{"data":{"id":"us/40-cfr-table-b-3-to-subpart-b-of-part-53","jurisdiction":"us","citation":"40 CFR Table B-3 to Subpart B of Part 53","heading":"Table B-3 to Subpart B of Part 53—Interferent Test Concentration, 1 Parts per Million","body":"Table B-3 to Subpart B of Part 53—Interferent Test Concentration 1\n[Parts per million]\nPollutant Analyzer type 2 Hydro-chloric acid Ammonia Hydrogen sulfide Sulfur dioxide Nitrogen dioxide Nitric oxide Carbon dioxide Ethylene Ozone M-xylene Water vapor Carbon monoxide Methane Ethane Naphthalene\nSO2 Ultraviolet fluorescence 5 0.1 4 0.14 0.5 0.5 0.5 0.2 20,000 6 0.05\nSO2 Flame photometric 0.01 4 0.14 750 3 20,000 50\nSO2 Gas chromatography 0.1 4 0.14 750 3 20,000 50\nSO2 Spectrophotometric-wet chemical (pararosanaline) 0.2 0.1 0.1 4 0.14 0.5 750 0.5\nSO2 Electrochemical 0.2 0.1 0.1 4 0.14 0.5 0.5 0.2 0.5 3 20,000\nSO2 Conductivity 0.2 0.1 4 0.14 0.5 750\nSO2 Spectrophotometric-gas phase, including DOAS 4 0.14 0.5 0.5 0.5 0.2\nO3 Ethylene Chemiluminescence 3 0.1 750 4 0.08 3 20,000\nO3 NO-chemiluminescence 3 0.1 0.5 750 4 0.08 3 20,000\nO3 Electrochemical 3 0.1 0.5 0.5 4 0.08 3 20,000\nO3 Spectrophotometric-wet chemical (potassium iodide) 3 0.1 0.5 0.5 3 0.5 4 0.08\nO3 Spectrophotometric-gas phase, including ultraviolet absorption and DOAS 0.5 0.5 3 0.5 4 0.08 0.02 20,000\nCO Non-dispersive Infrared 750 20,000 4 10\nCO Gas chromatography with flame ionization detector 20,000 4 10 0.5\nCO Electrochemical 0.5 0.2 20,000 4 10\nCO Catalytic combustion-thermal detection 0.1 750 0.2 20,000 4 10 5.0 0.5\nCO IR fluorescence 750 20,000 4 10 0.5\nCO Mercury replacement-UV photometric 0.2 4 10 0.5\nNO2 Chemiluminescent 3 0.1 0.5 4 0.1 0.5 20,000\nNO2 Spectrophotometric-wet chemical (azo-dye reaction) 0.5 4 0.1 0.5 750 0.5\nNO2 Electrochemical 0.2 3 0.1 0.5 4 0.1 0.5 750 0.5 20,000 50\nNO2 Spectrophotometric-gas phase 3 0.1 0.5 4 0.1 0.5 0.5 20,000 50\n1 Concentrations of interferent listed must be prepared and controlled to ±10 percent of the stated value.\n2 Analyzer types not listed will be considered by the Administrator as special cases.\n3 Do not mix interferent with the pollutant.\n4 Concentration of pollutant used for test. These pollutant concentrations must be prepared to ±10 percent of the stated value.\n5 If candidate method utilizes an elevated-temperature scrubber for removal of aromatic hydrocarbons, perform this interference test.\n6 If naphthalene test concentration cannot be accurately quantified, remove the scrubber, use a test concentration that causes a full-scale response, reattach the scrubber, and evaluate response for interference.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER C—AIR PROGRAMS","PART 53—AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS","Subpart B—Procedures for Testing Performance Characteristics of Automated Methods for SO2, CO, O3, and NO2"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"02c9a342439ed8d3549832ef91a0c7c6f5ac6414dfd05504beb3afd576dc6886","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-table-b-2-to-subpart-b-of-part-53","next":"us/40-cfr-table-b-4-to-subpart-b-of-part-53"},"notice":"GroundRules: Original legal text. Not legal advice."}