Sorbent Pens™ for Quantitative Air Monitoring

Sorbent Pens mark the latest innovation in quantitative air monitoring from Entech Instruments. These adsorbent based samplers can either be used to collect air via diffusion without the aid of a pump or vacuum device (Diffusive Sorbent Pens, or DSPs), or they can be actively sampled by drawing air through them (Active Sorbent Pens, or ASPs). [expand title=”Read More” swaptitle=”Minimize”] Unlike the standard thermal desorption tubes that use the same geometry to do either diffusive or active sampling, the Sorbent Pens have been optimized to improve their performance for both of these “very different” sample collection approaches. This has been done to optimize the quantitative results, and to increase the durability and lifetime of each adsorbent based air monitoring device.[/expand]

Perfect for US EPA Method 325 Compliance

Passive Sampling on ¼” OD Tubes

The Sorbent Pen Does it Better!

New Diffusive Sorbent Pen and 5800 SPDU (Sorbent Pen Desorption Unit) provide great results for compounds ranging from Benzene to Xylenes, with canister like performance and reproducibility.

Diffusive Monitoring of BTEX

Collection Times from 8 hours to 2 weeks

The sampling end of the DSP Sorbent Pen exactly meets EPA 325 requirements for diameter and distance to adsorbent

Complete Sorbent Pen Air Monitoring System

View chromatographs below

4200 Sorbent Pen Spiking System

Fully automated way to accurately spike standards onto Sorbent Pens

DSP Badge Personal Monitors

More Reliable and Sensitive than Solvent Extraction Badges

Higher sensitivity due to much greater percentage of sample reaching the detector during analysis (thermal desorption rather than solvent extraction)

Benefits of passive/diffusive sampling:

Entech Sorbent Pens™ represent in advancement passive ’diffusive’ sampling, incorporating many subtle but critical engineering design elements that ensure quantitative recovery, reproducibility, and cost effective long term use. The result of decades of research into volatile chemical sampling and analysis has resulted in a sampler so accurate and reproducible that the data is almost unbelievable!

[expand title=”Read More” swaptitle=”Minimize”] Passive or diffusive sampling is defined as the unassisted molecular diffusion of gaseous analytes through a diffusive region and onto an adsorbent. The DSP (Diffusive Sorbent Pen) does not require a pump and contains no moving parts. After sampling, the adsorbed analytes are desorbed directly into the GC or GCMS of choice.
• Compact, portable, unobtrusive, and inexpensive
• Offers indication of average pollution levels over time periods of 8 hours to several weeks
• Requires no supervision, is noiseless and can be used in hazardous environments
• Low cost allows for sampling at multiple locations (e.g., for highlighting pollution “hotspots”; or determining long term data trends in a specific geographical area)
• Amenable to personal monitoring (breathing zone), indoor air analysis, and outdoor ambient air analysis [/expand]

Entech Sorbent Pen Hood

US EPA
Method 325

Passive Sampling on ¼” OD Tubes

The Sorbent Pen Does it Better!

• Meets requirements of U.S. EPA Method 325 finalized Fall 2015
• 8 hr – 2-week passive sampling provides highly reproducible results for BTEX and similar boiling range VOCs.
• More reproducible than radial samplers because the sample is backflushed during thermal desorption rather than pushed through the entire adsorbent bed.
• Carbon Tetrachloride is quantitatively recovered, so Global background of 70 ppt can be used to validate proper sampling when performing GCMS or GC/FID/ECD

Sorbent Pen Air Monitoring System

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Diffusive Monitoring of BTEX

• The sampling end of the Diffusive Sorbent Pen™ exactly meets EPA 325 requirements for diameter and distance to adsorbent
• A diffuser is used at the end of each tube to prevent convective transfer during windy days
• No LN2 needed. Typical split of 20:1 produces low part per trillion detection limits
• A 0.5um x 5m pre-column and an Entech CL-BTEX-30 main column allow compounds heavier than BTEX to be backflushed off of the pre-column for much shorter run times
• Internal Standard can be added to each tube before analysis

Perfect peak shape without LN2 focusing. Back-Flushing eliminates ghost peaks and reduces run times

Perfect peaks chromatography

Triplicate sampling of 325 Sorbent Pen & virtually perfect overlap of BTEX compounds

method 325

325 Sorbent Pen Comparison to Canister Sampling and Triplicate Pen Results at Elevated LevelsBTEX

325 Sorbent Pen

4200 Sorbent Pen Spiking System

• Fully automated way to create accurate spiking of standards onto Sorbent Pens
• Separate Calibration Standard and Internal Standard spiking ports to prevent any possibility of cross contamination
• Can spike 1 to 200cc of calibration standard or 5cc of internal standard automatically using calibrated reservoirs
• Self-purges using UHP Nitrogen
• Compatible with all Sorbent Pens, but primarily intended for DSP and AAM Air Monitoring Pens
• Not compatible with 3.5” TD Tubes
• Single model handles all voltages (90-250VAC)

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Benefits of passive/diffusive sampling:

• Calibrations were performed over a 200x range. The 4200 performed all spikes automatically
• All compounds had %RSDs within 4-7%
• US EPA Method 325 allows for up to a 30% Relative Standard Deviation, so the Sorbent Pen easily meets these criteria.
• Concentrations were based on the sampling rate for Benzene, and how much would have loaded during the 2 week sampling period specified in Method 325

New DSP Badge Samplers

More Reliable and Sensitive than Solvent Extraction Badges

• Diffusive sampler that collects a wide range of compounds
• Several adsorbents available depending on compounds to be collected
• The DSP Badge has several advantages
– Higher sensitivity due to a much greater percentage of sample reaching the detector during analysis (thermal desorption rather than solvent extraction)
– 20-60 times lower sampling rates, so far less likely to “starve” during sampling (common problem with other badges) Easier analysis. Just spike with 4200 and desorb

Dual Sampler also Available

• Allows DSP Badges with different adsorbents to be used together to increase range of chemicals to be monitored
• Perfect when duplicates are needed
• Uses diffusers on the Pen inlets to prevent convective transfer, so diffusion is the only transport mechanism onto the adsorbent
• Just like badges, chemicals will have different diffusion rates, but the Diffusive Sorbent Pens have adopted the same inlet geometry used by 3.5” diffusion TD Tubes, so sampling rates for a large number of compounds are already known.

DSP Badge Personal Monitors

Note: For diffusive sampling, each compound must irreversibly “stick” to the adsorbent in order for quantitative collection to occur. This is why the lowest acceptable carbon number is “higher” than with active sampling. Also, carbon number ranges above are approximate and must be verified for each compound.

325 Sorbent Pen / 5800 SPDUAdvantages over Classical 3.5” TD Tubes

• Improved design allows much lower blank levels
• Tube ends will not crush, as classical compression fittings are avoided
• This keeps sampling rates the same from tube to tube
• Direct desorption into GC improves recovery and reproducibility
• Pre-Column backflush eliminates the buildup of high molecular weight compounds
– Simple replacement of liner and pre-column creates an entirely new flow path, essentially creating a “new” system
– Very simple to operate, understand, and maintain
– The secondary traps and transfer lines in externally desorbed TD tube systems allow deposition of 4-7 ring PAH compounds that will eventually reduce recovery of light compounds while increasing column bleed and bakeout times. Dicult to replace flow path
• The 5800 SPDU and the 7200A can both connect into the same GCMS simultaneously with no replumbing to switch from Sorbent Pens to Canisters.

Download the DSP Brochure here!

Sorbent Pens mark the latest innovation in quantitative air monitoring from Entech Instruments. These adsorbent based samplers can either be used to collect air via diffusion without the aid of a pump or vacuum device (Diffusive Sorbent Pens, or DSPs), or they can be actively sampled by drawing air through them (Active Sorbent Pens, or ASPs).