Flash-VASE™ Applications include:
Flash-VASE™ provides for precise analysis of VOCs & SVOCs in matrices with low volatility.
Introducing Flash-VASE. What Is It?
Flash-VASE is a next generation Thermal Extraction technique that places the sample in very close proximity to the collection sorbent, and uses static extraction under vacuum to more efficiently and completely recover volatile through semi-volatile compounds. Flash-VASE places the sample within a few centimeters of the collection sorbent, with no flowing gases to heat up the sorbent during the extraction which is a known problem with dynamic headspace techniques, so the collected compounds stay optimally close to the front of the sorbent bed for fast and complete release to the GC. Extraction under a vacuum allows recovery of chemicals at a lower temperature, reducing or avoiding breakdown of the matrix itself. Flash-VASE has a tremendous number of advantages over other thermal extraction techniques, allowing Chemists to truly “See What’s Really There™”, in a way that keeps the analytical system clean and free from carryover.
Flash-VASE is intended for samples containing relatively low moisture and solvent levels, as the sample is heated anywhere from 30 °C to 330 °C while in a closed system, so the potential for generating a substantial amount of vapor during Thermal Extractions should be considered. However, small amounts of water can be Flashed onto the Sorbent Pen with removal afterwards either by cooling the vial on a cold tray to pull water back down out of the Pens, or by placing a vacuum on the Pens to pull the water off prior to thermal desorption into a GCM
Sorbent Pen Selection Guide
FSP Sorbent Pens - For 2, 6, 20 and 40 mL Vial Flash-VASE
Flash-VASE – Technique Selection Guide
Sample Type: Solids/Liquids w/ Low Volatility Matrix
Applications: Odors/Contaminants/Aromas in Packaging, Polymers, Powders, Foams, Synthetics, Natural Products, Heavy Oils
Extraction Temperatures: 2-Stage Ramp
– Front 9: 30 °C to 200 °C
– Back 6: 30 °C to 330 °C
Extraction Times: 2-60 Min (Matrix Dependent)
Operational Mode: Static Vacuum Thermal Extraction
BP Range: -50 °C to >500 °C (depending on extraction temperatures and sorbents used)
Vial Sizes: 2, 6, 20, or 40mL
Typical 5800A Mode: SPLIT or SPLITLESS
Water Management: Split Injection / Post Extr. Vial Cooling / Post Extr Vac. Dehydration
Flash-VASE Process
Weigh/measure sample into vial, attach vacuum sleeve and Sorbent Pen, and evacuate the Pen/Vial assembly, with optional fill/evac with Nitrogen to further Lower Oxygen Levels
Place Vial/Pen assemblies in Flash-VASE module and perform extractions while under vacuum by heating sample vial to any temperature between 30-330 °C
Remove excess water either through cold tray dehydration or by forward vacuum extraction
Desorb Pens using 5800A SPDU either manually or using an SPR Rail Autosampler
Extreme Precision, By Design
Flash-VASE provides incredibly reproducible results, by eliminating the inconsistencies inherent in dynamically purged Thermal Extractions. Below is an example of 8 replicate Cannabis analyses for Monoterpene and Sesquiterpene profiling, and these 8 runs almost perfectly overlap. The Flash-VASE extraction times in these examples was just 5 minutes, at 100 °C. Higher temperatures will yield reproducible recovery of the Cannabinoids present in Cannabis.
Flash-VASE utilizing the Vacuum X-traction Bar (VXB)
The Vacuum X-traction Bar (VXB) supports sample extraction onto Sorbent Pens and the cleanup of associated extraction hardware (sleeves, O-rings, etc). The VXB allows extractions to be performed in the sample preparation area, with only the extracts on Sorbent Pens brought into the GCMS laboratory. This is similar to how sample preparation techniques are currently performed, except the Entech vacuum extraction methods are easier, cleaner, and more sensitive, all without the use of hazardous solvents. The VXB comes in 30” and 50” sizes, allowing for convenient above the bench management of the Flash-VASE Modules. Other modules may also be connected, such as the 3700 Thermal Vacuum Cleaning System, which is utilized to restore background-free extraction hardware before performing the next set of extractions.
The Flash-VASE Workflow
Flash-VASE Equipment
Click on the image to view the list
Flash-VASE Modules & Pumps
Cold Dehydration Tray and Accessories
Extraction Vials, Sleeves, Components, and Accessories
VXB - Vacuum X-traction Bars
Flash-VASE Controllers
FVASE15-B02(-HV) Bundles
| Methods | FLASH-VASE | Micro-Chamber Extraction | Direct Thermal Extraction/DHS |
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| Extraction System / Sample Prep | Glass Vials (2, 6, 20, or 40mL) are used as extraction chambers whereby samples are placed under vacuum to reduce required recovery temperatures, with subsequent heating of the vial from ambient up to 280 deg C to extract volatile to semi-volatile compounds | Microchamber thermal extraction is a sampling technique used to collect volatile and semi-volatile organic compounds (VOCs and SVOCs) released from products or materials. The technique involves using a compact unit with cylindrical chambers that can withstand temperatures up to 250°C. The released compounds are collected onto sorbent tubes for analysis by TD-GC-MS. | DTE (Direct Thermal Extraction) is a technique used to desorb volatile through semi-volatile compounds directly into a GCMS by placing the solid sample into a glass tube and using the GC carrier gas to thermally desorb the sample directly onto the GC column, with optional LN2 focusing |
| Extraction Technique | VASE- Vacuum Assisted Sorbent Extraction in a closed system. No breakthrough possible during sample heating | Flow through Dynamic Headspace in an “Open System”. Breakthrough of lighter compounds possible during sample heating while trapping the evolving compounds | The tube containing the sample is heated to release the analytes, which are then transferred to the GC column for separation and detection. |
| Water/Moisture Removal | After Extraction, the vial can be cooled to draw moisture back into vial, as typically there is little affinity of moisture to the sorbent. Only possible due to extraction in a “closed system”. Limiting moisture improves GCMS performance | Moisture must be purged through the sorbent, resulting in potential loss/breakthrough of lighter VOCs of interest | Split injection is the only means to limit the amount of water reaching the GCMS. Water may clog LN2 focuser if excessive. |
| Desorption System | Specialized Thermal Desorption System Installed Into GC. | Thermal Desorption System located next to the GC requiring the use of long transfer lines and potentially cold or focusing traps. | Extracted analytes are introduced into the GC column either by transfer from a cold trap or by direct injection |
| Injection Technique | Split or Splitless | Split or Splitless | Split or Splitless |
| Effective BP Range | -40C to 550C, depending on sorbents | Highly Dependent on Sorbents due to flow through trapping and further penetration of compounds into sorbents. Potential loss of compounds from sample to trap, through longer flow path | Recovery of compounds performed under pressure of carrier gas, which may limit diffusion of heavier compounds out of samples matrix. Recovery is matrix dependent. |
| Ad/Absorbent Phases | All phases, 1, 2, or 3 beds weak to strong. 2 Beds Typical | Activated Charcoal, Tenax TA, Carbopack X, and Porapak Q, among others (is this what they state on their website?) | No adsorbents used during Direct Thermal Extraction |
| Carry Over – Extraction System | Glass vials are low cost and disposable saving cleaning time. Vacuum sleeves (Sorbent/Vial interface) cleaned using specialized steam + dry cleaning in 1L vials under vacuum. | Microchamber must be thoroughly cleaned between sample analysis to avoid carryover. Substantially more surface area to clean up than other two techniques. | Residual analytes from previous samples can potentially contaminate subsequent samples, leading to false positives or inaccurate results. Careful cleaning of the DTE system and appropriate blank runs between samples can minimize carryover issues, but they still need to be considered when using this technique. |
| Carry Over – Adsorbent Traps | No active flow through traps, so compounds stay maximally close to trap entrance. More complete recovery during desorption, with far less carryover than Dynamic Headspace Sampling | Channeling into sorbent caused by inconsistency in sorbent packing due to expansion and contraction during heating and cooling cycles may require much longer bakeout times to totally remove chemical residual from last sampling event. This is inherent with most Dynamic Headspace sampling techniques | No adsorbent used |
| Distance to head of GC column from heated desorption point. | 1-2cm | Potentially meters long. | Direct GC Inlet. |
| Advantages of Flash-VASE & Other Key Differentials. | No Transfer Lines: Extracted sample is injected nearly at the head of the analytical column avoiding long transfer lines where losses and cross-contamination may occur.
Avoids channeling: Static vacuum extraction allows for a consistent and graduated deposition of analytes based on BP and size, eliminating issues with channeling which can cause losses of heavier compounds that find their way deeper into the adsorbent or potentially into a stronger bed where they may not come off. Reproducibility Issues: Vacuum eliminates “low flow dead volume” concerns found in other two techniques. The entire sample is exposed to the vacuum and heat equally |
Dynamic-Flow Conditions: The use of an extraction gas may cause heavier analytes to deposit deeper than desired in the sorbent trap and may also sweep heavy unwanted compounds onto the trap.
Long transfer lines used in the microchamber technique can cause issues with compound degradation or loss during transfer from the microchamber to the gas chromatography (GC) column. This is because the long transfer lines can cause some of the desorbed compounds to condense or react with the transfer line material or with other compounds in the sample matrix. Reproducibility Issues: Exposure to the extraction gas may vary based on the cell loading, and the consistency of sample particle size and shape. |
Matrix effects: Typically must heat the sample higher than other two techniques, as injection times are limited. Thermal decomposition of the matrix is more likely, which can lead to the formation of interfering compounds and reduce the sensitivity of the analysis.
Incomplete extraction: Some analytes may not be completely extracted due to low thermal stability or short extraction times, leading to lower recoveries and reduced sensitivity. Reproducibility issues: Exposure to the desorb gas may vary based on the tube loading, and the consistency of sample particle size and shape. Sample handling concerns: May be difficult to load the sample into ¼" OD glass tubes, requiring further grinding/sample preparation which may cause loss of some compounds. Flash Back Concerns: May cause contamination if the concentration of volatiles are too high, causing significant gas expansion that can push the sample “backwards” into the carrier gas delivery lines. |
| Extraction Time | 2-20 min | 2-20 min | 1-5 min |
Compare All Sorbent Pen Extraction Techniques For Complete Coverage of VOC to SVOC Analysis Of Virtually Any Matrix
| Label | Vase | F-Vase | Feve | LVSH |
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LABEL |
VASE |
Flash-VASE |
FEVE |
LVSH/X-LVSH |
Full Name |
Vacuum Assisted Sorbent Extraction |
Flash-VASE |
Full Evaporative Vacuum Extraction |
(Extremely) Large Volume Static Headspace |
Sorbent Pen Type |
HSP |
FSP |
FSP |
ASP |
Vial Size |
20, 40, 125mL |
2, 6, 20mL |
2, 6 mL |
250, 500, 1000mL |
When to Use |
Liquid or Solid Sample Compositional Analysis. SPME Alternative |
Samples with low volatile contents (solids, powders, polymers, packaging, oils) |
Volatile Matrix with low solid contents (water, beverages, solvent extracts) |
Measurement of equilibrated headspace to determine partition coefficients of aroma compounds. |
Extraction Technique |
Vacuum, Diffusive, Closed System, Mechanical Agitation |
Diffusive Vacuum Thermal Extraction, Closed System |
Matrix Evaporative Transfer followed by heated, Diffusive Extraction in Open System, Matrix eliminated |
Dynamic, Fully equilibrated headspace, Static, Open System |
Vial Temp Range |
30° to 70° C |
30° to 280° C |
30° to 280° C |
30° to 70° C |
BP Range |
-50° to 450° C |
-50° to 550° C |
80° to 550° C |
0° to 450° C |
Water Management |
Cold tray dehyd., Dry Purge, Split Inj. Capillary Focusing Trap |
Cold tray dehyd., Dry Purge, Split Inj. |
Vacuum Removal |
Dry Purge, Split |
Typical Pen Cycle Times |
200-2000 |
200-1000 |
500-2000 |
100-200 (except not for disposible / replaceable inlet filter) |
Competitive Technologies Displaced |
SPME, SPME Arrow, SPE, SBS |
Micro Chamber, Direct Thermal Extraction, DHS |
SBSE, Hi-Sorb, Full Immersion SPME |
All other non-static, low sensitivity techniques |
Typical Sorbent Combinations |
Tenax, Tenax / CPX, PDMS GB / Tenax, Tenax / Carboxen |
Tenax, Tenax / CPX, PDMS GB / Tenax, Tenax / Carboxen |
PDMS GB / Tenax, Tenax / CPX |
PDMS / Tenax, Tenax / Carbopack X |
Common Applications |
Food, Beverage, Flavor, Aroma, Water, Consumer Products |
Volatiles / Odors in Packaging, Polymers, Powders, Foams, Synthetics, Natural Products, Cannabis, Heavy Oils |
SVOCs in Water, Flavors / Aromas in Thermally Labile samples, Pesticides in foods. |
Aroma / Flavor Profiling |
Definitions:
Open System - Unretained compounds/gases allowed to pass through sorbent for removal by pump/vacuum.
Closed System - Completely isolated during extraction, so breakthrough of even the lightest compounds isn't possible. Allows recovery of wider boiling point compounds.
Flash-VASE A Safer and Better Way to do Thermal Extraction
Many systems attempt to perform thermal extraction by placing a sample into a tube and then directly thermally desorbing it into a GC. However, there are several draw-backs associated with this approach:
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Samples may not transfer quickly from the sample to a GC column since chemicals of interest will not release very fast from many matrices, causing poor peak shape unless a secondary trapping or focusing system is used- Therefore, direct desorption methods often have to heat samples hotter to reduce band broadening, but higher temperatures will increase thermal degradation of the target compounds and the matrix
- Liberated compounds must remain in contact with the matrix longer during a pre-heating step, rather than allowing their removal once they become mobile
- Chemicals must diffuse out of the matrix at positive GC carrier gas pressures which slows down outgassing rates relative to a vacuum thermal extraction approach
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Samples with a high volatiles content can backflash into the GC carrier gas delivery lines, permanently contaminating the lines until the entire injection system is removed and solvent rinsed. -
Many matrices simply cannot be heated to GC injection temperatures, even momentarily, without changing them chemically, potentially creating artifact chemicals that were not in the original sample -
There is no water/moisture management opportunities when directly desorbing a sample into a GCMS -
Loading a sample into a 1/4” glass tube before direct desorption is more difficult than loading it into a vial, and some sample may drop into the desorber or injector, creating a background until removed
Flash-VASE solves all of these problems by performing an offline vacuum thermal extraction, followed by a moisture removal step if necessary using either a cold plate or applied vacuum once the Pen is removed from the sample vial. This not only improves the performance of thermal extraction solutions, Flash-VASE may be the only way to perform thermal extraction on many thermally labile matrices.
Flash-VASE Improves Performance over Off-Line Dynamic Thermal Extraction
Other thermal extraction systems use small chambers or micro chambers which attempt to thermally extract samples by heating them, flowing a gas over them, and delivering the desorb gas through an outlet port/fitting and into a classical sorbent tube. There are numerous problems associated with this approach as well:
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The cell or chamber can become contaminated when exposed to higher concentration samples
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Difficulty in removing contamination in tubing/fittings between the chamber and the TD Tube
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Loss of high volatility compounds that breakthrough the sorbent in this “open” system
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Loss of low volatility compounds that adsorb to surfaces prior to reaching the TD tube
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Heating of the front of the sorbent bed can occur when trying to maintain a hot transfer system all the way to the collection sorbent. Hot gas introduced onto a sorbent will allow compounds to penetrate further into the sorbent, resulting in lower thermal desorption recoveries and greater potential for carryover
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Channeling Effects are exhibited while flowing through a sorbent trap, causing reduced recovery, increased carryover, and increased thermal degradation by requiring higher desorption temperatures during analysis
Flash-VASE eliminates these concerns as well. A glass vial is the entire “sample chamber”, which is used once and discarded, so no chance of carryover. There are no transfer lines and connective fittings in the flow path, as the opening of the Sorbent Pen is right at the top of the vial. There is no hot carrier gas to heat up the sorbent, so the penetration of compounds into the sorbent is far less, making their recovery during thermal desorption more complete and at lower desorption temperatures. The Flash-VASE closed system means that even very light compounds will be recovered, as long as they have more affinity for the sorbent in the Pen than they do for the heated sample matrix. Finally, the extraction occurs diffusively, eliminating channeling and all of the negative effects this has on recovery, carryover, and sampler lifetimes.
Compare All Sorbent Pen Extraction Techniques For Complete Coverage of VOC to SVOC Analysis Of Virtually Any Matrix
