Gas mixtures may include, but are not limited to; natural gas, coal seam gas, ambient air and air from occupational environments.
TEG is a straight-chain dihydric alcohol terminated on both ends by a hydroxyl group. It is a clear, practically colourless and odourless liquid at room temperature.
ALS Method Code
Limits of Reporting (LOR)
0.4μg/sampler, 0.1mg/m3, 0.02ppmV
The ALS method (EP253) is based on NIOSH Method 5523, where glycols are collected on OSHA Versatile Sampler (OVS) tubes. Samples are collected by attaching an open tube to a collection train connected to a sample pump and pulling a known volume of air through the tube. The sampling tubes contain an absorbent resin (XAD-7) which retains glycols. Once at the laboratory, the resin sections are removed and extracted into methanol. Analysis is by High Performance Liquid Chromatography, Tandem Mass Spectroscopy (HPLC-MSMS).
Figure 1. Occupational Safety and Health Administration (OSHA) Versatile Sampler (OVS) Tube
Limits of reporting (LOR) are provided below. The LOR is based on a minimum sampling volume of 5 litres (up to 60 litres), with sampling rates from 0.5 litres/minute to 2 litres/minute.
|Analyte||Cas Number||Limit of Reporting (LOR)|
|Triethylene Glycol (TEG)||1127-27-6||0.4μg/sampler||0.1 mg/m3||0.02 ppmV|
Where field sampling data is not provided, results are reported in μg TEG per sampler units. Results can also be reported in mg/m3 and ppmV (parts per million volume) units, based on the volume of air sampled. The field data required to calculate the sampling volume are provided below. Some high volume samplers automatically calculate the totalised corrected volume of air sampled, in which case only the volume data needs to be supplied to the laboratory. NATA accreditation only covers mg/m3 and ppmV units where the sampling process is included under the sampler’s Scope of NATA accreditation. Accreditation details for the NATA endorsed field data must be provided to the laboratory in order for ppmV results to be provided on a NATA endorsed report.
Field sampling data required for converting μg/sampler units to mg/m3 and ppmV:
- Initial flow rate (L/min)
- Final flow rate (L/min)
- Sampling time (min)
- Mean ambient temperature (Kelvin)
- Mean ambient barometric pressure (kPa)