JEOL Resources

Structural analysis of polyethylene terephthalates with different crystallinity using JMS-S3000 "SpiralTOF™-plus 2.0"

Thu, 27 Aug 2026 16:18:20 GMT

MSTips No. 407

Poly (ethylene terephthalate) (PET) is a thermoplastic polyester obtained by polycondensation of ethylene glycol and terephthalic acid, and has excellent properties such as transparency, toughness, rigidity, and heat resistance (Figure 1). PET can be roughly divided into two types depending on processability: crystalline PET (C-PET) and amorphous PET (A-PET). C-PET has a high density due to the regular arrangement of the molecules in the crystallized part, and is characterized by high strength and heat resistance. A-PET is characterized by high impact strength and easy bending. However, due to long-term use or exposure to heat, the amorphous portion of A-PET slowly crystallizes, causing internal stress due to changes in density and breaking the polymer chains, resulting in poor flexibility, impact resistance, and strength. Therefore, a polymer was devised in which about 30-40% of the ethylene glycol in PET was replaced with cyclohexanedimethanol; this polymer is called glycol-modified PET (G-PET, PETG) (Figure 2). G-PET is treated as an amorphous resin because the polymer does not crystallize during molding. In a previous report [1], we performed structural analysis of two types of commercially available PET resins (PET film and PET plate) using reactive pyrolysis GC-TOFMS and NMR, and confirmed that the PET film was PET and the PET plate was G-PET. In this report, we analyzed the oligomer region of the same samples using a high-resolution MALDI-TOFMS JMS-S3000 "SpiralTOF™-plus 2.0" in combination with Kendrick Mass Defect (KMD) analysis.

Off-flavor analysis in natural rubber by using HS-GC/MS/MS

Thu, 27 Aug 2026 16:16:03 GMT

MSTips No. 406

Natural rubber is used in a wide range of products from daily necessities such as shoe soles and hoses to industrial products such as tires. It is important to control off-flavor components in natural rubber, because the sap of natural rubber trees has a strong odor. In general, the SCAN/SIM measurement by HS-GC/MS is used for this analysis. However, it has possibility that the SIM measurement is affected by matrix components, because some natural rubbers contain many matrix components. Therefore, it is difficult to analyze off-flavor components contained in trace amounts by using the SIM measurement. On the other hand, the SRM measurement of GC/MS/MS use a combination of selected precursor ion and generated product ion from its selected precursor ion, so selectivity of detection ion and detection sensitivity will be improved. As a result, the influence of matrix components can be reduced, and it is possible to detect components contained in trace amounts. In this application, we report the analysis of off-flavor components in natural rubber by using HS-GC/MS/MS.

End group analysis of poly(methyl methacrylate) using MALDI-TOFMS and GC-TOFMS

Thu, 27 Aug 2026 16:13:55 GMT

MSTips No. 404

Mass spectrometry can be used to analyze synthetic polymers, providing a variety of information, such as the main chain structure, end group structure, and molecular weight distribution (average molecular weight, polydispersity). Analysis of end group structure is particularly important for the following reasons.

The physical properties of polymer materials can change depending on the end groups, even though they are relatively small part of the whole polymer molecules.
End group structure might change (or degrade) due to environmental exposures.
End group structure can provide insight into the polymerization mechanism.

MALDI is a soft ionization method that allows the observation of polymer molecules as singly charged ions. Using high-resolution MALDI-TOFMS, it is possible to elucidate the elemental compositions of end groups from the accurate masses. On the other hand, pyrolysis GC-TOFMS analyzes the pyrolysis products produced by instantaneous heating of a polymer. Mainly monomers and dimers are observed, but if pyrolysis products containing end groups are observed, structural information on the end groups can be obtained. In this report, we performed structural analysis of the end groups of poly(methyl methacrylate) by using MALDI-TOFMS and pyrolysis GC-TOFMS in a complementary manner.

Confirmation of the chemical formula of heat/light sensitive compounds using field desorption coupled with high-resolution mass spectrometry

Thu, 27 Aug 2026 16:11:18 GMT

MSTips No. 403

Field desorption (FD) is a soft ionization technique useful for producing molecular ions in an MS ion source. The combination of high-resolution time-of-flight mass spectrometry (HRTOFMS) and FD is useful for direct MS measurement of a sample, and provides information for identifying the chemical formula of synthetic compounds and confirming the molecular weight. Since FD-HRMS vaporizes and ionizes a sample rapidly in a vacuum, and does not use a gas chromatograph, it has advantages for measuring unstable compounds, such as those sensitive to heat and light.

The FD emitter consists of carbon whiskers on a tungsten wire, and is inserted into the ion source using a probe. After coating the emitter with a sample solution and installing the probe to MS, FD measurement is performed by turning on the high voltage in the mass spectrometer. The most common method for coating the FD emitter is using a micro-syringe. This application note reports the syringe sampling procedure, and measurement results of example compounds that are sensitive to heat and light.

Analysis of mPEG5K-Phosphate using JMS-S3000 "SpiralTOF™-plus 2.0"

Thu, 27 Aug 2026 16:09:12 GMT

MSTips No. 402

The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is a powerful tool for polymer analysis. Since MALDI generates mainly singly-charged ions, m/z values from the mass spectrum are the same as the polymer ion's mass. In general, polymer analysis by MALDI-TOFMS is performed in positive ion mode because the sample solution is added to the matrix and cationizing agent solution. On the other hand, a polymer including sulfate or phosphate groups at the end group can be measured in the negative ion mode. In MSTips No. 333, we reported the measurement results of anionic surfactants less than m/z 1000. In this application note, we report the measurement of polyethylene glycol (average molecular weight 5000) having phosphate groups as an end group.

Analysis of Simazine and Thiobencarb by GC-MS method using hydrogen carrier gas

Thu, 27 Aug 2026 16:06:37 GMT

MSTips No. 401

Helium (He), which is widely used as a carrier gas for GC, may face problems such as temporary price increases or unstable supply conditions due to various reasons, and when supply delays occur, it is necessary to consider using another type of carrier gas as an alternative. Hydrogen and nitrogen are the main alternative gases being considered. Hydrogen, in particular, has a wide linear velocity range for optimum separation and is suitable as a carrier gas for GC. In this report, simazine and thiobencarb, pesticides subject to environmental standards for water pollution, were measured with hydrogen carrier gas. The results show good linearity of the calibration curve and reproducibility at the lower limit of quantification.

Structural Analysis of Polyethylene Terephthalates with Different Crystallinity using Reactive Pyrolysis GC-TOFMS and NMR

Thu, 27 Aug 2026 16:04:26 GMT

MSTips No. 400

Polyethylene terephthalate (PET) is a thermoplastic polyester that is obtained by polycondensation of ethylene glycol and terephthalic acid and has excellent transparency, toughness, rigidity, and heat resistance (Figure 1). PET can be roughly divided into two types, crystalline PET (C-PET) and amorphous PET (A-PET), depending on the processing method. C-PET has the characteristics of high strength and heat resistance due to the regular arrangement of the molecules in the crystallized part, which increases the density. A-PET is characterized by high impact strength and easy bending. However, the amorphous portion of A-PET slowly crystallizes due to long-term use and heat history, causing changes over time. Changes in density generate internal stress that cuts polymer chains, which can lead to deterioration in flexibility, impact resistance, strength, etc. Therefore, a polymer was devised in which about 30-40% of the ethylene glycol in PET was replaced with cyclohexanedimethanol, and this is called glycol-modified PET (G-PET, PETG) (Figure 2). G-PET is treated as an amorphous resin because the polymer does not crystallize even during the molding process.

In this application note, two types of commercially available PET resins are analyzed by reactive pyrolysis GC-TOFMS and NMR, and the results of analysis to determine whether they are PET or G-PET are reported.

Composition analysis of EO-PO copolymers using JMS-S3000 “SpiralTOF™-plus2.0” and “msRepeatFinder V6”

Thu, 27 Aug 2026 16:02:26 GMT

MSTips No. 399

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOFMS) is a powerful tool for polymer analysis. Since MALDI mainly produces singly charged ions, the m/z values in the mass spectrum is the masses of the polymer ions. By using high mass-resolution MALDI-TOFMS, it is possible to easily distinguish polymer series based on differences in repeating units and end group composition, and to calculate the molecular weight distribution of each series. Recently, the Kendrick Mass Defect (KMD) method has made it possible to easily visualize polymer series contained in complex high mass-resolution mass spectra. When the molecular weight of a sample is several thousand or more, it is known that electrospray ionization (ESI), a typical soft ionization method along with MALDI, tends to produce mainly multiply charged ions, making it difficult to directly analyze the mass spectrum, let alone perform KMD analysis. Therefore, the combination of the high mass-accuracy of the JMS-S3000 “SpiralTOF™-plus2.0” and KMD analysis is particularly effective for the analysis of copolymers. Here, we will report on the binary copolymer search function newly added to msRepeatFinder V6 and the resulting compositional analysis of EO-PO copolymers using the degree of polymerization plot.

Analysis of di(2-ethylhexyl)phthalate, dichloroacetonitrile and chloral hydrate by GC-MS method using nitrogen carrier gas

Thu, 27 Aug 2026 15:59:45 GMT

MSTips No. 398

Helium (He), which is widely used as a carrier gas for GC, can have problems such as temporary price increases and unstable supply conditions due to various reasons, and when supply delays occur, it is necessary to consider using another type of carrier gas as an alternative. Hydrogen and nitrogen are the main alternative gases being considered, with nitrogen gas being relatively easier to introduce into GC-MS when safety is a priority. In this report, di(2-ethylhexyl)phthalate, dichloroacetonitrile, and chloral hydrate, which are water quality control target items in water quality testing, were measured by the same column using nitrogen carrier gas. (For He, see MSTips No.325.) As a result, good linearity of the calibration curve and reproducibility at the lower limit of quantification were obtained for all compounds, and are presented in this report.

Analysis of di(2-ethylhexyl)phthalate, dichloroacetonitrile and chloral hydrate by GC-MS method using hydrogen carrier gas

Thu, 27 Aug 2026 15:57:30 GMT

MSTips No. 397

Helium (He), which is widely used as a carrier gas for GC, may face problems such as temporary price increases or unstable supply conditions due to various reasons, and when supply delays occur, it is necessary to consider using another type of carrier gas as an alternative. Hydrogen and nitrogen are the main alternative gases being considered. Hydrogen, in particular, has a wide linear velocity range for optimum separation and is suitable as a carrier gas for GC. In this report, di(2-ethylhexyl)phthalate, dichloroacetonitrile, and chloral hydrate, which are water quality control target items in water quality testing, were measured using hydrogen carrier gas by the same column. (For He, see MSTips No. 325.) As a result, good linearity of the calibration curve and reproducibility at the lower limit of quantification were obtained for all compounds, and are presented in this report.