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Comprehensive two-dimensional gas chromatography (GC x GC) in combination with high-resolution mass spectrometry is a powerful tool for the analysis of complex mixtures. In this work, we analyzed a diesel fuel sample by using GC x GC in combination with a new high-resolution time-of-flight mass spectrometer (HR-TOFMS) . Field ionization (FI) produced molecular ions for all components and exact mass measurements were used to obtain elemental compositions. A traditional Kendrick Mass Defect (KMD) plot was used to identify hydrocarbon groups in the diesel fuel sample.

Triazolam is a benzodiazepine with a very short elimination half-life. The range is reported to be 1.5 to 5.5 hours. Due to its frequent use as a sedative and its potential to affect human activities such as driving, an unambiguous and sensitive analysis method is needed for its identification and quantitation. Generally, for determination of triazolam, screen tests are performed in biological samples followed by confirmation and quantitation with GC/MS. Here, we demonstrate the feasibility by using the JEOL AccuTOF™ GC, time-of-flight mass spectrometer with accurate mass measurement and negative ion chemical ionization (NCI) capabilities for triazolam determination. D4-triazolam was used as internal standard. The mass accuracy without internal reference is smaller than 2 mmu. The limit of detection is 5 ng/mL. The quantitation standard curve can be linear from 5 ng/mL to 1000 ng/mL with R2 of 0.9992. To the best of our knowledge, this is the first time that triazolam has been detected by GC/time-of-flight mass spectrometry with accurate mass measurement.

Field Desorption (FD) is a technique that ionizes analytes by electron tunneling from the analyte molecules to a solid surface (emitter) in a high electric field. The sample is applied directly onto the emitter and heated by applying an electric current through the emitter for desorption and ionization. FD has been used for the analysis of nonvolatile compounds, synthetic polymers, etc., as a soft ionization method to produce molecular ions with little or no fragmentations. As a result, the average molecular weight of a sample can be calculated directly from the masses (or “m/z”) and intensities for all of the ions observed in the FD mass spectrum. Furthermore, by applying group-type analysis, the components can be classified into types based on their functional groups and/or unsaturations. Average molecular weight, polydispersity index, or relative abundance of each type can also be obtained. In this work, new and used rotary vacuum pump (RP hereafter) oils were analyzed by FD. Afterwards, the change in their compositions was determined by performing group-type analysis on the resulting mass spectra.

Advances in mass spectrometry are enabling analysis of micro samples and unknown components that were not observable before. As the volume of information acquired from mass spectrometry increases, researchers are calling for simple techniques to analyze numerous components observed, and as a result, there is a rise in demand for comprehensive analytical techniques including multiple classification analysis. In this work, we will introduce a new technique for non-target analysis, which combines comprehensive analysis using high resolution GC-TOFMS and unknown component analysis using soft ionization.

Advances in mass spectrometry are enabling analysis of micro samples and unknown components that were not observable before. As the volume of information acquired from mass spectrometry increases, researchers are calling for simple techniques to analyze numerous components observed, and as a result, there is a rise in demand for comprehensive analytical techniques including multiple classification analysis. In this work, we will introduce a new technique of non-targeted analysis, which combines comprehensive analysis using high resolution GC-MS and unknown component analysis using soft ionization and EI.

Migration of mineral oil from packaging into food has become a health concern, especially since mineral oil affects the liver and lymph nodes. There are two types of mineral oil: mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). Both types are generally measured using online coupled liquid chromatography–gas chromatography–flame ionization detection 2only to separate and detect target fractions, and it may miss other important, unexpected compounds. By contrast, two-dimensional gas chromatography–high-resolution time-of-flight mass spectrometry (GCxGC–HRTOF–MS) is a comprehensive technique for analyzing complex samples. Using EI with this method allows for NIST database searches. Moreover, using a combination of high-resolution molecular-ion information generated via soft-ionization techniques with an EI NIST database search can result in more-reliable assignments. In this study, we used GCxGC–HRTOFMS with EI and photoionization (PI) soft-ionization techniques to identify compounds in cardboard.

Electron ionization (EI) is a common ionization technique for gas chromatography/mass spectrometry (GC/MS). However, EI often does not produce strong molecular ions (M+・) because the excess energy generates fragment ions during the ionization process. The detection of the molecular ion is very important for confirming the molecular weight of the target compounds. Therefore, a soft ionization technique is often necessary to determine the molecular weight information. Field ionization (FI) is well known as one of the softest ionization techniques commercially available. Similarly, photoionization (PI) can produce molecular ions. In this application note, the characteristics of PI and FI were investigated by using various compounds. Furthermore, the performance between EI, FI and PI for these compounds in diesel fuel were investigated.

The AccuTOF GCv 4G is JEOL's third generation high resolution GC-TOFMS. New, enhanced features of the system include: 1) Recording speed: up to 50 spectra/sec 2) Mass resolution: 8,000 or more (m/z 614, FWHM) 3) Mass accuracy: 1.5 mmu or 4 ppm 4) Mass range: m/z 4 to 5,000 Comprehensive 2D GC (GCxGC) is a chromatographic separations technique that uses 2 columns with different polarities arranged in a series. Featuring higher resolution than conventional capillary GC analysis, it is a powerful tool for the measurement of multiple components in a complex mixture. However, because there is a cryo-trap before the 2nd column, the resulting peaks in the chromatograms are extremely narrow. As a result, the system requires a detector capable of high speed data recording. The TOFMS is an ideal detector for the 2D GC system. In this work, we analyzed aroma oil using a GCxGCHRTOFMS system, in which the AccuTOF GCv 4G was used with a Zoex GCxGC system to examine the spectrum recording speed and mass accuracy.

Skin is an active metabolic tissue that synthesizes a variety of complex lipid compounds. Sebum, an oily material secreted by the skin, is known to provide a moisturizing effect, sunlight protection, and antibacterial protection for the skin surface. Sebum consists of a complex mixture of free fatty acids, squalene, cholesterol, wax esters, diacylglycerols and triacylglycerols. These species and their concentrations vary depending on skin conditions. Lipid compounds are generally measured by using GC–FID, GC–MS or LC–MS. However, these methods are often unable to separate all of the individual compounds under the same measurement conditions. In addition, it can be difficult to definitively identify each lipid compound due to co-elution. On the other hand, two-dimensional GC - high resolution time-of-flight mass spectrometry (GCxGC–HRTOFMS) is a powerful tool for identifying analytes in complex mixtures such as crude oils. The purpose of this work is the comprehensive detection and identification of lipid compounds in sebum by using GCxGC-HRTOFMS.

Perfumes are known to be complex mixtures that typically contain a variety of compounds. Their scents are strongly affected by these compounds and their quantity ratios. Additionally, these ratios can change over time, thus changing the perfume’s scent. Two-dimensional gas chromatography/time-of-flight mass spectrometry (GCxGC-TOFMS) is an effective technique for measuring complex samples like perfumes. Using electron ionization (EI) allows for database searches. However, these searches may result in mis-assignments without the additional high-resolution molecular ion information that can be generated through soft ionization techniques. In this study, we used GCxGC-HRTOFMS with EI and the soft ionization techniques of FI (Field Ionization) and PI (Photoionization). Additionally, we measured the changes in intensity over time for the top note/middle note/base note compounds.

Other Resources

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    Corona - Glow Discharge (DART Ion Source)

    January 28, 2022
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