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Radionuclide Production
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
The ion source is usually placed in the centre and inside the vacuum (internal) but can in larger machines be external. The ions are then injected from the outside through a central hole in the magnet. The main idea of the ion source is to have a slow flow of gas that is made into plasma by an arc discharge. Through a collimator the wanted ion species are extracted and accelerated in a static electric field. There are several types of ion sources with different operating characteristics. In modern accelerators, usually negative ion (protons or deuterium with two orbit electrons) are used to facilitate extraction of the beam.
Ion Beam Analysis: Analytical Applications
Published in Vlado Valković, Low Energy Particle Accelerator-Based Technologies and Their Applications, 2022
Klein and Mous (2017) describe the cesium sputter ion source designed to fulfill the stringent requirements of AMS. It has a storage capacity of up to 200 samples for unattended operation and accepts solid as well as gaseous CO2 samples. The samples are stored in a separate vacuum chamber and transported upon use into the hot central part of the ion source, thereby minimizing cross-talk between the samples.
Qualitative and Quantitative Determination of Bioactive Phytochemicals in Selected Cassia Species Using HPLC-ESI-QTOF-MS and UPLC-ESI-QqQLIT-MS/MS
Published in Brijesh Kumar, Vikas Bajpai, Vikaskumar Gond, Subhashis Pal, Naibedya Chattopadhyay, Phytochemistry of Plants of Genus Cassia, 2021
Brijesh Kumar, Vikas Bajpai, Vikaskumar Gond, Subhashis Pal, Naibedya Chattopadhyay
Mass spectrometric analysis was performed on Agilent 6520 QTOF mass spectrometer in positive ESI mode. The resolving power of QTOF analyser was set above 15,000 (FWHM, full width at half maximum) and spectra were acquired within a mass range of m/z 100–1000. Nitrogen was used as nebulising, drying and collision gas. Capillary temperature was set to 350 °C and nebuliser pressure to 40 psi and the drying gas flow rate was 10 L/min. Ion source parameters such as Vcap, fragmentor, skimmer and octapole radio frequency peak voltage were set to 3500 V, 150 V, 65 V and 750 V, respectively. The chromatographic and mass spectrometric analyses, including the prediction of chemical formula and exact mass calculation, were performed by using Mass Hunter software version B.04.00 build 4.0.479.0 (Agilent Technology).
Potential application of mass spectrometry imaging in pharmacokinetic studies
Published in Xenobiotica, 2022
Chukwunonso K. Nwabufo, Omozojie P. Aigbogun
As MSI follows the principle of MS, analytes of interest will need to be ionised and then separated according to their m/z. The former is performed by an ion source while the latter is done by a mass analyser. The type of ion source and mass analyser deployed for MSI analyses is primarily dependent on the physicochemical properties of the analyte of interest and the overall goal of the research work, i.e. quantitative, or qualitative analyses, respectively. For example, matrix-assisted laser desorption ionisation (MALDI) is bested suited for soft ionisation of compounds that are labile and easily fragmented such as proteins and peptides while atmospheric pressure chemical ionisation (APCI) is suitable for less polar compounds that are not labile. Additionally, low resolution mass analysers such as triple quadrupole and linear ion trap are adequate for targeted quantitative analyses through the superior selectivity conferred by the multiple reaction monitoring scan. However, high resolution mass analysers such as time-of-flight (ToF), orbitrap, and fourier transform ion cyclotron (FTICR) resonance are most useful for both targeted and non-targeted identification of analytes through accurate mass measurement.
The common indoor air pollutant α-pinene is metabolised to a genotoxic metabolite α-pinene oxide
Published in Xenobiotica, 2022
Suramya Waidyanatha, Sherry R. Black, Kristine L. Witt, Timothy R. Fennell, Carol Swartz, Leslie Recio, Scott L. Watson, Purvi Patel, Reshan A. Fernando, Cynthia V. Rider
All calibration standards and study samples were analysed using the previously published GC-MS method for quantitation of α-pinene oxide (Fernando et al. 2021) while monitoring for α-pinene. Briefly, a Hewlett Packard 7890 A gas chromatograph coupled to a 5975 A mass-selective detector (Agilent Technologies, Santa Clara, CA) was used with an Agilent DB-5MS column (30 m × 0.25 mm, 0.25-µm film thickness) and a carrier gas at a flow rate of 1.2 mL/min. The GC oven was held at 40 °C for 5 min, ramped to 140 °C at 5 °C/min and then to 300 °C at 20 °C/min and held for 5 min. The injector temperature was 200 °C. The ion source was operated in electron ionisation mode at 70 eV. The mass spectrometer transfer-line, ion source, and quadrupole temperatures were 280, 230, and 150 °C, respectively. The ions monitored were m/z 93 for α-pinene and limonene and m/z 109 for α-pinene oxide and limonene oxide. The retention times for α-pinene, limonene, α-pinene oxide and limonene oxide were ∼14.8, 17.7, 19.7, and 20.8 min, respectively.
In vitro and in vivo evaluation of a sustained-release once-a-day formulation of the novel antihypertensive drug MT-1207
Published in Pharmaceutical Development and Technology, 2021
Napoleon-Nikolaos Vrettos, Peng Wang, Yan Zhou, Clive J. Roberts, Jinyi Xu, Hong Yao, Zheying Zhu
MT-1207 in plasma samples was determined by a validated UPLC-MS/MS method using verapamil hydrochloride as an internal standard. Each time 10 μL of plasma sample were pipetted in 1.5 ml Eppendorf® tube. 200 μL of verapamil hydrochloride 2 ng/mL in acetonitrile were added and vortex was carried out for 5 min. Centrifugation was then carried out at 15000 rpm for 5 min and 100 µL of supernatant were collected for UPLC-MS/MS analysis. The ion source was an electrospray ionisation source (ESI). A positive ion scanning method was used for detection. The solvent gas (nitrogen) flow rate was 1000 L/h, the temperature of the solvent gas was 500 °C, and the capillary voltage was 3.0 kV. The scanning method was Multiple Response Monitoring (MRM). The cone voltage was set at 40 V, while the collision energy was 20 eV. For quantitative analysis, the ion pairs used had m/z 393.26 → 274.04 (MT-1207) and m/z 455.25 → 156.06 (internal standard). The samples were applied to an ACQUITY Ultra Performance Liquid Chromatography system with Xevo TQ-XS Triple Quadrupole Mass Spectrometer with operating software MassLynx V4.2 (Waters Technology Limited Company). The column used was an ACQUITY UPLC BEH C18 liquid chromatography column (2.1 × 50 mm, 1.7 μm). The mobile phase consisted of 0.1% formic acid in water (mobile phase A) and acetonitrile (mobile phase B). Verapamil hydrochloride was used as the internal standard for determination. The gradient elution was: 0–1.2 min: 20–45% B, 1.2–1.5 min: 45–95% B, 1.5–1.8 min: 95% B, 1.8–2.5 min: 95–20% B. The flow rate was set at 0.5 ml/min. The column temperature was set at 45 °C.