Analytical Instrument Documents

Field Ionization (FI) is a soft ionization method that ionizes analytes by electron tunneling from analyte molecules to a solid surface (emitter) in a high electric field. The vaporized analyte molecules are introduced into the proximity of the emitter in order for ionization to occur. In this work, we analyzed functional monomers (building blocks for functional polymers) by GC/EI and GC/FI methods and then compared the resulting mass spectra.

Elemental compositions are commonly determined from high-resolution mass spectra and accurate mass measurements. Given a measured mass (m/z) and a range of elements that can be present, software calculates the exact mass for each combination of elements and reports all elemental combinations that match the measured mass within a specified error tolerance. Improving the mass accuracy reduces the number of elemental compositions, but mass accuracy alone may not be sufficient to determine the correct elemental composition for an unknown sample. JEOL AccuTOF™ mass spectrometers (the AccuTOF™-DART®, the AccuTOF™-GCX and the AccuTOF™-GCX Plus) are capable of accurate isotope measurements that can be used to determine elemental compositions from high-resolution mass spectra. Matching the measured abundances and exact masses for isotope peaks can be more effective than mass accuracy alone.

Includes 49 application notes in the following categories: Introduction, Materials & Chemistry, Petroleum & Petrochemicals, Environment & Food Safety, and Food, Flavors, and Fragrances

Pesticides have been widely used all over the world. Although the use of pesticides is strictly regulated in many countries, laboratories still monitor their residues due to their toxicity and highly persistent nature. The most common method for pesticides identification is GC/MS with select ion monitoring (SIM). Since most of samples contain many different components, a long GC separation is generally needed when a low-resolution SIM MS is used. This is very time-consuming. Fast GC has been available for several years; however, the combination of fast GC with mass spectrometry had not been commercially available until high acquisition rate time-of-flight mass spectrometry was introduced. Here, we describe a new method by using fast GC/time-of-flight MS to identify 67 pesticides. The high resolution time-of-flight MS always yields high quality library searchable spectrums without compromising the sensitivity. The method is simple, fast, and reliable.

The AccuTOF GCx has high sensitivity, high mass resolution, high mass accuracy, a wide dynamic range and a high speed acquisition rate, all simultaneously. Additionally, JEOL has developed a pesticides exact mass database that consists of 5 ions each for 375 different compounds which means that there are 1,875 total exact masses for multi-residue pesticide analysis. And because the TOF continuously collects the complete m/z region for each mass spectrum, we do not need to setup any SIM or SRM conditions, as is done for QMS and QqQMS systems. Therefore, the TOFMS can be used for both quantitative and qualitative analysis, simultaneously. In this application note, we show a portion of the pesticide database and the advantages of the GC/HR-TOFMS system for the multi-residue pesticide analysis.

Solid phase microextraction (SPME) is a well established sampling technique that is often used to isolate volatile organic components in gaseous mixtures. Once the compounds have been collected, the SPME fibers are typically placed into a heated GC inlet which thermally desorbs these components into a GC-MS system for analysis. Normally, this analysis can take between 10 and 30 minutes to complete depending on the complexity of the samples. In this work, the Direct Analysis in Real Time (DART™) heated gas stream is used to desorb and directly introduce a SPME sample into a high-resolution mass spectrometer. This methodology produces comparable information to the traditional GC-MS technique but streamlines the results into only a few seconds of analysis time.

Direct control of solid materials for pesticide residues is a challenging task enabling fast contamination screening. In our study, we investigated direct analysis of strobilurin fungicides in milled wheat grains. Strobilurins, systemic pesticides originated from natural fungicidal derivatives, play an important role in control of various plant pathogens. Because of their unique protective properties, significant yield enhancements and longer retention of green leaf tissue, strobilurins have been widely used in agriculture since their introduction on the market in 1992. As other pesticides, these compounds are involved in control and monitoring surveys underta

Smokeless powders are often used in improvised explosive devices. The formulations for smokeless powders vary between manufacturers and between brands from a given manufacturer; ingredients include energetics, stabilizers, plasticizers and deterrents. Both chemical composition and morphology are important in characterizing smokeless powders. Chemical analysis of smokeless powders can provide valuable forensic evidence. Observation with the SEM can reveal morphological information to help with identification. Here we show how SEM-EDS analysis can be used to identify inorganic components, and how the AccuTOF-DART mass spectrometer can rapidly identify the organic components and provide a chemical fingerprint that can be used to identify individual powder particles.

Recent events have led to the recall of both pet food and dairy food products from international consumer markets. In both cases, melamine was added to these products to show a higher chemical signature for proteins, which in turn would increase the reported quality of the food. Unfortunately, the effect of this melamine addition caused the death of both pets and babies that consumed these tainted products. As a result, there is growing government and consumer concern towards the presence of melamine in food products. Because of this concern, there is a need for a rapid and accurate test to quickly determine the presence of melamine in these food products. Previously, the JEOL AccuTOF-DART was shown to be an effective technique for determining the presence of melamine in pet food. In this work, we extend the application of AccuTOF-DART to show that melamine can be rapidly detected when it is present in dry nonfat milk.

Thiabendazole is an anthelmintic and a highly persistent systematic benzimidazole fungicide that is widely used for controlling spoilage in citrus fruit. It is considered a General Use Pesticide (GUP) in EPA Toxicity Class III – Slight Toxicity. A small piece of orange peel (a few square millimeters in size) from a Florida orange was placed in the DART sampling region. Compounds present in the peel were detected within seconds. Among these were the familiar orange-oil flavor components such as limonene and sinensal as well as polymethoxylated flavones that are attributed with antioxidant and cholesterol-reducing properties.