Sputtered Silicon Solid Phase Microextraction Fibers with a Polydimethylsiloxane Stationary Phase with Negligible Carry-Over and Phase Bleed

Authors: Tuhin Roychowdhury2,  Dhananjay Patel2, Dhruv Shaha2, Anubhav Diwan3, Massoud Kaykhaii4,
Jason Herrington1, David  Bell1,  Matthew Linford2

1. Restek Corporation, 2. Department of Chemistry & Biochemistry, Brigham Young University, 3. Moxtek, Inc.,
4. Department of Chemistry, Faculty of Sciences, University of Sistan and Baluchestan

Published By: Journal of Chromatography A

Year of Publication: 2020

Link: https://doi.org/10.1016/j.chroma.2020.461065

We report the preparation of high performance, sputtered, polydimethylsiloxane (PDMS)-coated solid phase microextraction (SPME) fibers that show negligible carry-over and phase bleed. This process involves sputtering silicon onto silica fibers and functionalizing the resulting porous nanostructures with ultrathin films of vapor-deposited PDMS. Different thicknesses of silicon (0.25, 0.8, and 1.8 µm) and PDMS (8, 16, and 36 nm) were produced and their extraction efficiencies evaluated. The deposition of PDMS was confirmed by time-of-fight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), and contact angle goniometry on model, planar silicon substrates. These fibers were investigated using direct immersion SPME coupled with gas chromatography-mass spectrometry (GC-MS) analysis of a series of polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic pollutants. The 1.8 µm thick silicon coating with 16 nm of PDMS (Si (1.8 µm)/PDMS (16 nm)) produced the best response among the combinations tested. Conditions for the extraction of PAHs with this fiber were optimized and its extraction performance was compared to that of a commercial 7 μm PDMS fiber. The linearity (1 – 110 µgL−1), repeatability (RSD%, n=3) (17% ave.), and minimum detection limits (0.6 – 1.5 µgL−1) of the sputtered fibers were determined and found to be superior to the commercial 7µm PDMS fiber in many respects. Carry-over and phase bleed from commercial PDMS-based SPME fibers are two of their major drawbacks, which decrease their lifetimes and usefulness. Minimal carry-over and phase bleed were observed for our sputtered PDMS-coated fibers. In particular, our fiber only shows 12 % of the phase bleed of the comparable commercial fiber. In addition, it shows no carry-over for analytes with retention times greater than pyrene, and only 5 % of the carry-over of the other analytes. Our fibers could be used for at least 300 injections without any significant loss of performance.

Hunting Molecules in Complex Matrices with SPME Arrows: A Review

Author(s): Jason Herrington, German Gómez-Ríos, Colton Myers, Gary Stidsen, David Bell
Restek Corporation

Published By: Separations

Special Issue: Development of Alternative Green Sample Preparation Techniques

Year of Publication: 2020

Link: https://doi.org/10.3390/separations7010012

Thirty years since the invention and public disclosure of solid phase microextraction (SPME), the technology continues evolving and inspiring several other green extraction technologies amenable for the collection of small molecules present in complex matrices. In this manuscript, we review the fundamental and operational aspects of a novel SPME geometry that can be used to “hunt” target molecules in complex matrices: the SPME Arrow. In addition, a series of applications in environmental, food, cannabis and forensic analysis are succinctly covered. Finally, special emphasis is placed on novel interfaces to analytical instrumentation, as well as recent developments in coating materials for the SPME Arrow.

Quickly and Efficiently Extract Both Volatiles and Semivolatiles with New Triple-Phase SPME Fibers and Arrows

Restek first launched solid phase microextraction (SPME) automated sample preparation fibers to reduce sample handling and solvent consumption in many industries, such as environmental, food, and clinical. Soon after came rugged Restek PAL SPME Arrows, a revolution in microextraction that combines exceptional robustness with faster extraction times and trace-level sensitivity. Now, both fiber and Arrow lines are being expanded, including the addition of a sought-after triple-phase offering.

Of significant interest to many analysts, new triple-phase SPME fibers and Arrows provide exceptional versatility. This divinylbenzene (DVB)/carbon wide range (WR)/polydimethylsiloxane (PDMS) combination can be used for quick and efficient extraction of a wide range of both volatiles and semivolatiles, and it is an excellent choice for decision-making during method development because it combines the characteristics of three popular phases.

Restek’s full SPME line of fibers, Arrows, and accessories can be found at www.restek.com/SPME

Now Available for SPME Arrow: The Longer Life and Simplicity of Merlin Microseal Septa

Analysts have long enjoyed the benefits of Merlin Microseal septa for their traditional and SPME fiber injections—and now, you can switch to these innovative septa for your SPME Arrow applications, too!

The advantages of the Merlin Microseal septum include elimination of septum coring, longer life, and consistently low insertion force for injections. The Microseal septum incorporates two separate sealing mechanisms. These sliding seals eliminate septum coring and the resulting accumulation of septum crumbs in the injection port liner.

The Restek PAL SPME Arrow is a larger-diameter solid phase microextraction (SPME) probe with a rugged construction that ensures longer life, higher sample throughput, and better sensitivity over traditional SPME fibers. The Merlin Microseal for SPME Arrow is available for many popular instruments and both Restek PAL SPME Arrow sizes (1.1 mm and 1.5 mm). Installation is simple, requiring no modification of the injection port; although, due to the relatively large diameter of Restek PAL SPME Arrows, you must install an instrument-specific GC inlet conversion kit from Restek prior to use.

In addition to these new septa for SPME Arrow applications, Restek also offers Merlin Microseal adapter kits and septa for use in general-purpose (3 to 100 psi), low-pressure (1 to 45 psi), and SPME fiber (3 to 100 psi) applications.

Order your Merlin Microseal septa today at www.restek.com/merlin
You can also learn more about Restek’s full line of SPME products at www.restek.com/spme

Restek to Present at ExTech 2018

Restek is pleased to sponsor the 20th International Symposium on Advances in Extraction Technologies (ExTech) this year and will be presenting a technical talk on analyzing residual solvents in cannabis concentrates. You’ll find details about our presentation and new SPME Arrow technology below. We hope you can join us for this exciting conference on the cutting edge of sample extraction!


Thursday, June 21 (9:20-9:35 a.m.)

O_27     A Simple Approach to Analyzing Residual Solvents in Cannabis Concentrates via HS-GC


Colton Myers, Jason S. Herrington (presenter), Gary Stidsen, Ashlee Reese, Steve Kozel

For more information, email Jason Herrington.


Abstract: With more states legalizing the medical and recreational use of cannabis, analytical methodologies that will ensure consumers receive safe products are urgently needed. Currently, there is a growing trend in new cannabis formulations. These formulations increasingly use cannabis concentrates, which are made by extracting chemical compounds, such as delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), from the cannabis plant. To do this, producers use a variety of solvents in their extraction processes. This study focused on analyzing residual solvents in cannabis concentrates with an approach similar to the USP <467> sample preparation technique. Residual solvents were also extracted with the more “classical” approach of HS-syringe and as well as with a large volume HS-SPME approach that utilized SPME Arrows. Comparison results and a simple solution for analyzing residual solvents in these complex matrices will be presented.


About SPME Arrows

The Restek PAL SPME Arrow system (patent pending) is a revolutionary change in microextraction that combines exceptional robustness with faster extraction times and trace-level sensitivity. In contrast to traditional SPME fibers, SPME Arrows contain significantly more phase volume, which allows more target analyte to be extracted in less time. In addition, the stainless steel construction, unique Arrow tip, inner stabilizing rod, and outer sheath design fully protect the phase, minimizing both mechanical damage and analyte loss during sample transfer.


Come see us at ExTech or contact your Restek representative for more information about SPME Arrows.

Set Your Sights on Superior Performance with Restek PAL SPME Arrow and Test Mix

SPME Arrows and Test MixTraditional SPME fiber technology has some significant drawbacks including poor mechanical stability and a small phase volume. The Restek PAL SPME Arrow system is a revolutionary change in microextraction that combines exceptional robustness with faster extraction times and trace-level sensitivity. In contrast to traditional SPME fibers, SPME Arrows contain significantly more phase volume, which allows more target analyte to be extracted in less time, significantly increasing sample throughput. In addition, the stainless steel construction, unique Arrow tip, inner stabilizing rod, and outer sheath design fully protect the phase, minimizing both analyte loss and mechanical damage. Use with our new SPME test mix to ensure performance after each installation. This mix is a certified reference material (CRM) with verified composition and stability.



Going to ExTech/ISSS 2016? Attend the Restek / CTC Analytics Workshop on #SPME Technology

SPME_CRMIn addition to being in booth #2C to discuss how Restek’s GC & LC columns and accessories, sample preparation, reference standards, and other chromatography solutions can benefit your lab, we are partnering with CTC Analytics to present a workshop on solid phase microextraction (SPME) technology. If you will be in Poland for ExTech/ISSS, we invite you to attend:

Sunday, July 3 / 10:00–13:00 / Faculty of Chemistry, Nicolaus Copernicus University, Toruń
Sample Preparation Workflow Automatization — Advances in SPME Technologies
Presenters: Gary Stidsen (Restek Corporation), Mevio Heierli (CTC Analytics)

Registration begins at 9:00

With patents for SPME fibers maturing, there are new opportunities to make improvements in SPME fiber polymers and fiber construction. This has led to improvements in automation technologies, allowing laboratories to be more efficient and improve data quality. This workshop will focus on SPME technology improvements and how new technologies are being used in automation to reduce manual sample prep and improve data quality. The following topics will be discussed:

a) SPME fiber improvements.
b) New SPME Arrow technology.
c) Moving from manual to automated integrated laboratory workflows.
d) Improving reproducibility and reliability through laboratory automation.

For more information, visit the ExTech/ISSS website at www.extech-isss2016.pl/workshops