Inorganic Chemical Testing &
Reactive Gases Laboratory
AIHA LAP accredited laboratory for inorganic chemical testing and reactive gas monitoring — H₂S, SO₂, Cl₂, NH₃, NO₂, O₃, CO, HCN, and phosgene. NIOSH 6013–6019 methods via Ion Chromatography and UV-Vis analysis. OSHA PEL and ACGIH TLV compliance reporting from our Houston TX laboratory.
Reactive gases cause irreversible injury within seconds — most have no visible color, and several have IDLHs within striking range of their OSHA PELs
Narrow Margins Between PEL & IDLH
For chlorine, the OSHA PEL (ceiling 1 ppm) is only 10× below the IDLH (10 ppm). For H₂S, the ACGIH TLV of 1 ppm is 50× below the IDLH of 50 ppm — but the aging OSHA ceiling of 20 ppm is only 2.5× below IDLH. Inorganic chemical testing against both limits is the only way to understand actual risk margin.
Delayed-Onset Toxicity Is a Hidden Danger
Nitrogen dioxide (NO₂) can cause pulmonary edema with a latency of 4–48 hours after exposure — workers feel fine initially. Phosgene similarly causes delayed lung injury hours after a seemingly minor exposure. Inorganic chemical testing during suspect events creates the documentation record needed for medical response.
OSHA PELs Are Dangerously Outdated
Most OSHA reactive gas PELs were set in 1971. ACGIH TLVs for SO₂ (0.25 ppm vs OSHA 5 ppm — 20× difference), NO₂ (0.2 ppm vs OSHA 5 ppm ceiling — 25× difference), and H₂S (1 ppm vs OSHA 20 ppm ceiling — 20× difference) reflect decades of additional toxicological evidence.
OSHA Requires Documented Monitoring Programs
Facilities handling listed toxic gases above certain quantities are subject to OSHA PSM (29 CFR 1910.119), EPA RMP, and OSHA General Duty Clause obligations. For facilities with process safety requirements, documented inorganic chemical testing is part of the Process Hazard Analysis and incident investigation record.
10 Inorganic Chemicals & Reactive Gases — IDLH Reference Panel
Every gas listed below is analyzed by AGT Labs in-house using NIOSH-validated methods and IC or UV-Vis instrumentation. IDLH values shown are NIOSH-established limits — concentrations that are immediately dangerous to life and health.
Each Gas Requires a Chemically Specific Collection Medium
Unlike solvent testing — where a single charcoal tube captures many compounds — inorganic chemical testing demands gas-specific sorbent chemistry. Using the wrong medium produces zero recovery and completely invalid results. AGT Labs advises on correct media selection for every project based on your target analytes.
All ten gases are analyzed by in-house instrumentation at our Houston TX AIHA LAP accredited laboratory — no send-outs, no delays from third-party labs, and full chain of custody from receipt to final report.
- H₂S — silver nitrate sorbent tube, sulfide IC detection (NIOSH 6013)
- SO₂ — sodium carbonate filter, sulfate IC detection (NIOSH 6004)
- Cl₂ — sodium sulfite sorbent tube, chlorate IC detection (NIOSH 6019)
- NH₃ — sulfuric acid sorbent tube, ammonium IC detection (NIOSH 6015)
- NO₂ — sodium iodide sorbent tube, nitrite IC detection (NIOSH 6014)
- CO — molecular sieve tube, GC-TCD analysis (NIOSH 6604)
- O₃ — indigo carmine filter, UV-Vis spectrophotometry (NIOSH 6005)
- HCN — KOH sorbent tube, cyanide IC detection (NIOSH 6010)
- ClO₂ / Phosgene — dedicated impinger or colorimetric media
OSHA PELs, ACGIH TLVs & NIOSH RELs — Gas by Gas
Critical note: the ACGIH TLV is 2–25× more protective than the OSHA PEL for most reactive gases. OSHA PELs were set in 1971 — AGT Labs reports inorganic chemical testing results against all three limits in every compliance report.
Hydrogen Sulfide
NIOSH 6013 · Silver nitrate tube · IC
Sources: petroleum refining, wastewater, confined spaces (manholes, digesters). Workers can be overcome instantly above 150 ppm when the gas paralyzes the olfactory nerve.
Sulfur Dioxide
NIOSH 6004 · Na₂CO₃ filter · IC
Generated by combustion of sulfur-containing fuels, petroleum coking, smelting, and sulfuric acid manufacturing. Major asthmogen even at sub-PEL concentrations.
Chlorine
NIOSH 6019 · Na₂SO₃ tube · IC
Water treatment, pulp/paper bleaching, food sanitation, chemical manufacturing. Cl₂ causes severe pulmonary edema rapidly at IDLH. Very narrow safety margin.
Ammonia
NIOSH 6015 · H₂SO₄ tube · IC
Nitrogen Dioxide
NIOSH 6014 · NaI tube · IC
Generated by diesel engines, welding in confined spaces, silos, and blasting. Largest OSHA/ACGIH limit gap (25×) of all common industrial gases.
Carbon Monoxide
NIOSH 6604 · Mol. sieve tube · GC-TCD
Odorless, colorless. Binds hemoglobin 240× more strongly than O₂. Sources: combustion engines, forklift operations indoors, boilers, furnaces, generators.
Ozone
NIOSH 6005 · Indigo carmine filter · UV-Vis
ACGIH TLV is work-rate dependent — heavy physical labor lowers the TLV to 0.05 ppm due to increased respiratory volume. Generated by UV systems, arc welding, plasma cutting, copiers, electrostatic precipitators.
Hydrogen Cyanide
NIOSH 6010 · KOH tube · IC
Generated by combustion of nitrogen-containing materials, electroplating with cyanide salts, chemical synthesis, fumigation, and fire/explosion events. Also a skin absorption hazard.
Chlorine Dioxide
NIOSH 6011 · Impinger · UV-Vis
Phosgene
NIOSH 6009 · Colorimetric / IC
Generated by thermal degradation of chlorinated solvents (TCE, DCM) in hot work or near flames. Also used in chemical synthesis of isocyanates and polycarbonates. IDLH only 20× above PEL.
NIOSH Method Selection — Media, Collection & Analysis
Each reactive gas requires a gas-specific collection medium. The wrong medium produces zero recovery. AGT Labs advises on correct media for every combination of target gases before any inorganic chemical testing samples are collected.
H₂S & SO₂ — Sulfur Compounds
H₂S is collected on silver nitrate-impregnated sorbent tube — the gas converts AgNO₃ to Ag₂S precipitate, which is dissolved and quantified by IC with sulfide-specific detection. SO₂ uses sodium carbonate-coated filters with IC sulfate analysis. Both require separate dedicated tubes — they cannot share the same collection medium. Flow rate 100–200 mL/min personal sampling pump. Samples are stable at room temperature for 14 days if sealed promptly.
Cl₂ & ClO₂ — Halogen Gases
Chlorine (Cl₂) is collected on a sodium sulfite-impregnated sorbent tube — Cl₂ oxidizes Na₂SO₃ to form chlorate anion, which is measured by IC. Chlorine dioxide (ClO₂) requires a midget impinger with an alkaline absorbing solution and UV-Vis spectrophotometric analysis at 359 nm. ClO₂ is highly reactive and unstable — samples must be analyzed within 24 hours and cannot be shipped. On-site or dedicated batch shipment only.
NH₃ & NO₂ — Nitrogen Gases
Ammonia is collected on a sulfuric acid-treated sorbent tube — NH₃ reacts to form ammonium sulfate, then IC ammonium analysis. Nitrogen dioxide (NO₂) is trapped on a sodium iodide-impregnated tube — NO₂ oxidizes iodide to form nitrite anion, measured by IC. Both methods are NIOSH 6000-series validated personal breathing-zone methods with pump flow rates of 100–200 mL/min. Hold time 14 days refrigerated for both.
CO — Carbon Monoxide
Carbon monoxide is collected on 13X molecular sieve sorbent tube at 50 mL/min pump flow. The tube is thermally desorbed and CO is analyzed by gas chromatography with thermal conductivity detection (GC-TCD) — not IC. CO cannot be collected with the same media used for other inorganic gases. Real-time CO monitoring with electrochemical direct-reading instruments is available to supplement personal sampling in confined spaces and for continuous area monitoring. GC-TCD detection limit is well below the ACGIH TLV of 25 ppm.
O₃ — Ozone
Ozone is collected on an indigo carmine-impregnated filter — O₃ bleaches the indigo dye in direct proportion to ozone concentration. UV-Vis spectrophotometric analysis at 600 nm. Ozone is the most photolabile of all target gases — samples must be protected from direct light during and after collection, transported in opaque containers, and analyzed promptly. Pump flow rate 1–2 L/min. Hold time is shorter than most gases — analyze within 24 hours of collection for best results.
HCN & Phosgene
Hydrogen cyanide is collected on a potassium hydroxide (KOH)-impregnated sorbent tube — HCN is captured as cyanide anion, then quantified by IC with cyanide-specific detection. Phosgene (COCl₂) uses a dedicated impinger with absorbing solution or colorimetric dosimeter tube. Both of these gases require advance notification to AGT Labs before sampling — specialist media preparation and sample handling protocols apply. Phosgene samples must be shipped immediately on ice with priority courier.
Confined Space Entry — Critical Note on H₂S, CO, and O₂ Deficiency Monitoring
Passive diffusion badges and time-integrated sorbent tubes are NOT acceptable as the sole monitoring method for confined space entry under OSHA 29 CFR 1910.146. Permit-required confined spaces must be tested with calibrated direct-reading instruments (multi-gas meters) that provide real-time readings before entry and continuous monitoring during occupancy. AGT Labs provides complementary personal tube sampling to document the 8-hour TWA exposure record for H₂S and CO — this is the accredited laboratory documentation that supports incident investigation, workers' compensation, and OSHA inspection response. It does not replace pre-entry atmospheric testing. If H₂S exceeds 150 ppm, the olfactory nerve is paralyzed and the gas loses its own warning odor — continuous real-time monitoring becomes the only warning system.
Where Inorganic Chemical Exposures Occur
Reactive gas exposures are process-specific and frequently task-specific — peak concentrations during maintenance, start-up, and upset conditions are often 10–50× higher than routine operation levels. Task-based short-term sampling is critical for understanding the full exposure profile, not just the 8-hour TWA.
AGT Labs designs inorganic chemical testing programs around the highest-risk tasks — not just routine shift monitoring — to capture the exposures that matter most for worker health and OSHA compliance.
Where Reactive Gas Exposures Occur by Industry
Petroleum Refining & Petrochemical
H₂S, SO₂, and CO personal monitoring for hydroprocessing, fluid catalytic cracking, sulfur recovery, and coking operations. OSHA PSM program documentation. AGT Labs serves multiple Houston-area refineries with routine and emergency inorganic chemical testing programs.
Water & Wastewater Treatment
Chlorine gas (Cl₂) is used for primary disinfection of drinking water and wastewater. H₂S is generated by anaerobic digestion in sewer systems, digesters, and wet wells — creating acute confined space hazards in manholes and lift stations. Chlorine dioxide (ClO₂) is used as an alternative disinfectant in advanced water treatment facilities.
Pulp, Paper & Bleaching
Sulfur dioxide and hydrogen sulfide are generated in Kraft pulping (black liquor combustion, recovery boilers). Chlorine and chlorine dioxide are used in pulp bleaching sequences. ClO₂ has largely replaced elemental Cl₂ in modern bleach plants, but both gases are present during transitions and equipment maintenance activities.
Chemical Manufacturing
Chemical synthesis and reaction operations generate a wide range of toxic gases depending on feedstock and reactions — Cl₂, SO₂, HCN, phosgene, and NH₃ are all produced in various chemical manufacturing processes. Phosgene is used in isocyanate and polycarbonate synthesis. HCN is generated in electroplating with cyanide chemistry and in combustion of nitrogen-containing materials.
Welding, Cutting & Combustion
Nitrogen dioxide (NO₂) is generated by all high-temperature combustion processes — arc welding (especially MIG/MAG in confined spaces), plasma cutting, and diesel engine exhaust. Carbon monoxide is produced by incomplete combustion in forklift operations, welding, and indoor generator use. Ozone is produced by UV arc radiation in welding and plasma cutting processes — highest in stainless steel TIG welding.
Food Processing & Refrigeration
Industrial ammonia (NH₃) refrigeration systems are the dominant hazard in food cold chain facilities — ice cream plants, meat processing, seafood storage, and produce distribution centers. Large NH₃ charge volumes and aging pipe systems create significant leak potential. OSHA PSM thresholds (10,000 lb NH₃) trigger formal process safety management programs with documented monitoring requirements.
Sampling Strategies for Inorganic Chemical Testing
No single strategy covers all reactive gas scenarios. The right sampling design depends on whether the goal is routine compliance, acute event documentation, or engineering control verification.
Personal Breathing-Zone Monitoring (8-hr TWA)
NIOSH-method sorbent tubes clipped to the worker's lapel collar for full-shift sampling. Produces the 8-hour TWA result that is compared directly to OSHA PEL and ACGIH TLV. Required for routine compliance documentation and OSHA inspection response.
- Primary compliance sampling method for all gases
- Most accurately captures actual worker breathing-zone concentration
- Documented on COC with process and pump calibration data
Short-Term Exposure (STEL) & Task-Based Sampling
15-minute integrated samples collected during the highest-exposure tasks — chemical transfers, maintenance, equipment opening, and start-up/shut-down. Compared to ACGIH STEL. Identifies whether specific tasks drive overall exposure risk even if the 8-hr TWA appears acceptable.
- Essential for gases with STEL limits (NH₃, SO₂, NO₂)
- Captures task-based peak exposures missed by 8-hr integration
- Supports targeted engineering control design
Area & Source Monitoring
Fixed-location sorbent tubes or impingers placed near emission sources — tanks, reactors, vents, and process equipment — to map the geography of gas releases. Identifies specific emission points for LEV design and supports leak detection programs under OSHA PSM or EPA RMP.
- Source identification and quantification
- Ventilation effectiveness verification
- Before-and-after engineering control validation
Confined Space Pre-Entry & Rescue Documentation
Complementary laboratory sampling during or after confined space entry operations to document TWA exposures for H₂S and CO. Supplements real-time direct-reading instruments required by OSHA 1910.146. Creates the accredited lab record that supports incident investigation and workers' compensation documentation.
- Does NOT replace real-time pre-entry atmospheric testing
- Creates AIHA LAP accredited exposure documentation
- Essential for OSHA 300 log and incident investigation
Emergency Incident Response Sampling
Rapid deployment sampling following a gas release event — chlorine leak, H₂S incident, or ammonia refrigeration failure. Post-incident air sampling documents the concentration field during and after the event, supporting incident investigation, regulatory reporting, and medical management of exposed workers.
- Rush TAT available — call (713) 453-6090 directly
- Supports OSHA 300 incident reporting requirements
- Multiple media kits available for rapid field deployment
Engineering Control Verification
Before-and-after sampling to quantify the exposure reduction achieved by installation of local exhaust ventilation (LEV), process enclosures, or scrubbers. Regulatory and best-practice guidance requires documented exposure measurement after any significant change in ventilation, process, or chemicals used.
- Quantifies actual LEV effectiveness vs. design specification
- Required documentation for OSHA PSM change management
- Supports IH consultant written control program documentation
What You Receive — Reactive Gas Monitoring Report
Every AGT Labs inorganic gas report is issued on AIHA LAP accredited letterhead and includes everything an IH professional or OSHA inspector needs to evaluate the compliance status of your facility.
| Report Component | Details | Standard |
|---|---|---|
| Measured Concentration | Results in both ppm and mg/m³ for each target gas. TWA and STEL where applicable. Field blank concentration subtracted. | All samples |
| Regulatory Comparison | Direct comparison table: measured result vs. OSHA PEL, ACGIH TLV, NIOSH REL, and IDLH. Percent of limit calculated for each standard. | All samples |
| OSHA / ACGIH Disparity Flag | When the OSHA PEL is significantly less protective than the ACGIH TLV, the report explicitly flags this and notes that OSHA PEL compliance does not confirm worker health protection. | Where applicable |
| Method QA/QC Data | Method blank results, spike recovery, duplicate precision, pump calibration flows (pre and post), and sampling volume documentation. | All samples |
| Sampling Narrative | Summary of sampled tasks, process conditions, collection media, pump flow rates, and sample duration. Converts raw field notes to structured documentation. | All samples |
| Control Recommendations | Where results exceed or approach limits, the report includes preliminary engineering control and administrative control recommendations specific to the gas and process involved. | On exceedances |
Turnaround Times & Reactive Gas Sampling Media
Sampling Kits — Gas-Specific Media
- Silver nitrate tubes (NIOSH 6013) — hydrogen sulfide (H₂S)
- Sodium carbonate filters (NIOSH 6004) — sulfur dioxide (SO₂)
- Sodium sulfite tubes (NIOSH 6019) — chlorine (Cl₂)
- Sulfuric acid tubes (NIOSH 6015) — ammonia (NH₃)
- Sodium iodide tubes (NIOSH 6014) — nitrogen dioxide (NO₂)
- 13X molecular sieve tubes (NIOSH 6604) — carbon monoxide (CO)
- Indigo carmine filters (NIOSH 6005) — ozone (O₃)
- KOH tubes (NIOSH 6010) — hydrogen cyanide (HCN)
- Impingers + absorbing solutions — ClO₂ and phosgene (call first)
- Calibrated personal pumps (loaner) + COC documentation
From Field Sampling to Certified Reactive Gas Report
Identify Target Gases
Send AGT Labs your SDS sheets and process description. We confirm the correct NIOSH method and sampling media for each gas and prepare your kit — wrong media produces zero recovery.
Deploy Gas-Specific Media
Clip sorbent tube or impinger to worker lapel or area stand. Record exact start/stop time, pump flow rate (pre/post calibration), temperature, humidity, and tasks performed on COC.
Seal & Ship Per Hold Times
Seal all tubes immediately. Refrigerate where required. Ship ClO₂ and O₃ within 24 hours. All other NIOSH 6000 series: 14-day hold time refrigerated. Include field blank tubes for QA/QC.
IC / UV-Vis / GC Analysis
In-house extraction, dissolution, or desorption followed by ion chromatography, UV-Vis spectrophotometry, or GC-TCD depending on the target gas. All analysis performed at our Houston TX lab.
AIHA LAP Accredited Report
Results vs. OSHA PEL, ACGIH TLV, NIOSH REL, and IDLH. QA/QC data included. OSHA/ACGIH limit disparities flagged. Control recommendations on exceedances. Lab accreditation number on all reports.
Inorganic Chemical Testing — FAQ
What NIOSH method is used for hydrogen sulfide (H₂S)?
What is the OSHA PEL for chlorine gas?
What is the OSHA PEL for SO₂ and why is the ACGIH TLV so different?
What is the OSHA PEL for nitrogen dioxide and why does NO₂ cause delayed injury?
What is the IDLH for hydrogen sulfide and what does olfactory paralysis mean?
What sampling media is needed for ozone (O₃) monitoring?
What is the OSHA PEL for carbon monoxide and why is CO so dangerous?
What industries most commonly need inorganic chemical testing?
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ISO/IEC 17025 · AIHA LAP · NIOSH 6013–6019 · IC · UV-Vis · GC-TCD · 10 Gases · Houston TX
