NorthKawamura Model 721 Toluene / Xylene / Ethylbenzene Air Sampling Detection Tube

Overview

The NorthKawamura Model 721 is a chemically impregnated colorimetric gas detection tube designed for rapid, on-site qualitative and semi-quantitative determination of toluene, xylene (o-, m-, p-isomers), and ethylbenzene vapors in ambient air. It operates on the principle of length-of-stain color development: when a known volume of air is drawn through the tube via a calibrated hand pump or motorized sampling device (e.g., ASP-1200), target aromatic hydrocarbons react with pre-deposited reagents—typically sulfonic acid derivatives or modified silica gel matrices—generating a visible color front. The length of the stained zone is directly proportional to the concentration of analyte(s) present, enabling immediate visual estimation against printed calibration scales on the tube body. This method complies with JIS K 0321 (2021) for colorimetric gas detection tubes and aligns with ISO 8518:2022 for manual air sampling devices used in workplace and indoor environmental monitoring.

Key Features

• Triple-analyte capability: Simultaneous detection of toluene, total xylenes, and ethylbenzene without cross-interference under typical indoor conditions (20–25 °C, RH < 70 %)
• Pre-calibrated linear response: Stain length vs. concentration relationship validated across three concentration ranges per analyte (e.g., 0.5–10 ppm for toluene; 1–20 ppm for xylenes; 0.3–6 ppm for ethylbenzene)
• Stable shelf life: 24 months from date of manufacture when stored at 5–25 °C in original sealed aluminum pouch; desiccant included
• Integrated reference scale: High-contrast printed calibration markings with ±10% reading tolerance per JIS K 0321 Annex B
• Compatible with standard 100 mL and 200 mL manual pumps (e.g., Gastec CC-100) and motorized systems including ASP-1200 (flow rate: 100 mL/min ±5%, 10 min draw)
• No power, no software, no consumables beyond the tube itself—ideal for field triage, post-spill screening, and HVAC commissioning verification

Sample Compatibility & Compliance

The Model 721 is validated for use in non-condensing, particle-free air samples collected from indoor environments, laboratories, paint storage areas, printing facilities, and vehicle cabins. It is not intended for use in high-humidity (>80% RH), high-temperature (>40 °C), or oxidizing atmospheres (e.g., chlorine, ozone >0.1 ppm). Interference testing per ISO 8518 Annex D confirms negligible response to common co-volatiles including acetone (≤500 ppm), ethanol (≤1000 ppm), and formaldehyde (≤5 ppm). Each batch undergoes lot-specific calibration traceability to NMIJ (National Metrology Institute of Japan) certified gas standards. Documentation includes Certificate of Conformance (CoC) and JIS-compliant test report per shipment.

Software & Data Management

As a passive, analog detection system, the Model 721 requires no embedded firmware, drivers, or proprietary software. Quantitative interpretation relies solely on visual comparison against the printed scale. For digital recordkeeping, users may log readings manually into LIMS or EHS platforms using standardized fields: sample ID, date/time, pump model/lot, draw volume, observed stain length (mm), estimated concentration (ppm), and operator signature. When deployed in regulated environments (e.g., ISO 14001-certified facilities or OSHA-regulated workplaces), documentation must include pump calibration certificate (valid ≤6 months), tube lot number, and environmental conditions at time of sampling—satisfying GLP-aligned data integrity requirements per EPA Method IP-1A guidance.

Applications

• Routine indoor air quality (IAQ) surveys in offices, schools, and residential buildings following renovation or solvent-based coating application
• Emergency response screening after suspected VOC leaks or improper solvent storage in industrial settings
• Verification of fume hood performance and local exhaust ventilation efficiency during maintenance audits
• Pre-occupancy testing for LEED IEQ Credit 3.2 (Indoor Air Quality Assessment) and WELL Building Standard W09
• Compliance checks against Japanese Indoor Air Quality Law (Ministry of Health, Labour and Welfare Notification No. 77) limits: toluene ≤ 200 µg/m³ (~50 ppb), xylene ≤ 100 µg/m³ (~25 ppb), ethylbenzene ≤ 200 µg/m³ (~50 ppb)
• Training tool for occupational hygiene technicians due to its intuitive visual output and minimal procedural complexity

FAQ

What is the minimum detectable concentration for each analyte?
Toluene: 0.5 ppm; Xylenes: 1.0 ppm; Ethylbenzene: 0.3 ppm — based on 100 mL air draw at 100 mL/min.
Can the tube be reused after sampling?
No. The reaction is irreversible; each tube is single-use only per JIS K 0321 Clause 6.2.
Is temperature correction required during analysis?
Yes. Readings must be adjusted using the temperature compensation chart provided in the instruction leaflet if ambient temperature falls outside 20–25 °C.
Does this tube meet OSHA or NIOSH method equivalency?
It is not certified as equivalent to OSHA ID-152 or NIOSH 1501, but serves as a screening tool preceding full laboratory analysis per those methods.
How should expired tubes be disposed?
Dispose as hazardous chemical waste per local regulations; do not incinerate or drain contents—reagents contain sulfonic acid derivatives classified under UN 3265.