Analytical Instrument Documents

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.

Compounds which are generated upon heating polymer materials include monomers, additives and fragments characteristic of the polymer materials. Low molecular weight compounds generated by pyrolysis and/or locally desorption are observed. The relationship between the behavior of evolved gas compounds and the heating temperature is important for understanding the chemical characteristics of polymer materials. A gas chromatograph (GC) - mass spectrometer (MS) with thermogravimetric / differential thermal analyzer (TG/DTA) or pyrolyzer (Py) is generally used to identify the thermally evolved gas compounds from polymer materials. However, GC with a low-resolution MS such as quadrupole MS (QMS) may have difficulty monitoring low molecular-weight compounds generated by heating, since the GC is not used to provide chromatographic separation and QMS has poor mass spectrometric separation in the low mass region. (For example, N2+·, CO+· and C2H4+· are detected as the same signal of nominal mass m/z 28.) We report the use of Py - GC - high resolution time-of-flight MS (HRTOFMS) for monitoring the low-molecular weight compounds generated upon heating the polymer materials. This report focuses on the generation of low molecular weight compounds near m/z 18, 28, and 4.

This report shows the analyses of the phenolic polymer antioxidants shown in Fig. 1. These samples were analyzed by using the AccuTOF-GCV with both direct insertion probe（DIP）electron ionization (EI) and field desorption (FD).

Three polydimethylsiloxane compounds: octamethylcyclotetrasiloxane (sample 1), decamethylcyclopentasiloxane (sample 2) and octa(dimethylsiloxy)silsesquioxane (sample 3), were analyzed using a GC/TOFMS. The first two samples are relatively small molecules with molecular weights of 296 and 370, respectively, so they were introduced into the system through the mass reference sample inlet (reservoir). Sample 3 is a much bigger molecule with a molecular weight of 1,016 that could not be introduced through the reservoir. As a result, this sample was introduced by injecting it into the GC.

A UV and visible light curing adhesive is a liquid composed of monomer, oligomer, initiator and additives. These adhesives cure over a short period of time when they are exposed to the appropriate light. In this report, a photo polymerization initiator found in a UV light curing adhesive was analyzed by electron ionization (EI) and field ionization (FI) using the high resolution and high mass accuracy capabilities of the AccuTOF-GC.

Organogermanium compounds are organometallics that contain a carbon to germanium chemical bond. Germanium shares group 14 in the periodic table with silicon, tin and lead and the chemistry of organogermanium is somewhat similar to that of organosilicon compounds and organotin compounds. While metallic germanium is widely used in semiconductor devices, infrared light sensors, etc., organogermanium is advocated as a non-toxic alternative to many toxic organotin reagents. In this work, we report the analyses of organogermanium compounds by field desorption (FD) using the JMS-T100GC “AccuTOF-GC” time-of-flight mass spectrometer.

Ionic liquids are liquids that are predominantly comprised of ions and ion-pairs. More recently, this term has generally referred to salts that are in a liquid state at room temperature. Ionic liquids are electrically conductive and have an extremely low vapor pressure. Additionally, many of these liquids have low combustibility and excellent thermal stability. As a result of these properties, ionic liquids are expected to find many applications as functional materials.