Analytical Instrument Documents

Every cook knows that chopping onions releases chemicals that cause eye irritation. The lachrymator released by chopped onions and related plants is formed by the action of a pair of enzymes on a cysteine derivative to ultimately form propanethial S-oxide (C3H6SO), the compound that causes eye irritation.

The explosive peroxide compounds triacetone triperoxide (TATP) and hexamethylenetriperoxide diamine (HMTD) are difficult to detect by conventional mass spectrometry methods. These compounds can be easily detected by the Direct Analysis in Real Time (DART™) ion source.

According to a recent report in Nature, freshly pressed extra-virgin olive oil contains a compound, oleocanthal, that has properties similar to the common anti-inflammatory drug, ibuprofen. We used DART to rapidly examine cooking oils for the presence of this compound. Fresh-pressed extra-virgin olive oil from a specialty food store was compared with a medium-quality grocery-store brand. Sesame oil and a low-quality spray-on cooking oil were also examined. No sample preparation was required.

Tomatoes are rich in lycopene, a hydrocarbon antioxidant that is the source of the red coloring in ripe tomatoes. The potential benefits of nutritional antioxidants such as lycopene have received a great deal of attention in the popular media. A piece of tomato skin was placed in front of the DART and the positive-ion mass spectrum was recorded.

There has been a recent trend in mass spectrometry towards the development of “open-air” ionization sources. These techniques allow for the rapid analysis of samples at atmospheric pressure with little or no sample preparation. The Direct Analysis in Real Time (DART™) ion source, which is ideal for the analysis of small molecules, represents the first and simplest of the open-air techniques.1 This source creates ions based on the interactions of long-lived excited state neutral atoms or molecules (“metastables”) with the sample and atmospheric gases.

The AccuTOF time-of-flight mass spectrometer equipped with Direct Analysis in Real Time (DART™) has been used to detect a wide variety of explosives in or on a variety of materials ranging from solutions to samples deposited on surfaces ranging from ABS plastic to metal, clothing and cardboard. Detection is rapid, specific, and sensitive.

Please see the following publication: “Versatile New Ion Source for the Analysis of Materials in Open Air under Ambient Conditions” Robert B. Cody, James A. Laramee and H. Dupont Durst, Analytical Chemistry 77 (8), 2297- 2302, 2005

DART provides very simple mass spectra that are free of multiple charging and alkali metal cation adducts such as [M+Na]+  and [M+K]. This facilitates identification of target compounds in mixtures and simplifies assignment of elemental compositions for unknowns.

Includes 44 application notes in the categories of Introduction and fundamentals, Drug Analysis, [Food, Flavors, and Fragrances], Forensics, Homeland Security, Industrial Materials, and Organic Chemistry.

In a recently published comparison of the ambient ionization techniques direct analysis in real time (DART™) and DESI, it was reported that a protonated molecule was not observed for DART, whereas the protonated molecule could be observed for DESI and DAPCI. This is an incorrect observation, resulting from the use of different experimental conditions for DART than were used for the other two techniques. Mass spectra of aspirin measured on a JEOL AccuTOF-DART™ mass spectrometer under the correct operating conditions are shown here. All assignments for the mass spectral peaks were confirmed by exact mass measurements.

rss

Other Resources

Walkup NMR
  • See how the Delta NMR software allows users to just "walk up" and start NMR experiments
  • Mass Spec Reference Data
  • View our page of useful molecular references for Mass Spec
  • Tutorials (Mass Spec)
  • Documents on the basics of mass spectrometry
  • Delta NMR software Tutorials
  • Videos on how to use the Delta NMR software
  • No-D NMR
  • Description of No-D NMR and how it can be used to eliminate the need for deuterated solvents
  • Non Uniform Sampling (NUS)
  • Description of how NUS is used to greatly reduce the time needed for running NMR experiments
  • NMR Basics
  • Overview of the Basics of NMR Theory
  • NMR Magnet Destruction
  • See our presentation of the slicing open of a JEOL Delta-GSX 270 MHz NMR Magnet
  • NMR Training
    Basic Operations and System Management for JEOL NMR Users
    Mass Spec Training
    Learn more about spectrometer operation and maintenance, data collection and processing, and advanced MS software operation.
    JEOLink NMR Newsletter
    We publish and send out this NMR newsletter to our customers. They can also be viewed here.
    Mass Media Newsletter
    We publish and send out this Mass Spec newsletter to our customers. They can also be viewed here.
    © Copyright 2023 by JEOL USA, Inc.
    Terms of Use
    |
    Privacy Policy
    |
    Cookie Preferences