News from LabRulezGCMS Library - Week 34, 2024

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 19th August 2024? 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 to you a posters from ASMS 2024 by LECO, Agilent Technologies, Shimadzu, and Thermo Fisher Scientific!

1. LECO: Evaluation of the NIST Library Matching Quality of Mass Spectra Generated by the GC-HR-TOFMS with Multi-Mode Ionization Source

• poster / ASMS 2024

Introduction: Comparison of electron ionization spectra against standardized libraries is a staple approach to compound identification in non-targeted GC-MS analysis. High-quality matches are central to the pace of, and confidence in, such analyses. Recent developments in gas chromatography high resolution mass spectrometry have progressed non-targeted analysis applications to a wide variety of studies. However, modern ion-optical design principles which allow gains in sensitivity and resolving power may inadvertently alter fragmentation patterns, which may in turn affect the reliability of automated comparisons against standard libraries. Thus, thorough evaluation and validation of the high-quality spectra matching to the standard libraries, like NIST, is necessary for comprehensive assessment of the promised benefits of new technologies.

Conclusions: This multi-mode ionization source, as assessed using these 207 diverse analytes, generates fragmentation patterns which align very well with the NIST spectral library. Across all analytes in standard solutions, the mean library match score was 935 and the standard deviation for this value was 24.2. Mean match scores were agreeable regardless of moieties present. Percent differences for MRPS #2 spiked into a Pu’er Tea and MRPS #8 spiked into a dietary supplement were - 3.75 % and -1.44 %, illustrating how the system can easily maintain spectral confidence even in complex matrices. Overall, this study suggests the electron ionization mode of this multimode ion source, in combination with its high-resolution time of flight mass analyzer, yields spectra in excellent agreement with the quadruple dominated NIST library.

2. Agilent Technologies: Fast Analysis of 140 Environmental Compounds by GC/MS/MS

• poster / ASMS 2024

Introduction: Pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) are persistent environmental pollutants with the potential for bioaccumulation.¹ Previously, these compound classes have been analyzed using gas chromatography with an electron capture detector (GC-ECD), but this requires full chromatographic separation of all analytes for confident chemical identification. With a triple quadrupole detector (QQQ), analysis time significantly drops due to mass identification eliminating the need to chromatographically separate all components. Further, multiple reaction monitoring (MRM) mode on the QQQ provides a higher confidence in peak identification than analysis by scan or selected ion monitoring (SIM) mode. Combining chromatographic separation and MS/MS analysis is especially useful for PAHs and PCBs where multiple analytes may have the same m/z value.

Conclusions: Transitioning methods from GC-ECD to GC/MS/MS is highly beneficial.

By running in MRM mode, we enable the following:

• Significant time-savings
• Increased confidence in hits
• Sample quantification remains the same

3. Shimadzu: Novel High Sensitivity Detector for GC/MS

• poster / ASMS 2024

Overview

• We have developed a novel high sensitivity detector which has a simple structure to achieve high ion transmission and eliminate neutral molecules simultaneously.
• Signal to noise ratio (S/N) was 1.5 times higher than that with a conventional detector.

Introduction:

In GC/MS, numerous neutral molecules originated from carrier gas pass through quadrupole mass filter without being removed, and thereby they are finally transferred to ion detector. When they enter the detector, they may cause noise in the detecting signal. For this problem, some detector structures have already been proposed to remove these neutral molecules. However, they have complex structures and the room for improvement of ion transmission. In this study, we have developed the new high sensitivity detector which has a simple structure to achieve high ion transmission and to eliminate neutral molecules simultaneously.

Conclusions:

• We have developed the new high sensitivity detector and achieved the high ion transmission and removal of neutral molecules simultaneously.
• Signal intensity was increased by 1.2 times and noise was reduced by about 20%, S/N was 1.5 times higher than that with the conventional detector.
• This noise reduction effect will be larger in the high flow analysis. In addition, this detector is promising to extend the lifetime of the detector due to less contamination from neutral particles in the conversion dynode and electron multiplier.

4. Thermo Fisher Scientific: Utilizing hydrogen carrier gas for sensitive analysis of pesticides in food using gas chromatography mass spectrometry

• poster / ASMS 2024

Abstract

Purpose: To demonstrate the performance of the Thermo Scientifc HeSaverH2Safer kit for iConnect split-splitless (SSL) injection module for trace analysis of pesticides using H2 as a carrier gas as a safe and sustainable solution for laboratory operations

Methods: In this study, hydrogen was used as a carrier gas for GC-MS/MS analysis of trace levels of pesticides in food. The GC was fitted with a new hydrogen safer split/splitless injector, with chromatographic separation performed on a TG-5 SIL MS (30 m × 0.25 mm, 0.25 μm) capillary GC column. The chromatographic conditions applied ensured critical pair separation was achieved. The GC-MS/MS system was equipped with an advanced electron ionization (AEI) source to increase sensitivity for analyte detection. Quantification and assessment of critical regulatory requirements, such as linearity and sensitivity, were performed in a single software.

Conclusions

• The use of the HeSaver-H2Safer technology allows for a safe and compliant use of hydrogen as an alternative carrier gas in GC/GC-MS applications without the need to install a hydrogen sensor and removes any risk of unwanted reactions with the sample in the hot SSL injector.
• When used with hydrogen, the limited carrier gas consumption offered by the HeSaverH2Safer mode permits a very controlled system demand for hydrogen, making this solution ideal for laboratories working with hydrogen generators.
• Migrating the GC-MS/MS method from helium to hydrogen requires an adaptation of method parameters to address (i.e., retention time shift and different fragmentation patterns).
• 97% of pesticides in baby food and 98% in honey showed a linear response in the concentration range 0.005–0.500 mg/kg and the relative standard deviation for N=5 repeats of each sample type at 0.01 mg/kg was equal or lower than 10% for 98% of the evaluated compounds.