWA (TLV listed under Pentane, All isomers)

Health Factors

Potential Symptoms: Eye, nose, throat and skin irritation; cough, sore throat; headache, shortness of breath; dizziness, drowsiness, loss of coordination, unconsciousness; irregular heartbeat; redness, dryness and cracking of skin; rash or burning sensation on contact with liquid; INGES ACUTE: Abdominal pain, nausea, vomiting; chemical pneumonitis (following aspiration of liquid)

Health Effects: Irritation-Eyes, Nose, Throat, Skin---Mild (HE16); Narcosis (HE8); Explosive, Flammable (HE18)

Affected Organs: Eyes, skin, respiratory system, CNS

Notes:

  1. OSHA does not have a PEL for 2-methyl butane.
  2. Vapor/air mixtures are explosive.
  3. No toxic effects of the vapor have been reported at levels less than 14,000 ppm, the minimum explosive limit in air.
  4. Metabolized in mice or by animal liver microsomes to various methyl-butanol derivatives and to 3-methyl-2-butanone. Potential use of any of these metabolites as markers of occupational exposure has not been reported.

Literature Basis:

  • International Chemical Safety Cards (WHO/IPCS/ILO): Isopentane.
  • Chiba, S. and Oshida, S.: Metabolism and toxicity of n-pentane and isopentane [Japanese]. Nippon Hoigaku Zasshi 45(2): 128-137, 1991.
  • Galvin, J.B. and Marashi, F.: 2-Methylbutane (isopentane). CAS# 78-78-4. J. Toxicol. Environ. Health A 58(1-2): 23-33, 1999.
  • Pohanish, R.P. (editor): Isopentane. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1341-1342.

Date Last Revised: 01/26/2005

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: Charcoal Tube (100/50 mg sections, 20/40 mesh)
    analytical solvent: (99:1) Carbon Disulfide:Dimethylformamide
    maximum volume: 4 Liters
    maximum flow rate: 0.2 L/min
    current analytical method: Gas Chromatography; GC/FID
    method reference: NIOSH Analytical Method (NIOSH 1500 [127 KB PDF, 8 pages])
    method classification: Partially Validated

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