To reduce exposure to air pollution several limits and target values for air quality have been set. The maximum value for benzene exposure is currently set at 0.7 mg/m3 (0.2 ppm). To determine Benzene in air Da Vinci Laboratory Solutions developed an automated GC solution equipped with a sampling technique. 

The Benzene in Air application is based on an Agilent Technologies 7890B GC configured with:

• a FID or TCD
• a custom programmed temperature vaporization (PTV) injector
• an analytical column and a pre-column
• a gas sampling unit

The sampling unit uses a sampling pump, a mass flow controller and a multi-positioning valve. The multi positioning valve allows sampling direct from e.g. a Tedlar bag or taking sample directly from open air. Up to 8 samples or standards can be automatically selected and analyzed.

Collect the samples in Tedlar bags and use the stream selection valve to select either standards, samples and/or multiple samples for an automated analysis. The system’s PTV injection port is modified to contain a sorbent tube as injection port liner which ensures a rapid adsorption and desorption of Benzene.

Alternatively collect the sample on a sorbent trap using a programmable sampling pump. The sorbent trap is placed in the PTV inlet and automatically purged prior to thermal desorption and subsequent analysis.

The gas sampling unit automates the process of sampling, adsorbing and desorbing. After benzene has eluted from the precolumn to the polar column, the remainder of the matrix is backflushed to vent. 
The Benzene in Air analysis requires 25 minutes.

To extend the analysis to C6-C8 aromatic compounds (BTEX Analysis) just switch the backflush after elution of o-Xylene.

The Benzene in Air application shows an excellent performance as demonstrated in the tables using a custom calibration gas standard.

Table One: Detection limits of Benzene in Air.

Table Two: Repeatability of Benzene in Air

• Automated gas sampling, absorbing and desorbing
• Based on a sampling technique for VOC's in Air
• Various options for sample collection possible
• Up to 8 samples or standards can be selected and sampled
• Analysis can be extended to BTEX in Air
• Excellent performance specifications

Please download the flyer or  contact us for more information