News from LabRulezGCMS Library - Week 40, 2024

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 30th September 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, Waters Corporation, and Thermo Fisher Scientific, and a poster from ASMS by Shimadzu!

1. Shimadzu: Analysis of Volatile PFAS in Water Using Head-Space Solid Phase Microextraction- Gas Chromatography/Mass Spectrometry (HS-SPME GC/MS)

• Poster / ASMS 

Introduction 

Per- and Polyfluoroalkyl Substances (PFAS) are environmental pollutants with recognized health and environmental concerns due to their probable toxicity, persistence, and ubiquitousness throughout the environment, and consumer and industrial products. PFAS encompass a large family of chemicals with varying physicochemical properties. These properties not only affect their toxicity and environmental fate, but also complicates chemical analysis.

In this work, a Head-Space Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry (HS-SPME GCMS) analytical method was developed to analyze six classes of volatile PFAS in water. This HS-SPME method presents the advantage of simplifying sample extraction and handling for the analysis of volatile PFAS in water, hence, minimizing operational costs, potential errors, and risk of sample-cross contamination.

Conclusion

This study demonstrated the use of a Shimadzu GC/MS-QP2020 NX single quadrupole instrument configured with the AOC-6000 Plus multifunctional autosampler and an automated head space solid phase microextraction unit for measurement of volatile PFAS compounds in water. Linear calibration curves were obtained for all compounds (R 2 ≥ 0.993 and RF %RSD < 20 %). The HS-SPME GC/MS-QP2020 NX method demonstrated qualitative and quantitative capability of analyzing PFAS compounds.

2. Thermo Fisher Scientific: Analysis of volatile organic compounds in drinking water according to U.S. EPA Method 524.4

• Application

Goal

Demonstration of an analytical method that meets the requirements outlined in U.S. EPA Method 524.4 for the quantitation of volatile organic compounds (VOCs) in drinking water, using the Teledyne LABS Tekmar Lumin Purge and Trap (P&T) concentrator paired with the AQUATek LVA autosampler system along with a Thermo Scientific™ ISQ™ 7610 MS system coupled with a Thermo Scientific™ TRACE™ 1610 gas chromatograph (GC) and Thermo Scientific™ Chromeleon™ Chromatography Data System (CDS). Target analyte linearity, method detection limit (MDL), minimum report level (MRL), and mid-point precision and accuracy were assessed to evaluate method performance.

Keywords: EPA, U.S. EPA 524.4, VOCs, phthalates, trace analysis, gas chromatography, single quadrupole mass spectrometry, selected ion monitoring, sensitivity, GRO, THM, volatiles, environmental lab, environmental sample analysis, analytical testing laboratories, ISQ 7610 MS, TRACE 1610 GC, GC-MS.

Introduction

Volatile organic compounds (VOCs) are man-made contaminants in various products that pose environmental and public health risks. These compounds are regulated in drinking water, and laboratories follow regulations including U.S. EPA Method 524.2.1 A previous application note described U.S. EPA Method 524.2,2,3 which is the most common method for VOC water testing in the USA. U.S. EPA Method 524.4 is an updated method that allows for nitrogen to be used as the purge gas, thus reducing helium consumption, and is now being more widely used. Targeting 75 VOCs, this method differs by offering more method parameter flexibility but stricter quality control, including the stringent calculation of the minimum reporting level for evaluating calibration checks.

Implementing U.S. EPA Method 524.4 can present multiple challenges for laboratories. Striking a balance between optimized method conditions and meeting the acceptance criteria, like detection limit requirements for various compound concentrations, is pivotal. Another major hurdle is managing the water matrix to minimize GC-MS system water introduction, which could lead to detrimental effects and delay sample reporting, thereby increasing public safety risks. Ultimately, maintaining consistency in test results to avoid sample reanalysis is crucial. Another factor for laboratories to consider is the fluctuating cost of helium, which is the analytical gas of choice for this analysis.
Reducing the use of helium—a limited resource—will enable the laboratory to reduce operational costs and increase profitability.

The following evaluation describes the use of the ISQ 7610 GC-MS system coupled with a TRACE 1610 GC with the Thermo Scientific™ HeSaver-H₂Safer™ split/splitless injector and Teledyne LABS Tekmar Lumin P&T concentrator paired with the AQUATek LVA autosampler for U.S. EPA Method 524.4.

Conclusion

The combined solution of the TRACE 1610 GC coupled with the ISQ 7610 system and the Tekmar Lumin P&T concentrator with the AQUATek LVA autosampler system successfully addresses the challenges of VOC analysis and provides a robust, sensitive solution needed for ensuring maximized sample throughput and regulatory method compliance for U.S. EPA Method 524.4.

• Excellent linearity for all compounds was demonstrated with the linear regression (r²≥0.995) of the calibration response factors passing all method requirements.
• MDL and precision for seven 0.5 ppb standards showed no interference from excessive water and produced very reproducible results.
• The precision for n=30 samples over 245 injections displayed <30% RSD for all compounds as the method requires and an average recovery of 91%.
• Utilizing HeSaver-H₂Safer technology reduced helium consumption for the method by 4 times, which provides a significant cost savings.

3. Waters Corporation: Extractables Analysis of Nasal Spray Devices Using Gas Chromatography and High- Resolution Mass Spectrometry With Soft Ionization

• Application

Abstract

Due to concern about the safety of components from plastic, it is crucial to screen for and identify potential extractables and leachables (E&L) in pharmaceutical packaging and medical devices. For volatile, and semi-volatile compounds, gas chromatography-mass spectrometry (GC-MS) with electron ionization (EI) is typically used. Compounds are determined using scientific libraries; however, where compounds are not listed or where the sensitivity of EI-MS is not sufficient, the identification process becomes challenging.

Here, we describe an E&L screening experiment using gas chromatography and a quadrupole time of flight high-resolution mass spectrometer (QToF-HRMS) with atmospheric pressure gas chromatography (APGC) for soft ionization. A data independent acquisition (DIA) strategy is utilized to aid screening and elucidation which are combined in a screening software solution.

Benefits

• GC-QToF MS with APGC as an orthogonal technique to LC-QToF-MS allows for comprehensive compound coverage with increased sensitivity compared to typical EI techniques
• The UNIFI™ application within the waters_connect™ platform provides customized workflows to simplify screening and structural elucidation in complex datasets
• The Xevo™ G3 QTof Mass Spectrometer enables confident identification of E&L components in complex matrices through novel ion optics and detection system which maximize transmission
• Soft ionization using the APGC™ source allows for the detection of molecular ions from which elemental compositions can be derived to aid compound identification and confirmation 
• MSE, a data independent acquisition, increases confidence in identifications when screening against a library and provides additional information to aid structural elucidation

Conclusion 

When undertaking E&L screening analyses it is important to use a range of analytical techniques to account for different compound chemistries. GC-QToF MS with APGC as an orthogonal technique to LC-QToF-MS allowed for comprehensive compound coverage with increased sensitivity compared to typical EI techniques. Due to the soft ionization of APGC, the intact molecular ion is often present in the spectra. This combined with a data independent acquisition, MS^E mode, utilizes full spectral acquisition of the accurate mass information of both precursor and fragment ions.

This approach boosts confidence in component identifications when screening against an MS/MS library, while minimizing false positives. For instance, in the LC-QToF-MS there were just under 40 potential compounds matches in sample E48 after considering factors such as retention time match, mass accuracy below 3 ppm, and the presence of at least one fragment ion. A further 38 compound matches in sample E48 were tentatively identified using GC-QToF MS with APGC, with mass accuracy below 3 ppm, and the presence of at least one fragment ion.

MS^E data also aids in the structural elucidation of unknown substances by utilizing accurate mass and corresponding fragment ions, facilitating comprehensive characterization. This data increases confidence in identifications of components and assists with structural elucidation of unknowns to ultimately aid full characterization. For example an unknown with protonated m/z 284.2703 was tentatively identified as a N-(2-(1-piperazinyl)ethyl)decanamide (mass error 2.33 ppm) by the software.

For the extractables analysis of nasal sprays the UNIFI application within the waters_connect platform provided SST benchmarking, screening against a library, summary plots to identify trends, filtering of AET levels, binary compare mode to isolate relevant unknowns, and a Discovery Tool for elucidation of unknowns.

4. Agilent Technologies: Analysis of Volatile Compounds Identified in Rubber Gasket Extracts Using GC/MSD and High-Resolution GC/Q-TOF

• Application

Abstract

Chemicals that are part of polymeric container closure systems (CCS) and drug delivery systems have the potential to migrate into drug products during manufacturing, storage, transport, and delivery, and must be identified in the final products to ensure their safety.

This application note presents a rubber gasket extractables study using a unit mass resolution gas chromatography/mass selective detector (GC/MSD) and a high-resolution gas chromatography/quadrupole time-of-flight (GC/Q-TOF) mass spectrometer to establish a process for identifying GC-amenable extractables and leachable (E&L) compounds.

Introduction

Elastomeric gaskets, plungers, and O-rings are common sources of leachable compounds in the manufacturing, storage, and delivery of drug products. E&Ls derived from elastomeric components may impact the stability and efficacy of small and large molecule drug products¹, and therefore need to be characterized thoroughly. Exposure to some E&L chemicals, such as phthalates and nitrosamines, even at low levels, may cause safety concerns.² Chemicals derived from the elastomer manufacturing process typically include accelerators, activators, antioxidants, fillers, plasticizers (including phthalates), mold release agents, and other additives³ that may leach into the final product. Some additives present in elastomer packaging materials may also contain polycyclic aromatic hydrocarbons (PAHs)⁴ and aliphatic hydrocarbons.

GC/MS is a commonly used technique for analyzing volatile and semivolatile organic compounds in the E&L space. This study demonstrates the capabilities of GC/MSD to identify GC-amenable compounds present in a solvent extract of a rubber gasket by leveraging chromatographic deconvolution in combination with retention index (RI)-based filtering. Adding a high-resolution accurate mass GC/Q-TOF into the E&L workflow provided a higher number of identified chemicals. It also increased confidence in compound identification and enabled structure elucidation of unknown compounds.

The study was performed in the Network Workstation configuration using Agilent OpenLab Electronic Content Management (ECM) XT as the data repository. This configuration enabled tools that facilitate compliance with various national and EU electronic record regulations, including audit trails, user authentication, role-based permission controls, and remote data storage.⁵

Conclusion

The GC/MSD is an effective and accessible tool for the analysis of volatile and semivolatile compounds in complex E&L extracts. The established workflow includes deconvolution and an RI-based library search with the data acquisition performed in a compliant environment.

The high-resolution Agilent 7250 GC/Q-TOF enabled the identification of additional components with increased confidence, as well as structure elucidation of the unknown compounds.

Furthermore, using the novel ultra-low bleed Agilent J&W DB-5Q GC column resulted in a significant decrease in background, which helps in the identification of late-eluting compounds.