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Chemical Sampling Information (CSI)
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General Description

Synonyms: Methyl phosphite, Trimethoxyphosphine, Trimethyl ester of phosphorous acid

OSHA IMIS Code Number: T125

Chemical Abstracts Service (CAS) Registry Number: 121-45-9

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: TH1400000; 59624

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: UN 2329 Flammable Liquid 130

NIOSH Pocket Guide to Chemical Hazards, Trimethyl phosphite: Chemical description, physical properties, potentially hazardous incompatibilities, and more

Chemical Description and Physical Properties:

colorless liquid, insoluble in water; soluble in hexane, benzene, acetone, alcohol, ether, carbon tetrachloride & kerosene
boiling point: 108-108.5 C
flash point: 37.7 C
molecular weight: 124.09
molecular formula: C3H9O3P

Exposure Limits

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 2 ppm, 10 mg/m3 TWA

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 2 ppm TWA


Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • note: Compound appears to react over time to form another compound after desorption and even on sitting in solution. It may be forming trimethly phosphate but no confirmation of that.
Conditions: 30 m SE30 1 u film, 80 deg C isothermal

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Page last updated: 06/10/1996