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Exposure Assessment
Published in Samuel C. Morris, Cancer Risk Assessment, 2020
Having thus demolished the concept of index compounds, only one reason remains to justify their use: there is generally no practical alternative. Complete characterization of the mixture with gas chromatography/-mass spectrometry (GC/MS) is time-consuming, expensive, and, perhaps most importantly, produces a result as complex as the mixture itself, thus defying the comparison of different mixtures. The only practical solution appears to be to use an index, but when comparing different mixes, to fall-back on an ad hoc comparison of the GC/MS scan as a means of tempering the use of the index with some idea of uncertainty. Current thinking would seem to tend toward use of the aggregate indices such as benzene soluble organics for this purpose. Perhaps this might be coupled with additional information from short-term bioassays (see Chap. 10) and a quantitative factor developed to modify the index value. This remains an area open to both long-term basic research and to development of practical solutions.
Detection Technology
Published in Rick Houghton, William Bennett, Emergency Characterization of Unknown Materials, 2020
Rick Houghton, William Bennett
Gas chromatography-mass spectrometry (GC-MS) instruments utilize, as the name suggests, a gas chromatograph in line with a mass spectrometer. The gas chromatograph separates molecules based on their volatility as they diffuse through a column of gas and information is obtained on the time it takes (retention time) for the individual components that make up the sample to migrate to the end of the gas column. As a separation technology, a gas chromatograph may be coupled to any number of detection instruments. It is included here as a common form of field detection technology.
Organometallic Compounds in the Aquatic Environment
Published in B. K. Afghan, Alfred S. Y. Chau, Analysis of Trace Organics in the Aquatic Environment, 2017
Gas chromatography-mass spectrometry (GC-MS) systems have not been extensively used in the analysis of organometallic compounds, apparently because of the following reasons: (1) high initial cost of installation, (2) sensitivity is not particularly superior to atomic spectrometry, (3) deposits of metals on the interface are detrimental to the system, and (4) a specially trained operator is required. All these disadvantages discourage the use of GC-MS systems.
Impact of immobilized algae and its consortium in biodegradation of the textile dyes
Published in International Journal of Phytoremediation, 2023
Mostafa M. El-Sheekh, Shimaa M. El Shafay, Abd El-Raheem R. El-Shanshoury, Ragaa Hamouda, Dalia Y. Gharieb, Ghada W. Abou-El-Souod
Gas chromatography-mass spectrometry (GC-MS) includes two effective techniques for determining compounds that have lower exposure limits and the potential for quantitative analysis. This analysis was performed before and after treatment by the dye after 7 days of incubation to determine the degradable products of dyes. Using Agilent 6890 gas chromatograph equipped with an Agilent mass spectrometric detector, with a direct capillary interface and fused silica capillary column PAS-5 ms (30 m × 0.32 mm × 0.25 µm film thickness). The GC temperature program was started at 60 °C (2 min) elevated to 300 °C at a rate of 5 °C/min, and the injector temperature was set at 280 °C, respectively. The use of spectral databases and mass Wiley Nist to determine the discrete peaks (Hadibarata et al.2012).
Synthesis and characterisation of rubber seed oil trans-esterified biodiesel using cement clinker catalysts
Published in International Journal of Sustainable Energy, 2019
V. Aarathi, E. Harshita, Atira Nalinashan, Sidharrthh Ashok, R. Krishna Prasad
Gas chromatography–mass spectrometry (GC–MS) is an instrumental method used to find the different components of a sample. GC–MS is used for the separation of different compounds. The final composition of the biodiesel sample was analysed using a Thermo GC Trace Ultra version 5.0 Thermo MS DSQ II with a DB-5 MS Capillary Standard non-polar column with an internal diameter of 0.25 mm and a film thickness of 0.25 μm. The carrier gas used was Helium, with a flow rate of 1 ml/min. The temperature programming was set as 70°C and raised to 260°C at 6°C/min. Volume of sample injected was 1 μl. The GC image was obtained for CaO and cement clinker catalysts, and the mass spectroscopy image for the significant peaks was identified. The GC images for CaO and cement clinker catalyst are shown in Figures 14 and 15, respectively.
Deep desulfurization of kerosene by electrochemical oxidation and extraction in Mn2+/Mn3+ electrolyte
Published in Petroleum Science and Technology, 2018
Xiao-dong Tang, Shuang Jiao, Jing-jing Li, Na Hu
The changing of sulfur compounds in kerosene before and after electrochemical oxidation was analyzed by Fourier Transforms Infrared Spectra (FTIR, Beijing Beifen-Ruili Analytical Instruments Co. Ltd.). The gas chromatography-mass spectrometry (GC-MS,7890A GC system with a HP-5MS capillary column (30 m × 0.25 /mm × 0.25 µm) and 5975C MSD, Agilent Technologies, Inc.) was used to analyze the model oil before and after electrochemical oxidation. In addition, the total desulfurization efficiency (Xs) was calculated as follows: