AIR SAMPLING ARTICLE

New Market Opportunities for VOC Air Sampling Labs

By Irene DeGraff, Product Marketing Manager

Expand into new markets with existing equipment.
New applications for air sampling canisters and thermal desorption tubes.
Quick comparison table contrasts sampling techniques.

As the economy contracts, many labs are looking for new market opportunities. Fortunately, the existing equipment and expertise used for VOC air sampling and analysis can be used for a variety of applications beyond typical environmental monitoring. By broadening market reach, labs can increase both capabilities and revenue without incurring additional expenditures for equipment or staff. Air canisters and thermal desorption tubes, the workhorses of VOC air sampling, are broadly applicable techniques that can be used by labs to enter new markets with applications such as:

Enter new markets based on the versatility of existing sampling equipment.

industrial hygiene
odor profiling for flavor & fragrance testing
chemical warfare agents
material emissions from consumer products

Canisters and thermal desorption sorbent tubes are all encompassing techniques that can be utilized in a host of sampling environments. With these complementary techniques, a broad range of volatiles—and many semivolatile compounds—can be collected and subsequently analyzed at low part-per-billion concentrations. While these techniques have many similarities, such as reusability and long product lifetime, they also differ in some regards. Use Table I to compare these versatile techniques and determine which is best for a given application.

Both techniques are suitable for GC/MS applications that require trace-level analysis of volatile compounds, and instrument manufacturers have responded by creating sample concentrators that can accommodate both types of these sampling devices on a single analytical platform (Figure 1).

Exploring the new markets that can be served using air sampling canisters and thermal desorption tubes creates an opportunity for labs to expand beyond traditional environmental VOC air monitoring. Serving new markets with existing staff and equipment is a smart way to survive, or even thrive, during tough economic times.

Table I: Comparison of thermal desorption tube and canister sampling for VOCs.

Similarities Between Thermal Desorption Tubes and Canisters

Reusable sampling device.
Long product lifetime.
Long-term sample stability.
Blank certification required prior to sampling.
Sample concentration required before GC/MS analysis.
Dry purge helpful to remove moisture before GC injection.
Ppt sensitivity.
Method acceptance.
Collection of wide range of VOCs with single device.
Useful for screening of unknowns.
Leak tightness critical to maintaining sample integrity and preventing contamination of a clean device.

Differences Between Thermal Desorption Tubes and Canisters

	Thermal Desorption Tubes	Canisters
Methods	US EPA TO-17 ASTM D6196 ISO 16017, ISO 16000-6 NIOSH 2549	US EPA TO-14A, TO-15 ASTM D5466 OSHA PV2120 NIOSH Protocol Draft
	World-wide acceptance	Gold standard for US ambient air market
Applications	Ambient air, indoor air, industrial hygiene Material emissions Food & flavor Chemical weapons	Ambient air, indoor air, vapor intrusion, emergency response
	C3 to C30	<C3 to ~C10
Handling	Light weight for personal monitoring and general ease of use	Larger and heavier; more costly to ship
Sampling	Active sampling with sampling pump or diffusive sampling without pump is possible with determined diffusion coefficients for each compound.	Passive sampling, no sampling pump required. Long-term sampling possible without battery to recharge.
	Integrated sampling only	Grab & integrated sampling
	Concentrated sample	Whole air
	Proper sorbent selection recommended in methodology.	N/A
	Must sample below sorbent breakthrough volumes to avoid sample loss and irreversible adsorption on sorbent	N/A
	Large sample volumes >100L	Sample volume is function of canister size, 15L max
Analysis	Tube dimensions are instrument specific	Compatible with all manufacturer sample concentrators
	1 injection, more injections possible for some instrumentation	Multiple sample injections
	Concentration range ppt to ppm	ppt to ppm
	Some sorbents prone to artifact formation.	Low blanks when properly cleaned.
Storage	Sample storage at 4°C recommended for multi-bed tubes to prevent potential migration of compounds to more retentive sorbent which maybe difficult to recover.	Room temperature
Cleaning	Analytical process automatically cleans tube for reuse. Cleans as it analyzes. Conditioning/cleaning and analysis incorporated in one thermal desorption unit.	Canister cleaning requires separate equipment as additional step prior to background certification and sampling.
Cost	$50-130 each	$200-700 each