Analytical Instrument Documents

DART can ionize organic substance on solid surface in atmospheric pressure. By utilizing this feature, we analyzed organic contaminant adhered to a metal part.

DART can characterize additives in lubricating oils directly without sample preparation. The additives generally produce a strong signal without interference from the base oil. However, complementary information about nonpolar components of the base oil can be obtained by O2 ─• attachment chemical ionization, a simple analysis that can be easily and rapidly carried out with changing any hardware on the AccuTOF-DART mass spectrometer system.

In MS Tips No. D031 we introduced the example of high polar compound analysis with DART. This application note introduces the example of the analysis of low polar compounds.

Ionic liquids have drawn much attention from various engineering fields, such as tribology, because of their unique properties of electrical conductivity, extremely low vapor pressure, low viscosity, low combustibility, etc. The sample was analyzed by dipping a glass rod to the sample and presented it directly to the DART™ ion source.

The identification of pressure-sensitive tapes such as duct tape and electrical tape is an important forensic application. Here we show the application of thermal desorption and pyrolysis combined with Direct Analysis in Real Time (DART) mass spectrometry to distinguish between manufacturers and brands of duct tapes. X-ray fluorescence (XRF) provides complementary information about the atomic composition of the different tapes.

The AccuTOF-LC time-of-flight mass spectrometer equipped with a DART ion source and AutoDart HTC PAL autosampler, was used for examination of beer in this study. Donprep® immunoaffinity columns (R-Biopharm) was employed for selective isolation of target analyte from the sample. Briefly, 10 mL of beer with added internal standard (¹³C₁₅-deoxynivalenol, 500 ng/ml) were passed through the cartridge, which was then washed with 5 mL of water. Deoxynivalenol was subsequently eluted with 4.5 mL of methanol. Calibration standards containing deoxynivalenol in the range from 100 to 1500 ng/mL and fixed amount of internal standard (500 ng/mL) were prepared for quantification.

The AccuTOF-DART can detect a variety of substances in biological fluids such as urine, blood, and saliva with little or no sample preparation. These substances include drugs, amino acids, lipids, and metabolites.

JEOL introduced the AccuTOF-DART in 2005 as the first commercially available ambient ionization mass spectrometer system. The atmospheric pressure ionization interface (API) for the AccuTOF system, originally designed as a simple, rugged and reliable LC/MS interface, became the ideal platform for developing the Direct Analysis in Real Time (DART) ion source. Because the DART ion source can be positioned directly in front of the AccuTOF sampling orifice without additional interface hardware, a variety of ambient ionization techniques are available to the AccuTOF-DART operator without removing the DART ion source. The third-generation AccuTOF-DART 4G system is an “ambient ionization toolbox” that allows the analyst to choose ionization methods that are best matched to the samples to be analyzed.

Smokeless powders (Figure 1) 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. Chemical analysis of smokeless powders can provide valuable forensic evidence. Here we show that the AccuTOF-DART mass spectrometer can rapidly identify the organic components in smokeless powders and provide a chemical fingerprint that can be used to identify individual powder particles.

Figure 1 shows a schematic diagram of the AccuTOF atmospheric pressure interface. The API consists of two offaxis skimmers (designated “orifice 1” and “orifice 2”) with an intermediate ring lens, followed by a bent RF ion guide. The off-axis skimmer design traps contamination -- ions are electrostatically guided upward toward orifice 2 whereas neutral molecules are pumped downward. Any contamination that enters the API is either pumped away into the rough pump (RP) or trapped on the lower part of orifice 2. The bent RF ion guide provides an additional level of protection. This makes the AccuTOF an ideal mass spectrometer for DART analysis of dirty “real-world” samples such as mud, biological fluids, melted chocolate, polymers, and even crude oil. In addition, orifice 1 is easily accessible and is operated at low voltage and current, making it a convenient platform for ambient ionization sources.