News from LabRulezGCMS Library - Week 41, 2024

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 7th October 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 by Agilent Technologies, Thermo Fisher Scientific, and Shimadzu!

1. Shimadzu: Analysis of Organophosphorus Pesticides in Drinking Water using SPME-GCMS

• Application

User Benefits

• The inspection items of Organophosphorus pesticides (Diazinon, Parathion, Phenitrothion, Phenthoate, and EPN) in water
  quality can be analyzed simultaneously.
• The automation of fiber conditioning, pretreatment, and sample injection of SPME is possible using AOC-6000 Plus

Introduction

Organophosphorus pesticides (OPs) are a class of insecticides based on organophosphorus compounds. It is widely used to control insects on crops in the pesticide market. OPs disrupt the nervous system by ingestion and contact. These are a toxic substance that cause headaches, dizziness, nausea and convulsions. Because of the side effects of these OPs, in Korea, residual standards are also operated in the water quality environment field. In the past, solvent extraction was used as a pretreatment method for water quality testing, but this required excessive solvent use and complex extraction processes. Therefore, the simpler Solid Phase Micro Extraction (SPME)-Gas Chromatography-Mass Spectrometry (ES 05501.5) method has been revised and published by the National Institute of Environmental Research (NIER) [1].

This application news describes the suitability of OPs analysis using SPME automatic injection (AOC-6000 Plus) and GCMS-QP2020 NX for Diazinon, Parathion, Phenitrothion based on the Environmental Standards for drinking water pollution, and Phenthoate, EPN based on the Official test standards for environmental pollution.

Conclusion

This application news is to analyze five types of OPs according to the Standard for Quality Test of Drinking Water. The suitability of the analysis was confirmed using Shimadzu AOC-6000 Plus and GCMS-QP2020 NX.

All components showed good linearity with the R² value of 0.998 or higher in the concentration (0.1-10) μg/mL range. MDL, LOQ, accuracy, and precision were excellent at (0.03 to 0.06) ng/mL, (0.10 to 0.20) ng/mL, (87.6 to 108.2), and (2.2 to 4.9), respectively, and were found to satisfy the method criteria.

Based on these results, it was confirmed that the use of AOC-6000 Plus and GCMS-QP2020 NX can automate fiber conditioning, pre-treatment and GC injection, making it more convenient to analyze and obtain excellent analysis results.

2. Agilent Technologies: Novel Column Chemistry Raises the Bar on Sensitivity and Data Accuracy in the Analysis of Semivolatile Organic Compounds

• Application

Abstract

As ionization sources continue to advance, lowering limits of detection and increasing confidence in analyte identification, column technologies can also be used in conjunction to push the practical limits of sensitivity and data accuracy. Increases in the detection of analyte response also result in unwanted increases in the detection of background noise. Gas chromatography/mass spectrometry (GC/MS) column technology that lowers interfering column bleed ions and elevated bleed baselines, maintains peak shape for active compounds, and can withstand aggressive thermal cycling can greatly enhance the performance and productivity of GC/MS methods. This application note examines how column attributes like bleed, inertness, and thermal stability can further benefit the sensitivity and accuracy of an MS. This study illustrates achievable data parameters, like sensitivity limits at trace levels, retention time consistencies, and data accuracy for active semivolatile organic compounds (SVOCs), when the Agilent 7010D triple quadrupole GC/MS (GC/TQ) system is used.

Introduction

Governmental regulatory authorities have established method and performance criteria for GC/MS measurement of SVOCs that are identified as pollutants in environmental and industrial matrices. The United States Environmental Protection Agency (U.S. EPA) method 8270, for example, contains a list of over 200 compounds, some of which can be susceptible to unwanted chemical activity in the instrument flow path, resulting in data quality degradation. If the performance criteria of method 8270 are not met, system maintenance is often needed, such as liner replacement
followed by column trimming or replacement, resulting in unplanned instrument downtime.

Monitoring of the DFTPP tuning standard, which contains 4,4'-DDT, pentachlorophenol, and benzidine, validates the suitability of the flow path and monitors when maintenance should be performed. The breakdown of 4,4'-DDT to 4,4'-DDE, and 4,4'-DDD, as well as the tailing factors of benzidine and pentachlorophenol, tests the flow path inertness, indicating the activity of susceptible acidic and basic analytes. GC columns contribute the largest surface area in the sample flow path and, therefore, are a critical factor in controlling interferences in the analytical path. Agilent Ultra Inert (UI) GC liners, along with an inert GC column phase, can improve the robustness of SVOCs analyses.¹

Stationary phases used in GC/MS analysis of SVOCs are typically comprised of liquid polymers with a polysiloxane backbone. When heat is applied to the column during routine use, the terminal end of the stationary phase polymer can bend back and attack itself; this is called "backbiting." Ring structures, which are thermodynamically stable, are liberated from the stationary phase, increasing background noise and raising the baseline; this can be problematic for low signal-to-noise (S/N) analytes. Peak integration can become less repeatable, lowering quantitation accuracy. In addition, the increase in freed ring structures—which fragment in the ion source—and analytes can cause spectral interference in extracted mass spectra and decrease the qualitative score of a library spectral hit. The Agilent J&W HP-5Q and DB-5Q GC columns have an increased thermal stability at upper temperature limits, allowing for less spectral interference, lower levels of column bleed, and better data quality, especially for heavier analytes that may suffer from issues with lower S/N.²

The new Agilent high-efficiency ion source (HES) 2.0, as seen in Figures 1 and 2, is equipped with a novel dipolar RF lens that redirects carrier gas and low mass ions by > 95%. The deflected ions land on adjacent lenses and are pumped out before entering the mass analyzer, providing reduced noise and extended instrument robustness while maintaining sensitivity. A ramped RF amplitude versus mass is implemented to avoid spectrum tilt. The reduction of noise allows for a further increase of sensitivity to attogram-level detection limits. Built-in intelligence features such as SWARM autotune and early maintenance feedback further enhance instrument performance and diagnostic capabilities. The DB-5Q GC column and the HES 2.0 work in concert to increase the robustness of difficult analyses such as that of SVOCs.^3,4

Conclusion

This application note demonstrates that the Agilent J&W DB-5Q GC column can exceed the performance requirements of EPA method 8270. Agilent Ultra Inert chemistry across the sample flow path will maintain peak symmetry of problematic analytes, leading to improved limits of detection and accurate integration. Ultralow-bleed chemistry stabilizes baselines and reduces interfering bleed ions. High-temperature stability allows for the repeated temperature cycling needed for high throughput methods, even when analyzing heavy, complex soil matrices. The matching selectivity of the J&W DB-5Q compared to the Agilent J&W DB-5ms UI allows for seamless adoption, including compatibility with existing retention time locking libraries. The analytical performance of the DB-5Q coupled with the upgraded Agilent HES 2.0 allows for optimal sensitivity, as well as the ability to perform targeted and nontargeted analyses in tandem.

3. Thermo Fisher Scientific: Reduction of helium usage for the analysis of pesticide residues in botanical dietary supplements using GC-MS/MS with the HeSaver-H₂ Safer technology

• Application

Introduction

Consumer interest in botanicals has grown considerably over the past few years as they are considered to contribute to overall health and wellbeing. Supplements are the most popular botanical products sold over the counter in pharmacies, groceries and online stores, therefore, manufacturers must ensure that the raw materials are safe for consumption. Pesticides are chemicals used for crop protection against a variety of pests such as weeds, fungi, rodents, and insects. Because of their extensive use, pesticides can be found in the air, soil, water, and ultimately in the food chain. Despite their use being highly regulated, misuse of pesticides can lead to unwanted contamination of food or other plant-based consumer products, and have possible impacts on both human and environmental health.

When analyzing pesticides, GC-MS/MS is employed to detect trace levels. Helium is the most common carrier gas used for gas chromatography thanks to its high chromatographic efficiency and inertness. Recent price rises in helium and supply issues caused by shortages have led GC manufacturers, researchers, and analysts to investigate possible mitigation options that entail either switching to alternative carrier gases or reducing the helium consumption. The Thermo Scientific™ HeSaver-H₂Safer™ carrier gas saving technology 1 offers an innovative and smart approach to dramatically reduce carrier gas consumption, especially during GC operation. It consists of a modified SSL body connected to two gas lines: whereas an inexpensive gas (e.g., nitrogen or argon) is used for inlet pressurization, analyte vaporization and transfer to the analytical column, the selected carrier gas (e.g., helium or hydrogen) is used only to supply the chromatographic column for the separation process, with a limited maximum flow rate. When used with helium as carrier gas, the limited consumption helps to mitigate shortage issues while maintaining GC-MS performance without the need for instrument method re-optimization otherwise required in case of migration to a different carrier gas.

In this analysis a Thermo Scientific™ TRACE ™ 1610 gas chromatograph equipped with two Thermo Scientific™ iConnect™ split/splitless injectors, one operating as a standard SSL and the other one upgraded to work in HeSaver-H₂Safer mode using argon as pressurizing gas, was coupled to the Thermo Scientific™ TSQ™ 9610 triple quadrupole mass spectrometer and used to run a direct comparison to demonstrate consistency in the analytical results. Details regarding the standards, reagents and the sample preparation used in this study are reported in a previous application note.

Summary

The HeSaver-H₂Safer technology offers the advantage of nearly 4 times reduced helium gas consumption, without compromising GC-MS performance for the analysis of residual pesticides in botanical supplements, through a smooth and simple upgrade of a standard iConnect SSL injector module.

• The transition from the injection phase using an inexpensive pressurizing gas to the separation process using the best carrier gas is extremely fast (within a few milliseconds), ensuring a rapid gas replacement into the column and, thus, analogous performance compared to the use of a standard SSL injector.
• Existing validated methods can be used unchanged with consistent analytical performance in terms of injection repeatability, analyte transfer, linearity, recovery and robustness.
• Moreover, the HeSaver-H₂Safer technology provides additional advantages, such as discharging the pressurizing gas only through the split line for the majority of the time, protecting the column from possible contaminants.
• The Helium Gas Saver Calculator allows for easy and immediate estimation of helium cylinder lifetime and cost savings when using the helium-saver technology.