IRSST - Institut de recherche Robert-Sauvé en santé et en sécurité du travail

According to Decree 280-2024 published on February 28, 2024, in the Gazette officielle du Québec, the amendment to the Appendix 1 of the Regulation respecting occupational health and safety (RSST, RLRQ, c. S-2.1, r. 13) will come into force on March 14, 2024. These regulatory changes have not yet been incorporated into the current Substance Data Sheets of the Sampling Guide for Air Contaminants in the Workplace. An update is currently underway and will be available as soon as possible. Consequently, the information contained in the data sheets of substances modified or added in Decree 280-2024 is partially inaccurate or incomplete. Please consult our infoLABO (in French only) for more details. Please contact our client service: [email protected] for further information.

Methyl mercaptan  

French name in the regulation: Méthyl mercaptan
CAS : 74-93-1
Synonyms: Mercaptan méthylique; Méthanethiol

Exposure Standards in RROHS regulation

Permissible exposure values (PEV)
ppm mg/m3 f/cc Notes
TWAEV 0,5 0,98 - -
STEV - - - -
Ceiling - - - -
Carcinogenicity Sensitizer
Simple asphyxiantPercutaneous
Prohibited useProhibited recirculation
Minimum exposureExplosion hazard
Ototoxic

TWA adjustment for unusual work schedules

1B : No adjustment

CNESST – Toxicological Index Service

Consult REPTOX file: Methyl mercaptan

Analysis:

Méthyl mercaptan

Recommended method by the IRSST:
Method: NIOSH - 2542
Sampling device: SKC FLT225-9007 glass fiber filter impregnated with a solution of 5% (w/v) mercuric acetate
Parameters:
Flow rate: 0,1-0,2 L/min
TWA sampling volume: 10 L
STEL sampling volume: -
Remarks: Contact the IRSST before sampling. Protect the samples from light. The recommended volume is from 10 to 150 litres.
Principle: Gas chromatography with flame photometric detection (GC-FPD)
Remarks: Hydrogen sulfide, dimethyl sulfide, dimethyl disulfide, water vapor and propylene may cause interferences during the analysis.
NIOSH, Manual of Analytical Methods, 4th ed., Method 2542 Mercaptans, methyl-,Ethyl-, and n-Butyl, 1994.