Analytical Instrument Documents

High-resolution mass spectrometry (HRMS) continues to play an important role in the compositional characterization of larger organic molecules. In the field of polymer characterization, however, the application of HRMS has made only slow progress because of lower compatibility between matrix-assisted laser desorption/ionization (MALDI) and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS). In this study, a newly developed type of MALDI high-resolution time-of-flight mass spectrometry (TOFMS) with a spiral ion trajectory (MALDI spiral-TOFMS) was applied to the structural and compositional characterization of polymers. To create a graphical distribution of polymer components on a two-dimensional plot converted from complex mass spectra, we adopted a slightly modified Kendrick mass defect (KMD) analysis based on accurate masses determined using spiral-TOFMS. By setting the Kendrick mass scale based on the mass of the repeating units of a given polymer, components with common repeat units lined up in the horizontal direction on the KMD plot, whereas those components with different structures were shifted vertically. This combination of MALDI spiral-TOFMS measurement and KMD analysis enabled the successful discrimination of the polymer components in a blend of poly(alkylene oxide)s, the compositional analysis of poly(ethylene oxide)/poly(propylene oxide) block copolymers, and profiling of the end-group distribution of poly(ε- caprolactone)s synthesized under different conditions.

Traceability and authenticity of olive oils in Croatia were probed by a versatile analytical approach using spiral MALDI-TOF MS system for the triacylglycerol (TAG) analysis. Molecular ion patterns were shown to represent specific data for statistical analysis, in which differences of cultivar regions of Croatian coast were recognized. This pilot project allows indications to be followed in high throughput procedures with high number of samples to get statistically relevant data for discrimination of olive oils from different geographic sites. Additionally, the fragmentation in the TOF/TOF MS provided distinct highly valuable data for assignment of acyl residues. In this way molecular species with different fatty acid substituents can be clearly assigned and possible isomeric mixtures identified.

The structural characterization of copolymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) remains a challenging task, since their random comonomer distribution creates very complicated mass spectra. In this study, a high-resolution TOF mass spectrometer with a spiral ion trajectory was applied to the structural and compositional characterization of free radical copolymerized poly(methyl methacrylate-co-tert-butyl methacrylate), poly(MMA-co-tBMA)s in ethyl lactate acting as a chain transfer agent. Virtually complete peak assignments of the isobaric components within the poly(MMA-co-tBMA)s served to identify the end-group combinations and copolymer compositions of individual copolymer components, allowing the distributions of comonomer compositions and six types of end-group combinations to be evaluated.

Last Updated: September 2013

PaperSpray Principle: Samples and a polar solvent such as methanol are deposited onto a porous substrate such as filter paper or chromatography paper cut into a triangle. When a high voltage (typically ~3000V) is applied, Electrospray Ionization (ESI) occurs at the tip of the paper triangle. PaperSpray is simpler than ESI and does not require a pump, spray needle, desolvating gas or precise alignment.

The JMS-TQ4000GC Triple-Quadrupole Mass Spectrometer accurately measures trace or residual pesticides in agricultural materials, trace levels of regulated chemicals in tap water, and simplifies quantitative analysis of persistent environmental pollutants such as dioxins and PCB’s.

The new JMS-Q1600GC UltraQuad™ SQ-Zeta Single Quad Mass Spectrometer of JEOL is our 6th generation high-end Gas Chromatograph Quadrupole Mass Spectrometer.

Different ionization methods for MS applications: Electron Ionization (EI), Chemical Ionization (CI), Photo Ionization (PI), Field Ionization / Field Desorption (FI/FD) Electrospray Ionization (ESI ), CSI (Cold-Spray Ionization), Direct Analysis in Real Time (DART), and Matrix Assisted Laser Desorption / Ionization (MALDI).

JEOL, a world leader in SEM technology for six decades, offers scanning electron microscopes that enable imaging and analysis of the smallest details in forensic microscopy. JEOL SEMs are used for crime scene investigation, accident reconstruction, ballistics, explosives detection, toxicology, arson investigation, automated gun shot residue analysis, trace evidence, and failure analysis. The imaging and analytical ability of JEOL SEMs reveal physical and chemical evidence that might otherwise be easily overlooked.

JEOL introduced the DART ion source in 2005, and the technology quickly gained recognition, winning both the Pittcon Editor’s Gold Award and the R&D 100 Award. Since that time nearly 400 papers have been published by chemists using the AccuTOF-DART. The introduction of DART made it possible for the first time to carry out atmospheric pressure ionization for analysis of samples in open air.