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Chemical Sampling Information (CSI)
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General Description

Synonyms: 4-Methyl-3-penten-2-one; Isobutenyl methyl ketone; Methyl isobutenyl ketone; Isopropylidene acetone

OSHA IMIS Code Number: 1635

Chemical Abstracts Service (CAS) Registry Number: 141-79-7

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: SB4200000; 54967

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: UN1229 129 Flammable Liquid

NIOSH Pocket Guide to Chemical Hazards, Mesityl oxide: chemical description, physical properties, potentially hazardous incompatibilities, and more

Chemical Description and Physical Properties:

clear, pale yellow, or colorless liquid with a strong peppermint odor
molecular weight: 98
vapor pressure: 8 mm
boiling point: 266°F
melting point: -51°F

Incompatibilities: Oxidizers

Exposure Limits

OSHA Permissible Exposure Limit (PEL):

General Industry: 25 ppm, 100 mg/m3

Construction Industry: 25 ppm, 100 mg/m3 TWA

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 15 ppm, 60 mg/m3 TWA; 25 ppm, 100 mg/m3 STEL

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 10 ppm TWA

Health Factors

Potential Symptoms: Eye, skin, mucous membrane irritation; narcosis, coma; In animals: CNS effects

Health Effects: Irritation-Eye, Nose, Throat, Skin---Mild (HE16)

Affected Organs: Eyes, skin, respiratory system, CNS

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/Methanol
    alternate solvent: (99:1) Carbon Disulfide/Dimethylformamide
    maximum volume: 25 Liters
    maximum flow rate: 0.2 L/min (TWA)
    maximum volume: 3 Liters
    maximum flow rate: 0.2 L/min (STEL)
    current analytical method: Gas Chromatography; GC/FID
    sampling and analytical error: 0.12
    method reference: 1 (NIOSH 1301 [25 KB PDF, 5 pages])
    method classification: Fully Validated

Secondary Laboratory Sampling/Analytical Method (SAM2):

  • device: Detector Tube
    company: Kitagawa
    part #: 218U
    range #: 5-100 ppm
    class: Mfg

  • device: Instrumentation
    company: Infrared Spectrophotometer
    part #: MIRAN 1A & 1B
    range #: 0.8 ppm @ 8.2 um
    class: Mfg

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