Restek Activities at ISSS 2015 to Include Plenary Address by Jaap de Zeeuw

The 21st International Symposium on Separation Sciences (ISSS) is approaching quickly and Restek is pleased to sponsor this exciting conference. Join us June 30–July 3, 2015 in Ljubljana, Slovenia for top-notch workshops, lectures from leaders in the separation sciences, and a full social program. A plenary talk on the use of nitrogen as a carrier gas in GC will be offered by Jaap de Zeeuw. In addition, Hansjörg Majer will present posters on recent LC work at Restek. Both scientists are organizing a workshop that will be focused on simplifying method development; be sure to look for “Easy and Practical Strategies for Choosing the Optimal Column for Separating Your Target Analytes in GC and LC” in the program guide and join us for some excellent tips and tactics. Symposium attendees are also invited to visit with us at the Restek booth to discuss analytical work and participate in our Chromatography Mastermind game. Presentation abstracts are provided below.

Plenary Talk

Using Nitrogen Instead of Helium as Carrier Gas While Maintaining the Exact Same Separation Efficiency, Retention Times, and Peak Elution Order without Changing the Oven Temperature Conditions

(Jaap de Zeeuw)

For several reasons, there is interest in replacing helium with a different carrier gas in gas chromatography. Hydrogen is the obvious choice, but there are some concerns with safety and reactivity. It is also possible to use nitrogen, but this is often not considered because it has a low optimal velocity and flow rate. However, by using method translation and chromatogram modeling, it is clear that the loss of efficiency observed when using nitrogen can be perfectly compensated for by using a smaller ID capillary of a shorter length. By replacing a 30 m x 0.25 mm column with a 20 m x 0.15 mm column, identical separations can be obtained in the same analysis time when using nitrogen instead of helium–with the exact same oven programming condition. Even the inlet pressures are very close. The only price that has to be paid is a loss in loadability, which means that this concept will not work for every application, but it will be very useful for many. Besides the guaranteed availability, using nitrogen offers a big advantage in the cost and consumption volume of carrier gas, meaning cost per analysis will also benefit significantly.

A Multiclass Drug and Metabolite Screen of 231 Analytes by LC-MS/MS
(Dr. Hansjörg Majer
, Frances Carroll, Sharon Lupo, Dr. Shun-Hsin Liang, Ty Kahler, Ed Frankin)
The use of pain management drugs has been steadily increasing. As a result, labs are seeing an increase in patient samples that must be screened for a wide variety of drugs to prevent drug abuse and to ensure patient safety and adherence to their medication regimen. Therapeutic drug monitoring can be challenging due to the low cutoff levels, potential matrix interferences, and isobaric drug compounds. To address these challenges, many drug-testing facilities are turning to liquid chromatography coupled with mass spectrometry (LC-MS/MS) for increased speed, sensitivity, and specificity. In this example, a method was developed for a multiclass drug and metabolite screen containing 231 compounds. Experiments addressed mobile phase considerations, sample diluent, isomer resolution, drug interferences, and instrumentation capabilities. During mobile phase investigations, it was found that methanol provided the best retention of early eluting analytes, such as morphine, oxymorphone, nicotine, and norcotinine. Sample diluent was optimized to improve the peak shape of the early eluting compounds. Scan rates and retention time windows were optimized to insure enough data points per peak were collected. The final method used an optimized separation gradient analysis time of 10 minutes with a total cycle time of 12 minutes.

Column Performance: Comparison of the Superficially Porous Particle (SPP) to the Fully Porous Particle (FPP)
(Dr. Hansjörg Majer
, Sharon Lupo, Dr. Shun-Hsin Liang, Frances Carroll ,Ty Kahler)
Superficially porous particles (commonly referred to as SPP or “core-shell” particles) have been proven to provide fast and efficient separations. These particles feature a solid, impermeable core enveloped by a thin, porous layer of silica that decreases the diffusion path and reduces peak dispersion. As a result, significant improvements in efficiency and sensitivity can be achieved over fully porous particles (FPP) of similar dimension.

In this presentation, the performance of 5 µm SPP columns will be compared to columns packed with traditional 5 µm and 3 µm FPPs. The relationship between pressure and efficiency will be explored. In addition, analysis time, signal-to-noise ratio, peak width, and resolution will be evaluated in several chromatographic experiments. Each experiment will be performed on the same instrument using identical method conditions for each particle.

We will discuss the following potential advantages of 5 µm SPP columns over columns packed with traditional 5 µm and 3 µm FPPs. When used in the development of new assays, they allow the chromatographer to obtain fast analysis times and excellent method performance without changes in instrumentation. When substituted into existing methodologies that utilize 5 µm and 3 µm FPP columns, 5 µm SPP columns have the potential to dramatically decrease analysis times while improving efficiency and sensitivity.

New Restek® Rxi®-1301Sil MS GC Columns Are Ideal for MS

Rxi-1301Sil for newsRestek’s Rxi®-1301Sil MS GC columns give you the selectivity you need without the bleed. These new columns offer true cyano phase selectivity along with the highest thermal stability in the industry, which ensures you get dependable, accurate MS results and increased uptime. Improve the performance of existing methods for solvents, glycols, and other polar compounds with an Rxi®-1301Sil MS GC column.

Typical cyano-based 1301 columns are well suited for the analysis of solvents across a range of volatilities; however, they are prone to high bleed and poor robustness, which limits their utility for MS work. The new Rxi®-1301Sil MS column from Restek is a silarylene-based cyano stationary phase that not only provides the selectivity needed for analyzing less volatile compounds, but it also has the highest thermal stability and lowest bleed, resulting in excellent MS compatibility. Exceptionally high thermal stability also allows for more aggressive thermal ramping to eliminate carryover of high molecular weight compounds between analyses (i.e., increased uptime).

In addition to providing both stable 1301 selectivity and the lowest bleed/highest temperature limits in the industry, the Rxi®-1301Sil MS column is designed to provide maximum inertness. Each Rxi®-1301Sil MS column is tested with a QC mix that includes both acidic and basic probes to ensure inertness across multiple compound classes. Greater column inertness improves peak shape and response, ensuring more accurate quantitative results.

The new Rxi®-1301Sil MS column is ideal for the analysis of multiple compound classes across a range of polarities and volatilities. With its cyano-based selectivity and high thermal stability, it is the top performing 1301-type column for MS analyses.

Order today

Rapidly Analyze a Wide Range of Glycol Ethers by GC-MS Using the New Rxi®-1301Sil MS Column

Author(s): Rebecca Stevens and Chris English
Restek Corporation

Published By: Restek Corporation

Year of Publication: 2015


Abstract: Chromatographic conditions were developed for a fast GC-MS glycol ether analysis on the Rxi®-1301Sil MS column. This column provides better resolution and faster run times than the thick film cyanopropylphenyl-type columns commonly used for speciation of the glycol ethers.

Our MSACL U.S. 2015 Presentations Are Now Online

During MSACL U.S. 2015, we featured Restek’s Raptor™ Biphenyl column in our booth, corporate workshop, and posters. With ten years of unrivaled performance, Restek’s time-tested Biphenyl has long been the ideal column for clinical diagnostic, pain, and pharma labs alike. Pairing it with rugged Raptor™ particles makes it your best choice for fast, reliable results.

For those who weren’t able to catch all of our poster presentations, we have uploaded them to our MSACL page. Review them at your leisure, and feel free to get in touch with the authors directly to discuss them further.

Restek at MSACL US

Michelle Misselwitz to Present at BFR 2015 in Beijing

The 7th International Symposium on Brominated Flame Retardants (BFR 2015) will be held April 21–24, 2015 in Beijing. Michelle Misselwitz, a leader in BFR work at Restek, will attend and present her most recent work on improving the analysis of brominated flame retardants. With decades of combined experience in brominated flame retardant work, Restek is pleased to support this well-respected meeting as a corporate sponsor. Michelle’s presentations are described in the abstracts below.


Half the Column, Same Chromatogram: Trimming the GC Column for Maintenance While Maintaining Critical Resolution between BDE 49 and BDE 71

Monitoring of polybrominated diphenyl ethers (PBDEs) in biota and environmental matrices can be difficult due to sample complexity, structural isomers that must be separated chromatographically, and thermally-labile compounds that can break down during gas chromatography (GC). GC column and inlet maintenance is especially important for BDE analysis because nonvolatile matrix material persists in sample extracts and deposits onto the front of the column and liner. This can cause poor transfer of BDEs onto the GC column, which compromises quantification and sensitivity. That same material at the head of the GC column also leads to poor peak shapes and reduced resolution between critical congeners, such as BDEs 49 and 71.

Trimming a coil (0.5 m to 0.7 m) off of the front of the column and changing the inlet liner restores performance and significantly increases the column lifetime. While trimming a column instead of immediately replacing it saves time and money, care must be taken to properly translate the analytical method for the shorter column length in order to maintain the original separation. If the GC method is not translated after column trimming, the column flow rate will be very fast, which will decrease resolution and detectability. The flow rate may also exceed the pumping capacity of many mass spectrometers.

EZGC® method translation software can help analysts accurately adjust the GC oven program for shorter column lengths so that the elution profile of the original chromatogram is maintained. Using a 15 m x 0.25 mm x 0.10 µm Rtx®-1614 GC column—a column that was specifically designed to meet EPA Method 1614 resolution requirements for BDE congeners 49 and 71—we investigated how much of the GC column could be trimmed off for maintenance before the Method 1614 resolution requirement for BDE 49 and BDE 71 could no longer be met.


Modified QuEChERS Extraction and Shoot-and Dilute GC: Fast Sample Preparation and Analysis of Newer Brominated Flame Retardants in Fish

Sample preparation often is a bottleneck in a busy analytical laboratory. Soxhlet or pressurized liquid extractions (PLE) are commonly used, but they can take several hours and hundreds of milliliters of solvents. In addition, complex sample extracts may require extensive cleanup to remove fat or other nonvolatile compounds prior to injection on to the GC. Screening fish and other fatty foods for the presence of halogenated flame retardants is important from a human health perspective. In addition to commonly analyzed older BFRs of known concern, some of the newer high-production flame retardants, such as those found in Firemaster® 550, are increasingly being included as target analytes as they lack established data on food occurrence.

In order to develop a fast, effective screening method for both older and newer brominated flame retardants in fish, we paired a modified QuEChERS extraction with a quick extract cleanup on a primary secondary amine (PSA) cartridge. We then used “shoot-and-dilute” GC (split injection) instead of a traditional splitless injection to introduce samples onto the column. This allowed us to reduce the impact of matrix effects on compound response and it also increased instrument ruggedness. Using both GC micro-ECD and GC-MS/MS, we evaluated fish for both newer flame retardants (e.g., 2-ethylhexyl-2,3,4,5-tetrabromobenzoate and bis(2-ethylhexyl)tetrabromophthalate) and historically significant polybrominated diphenyl ethers (PBDEs).

The sample preparation method developed here allowed a set of six samples to be processed in less than 4 hours, using only 20 mL of solvent per sample. The combination of this sample preparation procedure and a rugged shoot-and-dilute GC-MS/MS analysis yielded good recoveries of target BFRs in tuna and sardine samples. Significant time and solvent savings were achieved with this sample preparation method and the shoot-and-dilute (split injection) approach allowed more samples to be analyzed before system maintenance needed to be performed.