Nitric acid

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.

Nitric acid

French name in the regulation: Acide nitrique

CAS : 7697-37-2

Exposure Standards in RROHS regulation

Permissible exposure values (PEV)

	ppm	mg/m³	f/cc	Notes
TWAEV	2	5,2	-	-
STEV	4	10	-	-
Ceiling	-	-	-	-

Carcinogenicity		Sensitizer
Simple asphyxiant		Percutaneous
Prohibited use		Prohibited recirculation
Minimum exposure		Explosion hazard
Ototoxic

TWA adjustment for unusual work schedules

II : Daily adjustment

CNESST – Toxicological Index Service

Consult REPTOX file: Nitric acid

Analysis:

Nitric acid

Method: IRSST - 211

Sampling protocol

Sampling device:
Sampling media required:

#IRSST	Description
974	Impregnated quartz filter in series with quartz filter, 37 mm, 3-part

Parameters:
Flow rate: 2 L/min
TWA sampling volume: 240 L
STEL sampling volume: 30 L
Remarks: The cassette consists of a 37 mm quartz fibers prefilter that will collect the acids in particulate form, followed by a Na2CO3 impregnated quartz fiber filter that will adsorb the acids in vapour form, the two filters separated by an inert spacer. The sampling cassette 974 is stable two months. The sample is stable for 7 days at 25°C and 28 days at 4°C. The recommended method needs a minimum of 3 field blanks.

Analytical protocol

Principle: Ion chromatography with conductivity detection (IC-CD)
Precision (%): 2,6
Minimum reported value: 8 µg
Remarks: All the nitrate ions not originating from the acid can cause a positive interference. Additionally, inorganic acids can react with co-sampled particulate matter on the pre-filter. Three ions can be determined simultaneously: bromide, chloride and nitrate. Analytical results are expressed as nitric acid.

Reference

IRSST. "Analyse des acides inorganiques volatiles". Méthode 211. Publiée.