News from LabRulezGCMS Library - Week 32, 2024

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 5th 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 applications and other documents by LECO, Agilent Technologies, Waters Corporation, and Shimadzu!

1. LECO: Non-Target Characterization of Complex Essential Oil and Fragrance Samples with GCxGC-MS/FID for Reliable Identification and Relative Quantitation in a Single Injection

• poster / Analytica

Introduction: Essential oils are extracts from plant materials that capture the plant's scent and flavors. They have a broad range of applications, as they can be both a finished product and an ingredient or intermediate in the creation of other products. Due to this versatility, the analysis of essential oils is an important area of research with a variety of analytical objectives.

Because flavors and fragrances are composed of tens or hundreds of ingredients, characterization of these individual species can be challenging. It is not practical to use numerous standards for the identification and quantification of all the individual species. Instead, it is common to use a workflow where MS provides identification and FID provides relative area % quantification, often with separate injections for each.

Additionally, two one-dimensional chromatographic separations with different stationary phases are also often required to isolate the individual compounds due to the complexity of these samples. Here, we demonstrate a possible improvement to this workflow by using a GCxGC-TOFMS/FID instrument that provides reliable identification and relative quantitation in a single injection. GCxGC provides enhanced chromatographic separation of individual analytes, thus removing the requirement for two separate 1D analyses. Coupling this with dual MS and FID detection enables both identification via the FID in one single injection.

Conclusion: Harnessing the power of a TOFMS coupled with a GCxGC platform and an FID allowed us to not only determine the presence and amounts of targeted analytes, but also discover non-target analytes.

This platform, based on GCxGC-TOFMS/FID, can improve workflows in your industry.

2. Shimadzu: Comprehensive Characterization of Diesel Fuel on GC×GC Utilizing Impressive High-Speed Scan Technology of GCMS-QP2050

• Application

User Benefits

• Comprehensive characterization of complex matrices such as diesel fuel is possible with 2D gas chromatography.
• The impressive high-speed scan technology of GCMS-QP2050 allows for effective peak separation.
• Intuitive comprehension of compounds distribution can be achieved with displaying the data in a two-dimensional image.

Introduction: Kerosene, diesel, and other petroleum products are mixtures containing over 100 different hydrocarbons. The properties of petroleum products, such as ignitability and viscosity, depend on their composition and greatly affect physical properties like combustion. Comprehensive two-dimensional gas chromatography (GC×GC) offers high separation performance by utilizing two different columns, which provides more reliable compositional information for complex mixtures compared to one-dimensional chromatography. In this application, qualitative analysis of diesel fuel using a GC×GC system with GCMS-QP2050 that is capable of high-speed scanning (30,000 u/sec) was conducted. No less than 30,000 u/sec scanning speed improved the separation of peaks that are too close to each other and enabled accurate identification of compounds.

Conclusion: Diesel, a complex mixture of hydrocarbons, was measured using GC×GC-MS. Each component on the two-dimensional image showed characteristic distribution based on its molecular structure, allowing for intuitively understanding of the composition of diesel. Additionally, GC×GC-MS demonstrated Excellentseparation performance for components, enabling more reliable identification of components of diesel compared to 1D GC-MS. The high-speed scan of GCMS-QP2050 (30,000 u/sec) contributesto more precise qualification analysis.

3. Shimadzu: Analysis of Trialkyl Phosphates as Markers for Lithium Battery Aging

• Application

User Benefits

• Lithium Batteries(LIB) decomposition and aging can be evaluated by monitoring Trialkyl Phosphates.
• A routine and fast GCMS method for the detection of Trialkyl Phosphates was developed.
• Trialkyl Phosphates can be detected with high sensitivity and selectivity in commercial liquid electrolytes

Introduction: The electrolyte solution is a crucial part of a typical Lithium-ion battery, consisting of Li salts (e.g. LiPF6), and organic carbonates. Decomposition and formation of phosphorous-based and other organic products starts already at the production stage of the electrolyte. The formation of such molecules does not affect the electrolyte/battery quality negatively, as long as the quantity is low enough. On the contrary, several decomposition products have a positive effect on the formation of the so-called SEI surface (Solid Electrolyte Interface) on the LIB anodes, which is crucial for the battery functionality. Nevertheless, this is a continuous chemical process and the increasing amount of some of the decomposition products is a clear indicator of the progressive aging of the battery/electrolyte. This application is demonstrating the GCMS analysis of Trialkyl Phosphates as reaction products of carbonates and LiPF6 salt. The choice of this compounds as markers for electrochemical battery aging is due to the fact, that their formation is very slow and depends only on a few external parameters, allowing to investigate the electrochemical aging (charge/discharge) by a simple comparison of before/after analyte content.

Conclusion: The presented application demonstrated the suitability of GCMS to investigate the aging of the LIBs using phosphatebased degradation products. This investigation is based on SCAN measurements. Here, a SCAN/SIM mode would be beneficial offering the possibility to detect the main compounds (carbonated, additives) and the degradation products in one measurement. A further improvement would be a dedicated SIM method for the mentioned phosphates with the highest selectivity and sensitivity.

4. Agilent Technologies: Analysis of Dithiocarbamate Pesticides in Tea Using GC/MS/MS

• Application Note -Food Testing and Agriculture

Abstract: Dithiocarbamate pesticides are commonly used to control fungal diseases in ornamental plants and crops, and for control of tea gray blight. The residue definition for dithiocarbamate pesticides is expressed as total dithiocarbamate, determined as mg CS₂/kg. Methods for analysis of CS₂ use extraction of the sample into an acidified stannous chloride solution with isooctane, where the dithiocarbamate residues are converted to CS₂, which is captured in isooctane and analyzed by GC/MS. This application note describes the analysis of dithiocarbamate residues in tea using an Agilent GC/MS/MS in both SIM and MRM modes. A limit of quantification of 10 ppb was achieved in tea samples. Linearity was established in matrix-matched standards with R2 > 0.999 for the range from 5 to 100 ppb, with average recoveries > 85% at the 10 ppb level of fortification.

Conclusion: Analysis of dithiocarbamate pesticides as CS₂, using isooctane as a sample preparation solvent, can lead to the combination of a relatively high boiling solvent with low boiling analytes. Hot spitless injections result in poor peak shapes for CS₂; better peak shapes can be obtained with cold injection in split mode. Further improvement in peak shapes can be achieved by using a multibaffled liner. Matrixmatched calibration standards ranging from 5 to 100 ppb were used to assess calibration performance, with linearity established at R² > 0.999 in both SIM and MS/MS modes. The method was validated following the criteria specified in SANTE 11312/2021v2, with the ability to detect CS₂ peaks down to 5 ppb using Agilent 7000D, 7000E, and 7010C GC/MS/MS instruments. Implementing a backflush method in the GC/MS analysis of tea samples can significantly improve the separation of target analytes from complex matrix components, enhancing sensitivity and throughput. Repeatability tests showed RSDs consistently below 4.2% for injections at 10 ppb concentration, indicating high precision and repeatability

5. Waters Corporation: Converting Target Analysis of Organochlorine Pesticides in Environmental Matrices from Electron Ionization GC-HRMS Using Helium Carrier Gas to Atmospheric Pressure Ionization GC-MS/MS Using Nitrogen Carrier Gas

• Application Note

Abstract: Organochlorine pesticides (OCPs) are among the high production volume chemicals produced in the past that had wide application and exhibit significant persistence in the environment. DDT, for example, has a half-life in sediment of up to 15 years meaning that it may not be 90% degraded for 45 to 60 years.¹ Furthermore, they are associated with a number of negative health effects when bioaccumulated in humans and animals. These are among the reasons that nine of the initial 12 compounds addressed by the 2004 Stockholm Convention on Persistent Organic Pollutants (POPs) belong to this compound class.²

Due to the complexity of matrices, such as sediment and biota, encountered when monitoring the fate, transportand occurrence of these compounds, it is necessary to employ techniques with high sensitivity, specificity, and robustness for these studies. In the past this has required the use of complex sample extraction and clean-up combined with electron ionization (EI) and high resolution mass spectrometry (HRMS) using magnetic sector instrumentation. However, in recent years the performance of Gas Chromatography Atmospheric Pressure Ionization Tandem Quadrupole Mass Spectrometry (GC-APCI-MS/MS) has demonstrated equal or better performance than the classic technique.³ In this work the Atmospheric Pressure Gas Chromatography (APGC™) ionization source on a Xevo™ TQ-XS Tandem Quadrupole System was used with both helium (He) and nitrogen (N₂) carrier gas to analyze sediment and biota extracts for the presence of 39 OCPs. Performance characteristics and sample quantification results for APGC-MS/MS were compared with results for the same aliquots run using GC-EI-HRMS.

Conclusion: The GC-EI-HRMS reference method separations and runtime were matched on the APGC-MS/MS system with only minor modification to the He carrier gas flowrate. Scaling of the column dimensions for use with N₂ carrier gas effectively reproduced the reference method separations and total runtime which allows the use of the same acquisition and processing files across both configurations. The comparison between the APGC He and N₂ carrier gas data shows that sensitivity is also maintained within a factor of two times between the two carrier gases. Analysis of extracted samples of biota and sediment indicate good agreement between the APGC N₂ carrier gas method and the EI HRMS reference method values. These results demonstrate the feasibility of modernizing the traditional reference method with a technique that is more easily integrated into most labs and more accessible for most operators.