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Analysis of Degraded Polymethyl Methacrylate by UV Irradiation - MSTips 324

Polymers can be degraded by the effects of light, oxygen, heat, etc. so it is important to understand how the polymer structures change during degradation. Pyrolysis gas chromatograph quadrupole mass spectrometer (Py-GC-QMS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOFMS) are powerful tools for analyzing polymeric materials. Py-GC-QMS is a method that instantaneously heats a sample with a pyrolyzer and then analyzes the pyrolysis products by GC-MS. Since most of the pyrolysis products are related to monomers and dimers, this technique allows for easy identification of the polymer substructures which is useful for identifying changes to the polymer when degradation occurs. MALDI-TOFMS involves a soft ionization technique that can directly ionize and analyze the intact polymer molecules and often produces singly-charged ions even for high molecular weight compounds. As a result, the m/z axis of the mass spectrum is equal to the mass of the ions, thus making it easy to interpret polymer distributions. Additionally, when MALDI is used with a high-resolution TOFMS, the accurate mass of each ion in the polymer series can be used to calculate their elemental compositions. Moreover, the molecular weight distribution of polymers can be calculated from the ion intensity distribution. In this work, we used Py-GC-QMS and high-resolution MALDI-TOFMS to evaluate the effects of UV irradiation on polymethyl methacrylate (PMMA).

Analysis of Coffee Aroma Compounds by Headspace Solid-Phase Microextraction (SPME) GC-MS with the JMS Q1500GC Master-Quad GC-MS System

The composition of volatiles from freshly ground roasted coffee is complex, with hundreds of chemical compounds contributing to the aroma. Headspace solid-phase microextraction was used to sample volatiles from five different coffees for analysis by GC-MS. Chemometric analysis revealed specific differences between coffees from different origins and different preparations.

GC-MS Analysis of Cocoa Butter Triglycerides

Cocoa butter is the edible fat extracted from cocoa beans that is used in the manufacture of chocolate. Cocoa Butter Equivalents (CBE) are a substance derived from palm oil and shea butter that are used as a substitute for cocoa butter in chocolate. European regulations govern the labeling of chocolate as containing CBE less than 5%. US regulations require that Cocoa Butter Equivalents be specifically labeled with wording such as “chocolate flavored” coating. Analysis of the triglyceride content of chocolate is a quality control measure. Analysis of a standard sample of cocoa butter triglycerides is presented here as an example of the use of the JEOL Q1500 quadrupole GC-MS system for the detection of lipids separated by using a high-temperature GC column (Restek Rtx-65TG).

Thermal-decomposition Process Analysis of Sodium Formate Using TG-MS

Thermogravimetry (TG) is used to measure weight changes of samples under programmed heat conditions. A system combining thermogravimetry/differential thermal analysis (TG/DTA) with mass spectrometry (MS) can be used for both qualitative and quantitative analysis of gases evolved from the TG furnace into the mass spectrometer. In this application note, we show qualitative analysis of the thermal-decomposition process for sodium formate using the “STA2500 Regulus” TG system (NETZSCH) and the gas chromatography–quadrupole mass spectrometry (GC/QMS) “JMS-Q1500GC” system (JEOL).

Semi-quantitative Analysis of Low-molecular-weight Cyclic Siloxane in Silicone Rubber via Pyrolysis GC/MS

Silicone rubber is made from low-molecular-weight (LMW) cyclic siloxane. Most LMW cyclic siloxane is used up during the polymerization process, and the residual cyclic siloxane is removed by subsequent heating and depressurization steps. Generally, the residual level of cyclic siloxane is <3% in silicone rubber, but in the field of electronic equipment manufacturing, residual cyclic siloxane levels must be < 1% in order to avoid contact failure of relays, connectors, etc. due to gases evolved by LMW cyclic siloxane. In this application note, we show semi-quantitative analysis results of LMW cyclic siloxane in silicone rubber that was analyzed using the EGA/PY-3030D pyrolyzer (Py) (Frontier Laboratories, Ltd.) and the gas chromatography–quadrupole mass-spectrometer (GC/QMS) instrument JMS-Q1500GC (JEOL).

Qualitative Analysis of Calcium Oxalate Using TG-MS System

A thermogravimetry/differential thermal analysis (TG/DTA) system is used to measure weight changes and relative temperatures of samples under programmed heat conditions. A system combining TG/DTA with mass spectrometry (MS) is called a TG-MS system, and is considered one of the best qualitative and quantitative analysis systems for inorganic materials because it can measure sample conditions, evolved gas species, and gas volume simultaneously. In this application note, we introduce the basic application of analyzing calcium oxalate using the TG-MS “STA2500 Regulus” system (NETZSCH) and the GC/QMS “JMS-Q1500GC” system (JEOL).

Phthalates Impurity Analysis of PVC Resin Made with Alternative Plasticizers

The phthalates used as plasticizers in polymer resins are endocrine-disrupting substances that are a risk to human health. Therefore, the use of phthalates is limited by various government agencies. In the field of electrical equipment manufacturing, diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), and di-2-ethylhexyl phthalate (DEHP) are regulated by the European Union’s Restriction of Hazardous Substances (RoHS) Directive. The use of DBP, BBP, DEHP, di-n-octyl phthalate (DNOP), diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP) in toys and baby care products is regulated in Europe, the United States, China, and Japan. Phthalates subject to regulation are being replaced with alternative substances. However, it is known that phthalates tend to contaminate the manufacturing process and storage areas. Some alternative materials (e.g., tris-2-ethylhexyl trimellitate [TOTM]) may contain regulated components (e.g., DEHP) as impurities. In this report, PVC cables for commercial products using alternative substances as plasticizers were analyzed by the pyrolysis/thermal desorption–gas chromatography–mass spectrometry (Py/TD-GC-MS) method described in IEC 62321-8: 2017 [1]. Any phthalates discovered were quantified, and spectral information was collected for other detected compounds.

Analyzing Photodegraded Styrofoam by Using Py/GC/MS with a Combination EI/PI Ion Source

Electron ionization (EI) is the most commonly used ionization technique in gas chromatography–mass spectrometry (GC-MS). This hard ionization technique (70eV) provides excessive energy to organic compounds that results in highly reproducible fragment ions with relatively high ion intensities. As a result, EI databases have been created that help with identifying the compounds of interest. Despite this ability to do database searches, some compounds (alkanes, alcohols, etc.) do not produce abundant molecular ions, thus making it difficult to differentiate similar compounds from each other. By contrast, photoionization (PI) is a soft ionization technique that uses a vacuum ultraviolet (VUV) light source to provide ionization energies in the range of 8–10eV. This range is optimal for the soft ionization of common organic compounds which have an ionization energy in the range of 8–11eV. This low ionization energy results in stronger molecular ion signals and less fragmentation than for EI. Combining an EI library search with PI molecular ion information can improve the accuracy of the qualitative analysis results. In this work, we report on the qualitative analysis of styrene foam (Styrofoam) before and after photodegradation, using pyrolysis (Py)-GC/MS with an EI/PI combination ion source.

Comparative analysis of mechanical pencil lead by TG-MS

Thermogravimetry (TG) is used to measure weight changes of samples under programmed heat conditions. A system combining thermogravimetry/differential thermal analysis (TG/DTA) with mass spectrometry (MS) is called a TG-MS system, and can be used for both qualitative and quantitative mass spectral analysis of evolved gas from the TG furnace. The TG-MS technique can also be used to analyze the thermal-decomposition process. This application note shows an example of comparative analysis of mechanical-pencil leads of different performances, grades, and manufacturers. These leads are made by baking a mixture of graphite and resin, and then dipping it in oil for hardness and smoothness. Since the resin is carbonized and baked out, the lead is composed of only carbon and oil. In this application note, we show TG-MS analysis results for these mechanical-pencil leads using a “STA2500 Regulus” system (NETZSCH) and a gas chromatography–quadrupole mass spectrometry (GC/QMS) “JMS-Q1500GC” system (JEOL).

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Corona - Glow Discharge (DART Ion Source)

January 28, 2022
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