News from LabRulezGCMS Library - Week 49, 2024

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 2nd December 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 you applications by Agilent Technologies and Thermo Fisher Scientific, a poster from AOAC by Shimadzu, and a poster from ASMS by LECO!

1. Agilent Technologies: Fast Analysis of 22 Terpenes in Hemp and Cannabis with the Agilent 9000 Intuvo GC with FID using Hydrogen Carrier Gas

• Application

Abstract

This application note describes the procedure for the analysis of 22 common terpenes in cannabis and hemp using the Agilent Intuvo gas chromatograph (GC) and flame ionization detector (FID), with hydrogen carrier gas, and post column backflush. The GC injection‑to‑injection cycle time was 10 minutes allowing for six samples per hour. A group of 1,200 hemp samples were analyzed to test the robustness of the method, and to determine a maintenance schedule.

Introduction

Terpenes are the main flavor and aromatic components of cannabis and hemp. Strains can be identified by their specific fingerprint for these terpenes. The abundance of particular terpenes may also indicate the character and usefulness of a particular strain. This identification also allows cultivators to monitor the consistency of their particular strains from one crop to the next, and to maintain better quality control. With ever‑increasing varieties of cannabis flowers and the number of individual tests performed, the overall speed of analysis time has become more important.

Helium has been used as the carrier gas for most GC analyses. Recent limitations on its availability have added to the cost of testing. This application focuses on a fast and robust analysis of 22 of the most common terpenes found for strain identification, as well as providing information for labeling purposes. This application utilizes hydrogen carrier gas with flame ionization detection (FID) to help shorten the analysis time and therefore, keep the cost per sample down.

Conclusion

This method proved to be a very robust, high throughput method with a GC cycle time of only 10 minutes (6 samples/hour). This study showed that the regular maintenance of changing liners, septa, and Guard Chips when needed, maintained retention time and curve stability. The use of backflushing helped keep the Guard Chip and inlet cleaner and minimized maintenance.

All calibration curves showed great linear response across the concentration range, through all 12 calibration standards, as seen in Figure 3.

Reminders can be set up using counters to alert the analyst when maintenance is needed according to the user's desired sample load. Being careful to install the liner in the same fashion helps to keep the tolerance of the CCV results within the ± 20% limits. It is noted and shown in Figure 4 that there may be additional terpenes present in samples that are not covered by the terpenes in the standards for this application. If this is of concern, a more encompassing standard may be used. Also, using a mass spectral detector may be more beneficial for the application.² Other matrices may require a
revised maintenance schedule.

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

• Poster (ASMS)

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 multi-mode ion source, in combination with its high-resolution time of flight mass analyzer, yields spectra in excellent agreement with the quadruple dominated NIST library.

3. Shimadzu / AOAC: Qualification and Quantification of Residual Pesticides in Ginger by GCMS using Simultaneous Ultra-fast Scan and SIM

• Poster (AOAC)

Introduction

Interest in food safety has grown, resulting in a trend of tightening global regulations for residual pesticides in produce. Selected Ion monitoring (SIM) in GC/MS is a common technique used for pesticide analysis while Scan mode is often used in non-targeted screening.

This study demonstrates a SIM analysis of pesticides, including calibration and repeatability in ginger root matrix. In addition to targeted analysis, in this work we performed simultaneous untargeted analysis with Ultra-fast Scan analysis, maximizing the use of the GCMS-QP2050. NIST library search results are shown for untargeted components.

Conclusion

The GCMS-QP2050 demonstrates sensitivity and reproducibility in analyzing pesticides in produce using SIM data obtained from simultaneous Scan/SIM analysis. Ultra-fast scan supports accurate identification of target compounds alongside SIM analysis without interference. Scan results provide MS spectrum patterns for identifying unknown compounds, assisting in non-target screening.

4. Thermo Fisher Scientific: Environmental analysis of polychlorinated biphenyls (PCBs) at reduced running costs using hydrogen as carrier gas

• Application

Goal

The aim of this application note is to compare the performance of the Thermo Scientific™ TSQ™ 9610 triple quadrupole mass spectrometer coupled to the Thermo Scientific™ TRACE ™ 1610 GC with hydrogen versus helium as the carrier gas for the determination of polychlorinated biphenyls. For guidance on the analytical performance of the proposed method, acceptance criteria as per U.S. EPA Method 1668 were considered.

Introduction

Polychlorinated biphenyls (PCBs) are a group of industrial organic chemicals consisting of carbon, hydrogen, and chlorine atoms. Due to their non-flammability, chemical stability, high boiling point, and electrical insulating properties, PCBs were used in hundreds of industrial and commercial applications including electrical, hydraulic equipment, plasticizers, plastics, rubber products, and dyes. The production of these compounds has been banned in the United States since 19771 because of their persistence in the environment and their tendency to enter the food chain and bioaccumulate in living organisms due to their lipophilicity.

There are currently 209 known PCBs congeners that can be divided into two groups according to their structural and toxicological characteristics:

• Non-dioxin-like PCBs (non-DL-PCBs), which represent the majority of the PCB congeners, are characterized by a lower degree of toxicity.
• Dioxin-like PCBs (DL-PCBs) include the 12 most toxic congeners (non‐ortho PCBs 77, 81, 126, 169 and mono‐ortho PCBs 105, 114, 118, 123, 156, 157, 167, 189), which have structures and toxicities similar to dioxins.

DL-PCBs are classified as persistent organic pollutants (POPs), and they have been regulated under the Stockholm Convention for POPs since 2001.² Following the Clean Water Act (CWA) in 1972, the United States Environmental Protection Agency (U.S. EPA) developed an analytical method, U.S. EPA Method 1668 and following revisions³ that can be applied for the determination of PCBs in wastewater, surface waters, soil, sediments, biosolids, and tissue matrices using gas chromatography coupled to high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS).³ However,
recent advances in gas chromatography-triple quadrupole mass spectrometry allow for high sensitivity and selectivity, leading to the consideration of GC-MS/MS as a reliable tool for PCBs analysis.

This application note reproduces the experiments described in a previously published application note,⁴ where polychlorinated biphenyls were analyzed using helium carrier gas. Here, helium was replaced by hydrogen. Additionally, the Thermo Scientific™ HeSaver-H₂Safer™ carrier gas saving technology was applied. HeSaver-H₂Safer technology offers a unique solution for laboratories to minimize carrier gas consumption during both standby and operational modes. When helium is used as carrier gas, the consumption can be drastically reduced without any changes to the analytical method or deterioration of performance. However, the Split-Splitless (SSL) injector modified to work in the HeSaver-H₂ Safer mode can be used also in conjunction with hydrogen as a carrier gas, where the limited and fixed carrier gas flow allows for safe usage without the need to install additional sensors. At the same time, the hydrogen gas consumption is equally reduced and will lead to further cost savings, allowing laboratories to run their instrumentation longer on a single gas tank or using gas generators.

Summary

The HeSaver-H₂Safer inlet allows laboratories full flexibility to select the carrier gas of choice between helium and hydrogen, while achieving a significant reduction of the consumption. With a simple upgrade to the standard Thermo Scientific™ iConnect SSL injector, the HeSaver-H₂Safer inlet allows for the use of an inert and inexpensive gas for inlet pressurization, whereas the main carrier gas flow is limited to the column flow only.

• The use of hydrogen as carrier gas has been demonstrated as an alternative to helium for the analysis of PCBs, reducing the overall cost of running the laboratory.
• The use of the HeSaver-H₂Safer inlet reduces the amount of hydrogen going into the gas chromatography system such that safe operation is assured anytime, and no hydrogen sensor is needed inside the GC oven.
• Hydrogen did not affect the linearity range; all compounds showed a linear response from 0.1 to 2000 ppb, with avarage R 2 >0.999.
• The TSQ 9610 triple quadrupole mass spectrometer provided excellent IDLs with hydrogen carrier gas, comparable to those obtained with helium.
• The variation of ion ratios was less than 12% for all PCBs at 0.05 ppb.