News from LabRulezGCMS Library - Week 20, 2025

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 12th May 2025? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!

👉 SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT GCMS AND RELATED TECHNIQUES

👉 Need info about different analytical techniques? Peek into LabRulezLCMS or LabRulezICPMS libraries.

This week we bring you technical note by Agilent Technologies, application note by Shimadzu and poster by MDCW!

1. Agilent Technologies: How Does Bleed Impact GC/MS Data and How Can It Be Controlled?

• Technical note
• Full PDF for download

Understanding column bleed 

Column bleed remains one of the most commonly observed yet misunderstood aspects of mass spectrometry (MS) data. Bleed elevates chromatographic baselines and creates spectral interference, lowering the quality of and confidence in your data. To understand bleed, it must first be considered where the bleed originates. While columns come in a wide variety of phase types, the most commonly used columns today, such as the 1, 5, and 624, are categorized as wall-coated open tubular (WCOT) columns. These columns are composed of fused silica tubing (with varying internal diameters, measured in mm), internally coated with a thin film of stationary phase (with varying thicknesses, measured in μm), as shown in Figure 1. This coated stationary phase interacts with analytes and creates the selectivity and retention characteristics of the chromatography; but, these same characteristics are the origins of column bleed.

Column phases can be made from a wide variety of polarities of liquid polymers with a polysiloxane backbone. When heat is applied, the terminal end of the stationary phase polymer starts to bend back and attack itself, which is called "backbiting." Ring structures, which are thermodynamically stable, become liberated and increase the noise and raise the baseline, as shown in Figure 2. The process is then repeated. The higher the temperature provided, the faster the reaction is driven, which is why there is an increase in baseline at temperatures above 300 °C. 

An increase in the rise of a baseline can be problematic for low signal-to-noise analytes, as peak integration can negatively impact data quality. Stable, flat baselines optimize the accuracy and repeatability of peak integration. When working with sensitive detectors, such as MS, an increase in the sensitivity of the detector also increases the background noise and bleed detection, causing excess column bleed to be detrimental to the sensitivity of trace level compounds.

Experimental

An Agilent 8890 GC coupled with a flame ionization detector (FID), and an Agilent 5977 Series B GC/MSD were used to collect data. Data acquisition was performed using Agilent OpenLab ChemStation and MassHunter acquisition software. Additionally, an Agilent Intuvo 9000 GC coupled with an FID was used to collect data. J&W DB-5Q and J&W HP‑5Q GC columns were compared to various conventional, commercially available 5ms GC columns.

Results and discussion 

Comparisons of bleed profiles at upper temperature limits 

To compare the thermal stability of the HP-5Q columns to conventional 5ms columns, columns were installed on an 8890 GC equipped with dual split/splitless inlets and dual FIDs, and experiments were done in tandem. After confirming that column connections were properly installed, free of leaks, and conditioned, the oven temperature was ramped up to temperatures of 330 and 340 °C and held for 10 minutes each. Then, the oven temperature was ramped to a final temperature of 350 °C (the programed MAOT of the column phases) and held for 30 minutes. As shown in Figure 4, both the DB-5Q and HP-5Q maintained ultralow FID response at the upper temperature limits, both maintaining column bleed levels below 1.0 pA at 340 °C. Also, when operating the columns at 350 °C (the programmed maximum temperature) over a period of 10 hours, both the DB-5Q and HP-5Q maintained bleed levels below 2.0 pA, while the conventional 5ms columns X and Y had bleed levels at 10 and 4 pA respectively, demonstrating the increased thermal stability of the DB-5Q and HP-5Q GC columns.

Conclusion 

While column bleed is a normal phenomenon, there are ways to decrease its impact on the analysis and sensitivity of the detector being used. Improved column technology, with the introduction of the Agilent J&W DB-5Q and HP-5Q GC columns, has provided an increase in thermal stability that dramatically reduces column bleed. The decrease in column bleed at high temperatures allows an increase in sensitivity of mass spectrometers, as the spectral interference from ions due to backbiting of column phase is reduced. This demonstrates that the DB-5Q and HP-5Q GC columns are optimal for use with sensitive detectors such as GC/MS, triple quadrupole GC/MS, and GC/Q-TOF.

2. MDCW: Group-type quantitation of hydrocarbons in aviation fuel using GC×GC–FID 

• Poster
• Full PDF for download

Accurate hydrocarbon composition of finished fuels, such as aviation fuel, is required to ensure quality control and to determine the effects of processes in fuel production. This has become even more important with the development of novel renewable fuels, such as sustainable aviation fuels (SAFs).

Here, we demonstrate the use of reverse fill/flush (RFF) flow-modulated GC×GC–FID and automated group-type data processing to provide fast and accurate quantitative information on hydrocarbon composition.

Experimental

• Samples: A reference standard and reference blends of both diesel and aviation turbine fuel. 
• GC×GC: Modulator: INSIGHT®-Flow reverse fill/flush (RFF) flow modulator (SepSolve Analytical); Modulation period (PM): 7.8 s. Carrier gas: H2. 
• Column set: ASTM D8396 reverse phase column set (SepSolve Analytical, PN: OEM-SEP-COLKIT-10) 
• FID: Total H2 flow (column & fuel): 50 mL/min; Air flow: 350 mL/min: Makeup gas flow: 5 mL/min; Temperature: 300 °C. 
• Software: ChromSpace® GC×GC software for instrument control and data processing

Results and discussion

Optimising the GC×GC separation 

Separation was optimised using a custom column set and larger loop volume, enabling excellent separation of the key chemical classes (Figure 2).

The INSIGHT-Flow modulator used in this study has an adjustable sample loop (in the range of 25-250 μL) for greater flexibility in method development. The reference standard was analysed in replicate (n=10) to assess method repeatability and precision. The relative standard deviation (RSD) of the raw peak areas were all <2%, while the calculated mass percent values were consistently within 0.5% of the known composition. 

Group-type classifications 

Group-type analysis of these key chemical classes was then performed on various fuels using the ‘stencil’ workflow in ChromSpace software (Figure 3). Once a stencil is created, it can be saved and applied to multiple data files in an automated batch sequence to generate area percent reports. This means that the method is then scalable across multiple GC×GC–FID platforms for fast classification. This proven workflow has already gained accredited status in a number of high-throughput environmental labs for the analysis of total petroleum hydrocarbons (TPH).

Conclusions

This poster has shown an end-to-end workflow for ASTM Method D8396, specifically: 

• Proven reverse fill/flush modulation using the INSIGHT-Flow, a modulator in operation in numerous high-throughput labs across the world. 
• Optimal class separation with a tried-and-tested column set. 
• Fast, straightforward group-type data processing with ChromSpace software. 
• Doubled productivity with optional dual-channel GC×GC technology. 
• A retrofittable solution for all popular GCs, allowing existing systems to be upgraded to GC×GC capability

3. Shimadzu: Analysis of Dechlorane Plus Residues in Environmental Water Using GCMS-TQ8050 NX with Boosted Efficiency Ion Source(BEIS) and Long-Life Filament

• Application note
• Full PDF for download

User Benefits:

• The combination of the BEIS and long-life filament enables high sensitivity analysis while maintaining long-term stability.
• The 13C-Dechlorane 602 is used as internal standard(IS) in the optimization method to avoid the interference of isotope IS with target components in MRM mode.

Dechlorane Plus (DP) is a synthetic substance mainly used as an adhesive, sealant and flame retardant for polymers in the industrial field. Due to its strong persistence and bioaccumulation, there is a significant risk to human and environmental health. In 2018, the European Chemicals Agency (ECHA) identified it as a Substance of Very High Concern (SVHC), and in June 2021 proposed to add it to Appendix XVII of the REACH regulation to restrict it, proposing to ban the production and use of DPs and prohibit the production and launch on the market of goods with DP content equal to or greater than 0.1% (by weight). In May 2023, the Stockholm Convention on Persistent Organic Pollutants (POPs) listed DP in Appendix A. At the same time, DP is also included in China's List of new pollutants under Key Control (2023 version). 

A method for the determination of residues of DPs in environmental water was established by using the Shimadzu GCMS-TQ8050 NX equipped with Boost Efficiency Ion Source and long-life filament. This application news provides an important analytical method for determine the residue levels of new pollutantsin environment with high sensitivity and good stability.

Quantitative Analysis

In the initial scheme, 13C-DP was used as the IS. However, due to the same retention time of 13C-DP and the target compound, the characteristic ions cause interference, resulting in a large calibration curve intercept and a high RF RSD (>80%). Therefore, 13C-Dechlorane 602 is used as the IS instead. Its retention time differsfrom target DP, which helps avoid the interference.

Evaluation of Durability in Analysis of Standard Solution and Samples

The sample solution and 0.5 ng/mL standard solution were tested to evaluate the long-term durability of response. A total of 500 analyses of the sample and 80 analyses of standard solution were conducted. Fig.3 shows the durability test results of the standard solution. The horizontal axis shows the number of analyses, while the vertical axis shows the peak area ratio for each analysis number. The results indicate that the changes in peak area ratio and ion proportion were within ±20% of the average value (calculated from very beginning 20 injections).

Conclusion

A method for the determination of DP residues in environmental water was established by using the Shimadzu GCMS-TQ8050 NX combined with BEIS and long-life filament. The target compound exhibited good linearity in the concentration range of 0.2 to 50.0 ng/mL and the RF RSD of calibration curve was less than 15 %. The standard solution of 0.2 ng/mL was injected for 10 consecutive times to measure the LOD with results of 0.063 and 0.103 ng/mL. The durability of DP response was investigated by alternating test of sample solution and standard solution, and the peak area ratio in standard solution fluctuated within 20% in 500 injection of samples. The recovery rate of 1 ng/mL in blank samples was around 102 %. The method has high sensitivity and good repeatability and is suitable for the determination of DP residues in surface water, groundwater, industrial wastewater, and domestic sewage.