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Mass Spectrometric Analysis
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
These studies used a quadrupole mass spectrometer (Finnigan 3300F) equipped with a chemical ionization source and positive ion-negative ion detection capability with a conversion dynode electron multiplier. The DCI probe, a coil of platinum wire, was linearly programmed from 0 to 2 A at 2 A/min. The voltage of the probe was kept to that of the ion volume. Positive and negative spectra were obtained under methane Cl conditions (0.5 torr). The electron multiplier was operated at 1300 V (the conversion dynode was ±3000 V), and the electron energy was 90 eV. The mass range to m/z 614 was calibrated with perfluorotributylamine in the positive mode (EI), and mass assignments above this were checked using a perfluorinated polyether (Fomblin-L). Spectra were obtained every 3 sec.
Fourier Transform Mass Spectrometry
Published in R. Michael Gendreau, Spectroscopy in the Biomedical Sciences, 1986
in which v is the observed ICR peak frequency. Exact mass determination for an unknown peak (by either interpolation or extrapolation from Equation 4) is then sufficiently accurate (<5 ppm) to determine the chemical formula in most cases. For example, a sample calibration table is shown in Figure 9 for perfluorotributylamine.
Evaluating Water bitter leaf (Struchium sparganophora) and Scent Leaf (Ocimum gratissimum) extracts as sources of nutraceuticals against manganese-induced toxicity in fruit fly model
Published in Drug and Chemical Toxicology, 2023
Adedayo Oluwaseun Ademiluyi, Opeyemi Babatunde Ogunsuyi, Josephine Oluwaseun Akinduro, Olayemi Philemon Aro, Ganiyu Oboh
An aliquot of the alkaloid extracts (1μL) was injected in splitless mode at an injection temperature of 110°C. Purge flow was 3mL/min with a total flow of 11.762mL/min; gas saver mode was switched on. Oven was initially programmed at 110°C (2min) then ramped at 10°C/min to 200°C (2min) then 5°C/min to 280°C (9min). Run time was 38min with a 3min solvent delay. The mass spectrometer was operated in electron ionization mode with ionization energy of 70eV with ion source temperature of 230°C, quadrupole temperature of 150°C, and transfer line temperature of 280°C. Prior to analysis, the MS was autotuned to perfluorotributylamine (PFTBA) using already established criteria to check the abundance of m/z 69, 219, 502, and other instrument optimal and sensitivity conditions. Analysis validation was conducted by running replicate samples in order to see the consistency of the constituent compound name, respective retention time, and molecular weight. These abundances were outputs from the NIST 11 library search report of the extracted constituents. Each compound identified via the NIST library search report has a corresponding mass spectrum showing the abundance of the possible numerous m/z peaks per compound.
Antimicrobial activities of Trichoderma atroviride against common bean seed-borne Macrophomina phaseolina and Rhizoctonia solani
Published in Egyptian Journal of Basic and Applied Sciences, 2020
Naglaa M. El-Benawy, Gamal M. Abdel-Fattah, Khalid M. Ghoneem, Yasser M. Shabana
Helium was used as a carrier gas at approximately 1 ml/min., pulsed split less mode. The solvent delay and the injection size were 3 min and 1.0 ml, respectively. The mass spectrophotometric detector was operated in electron impact ionization mode in ion energy of 70 e.v. scanning from m/z 50 to 500. The ion source temperature was 230°C and quadrupole temperature was 150°C. The electron multiplier voltage was maintained 1250 v above autotune. The instrument was manually tuned using perfluorotributylamine. The GC temperature program was started at 60°C for 2 min then elevated to 280°C at a rate of 5°C/min, and 10 min hold at 280°C the injector temperature was set at 280°C. Separated peaks were identified using Wiley and Nist 05 mass spectral database.
Undeclared formaldehyde levels in patient consumer products: formaldehyde test kit utility
Published in Cutaneous and Ocular Toxicology, 2019
Jason E. Ham, Paul D. Siegel, Howard Maibach
All samples were analysed using an Agilent (Santa Clara, CA) 7890B GC coupled to an Agilent 240 Internal EI/CI ion trap mass spectrometer. Samples were analysed in both electron ionization (EI) and chemical ionization (CI) modes with liquid acetonitrile serving as the CI reagent. Compound separation was achieved by an Agilent (Santa Clara, CA) HP-5MS (0.25 mm I.D., 30 m long, 1 µm film thickness) column and the following GC oven parameters: 40 °C for 2 min, then 5 °C min −1 to 200 °C, then 25 °C min −1 to 280 °C and held for 5 min. One microlitre of each sample was injected in the splitless mode with the injector temperature at 130 °C. The ion trap mass analyser was tuned using perfluorotributylamine (FC-43). Full-scan mass spectra were collected in the m/z range 40–1000. A single peak was in the observed in the GC/MS chromatogram for the PFBHA-formaldehyde oxime and the PFBHA-13C-formaldehyde-d2 oxime (which co-eluted) at 15.6 min. The main ions (% relative peak height) from EI spectra of the PFBHA-formaldehyde oxime only are 81(2), 99(5), 117(10), 165(15), 181(100), 195(25) and 198(0.01). The main ions (% relative peak height) from EI spectra of the PFBHA-13C-formaldehyde-d2 oxime only are 81(4), 99(5), 117(15), 161(20), 181(100), 195(12) and 198(50). PFBHA-formaldehyde recovery from each sample was adjusted based on percent recovery of the 4 ppm formaldehyde isotope added using the 198 ion from of the PFBHA-13C-formaldehyde-d2 oxime. Quantification of amount of total releasable formaldehyde from patients’ provided products was calculated using the 195 ion from sample analyses conducted in parallel with those in which the formaldehyde isotope had been added. Doubling of the derivatization time from 2 to 4 h at 70 °C did not increase the amount of measureable free formaldehyde from formaldehyde-releaser containing products suggesting the procedures employed were sufficient for complete hydrolysis of formaldehyde-releasers (data not shown). In the study for evaluation of the formaldehyde test kits, quantification of the formaldehyde was done from the CI spectra (GC/CI-MS) from isotopic dilution of the PFBHA-formaldehyde oxime 226 ion/PFBHA-13C-formaldehyde-d2 oxime 229 ion.