Analytical Instrument Documents

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 the 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 analyzed 2 samples in a high resolution GC-TOFMS, using EI, the most widely used ionization technique for GC-MS, and compared the data acquired by using a comprehensive analytical technique.

Petroleum waxes are a class of hydrocarbons that are solid at room temperature and are classified by the Japan Industrial Standards (JIS K2235) into 3 types: paraffin wax, micro crystalline wax, and petrolatum. A typical micro crystalline wax contains hydrocarbons having a carbon number of 30 to 60 and molecular weights between 500 and 800. In addition to paraffins, these waxes also include large quantities of isoparaffins and cycloparaffins. Field desorption (FD) is an ionization technique that utilizes the tunneling effect of electrons in the presence of a high electric field. The sample is applied directly onto an FD emitter filament, and then an electric current is applied to the filament to produce a high electric field across the emitter surface (including the whisker tips) to desorb and ionize the samples. As a soft ionization technique that minimizes fragmentation and produces molecular ions, FD has been previously used for analyzing refractory compounds and high molecular weight polymers. In this work we ionized a micro crystalline wax by using a JMS-T100GC AccuTOF-GC with FD ionization to do a sample type analysis that was based on the mass and intensity of the resulting ions.

JEOL has developed a unique EI/FI/FD combination ion source for the “AccuTOF GCv 4G”, a high- resolution GC-time-of-flight (TOF) MS system. This unique ion source provides the capabilities of GC/EI, GC/FI and FD measurements without having to break vacuum in order to switch between each ionization mode. Additionally, this combination is particularly powerful in that it provides library searchable fragmentation information by using EI and high mass accuracy molecular ion information by using FI and FD. In this work, we measured an antioxidant additive by using each ionization mode available on the AccuTOF GCv 4G combination ion source (EI/FI/FD).

Recently, JEOL introduced the AccuTOF-GC, an innovative GC/time-of-flight mass spectrometer (TOF MS) that is capable of both high data acquisition rates and easy exact mass measurements. The exact mass measurements can then be used to generate lists of possible elemental compositions, which is a powerful tool for identifying unknown compounds. Additionally, this information can be combined with the fragmentation information to help confirm the identity an unknown compound. In this work, the AccuTOF-GC system was used to identify an unknown compound in a liquid crystal extract.

The JEOL “AccuTOF GCv 4G” is a third generation GC/HRTOFMS system with high speed data acquisition capabilities of up to 50Hz which makes it well suited as the detector for comprehensive 2-dimensional GC (GCxGC) measurements. Along with the high speed data acquisition, this MS system also provides high mass resolution, accurate mass measurements, and high sensitivity, all simultaneously. Consequently, this GCxGC/HRTOFMS system is a powerful tool for the qualitative analysis of complicated samples. In this work, we measured commercially available tequila samples using GCxGC/HRTOFMS combined with solid-phase micro-extraction (SPME) preparation.

Average molecular weight is an important reference for evaluating samples with molecular weight distributions, such as crude oils, which are complex mixtures, or synthetic polymers. Almost all of the ions observed in field desorption (FD) and field ionization (FI) mass spectra are molecular ions since they are both soft ionization methods. The average molecular weight of a sample can be calculated directly from the masses (or “m/z”) and intensities of all of the ions observed by FD or FI. 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 be obtained.

Average molecular weight is an important reference for evaluating samples with molecular weight distributions, such as crude oils, which are complex mixtures, or synthetic polymers. Almost all of the ions observed in field desorption (FD) and field ionization (FI) mass spectra are molecular ions because they are both soft ionization methods. 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 or FI mass spectra. 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 be obtained.

The FastGC method is a very useful technique for doing rapid GC analyses that result in extremely narrow chromatographic peaks over a shorter time period than traditional GC analyses. Additionally, time-of-flight mass spectrometers (TOFMS) are capable of very fast data acquisition in comparison with other types of mass spectrometers so they are well suited as the detector for the FastGC technique. Furthermore, when the TOFMS is capable of high resolution measurements, the resulting mass spectra contain accurate mass information that can be used to calculate the elemental compositions for each observed m/z. In this application note, we describe the quanitative analysis of pyrazole pesticides (Fipronil, Ethiprole, Pyraflufen ethyl and Tebfenpyrad) on tea leaves by FastGC/HRTOFMS. Additionally, we confirm that a rapid analysis with high sensitivity is easy to perform and very useful for fast screening.

The FastGC method is a very useful technique for doing rapid GC analyses that result in extremely narrow chromatographic peaks over a shorter time period than traditional GC analyses. Additionally, time-of-flight mass spectrometers (TOFMS) are capable of very fast data acquisition in comparison with other types of mass spectrometers so they are well suited as the detector for the FastGC technique. Furthermore, when the TOFMS is capable of high resolution measurements, the resulting mass spectra contain accurate mass information that can be used to calculate the elemental compositions for each observed m/z. In this application note, we describe the qualitative analysis of pyrazole pesticides (Fipronil, Ethiprole, Pyraflufen ethyl and Tebfenpyrad) on tea leaves by FastGC/HRTOFMS. Additionally, we confirm that a rapid analysis with high sensitivity is easy to perform and very useful for fast screening.

Comprehensive two-dimensional gas chromatography (GC×GC) is a kind of continuous heart-cut GC system. Two different types of columns are connected via a modulator in the same GC oven. By using the two columns together, this technique provides very high separation capabilities when compared to one- dimensional GC analysis. However, GC×GC systems require a fast data acquisition detection system in order to record the very narrow time width peaks observed in the GC chromatograms. The JEOL AccuTOF-GC is a time-of-flight mass spectrometer (TOFMS) that fully meets this high speed data acquisition requirement at 25Hz (0.04sec) so it can be successfully used as the detection system in combination with GC×GC. In this work, the AccuTOF-GC was used for the qualitative analysis of polycyclic aromatic hydrocarbons in kerosene by GC×GC -TOFMS.

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