News from LabRulezGCMS Library - Week 2, 2025

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 6th January 2025? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!

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This week we bring you applications and other documents by Agilent Technologies, Thermo Fisher Scientific, and Shimadzu!

1. Shimadzu: GC-MS-Based Evaluation of Fatty Acid Composition in Microalgae

• Application
• Full PDF for download

Given the urgent need to mitigate climate change and reduce dependence on fossil fuels, there has been a substantial increase in research and development efforts focused on the production of Sustainable Aviation Fuel (SAF) from microalgae. As the fatty acids contained in microalgae are used as raw materials for SAF, the standardization of analytical methods for these fatty acids is imperative for accurately evaluating the potential of microalgae as a SAF source. This paper introduces a case study in which we validated an analytical method for fatty acids in microalgae biomass using the GCMS-TQ TM 8040 NX, a gas chromatography-mass spectrometer capable of high-resolution and high-sensitivity detection.

GC-MS Analysis Methods

GCMS-TQ8040 NX (Fig. 3A) was employed for FAME analyses. The detailed analytical condition is shown in Table 2. Retention times of target compounds were predicted using the Smart Metabolites Database (Fig. 3B) based on the retention indices of n-alkanes, and the analysis method was automatically created. Quantification of FAMEs was performed using Supelco 37 Component FAME Mix (Sigma-Aldrich). All values are presented as mean ±SD.

Conclusion

This application note presented a comparative validation of fatty acid analysis methods for microalgae using the gas chromatography-mass spectrometer GCMS-TQ8040 NX. Our results from conventional fatty acid analysis, which involved an extraction process, showed that the quantity of fatty acids detected in microalgae was influenced by the type and ratio of extraction solvents. Additionally, since optimal conditions differ among microalgal species, consideration of extraction solvents is necessary in analyses involving extraction processes. In contrast, the in situ analysis without an extraction process was found to result in lower fatty acid detection compared to the extraction-based method, indicating that further improvements are needed.

2. Agilent Technologies: Hydrocarbon Class Analysis of Conventional and Synthetic Aviation Turbine Fuels by ASTM D8396

• Application
• Full PDF for download

Flow-modulated GCxGC-FID using the Agilent Reverse Flow Modulator and 8890 GC.

This application note demonstrates the performance of the Agilent Reversed Flow Modulator (RFM) and Agilent 8890 GC through molecular group-type analysis of aviation turbine fuel and synthetic aviation turbine fuel (SATF) by comprehensive multidimensional gas chromatography with flame ionization detection (GCxGC-FID) per ASTM D8396. Method precision was explored using both hydrogen and helium carrier gases and yielded quantitative precision below 1.0 %RSD for 39 out of 42 compounds and 42 out of 42 compounds, respectively, across 10 consecutive replicate injections of a gravimetric standard. GCxGC data analysis was conducted using GC Image – GCxGC Edition, and the demonstration of reconciling GCxGC peak movement using GC Image's affine transformation capabilities is also highlighted. Finally, the method is used to show the group-type quantification of a reference jet fuel, an HEFA and an FT-SPK SATF, two kerosene reference materials, and a diesel-FAMEs blend.

Experimental

An 8890 GC was configured with an Agilent 7693A autosampler, split/splitless (SSL) inlet, RFM, and two flame ionization detectors (FID). The second FID is an optional but highly recommended addition and was connected to the outlet of the restrictor column to actively monitor and ensure that the modulation channel was not overfilled during the run. To facilitate modulation, the RFM was paired with a pneumatic switching device (PSD) connected to the carrier gas supply. Both the hydrogen and helium carrier methods used a "reverse column configuration". The first-dimension column was a mid-polar DB-17, and the second-dimension column was a non-polar DB-1HT. The DB-17 was chosen over a more-polar phase (such as a polyethylene glycol "wax" phase) for its robustness and ability to elute heavier polyaromatic species at lower temperatures. The DB-1HT was manually cut to a length of 5.00 m from an original length of 30 m. Both the hydrogen and helium carrier methods used uncoated deactivated fused silica with an internal diameter of 0.10 mm cut to lengths of 1.99 and 2.64 m, respectively, as the restrictor column. Detailed instrument configurations and method parameters can be found in Table 1, and a picture and flow schematic of the RFM is shown in Figure 2.

Conclusion

An Agilent 8890 GC configured with an Agilent Reversed Flow Modulator has been demonstrated as a simple, precise, and robust GCxGC flow modulator through the application of ASTM D8396 using both hydrogen and helium carrier. Identification of marker compounds and delineation between molecular classes was achieved using the template-based identification protocol within GC Image. Group-based quantification was demonstrated for conventional jet fuel, SATF as FT-SPK and HEFA-SPK, kerosene, and a diesel-FAME blend. A precision study was conducted with 10 consecutive replicate injections of a gravimetric mixture and showed quantitative precision of less than 1.0 %RSD for practically all 42 compounds over a concentration range of 0.50 to 5.50% mass. The exceptional retention time repeatability from Agilent's 6th-generation EPC technology combined with GC Image's advanced and intuitive image transformation capabilities establishes the foundation for long-term success with D8396 and future GCxGC test methods.

3. Thermo Fisher Scientific: Sensitive and cryogen-free analysis of epichlorohydrin and other VOCs in drinking water by using In-Tube Extraction Dynamic Headspace (ITEX-DHS) sampling coupled to GC-MS

• Application
• Full PDF for download

The aim of this study is to demonstrate the suitability of In-Tube Extraction Dynamic Headspace (ITEX-DHS) for the analysis of very volatile organic compounds (VVOCs), volatile organic compounds (VOCs), and epichlorohydrin (ECH) in drinking water, when coupled to a cryogen-free refocusing into a programmed temperature vaporizer (PTV) injector.

Instrumentation

A Thermo Scientific™ TriPlus™ RSH SMART autosampler² equipped with an ITEX-DHS tool was coupled to a Thermo Scientific™ TRACE ™ 1610 GC, configured with a Thermo Scientific™ iConnect™ programmed temperature vaporizer (iConnect-PTV) injector, and a Thermo Scientific™ ISQ™ 7610 single quadrupole mass spectrometer. The PTV injector was equipped with a liner packed with Tenax TA (P/N 45312145-UI), suitable for a cryogen-free refocusing of the most volatile compounds.

Chromatographic separation was achieved using a Thermo Scientific™ TraceGOLD™ TG-624 SilMS, 60 m × 0.25 mm × 1.4 μm column (P/N 26085-3330). This column provided high inertness and thermal stability with maximum temperatures up to 320 °C. The phase thickness makes this column ideal for volatile organics analysis. Helium was used as carrier gas, providing high chromatographic efficiency and inertness.

Conclusions

The results of these experiments demonstrate that the In-Tube Extraction Dynamic Headspace (ITEX-DHS) coupled to the ISQ 7610 GC-MS system equipped with an iConnect PTV injector provides an ideal solution for analytical science laboratories monitoring critical contaminants in drinking water.

• Dynamic headspace is a convenient solventless extraction and enrichment technique for VVOCs, VOCs, and ECH in drinking water with almost no sample preparation required.
• The ITEX-DHS sampling technology offers a robust and powerful enrichment of volatiles, removing typical issues involved when purging the aqueous samples and allowing for equivalent limits of detection to the P&T sampling technique.
• The ITEX-DHS sampling technology coupled to a Tenax TA packed liner and PTV injector allows for analyte trapping and refocusing prior to column transfer so that improved peak shapes for the early eluting compounds can be achieved.
• The ITEX-DHS enrichment capability combined with SIM acquisitions allows for sensitive analysis of ECH and other VOCs with limits of detection in the low ppt range (from 2 to 220 ng/L) ensuring adequate performance to meet the thresholds set by the current EU regulation.
• The reliability of the entire workflow (analyte extraction, enrichment, injection, and data acquisition) was demonstrated with absolute peak area repeatability <14% over n=10 injections of matrix-matched standards spiked at 0.25 μg/L.
• The integrated control for both autosampler and GC-MS in a single CDS ensures a streamlined automated workflow from sample extraction to sequence set up, data acquisition, and reporting.