The Gastec 122P Toluene Detector Tubes are designed for sensitive, low-level measurement of toluene (C6H5CH3) in air using a compatible automatic air sampling pump.

The 122P provides a quantitative measuring range of 100 to 7,000 µg/m³, with a detection limit of 50 µg/m³ under the specified sampling conditions. The detector system produces a white-to-pale-brown color change for visual determination of toluene concentration.

IMPORTANT: The Gastec 122P uses two connected tubes for each measurement. Each box contains 10 tubes for a total of 5 tests.

Automatic Air Sampling Pump Required

IMPORTANT: Gastec 122P Toluene Detector Tubes require a compatible automatic air sampling pump capable of maintaining a continuous 200 mL/min sampling rate.

Compatible Pump: Gastec GSP-501FT Automatic Air Sampling Pump

The 122P is an automatic air sampling pump detector tube and should not be treated as a standard hand-pump detector tube.

For the primary measuring range, the pump must maintain 200 mL/min for 30 minutes. For the extended measuring range, sampling is performed at the same 200 mL/min rate for 10 minutes.

Do not substitute a standard manual Gastec detector tube pump for the required automatic sampling method.

Measurement & Sampling Specifications

Measurement Range	Sampling Rate	Sample Volume	Correction Factor	Sampling Time
100–2,500 µg/m³	200 mL/min	6,000 mL	1	30 Minutes
2,500–7,000 µg/m³	200 mL/min	2,000 mL	2.8	10 Minutes

For measurements from 100 to 2,500 µg/m³, sample at 200 mL/min for 30 minutes, providing a total sample volume of 6,000 mL.

If the discoloration exceeds 2,500 µg/m³, prepare a fresh detector tube set and sample at 200 mL/min for 10 minutes, providing a total sample volume of 2,000 mL. Multiply the tube reading by the specified 2.8 correction factor for measurements up to 7,000 µg/m³.

Product Specifications

Brand: Gastec
Tube Type: Toluene Detector Tube for Automatic Air Sampling Pump
Part Number: 122P
Gas/Vapor Measured: Toluene
Chemical Formula: C6H5CH3
Measurement Range: 100–7,000 µg/m³
Primary Measurement Range: 100–2,500 µg/m³
Extended Measurement Range: 2,500–7,000 µg/m³
Detection Limit: 50 µg/m³ at 6,000 mL (minimum detectable concentration; not part of the quantitative measuring range)
Sampling Rate: 200 mL/min
Primary Sample Volume: 6,000 mL
Extended-Range Sample Volume: 2,000 mL
Correction Factor: 1 or 2.8 depending on measurement range
Primary Sampling Time: 30 Minutes
Extended-Range Sampling Time: 10 Minutes
Color Change: White → Pale Brown
Operating Temperature: 5–35°C (41–95°F), temperature correction not required
Operating Humidity: 0–80% RH, humidity correction not required
Relative Standard Deviation: 10% for 100–500 µg/m³; 5% for 500–2,500 µg/m³
Quantity: 10 Tubes
Tests per Box: 5 Tests
Shelf Life: 24 Months
Pump Requirement: Compatible Automatic Air Sampling Pump Required

Two-Tube Measurement System

The Gastec 122P requires two tubes to be connected together during each measurement.

Prepare the pretreatment tube and detector tube according to Gastec's instructions, break the required tube ends, and connect the tubes using the supplied rubber tubing before attaching the detector system to the automatic air sampling pump.

Because two tubes are consumed during each measurement, a box containing 10 tubes provides 5 complete tests.

Always follow the official Gastec 122P instruction manual for correct tube connection, orientation, and sampling procedure.

Low-Level Toluene Measurement

The Gastec 122P is designed for sensitive measurement of toluene in the µg/m³ concentration range, making it suitable for applications requiring substantially lower concentration measurement than conventional ppm-range detector tubes.

Its total quantitative measuring range extends from 100 to 7,000 µg/m³ using two sampling procedures.

The 50 µg/m³ detection limit represents the minimum concentration capable of producing a detectable reaction under the specified 6,000 mL sampling conditions. It is not part of the quantitative measuring range and should not be interpreted as a 50–7,000 µg/m³ measurement range.

During sampling, the detecting layer changes from white to pale brown.

Common Applications

Gastec 122P Toluene Detector Tubes may be used for applicable low-level toluene monitoring applications including:

• Residential Environment Air Monitoring

• Indoor Air Quality Testing

• Low-Level Toluene Monitoring

• Building & Facility Air Quality Investigations

• VOC Monitoring

• Environmental Atmospheric Monitoring

• Chemical & Solvent Vapor Investigations

• Industrial Hygiene Applications

• Laboratory & Research Applications

• Toluene Emission & Release Investigations

Other Substances Measurable

The Gastec 122P can also be used to measure certain other substances when the manufacturer's specified correction factors and sampling procedure are applied.

Ethyl Benzene

• Correction Factor: 1.1

• Sampling: 200 mL/min × 30 minutes

• Measuring Range: 110–2,750 µg/m³

Xylene

• Correction Factor: 5.4

• Sampling: 200 mL/min × 30 minutes

• Measuring Range: 540–13,500 µg/m³

These alternative measurements should be performed according to Gastec's official correction-factor instructions.

Operating Conditions

The Gastec 122P can be used from 5 to 35°C (41 to 95°F) without temperature correction.

The specified operating humidity range is 0 to 80% relative humidity, and humidity correction is not required.

Atmospheric pressure correction may be required according to the official Gastec 122P measurement procedure.

Possible Interferences

Certain coexisting substances may affect Gastec 122P measurements.

Xylene & Styrene: At concentrations of 1,000 µg/m³ or greater, may produce positive interference and a pale-brown color.

Aromatic Hydrocarbons: May produce positive interference and a pale-brown color.

Formaldehyde: At concentrations of 1/3 or less relative to the measured gas concentration, Gastec identifies no interference and no independent color change.

Gastec identifies ethanol, p-dichlorobenzene, alpha-pinene, and n-hexane as producing no interference and no independent color change under the manufacturer's stated test conditions.

Coexisting gases and vapors should always be considered when interpreting detector tube measurements.

Important

A compatible automatic air sampling pump is required for correct use of the Gastec 122P Toluene Detector Tubes.

For the primary 100–2,500 µg/m³ range, sampling is performed at 200 mL/min for 30 minutes, producing a total sample volume of 6,000 mL.

For the extended 2,500–7,000 µg/m³ range, prepare a fresh tube set and sample at 200 mL/min for 10 minutes, producing a total sample volume of 2,000 mL. Multiply the detector tube reading by the 2.8 correction factor.

Two tubes must be connected for each measurement. Therefore, 10 tubes provide 5 complete tests.

Do not use a standard manual detector tube pump in place of the required automatic sampling method.

Always follow Gastec's official instructions for tube connection, orientation, sampling rate, sample volume, sampling time, correction factors, atmospheric pressure correction, environmental conditions, possible interferences, and interpretation of results.

Compatible Pump: Gastec GSP-501FT Automatic Air Sampling Pump

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