News from LabRulezGCMS Library - Week 27, 2025

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 30th June 2025? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!

👉 SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT GCMS AND RELATED TECHNIQUES

👉 Need info about different analytical techniques? Peek into LabRulezLCMS or LabRulezICPMS libraries.

This week we bring you other document by Agilent Technologies and posters by Shimadzu / ASMS, Thermo Fisher Scientific / ASMS and Waters / ASMS!

1. Agilent Technologies: Understanding Solvent Focusing Gas Chromatography and How it can be Optimized for Splitless Injections 

• Other document (white paper)
• Full PDF for download

Discussions of the basic mechanism of gas chromatography (GC), samples can start as a liquid, solid, or a gas. These samples, when not in gas phase, are converted into a vapor made up of solvent and analytes that are then separated using a GC column. The type of film or stationary phase used in the column helps to separate the compounds of a sample mixture. Meanwhile, the role of the gaseous mobile phase is to move compounds through the column without chemically interacting with them.1 With splitless injections, almost the entire sample is transferred onto the column head, making it ideal for trace level analysis, but more susceptible to solvent interactions due to the large volume of solvent also introduced to the column. It is important to understand all the variables and how to optimize them to successfully perform splitless injections, including the role of the sample solvent and related solvent effects.

Sample preparation and solvent selection

Prior to efficient sample preparation methods for the analysis of pesticides, a guard column was used to help protect the analytical column from heavy matrix or nonvolatile analytes. The primary method of sample preparation used was solvent dilution in hexane or dichloromethane, which potentially passed through a filter, and then injected directly into the inlet and analyzed on a 5% phenyl phase type column. This can be referred to as the dilute and shoot method. As dichloromethane and hexane are both compatible solvents with a 5% phenyl phase, the guard column was only needed to protect the analytical column from matrix, and not from adverse wettability. 

With the adoption of more involved sample preparation techniques, traditionally used in liquid chromatography, samples typically finish their preparation in the polar solvent acetonitrile. For GC analysis solvent exchange is employed, which is the process of drying down a sample in one solvent under nitrogen gas and reconstituting it in another solvent such as hexane. This procedure is performed to ensure proper interactions between solvent and column phase. Since these cleaned up samples contained less matrix, the need for a guard column was decreased.6 Gradually the requirement for solvent exchanges was decreased to decrease the overall sample preparation time, but this left the prepared samples in a final solvent of acetonitrile.

Conclusion 

For a gas chromatography analysis to be successful there are many factors to be considered. These factors include injection speed, solvent choice, installation of the column, and the column phase selection. Solvent selection is important in more decisions than determining which solvent will dissolve analytes. Solvent selection can impact vaporization volume in the liner, as well as impact reconcentration at the head of the GC column. 

Splitless injections will be more affected by solvent selection, as there will be a greater amount of solvent introduced to the column and greater interactions between the solvent and column phase. If the solvent and column phase are mismatched, there will be an increase in the flooded zone, and a subsequent impact to the peak shape of analytes. To mitigate the problem of using a polar solvent with a nonpolar column, a guard column can be used to help refocus the solvent and analytes at the head of the analytical column and improve analyte peak shape.

2. Shimadzu / ASMS: PFAS in Bottled Water: A Simple Approach Using HS-SPME GC/MS/MS for Volatile Contaminant Analysis

• Poster
• Full PDF for download

Concerns about per- and polyfluoroalkyl substances (PFAS) contamination in bottled water, linked to significant health risks, are growing. The Food and Drug Administration (FDA) has published plans surveying bottled water for PFAS in 2024-2025. While Liquid Chromatography/Mass Spectrometry (LC/MS) is the primary analytical method for PFAS, it struggles to analyze certain PFAS related compounds like fluorotelomer alcohols (FTOHs), perfluoroalkyl iodides (PFIs), and (n:2) fluorotelomer iodides (FTIs). Gas Chromatography/Mass Spectrometry (GC/MS) offers a complementary approach for volatile PFAS. This study utilizes Head-Space Solid Phase Microextraction Triple Quadrupole Gas Chromatography/Mass Spectrometry (HS-SPME GC/MS/MS) to analyze PFAS in bottled water. This technique offers several advantages, including minimal sample preparation, making it a valuable tool for comprehensive PFAS analysis.

Methods

A volatile PFAS analysis method was developed on a Shimadzu GCMS-TQ8040 NX with an AOC-6000 Plus multifunctional autosampler equipped with a solid phase microextraction (SPME) module (Figure 1). 

Thirteen PFAS target compounds were included in the Multiple Reaction Monitoring (MRM) method. The PFAS chemical classes were perfluoroalkyl iodides (PFIs), (n:2) fluorotelomer iodides (FTIs), (n:2) fluorotelomer acrylates (FTACs), (n:2) fluorotelomer methacrylates (FTMACs), (n:2) fluorotelomer alcohols (FTOHs) and perfluoroalkane sulfonamides (FASAs). Internal standards (IS) FTOHs, FASAs and FTAC mass-labelled compounds were added to each vial prior to extraction. Concentrations of the target compounds were calculated using isotope dilution. 

An internal calibration curve was prepared in 10 mL of reagent water at concentrations of 2000, 1000, 500, 100, 50, 10, 2.5 and 1 ng/L. The IS were spiked at 100 ng/L to each calibrator. Sodium Chloride (NaCl) was added to each vial to achieve a final salinity concentration of 2% NaCl (w/v). These calibrators were vortex for 30 seconds and then placed on the AOC-6000 Plus autosampler rack for analysis. 

The optimized parameters of the HS-SPME GC/MS method for the targeted PFAS are listed in table 1. Quantitative and reference ions for each PFAS target are listed in table 2. The associated internal standard used for each compound is also listed in table 2. 

A laboratory control sample (LCS) was analyzed to determine the general performance of the method in a clean matrix. The bottled water samples were analyzed to determine the effect of matrix on method performance. The type of bottled water analyzed was purified water.

Conclusion

The PFAS family includes thousands of compounds across diverse chemical classes, making comprehensive analysis challenging and often necessitating multiple analytical techniques. LC-MS is widely used and well-established for PFAS analysis but is less effective for detecting certain compounds - particularly volatile PFAS. In contrast, GC-MS excels at analyzing volatile PFAS and serves as a valuable complement to LC-MS, offering a more complete and balanced approach to PFAS detection. By extending the range of detectable compounds, GC-MS helps overcome PFAS analysis limitations previously imposed by instrumentation constraints. This study demonstrates the strong performance of an HS-SPME GC/MS/MS method for measuring volatile PFAS in bottled water. The application presents a simple, rapid, robust, precise, and accurate workflow that significantly improves the ability to detect a broader spectrum of PFAS compounds in bottled water.

3. Thermo Fisher Scientific / ASMS: Large-scale targeted biomarker analysis of volatile organic compounds in breath by TD-GC-MS 

• Poster
• Full PDF for download

Breath analysis of volatile organic compounds (VOCs) is emerging as a promising tool in non-invasive disease diagnostics. While untargeted methods dominate current workflows, they often lack reproducibility and specificity. This study introduces a fully integrated, large-scale targeted workflow for VOC biomarker quantification using TD-GC-MS, aiming to support the development of Owlstone Medical’s Breath Biopsy VOC Atlas® and broader breathomics applications.

Materials and Methods

Breath samples were collected using the ReCIVA® Breath Sampler and CASPER® air supply to reduce ambient contamination. Samples were analyzed with a Markes TD100xr thermal desorber coupled to a Thermo Scientific Orbitrap Q Exactive GC-MS system, known as the Breath Biopsy OMNI® method. A total of 200 VOC targets were monitored, using 36 deuterated internal standards. All data acquisition and analysis were performed in Chromeleon CDS software in a secure, cloud-based enterprise environment.

Results

The workflow includes automated system suitability and intelligent run controls (SST/IRC) to avoid the loss of valuable patient samples. High-confidence compound identification was achieved using composite scoring, ion ratio matching, and HRAM spectral libraries. Method validation across two independent breath sample cohorts demonstrated strong precision, with over 70% of VOCs meeting the <20% RSD threshold across studies and sequences.

Conclusion

This targeted TD-GC-MS workflow provides a robust, compliant, and scalable solution for high-confidence breath biomarker analysis. The integration of cloud-based Chromeleon CDS, automated QC protocols, and HRAM detection supports reproducible, high-throughput studies that are essential for advancing clinical breathomics and precision medicine.

4. Waters / ASMS: GC-APCI-MS/MS Analysis of Polychlorinated Dibenzo-p-dioxins and Furans to Revised US EPA1613 Guidelines

• Poster
• Full PDF for download

In response to the U.S. EPA’s 2024 update of Method 1613 for the analysis of PCDD/Fs in wastewater, this study evaluates the performance of an alternative workflow using tandem quadrupole mass spectrometry (MS/MS) with APCI instead of traditional high-resolution mass spectrometry (HRMS). The goal was to demonstrate that such a system can meet all critical quality control (QC) metrics required by the revised method.

Materials and Methods

Analysis was carried out using a Waters Xevo TQ-XS tandem quadrupole MS with an APGC™ source, coupled to an Agilent 8890 GC and Gerstel CIS-4 PTV injector, with autosampling via PAL 3 RSI. Chromatographic separation used a Restek Rtx-Dioxin2 column. Calibration standards from Wellington Laboratories were diluted to test both linearity and detection limits, and internal QC metrics were adapted to accommodate the MS/MS platform.

Results

The adapted workflow successfully replicated key EPA1613 QC checks, including relative response factors, isotopic ratios (±15%), and detection limits. The system showed excellent mass accuracy and resolution, verified through an automated Python-based script. Ionization suppression events were detected and visualized, aiding sample quality assessment. Signal-to-noise ratio evaluation, even in low-noise MS/MS traces, was possible after modifying detector settings.

Conclusion

This work proves that a GC-APCI-MS/MS system can fully comply with revised EPA1613 guidelines. The platform demonstrated robust quantitative performance, reproducibility, and reliable QC monitoring. It represents a valid and cost-effective alternative to HRMS for regulatory dioxin and furan analysis in environmental samples.