News from LabRulezGCMS Library - Week 48, 2024

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 25th November 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 and other documents by Agilent Technologies, Thermo Fisher Scientific, Shimadzu, and a poster from Analytica by LECO!

1. Thermo Fisher Scientific: Determination of sulfur-containing compounds, formaldehyde, and organic halides in hydrogen for proton-exchange membrane fuel cell vehicles

• Application

Goal

The goal of this application note is to demonstrate a suitable analytical method that can be applied for the determination of sulfur-containing compounds, formaldehyde, and organic halides in hydrogen used for proton-exchange membrane fuel cell vehicles in compliance with the Chinese regulation (GB/T 37244-2018) by using thermal desorption coupled to gas chromatography-mass spectrometry and sulfur chemiluminescence detection (SCD).

Introduction

The past energy crisis and global warming led researchers to find alternative cleaner and emission-free energy sources. Hydrogen has been identified as a very promising energy carrier or fuel due to its exceptional energy per mass content. The proton-exchange membrane fuel cell (PEMFC) has garnered considerable attention and represents a breakthrough technology for automotive applications due to its capability to convert hydrogen and oxygen into electricity with only water as a by-product. Studies have shown that impurities such as CO, CO₂, NH₃, formaldehyde, halogenated compounds, and sulfur-containing compounds in hydrogen can cause serious damage to the performance of PEMFC by reducing its service life. Therefore, an accurate assessment of hydrogen purity is extremely important. This application note is focused on the determination of sulfur-containing compounds, formaldehyde, and organic halide impurities in hydrogen gas.

Conclusion

The results obtained in this study demonstrated that the Markes UNITY–CIA Advantage-xr pre-concentrator combined with the TRACE 1610 GC equipped with the SCD detector and connected to an ISQ 7610 single quadrupole mass spectrometer provides a highly performing solution for selective and sensitive analysis of some critical hydrogen impurities in compliance with the requirements of the Chinese regulation.

• R² values were ≥ 0.995 for all the investigated compounds with linear ranges from 0.1 to 10 nmol/mol for sulfur-containing compounds, from 1 to 400 nmol/mol for formaldehyde, and from 1 to 100 nmol/mol for organic halides, with RSD of response factors well below the
  acceptance limit of 30%.
• LODs calculated as 3.143 × S₀ resulted close to 0.01 nmol/mol for sulfur-containing compounds, 0.04 nmol/mol for formaldehyde, and between 0.06 and 0.095 nmol/mol for organic halides.
• Peak area repeatability was <12% for all the target analytes.

2. Shimadzu: Analysis of Diethylene Glycol in Glycerin Using Brevis GC-2050

• Application

User Benefits

• The compact Brevis GC-2050 allows for high-throughput analysis by increasing the number of operational units in the lab.
• Despite its small size, the Brevis GC-2050 achieves uncompromised analytical performance, enabling the analysis of concentrated glycerin in compliance with pharmacopeial standards.

Introduction

In response to the issue of contamination in pharmaceuticals and toothpaste with diethylene glycol, certain parts of the Japanese Pharmacopoeia were revised through Ministry of Health, Labour and Welfare Notification No. 32 (February 21, 2008). In Application News G259 “Analysis of Diethylene Glycol in Glycerin,” a measurement example conforming to the pharmacopoeial requirements is introduced using GC-2010. While each country has its own official methods, this application conducted measurements on a Brevis GC-2050 under
conditions where the Split/Splitless injection unit (SPL) temperature was set higher, taking into consideration that the sample component has a high boiling point, with reference to the Japanese Pharmacopoeia.

Conclusion

A sample was prepared for the analysis of concentrated glycerin as described in the Japanese Pharmacopoeia, and the analysis was conducted by the condition specified in the Japanese Pharmacopoeia. Good separation and reproducibility were confirmed.

3. Agilent Technologies: GC and GC/MS Frequently Asked Questions

• Guide

Table of Contents

In this eBook, you’ll find answers to the questions that Agilent technical experts hear most often from our GC and GC/MS customers. To instantly access the information you need, click the following links or use the navigation tabs at the bottom of each page.

General Knowledge

• How does chromatography work?
• Why is GC column polarity important?
• What is the significance of GC column dimensions?
• What are the basic principles and mechanisms of GC/MS?
• How do chemical and electron impact ionization differ?
• What is the difference between standard, mass spec, and Ultra Inert columns?
• What is headspace and how does it work?
• What is the difference between split and splitless?
• How do I choose the right carrier gas for my detector?
• What should I consider when using hydrogen as an alternate to helium carrier gas?
• How does the Agilent HydroInert source preserve spectral fidelity with hydrogen carrier gas?
• What solvent is best for liquid injection on GC/MS?

Maintenance

• How often should I change columns?
• How often should I change liners?
• How do I check for leaks?
• When should I replace the filaments?
• Can preslit vial cap septa prevent septa leakage into the inlet or sample?
• I use the MS with complex matrices every day. Should I tune daily or weekly?
• What chemicals should I use to perform a standard instrument check?
• When replacing and conditioning a column, should I install it into the MS?
• How does JetClean maximize instrument uptime and productivity?
• How do I prevent loss of column efficiency and resolution?

Method Development and Optimization

• How do I develop methods in MRM/SRM mode?
• How do I select an internal standard (ISTD) for my GC/MS analysis?
• How do I select the right MSD for my sample or analytical requirements?
• How do I choose the right mass spectrometer?
• What are the rules of thumb for choosing an inlet liner?
• What is a good approach for analyzing unknown compounds?
• Can I quantify GC/MS results in either scan or SIM mode?

Troubleshooting

• How do I improve peak shape?
• How do I improve resolution?
• How do I improve signal-to-noise levels?
• What causes spiking and how do I avoid it?
• What can cause a negative peak in GC/MS?
• Where do ghost peaks come from?
• What can cause split peaks, peak tailing, and drifting baselines?
• Why is water difficult to observe in GC and how can it be quantified using GC?
• How do I determine the source of contamination within my chromatograph?

4. LECO / Analytica: Cannabis Characterization Using GC and GCxGC with Time-of-Flight Mass Spectrometry

• Poster (Analytica)

Cannabis is a complex plant containing a variety of naturally occurring organic compounds in a wide range of concentrations, as well as xenobiotics (i.e., polyaromatic hydrocarbons, pesticides, etc.). Among these constituents, the cannabinoids, terpenes, and terpenoids are commonly recognized for their therapeutic properties. This plant has two main subspecies—Cannabis indica and Cannabis sativa—that can be differentiated by their different physical
characteristics. Indica-dominant strains are short plants with broad, dark green leaves and have higher cannabidiol content than the sativa plants in which THC content is higher. Sativa-dominant strains are usually taller and have thin leaves with a pale green colour.

The legalization of this drug has also led to an increasing amount of consumer products being infused with CBD, marketed and sold for medicinal and recreational purposes. Thus, it is imperative that we are able to determine its total composition as this is important in determining potency and medical effectiveness (Entourage Effect). In this study, we use GC with Time-of-Flight Mass Spectrometry (TOF-MS) to assist in the determination of its risks and
benefits. This powerful tool provides chromatographic separation with high-quality deconvoluted mass spectral data allowing for comprehensive analysis, identification, and quantification of targeted and non-targeted analytes.

Conclusion

GCxGC-TOFMS facilitates compound identification, Library searches, and Mass ∆ calculations. Data was used to develop maps for quantitative analysis, cannabis classification, and sample comparison. Cannabis comparison via statistical processing was performed using ChromaTOF Tile (based on Fisher ratios) and could also perform PCA analysis.