News from LabRulezGCMS Library - Week 37, 2024

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 9th 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, Shimadzu, and Thermo Fisher Scientific and poster by LECO from ACS meeting!

1. Thermo Fisher Scientific: Adhering to U.S. EPA Method 524.2 for the analysis of volatile organic compounds in drinking water

• application

Goal: Demonstration of a routine analytical method that meets the requirements outlined in U.S. EPA 524.2 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). Method linearity, method detection limit (MDL), precision, and accuracy were assessed to evaluate method performance.

Introduction: Analytical testing labs play a crucial role in monitoring surface, ground, and drinking water for volatile organic compounds (VOCs). Common by-products in the processing of household and industrial products, VOCs can contaminate water sources, potentially harming the environment and public health. To safeguard against this, labs use the U.S. EPA Method 524.21 to test water for the presence of VOCs, including four trihalomethane disinfection by-products. This procedure utilizes Purge and Trap (P&T) procedures to remove VOCs with high volatility and low water solubility from water samples, followed by gas chromatography-mass spectrometry (GC-MS).

Conclusion: The TRACE 1610 GC, the ISQ 7610 system, and the Tekmar Lumin P&T with the AQUATek LVA autosampler system together offer benefits for executing U.S. EPA Method 524.2. The Tekmar Lumin P&T concentrator enhances sample throughput through efficient trap cooling and moisture control, thus reducing peak interference and extending GC column life. The ISQ 7610 system’s VPI and ExtractaBrite ion source allow ionization source and analytical column replacement without venting the instrument, ensuring minimal downtime, and the XLXR™ detector offers extended linear dynamic range. The collective technology addresses routine VOC analysis challenges, ensuring robust sensitivity, maximized output, and consistent method compliance. The ISQ 7610 system equipped with the VPI coupled with the Tekmar Lumin P&T and the AQUATek LVA autosampler exceeds all the requirements outlined in U.S. EPA Method 524.2 for analysis of VOCs in drinking water:

• Excellent linearity for all compounds was demonstrated with the %RSD 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 average MDL result for all 83 target compounds was 0.06 ppb with a precision of 4.06%.
• The precision for n=31 samples over 189 injections displayed <30% RSD accuracy for all compounds as the method requires. The average precision for all 83 target compounds and 2 surrogates gave a %RSD of 6.43% with an accuracy of 98% recovering the compounds. Individually, 4-bromofluorobenzene and 1,2-dichlorobenzene-d4 had a 7.68% RSD with an accuracy of 98% and 4.95% RSD and an accuracy of 95%, respectively, over 189 injections and almost four days of uninterrupted analysis.

2. Shimadzu: Analysis of Denatured Fuel Ethanol with Brevis GC-2050 Using ASTM D5501

• application

User Benefits

• The compact design of the Brevis GC-2050 enables space-saving in the laboratory.
• As an alternative gas for helium, hydrogen can be used as the carrier gas.
•  Analysis of ethanol and methanol in fuels based on ASTM D5501 is possible.

Introduction

Bioethanol has attracted attention as a form of renewable energy which can be obtained from biomasssuch as corn and sugar cane. ASTM D5501 provides a test method for determination of the concentrations of ethanol and methanol in fuels for concentrations of ethanol from 20 to 100 wt% and concentrations of methanol from 0.01 to 0.6 wt%.

In this Application News article, measurements of the purity of ethanol containing gasoline as a denaturant as specified in ASTM D5501 were carried out with a Brevis GC-2050 gas chromatograph, using helium and hydrogen asthe carrier gases.

Conclusion

Ethanol purity tests were carried out as provided in ASTM D5501 using a Brevis GC-2050 gas chromatograph. The splitter linearity test showed no inlet discrimination so that accurate qualitative analysis could be made for denatured fuel ethanol with the wide boiling range components regardless of whether helium or hydrogen was used as the carrier gas.

3. Agilent Technologies: Analysis of Aldehydes in Beer by Agilent PAL3 Autosampler and 5977C GC/MSD

• application

Abstract

This application note describes a method for quantitation of four aldehydes (hexanal, furfural, phenylacetaldehyde, and trans-2-nonenal) responsible for off-flavors in beer using an Agilent 8890/5977C GC/MSD with an Agilent PAL3 (SPME) autosampler. The method used fully automated, solvent-free extraction and on-fiber derivatization. The aldehyde compounds were derivatized with the derivatization agent O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) using the on-fiber derivatization procedure. The derivatization agent was first adsorbed onto an Agilent 65 µm PDMS/DVB fiber. Next, the fiber was inserted into a 20 mL headspace vial containing a 2 mL beer sample with agitation at 60 °C for 30 minutes. Both extraction and derivatization procedures were automatically performed using the PAL3 autosampler. The method demonstrated excellent sensitivity, with detection limits of 0.0009 µg/L for hexanal, 0.52 µg/L for furfural, 0.015 µg/L for phenylacetaldehyde, and 0.003 µg/L for trans-2-nonenal. The limits of the quantification for the four compounds were 0.003, 1.72, 0.05, and 0.01 µg/L, respectively. The four aldehydes were successfully quantified in four beer samples purchased from a supermarket. Good repeatability was demonstrated with RSD < 4.9% based on three replicate injections of the four beer samples for all four aldehydes.

Conclusion

This application note describes the quantitative analysis of four aldehydes (hexanal, furfural, phenylacetaldehyde, and trans-2-nonenal) responsible for off-flavors in beer using an Agilent 8890/5977C GC/MSD with a PAL3 (SPME) autosampler. This method offers the advantages of full automation, rapid analysis, solvent-free extraction, and on-fiber derivatization. With this automated solution, excellent sensitivity was demonstrated for the detection of hexanal (0.0009 μg/L), furfural (0.52 μg/L), phenylacetaldehyde (0.015 μg/L), and trans-2-nonenal (0.003 μg/L). Four different brands of beer were analyzed, with hexanal detected in the range of 0.45 to 1.56 μg/L, furfural in the range of 6.62 to 50.37 μg/L, phenylacetaldehyde in the range of 6.64 to 10.51 μg/L, and trans-2-nonenal in the range of 0.031 to 0.062 μg/L. Good repeatability was demonstrated with RSD < 4.9% based on three replicate injections of the four beer samples for all four aldehydes.

4. LECO: Combining GC with MS and Olfactory Detection for a Variety of Food, Flavor, and Fragrance Analyses

• Poster / ACS

INTRODUCTION

Gas chromatography (GC) coupled with mass spectrometry (MS) is an important tool for the characterization of a wide range of food, flavor, and fragrance samples. The components most likely to contribute to the aroma of a sample tend to be volatile and semi-volatile analytes, and GC-MS is well-suited for this type of analysis. Complex samples are effectively separated into the individual analyte components with GC. Time-of-Flight (TOF) MS detection provides important information towards the identification of these potentially important components of the sample with full m/z range data that can be library searched and that is also optimal for deconvolution algorithms. The incorporation of olfactory (O) detection with this data is particularly helpful for connecting the identified features with their contributions to the overall aroma or flavor. This type of sensory directed analysis highlights regions of interest and leads to specific analytes of interest for a focused review of the data. This combination of tools can separate and identify analytes and then determine those that are most important for contributing to the sensory characteristics of the sample. A variety of samples were analyzed with this combination of tools, and the benefits of using the information together are highlighted.

CONCLUSIONS

In this work, the combination of a GC separation with MS and O for detection provided a powerful and efficient analytical platform to isolate individual analytes, identify those isolated analytes, and connect them to their sensory impacts. The olfactory data allowed for sensory directed analysis. In each case, the GC separation and full m/z range TOFMS data were crucial for determining the identification of the feature responsible for the characteristic aroma. This collection of tools was demonstrated for the characterization of the most aroma impacting components of a nutmeg essential oil, the distinction of sensory differences in cilantro, and the determination of an off-odor in beer.