Analytical Instruments Documents

rss

JEOL Resources

Documentation in support of your JEOL product.

Monitoring Rotary Vacuum Pump Oil Degradation by Using Field Desorption (FD)-TOFMS and Group-type Analysis Software

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.

Type Analysis of Micro Crystalline Wax (Petroleum Wax) by Using Field Desorption (FD) Ionization

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.

Rapid Analysis Using Deactivated Fused Silica Tubing(a.k.a. “Guard Column”) as the Sample Inlet (2)

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.

Rapid Analysis Using Deactivated Fused Silica Tubing(a.k.a. “Guard Column”) as the Sample Inlet (1)

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.

Qualitative Analysis by Comprehensive 2D GC / TOFMS[2]: Analysis of polycyclic aromatic hydrocarbons in kerosene

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.

Qualitative Analysis by Comprehensive 2D GC / TOFMS[1]: Comparison of kerosene and diesel oil

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 to analyze kerosene and diesel oil samples by GC×GC -TOFMS.

High-speed 50 Hz Data AcquisitionCapability for Comprehensive 2-dimensional GC Measurements

The comprehensive 2-dimensional GC (GC x GC) technique provides higher-separation capabilities for complex mixtures than the typical 1-dimensional GC measurements. However, the GC x GC technique requires high speed data acquisition, e. g. > 20 Hz, for the GC detectors due to the shorter 2nd GC column which elutes samples within just a few seconds (comparable to those used for the ultra-fast GC measurements). Recently, JEOL has developed a new generation GC-HRTOFMS system called the “AccuTOF GCv 4G”. The AccuTOF GCv 4G has high sensitivity, high resolution, high mass accuracy and high speed data acquisition, all simultaneously. In fact, this instrument can measure data using up to a 50 Hz data acquisition speed which is more than sufficient to do not only fast GC measurements but also GC x GC measurements.

Group-type Analysis of Crude Oil by Using GC/FI-TOFMS Part 2: Reproducibility of group-type analysis results

Field Desorption (FD) and Field Ionization (FI) are both techniques that ionize analytes by electron tunneling from the analyte molecules to a solid surface (emitter) in a high electric field. In the case of FD, the sample is applied directly onto the emitter and heated by applying an electric current through the emitter for desorption and ionization. In the case of FI, vaporized analyte molecules are introduced into the proximity of the emitter. Both FI and FD are soft ionization methods that generally yield intact molecular ions and, in most cases, produce very few fragment ions. Generally, these two techniques are used to ionize analytes that are easy to fragment and do not generally produce molecular ions during electron ionization (EI), such as hydrocarbons in crude oil.

Group-type Analysis of Crude Oil by Using GC/FI-TOFMS Part 1: Determination of average molecular weights

Field Desorption (FD) and Field Ionization (FI) are both techniques that ionize analytes by electron tunneling from the analyte molecules to a solid surface (emitter) in a high electric field. In the case of FD, the sample is applied directly onto the emitter and heated by applying an electric current through the emitter for desorption and ionization. In the case of FI, vaporized analyte molecules are introduced into the proximity of the emitter. Both FI and FD are soft ionization methods that generally yield intact molecular ions and, in most cases, produce very few fragment ions. Generally, these two techniques are used to ionize analytes that are easy to fragment and do not generally produce molecular ions during electron ionization (EI), such as hydrocarbons in crude oil.

GCxGC-EI and GCxGC-FI Measurements Using the EI-FI Combination Ion Source

Comprehensive 2-dimensional GC (GC x GC) provides higher-separation capabilities for complex mixtures than the typical 1-dimensional GC measurements. However, this technique requires high speed data acquisition, e. g. > 20 Hz, for the GC detectors due to the shorter 2nd GC column (comparable to those used for the ultra-fast GC measurements) which elutes samples within just a few seconds. Recently, JEOL has developed a new generation GC-HRTOFMS system called the “AccuTOF GCv 4G”. The AccuTOF GCv 4G has high sensitivity, high resolution, high mass accuracy and high speed data acquisition, all simultaneously. Also JEOL has developed a unique EI/FI combination ion source for this system which provides the capabilities of GC/EI and GC/FI 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.

Other Resources

The following resources are available for the JEOL Analytical Instruments:

Media

Corona - Glow Discharge (DART Ion Source)

February 22, 2020
121