News from LabRulezGCMS Library - Week 17, 2025
LabRulez: News from LabRulezGCMS Library - Week 17, 2025
Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 21st April 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 application notes by Agilent Technologies and Shimadzu, poster by MDCW / Mane SEA PTE and technical note by Thermo Fisher Scientific!
1. Agilent Technologies: Determination of Polychlorinated Biphenyl (PCB) by GC/MS According to EPA Method 1628
Using an Agilent 8890 GC with an Agilent 5977C GC/MSD in selected ion monitoring (SIM) mode
- Application note
- Full PDF for download
PCBs are synthetic compounds belonging to the chlorinated hydrocarbon family. Historically, PCBs were extensively used in various industrial applications, including electrical components, plasticizers, and pigments and dyes. However, due to their environmental persistence and potential health risks, their use was banned in 1979 under the Toxic Substances Control Act (TSCA). Classified as POPs, PCBs resist degradation and are known to bioaccumulate in aquatic life according to the EPA.1 In response to the need for effective monitoring of PCBs, the EPA has developed method 1628, which employs low-resolution mass spectrometry in SIM mode.2 This method is the first to measure all 209 individual PCB congeners, calibrating for 65 PCBs and screening for the remaining 144 congeners. The method includes 29 labeled PCB surrogates and three labeled PCBs as internal standards for analytical accuracy. In this application note, an 8890 GC with a 5977C GC/MSD was used to analyze PCBs in sand and soil, meeting all requirements for EPA method 1628.
Experimental
An 8890 GC with a 5977C GC/MSD was used for this work. The 8890 GC was configured with mid column backflush to prolong column lifetime. Detailed method parameters were set according to EPA method 1628 and are shown in Tables 1 to 3.
Results and discussion
Example chromatograms are shown in Figures 1 and 2. Figure 1 shows the separation of the 65 calibrated PCB congeners and the 32 labeled PCB congeners at 50 and 40 ppb, respectively. The analytical separation of all 209 PCB congeners and 32 labeled PCB congeners at 50 and 40 ppb is shown in Figure 2.
Per the method requirements for EPA method 1628, PCB congeners 28 and 31 must be chromatographically separated. The valley of the two peaks must be less than 80% of the height of the smaller peak, which is demonstrated in Figure 3. The method also requires that PCB congener 118 at 10 ppb has a signal to noise ratio (S/N) greater than or equal to 3:1. Figure 4 shows successfully meeting this method criteria with a S/N of 6.1 for PCB congener 118 at 10 ppb.
Conclusion
An Agilent 8890 GC with an Agilent 5977C GC/MSD was successfully used to analyze PCB congeners according to EPA method 1628. This method uses low-resolution SIM mode to quantitate 65 congeners while being able to see all 209 native congeners. All method requirements were met, including for linearity, resolution, and sensitivity.
2. MDCW / Mane SEA PTE: Unraveling The Distribution and Enantiomer Ratio of Selected Carotenoid-derived Aroma Compounds In Oolong Tea Using MD-GC Coupled with MS
- Poster
- Full PDF for download
Carotenoid-derived compounds (CDCs) are important contributors to the xcharacteristic flavour of oolong tea. These compounds can exist in different xisomeric forms that have similar structural, physical and chemical but different sensory properties, making their differentiation difficult but important.
However, the analysis of these carotenoid-derived compounds and determination of their enantiomeric distributions in tea is challenging due to their low concentrations and wide variability. In consideration of their impact on sensory perception, these challenges faced in their detection and quantification need to be addressed
OBJECTIVE: To develop and optimize two-dimensional gas chromatography methods for the detection of CDCs and investigate their enantiomer distribution in different oolong teas.
ANALYTICAL WORKFLOW
- Comprehensive Two-Dimensional Gas Chromatography (GCxGC)
- Heart-Cutting Two-Dimensional Gas Chromatography (GC-GC)
GCxGC-qTOF/MS OPTIMISATION
- Continuous cold jet to trap the analytes at the head of the 2D column
- Pulsed hot jet set at a fixed interval to release the trapped analytes
Modulation period: amount of time between hot jet pulses Hot jet duration: length of time when the hot jet is turned on
Conclusion
- The modulation period determines the time when the compounds are allowed to separate on 2D and should be optimized to avoid wrap-around of peaks while efficiently utilizing the separation space. On the other hand, hot jet duration determines the amount of compounds entering the 2D.
- The optimized parameters for modulation period (14 s) and hot jet duration (350 μs) were used.
- MD-GC can overcome the challenges faced by conventional GC in the separation of complex tea matrices.
- GCxGC: improves detection limit due to cryogenic trapping of the modulation step.
- GC-GC: removes interference from peaks of interest while improving quantification.
- Different cultivars and processing parameters result in different volatile compound compositions in oolong teas.
3. Shimadzu: High-Sensitivity Analysis of Formic Acid in Methanol Solution Using Jetanizer
- Application note
- Full PDF for download
User benefits:
- Using Jetanizer as a GC-FID nozzle makes it possible to accurately analyze formic acid in methanol solution.
- The Jetanizersimply replaces the conventional GC-FID nozzle, making it easy to install and inexpensive.
Green Transformation (GX) initiatives aim to transition from fossil fuels to green energy and balance greenhouse gas emissions reduction with economic growth. These initiatives are expected to use innovative technologies such as artificial photosynthesis, which utilizes sunlight to produce hydrogen and organic compoundsfrom water and carbon dioxide.
Research on such artificial photosynthesis, along with the analysis of impurities in chemical products and raw materials, highlights the demand for high-sensitivity analysis of formic acid. A simple method for analyzing formic acid is gas chromatography (GC), where a TCD detector is used for highconcentration samples, and a BID detector is used for lowconcentration samples. Unfortunately, the FID detector, a general-purpose detector, lacks sensitivity to formic acid. However, by replacing the FID detector with a Jetanizer (In-Jet type methanizer) that contains a catalyst in the FID nozzle and adjusting the analysis conditions, high-sensitivity measurement of formic acid at the ppm level becomes possible.
This Application News presents an example of the highsensitivity analysis of formic acid contained in a methanol solvent using Jetanizer as the GC-FID nozzle.
Features of the Jetanizer
The Jetanizer is a compact FID-Jet type methanizer that contains a catalyst filled inside (Fig. 1). As a result, it enables the detection of CO and CO2, which cannot be detected by a standard FID, by reducing them and converting them into methane. Additionally, the heating elements, sensors, and extra hydrogen gas supply lines previously required for methanizers are no longer necessary, allowing for direct installation and use just like a standard FID.
Measurement of Formic Acid in Methanol
The chromatograms of formic acid at various concentrations in methanol (1, 5, 10, 50, 100, 500, and 1000 ppm) and an enlarged view of the low concentration range are shown in Fig. 4. The calibration curve for N = 5 is presented in Fig. 5. Additionally, the overlaid chromatograms for continuous measurement at 10 ppm are shown in Fig. 6, and the RSD% of the area values for N = 5 at each concentration is provided in Table 2. Good reproducibility of the area was confirmed at each concentration.
Conclusion
High-sensitivity analysis of formic acid is essential for the impurity analysis of chemical products and raw materials, including GX. When analyzing formic acid using GC, it is necessary to select the appropriate detector based on the measurement concentration range. The method introduced here allows for the convenient analysis of formic acid by performing phosphoric acid treatment on the insert and column and utilizing a Jetanizer.
4. Thermo Fisher Scientific: What is the benefit of high mass resolving power on the Orbitrap Exploris GC Series?
- Technical note
- Full PDF for download
Why do I need high mass resolving power from Orbitrap technology?
- Resolve target analytes from interfering compounds and matrix ions of similar mass.
- Achieve sub-ppm mass accuracy to give data certainty in compound identification.
- Sub-ppm mass accuracy enables narrow mass extraction windows (± 5 ppm) to give high selectivity, which in turn makes peak detection algorithms efficient.
- Easily increase scope of analysis through full scan accurate mass data acquisition (Figure 1).
- Quickly and confidently propose elemental compositions for the identification of unknown features.
- Retrospective data processing of samples long after data acquisition.
- Have high mass resolving power and sensitivity. No compromise.
With resolving power of up to 240,000 and consistent sub-ppm mass accuracy, the Thermo Scientific™ Orbitrap Exploris™ GC 240 mass spectrometer is a unique laboratory tool for targeted and discovery workflows, where screening, quantitation, compound identification, and structural elucidation applications are required.
High-resolution Orbitrap mass spectrometry has been available with both liquid and gas chromatography for many years and has proven to be a highly valuable analytical technique.1-4 More recently, the technology in gas chromatography moved to join the Thermo Scientific Orbitrap Exploris Mass Spectrometer series. This new platform of a benchtop hybrid quadrupoleOrbitrap mass spectrometer opens up research opportunities in a system with a significantly reduced footprint, saving both energy and raw materials. The benchtop hybrid quadrupole-Orbitrap mass spectrometer provides new possibilities for increased mass accuracy, sensitivity, and selectivity for GC-amenable compounds. Figure 2 shows how the resolving power is in the ideal range for volatile small molecules, with resolving power increasing with lowering m/z.
The impact of mass resolution on selectivity for targeted analysis
High-resolution, accurate-mass (HR/AM) experiments typically provide a full scan analysis of a sample, and for small molecule analyses, the scan range is typically 50–600 Da. Orbitrap technology provides the required selectivity to resolve the target compound from other compounds or from matrix ions of similar mass. For targeted compound analysis, the accurate mass of the diagnostic ion is extracted with a narrow mass extraction window (typically < 5 ppm). This narrow window is possible only when the instrument provides sufficient mass accuracy, for which high mass resolving power is essential. However, when two mass profiles overlap, the measured mass profile is the sum of the two individual profiles. This overlap results in the incorrect assignment of the mass of the target compound. The problem is demonstrated in Figure 3, where a QuEChERS leek extract in acetonitrile was analyzed four times at resolving powers of 15K, 30K, 60K, and 120K (m/z 200).
Being able to separate two compounds that are close in mass is one of the significant advantages of high-resolution accurate mass. This is demonstrated in Figures 4A-C where the compounds flurenol methyl ester C15H12O3 m/z = 240.0781 and dimetilan C10H16N4O3 m/z = 240.1217 were analyzed at equal intensity at three different resolving power levels of 30,000, 60,000, and 240,000. The zoomed spectra show excellent separation at all resolution levels, with improvements at 60K and 240K showing the clear benefits. When analyzed at 10:1 ratio (Figure 5), there is still good separation and mass accuracy. The latter reflects the real world where compounds will be at varying intensities, and it is essential that mass accuracy is maintained to make confident identifications.
