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Selenium Determination using Oxygen Mass-Shift Interference Removal Technology with LC-ICP-MS/MS

Smith, Skyler W
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535701577136671

Abstract Details

2018, PhD, University of Cincinnati, Arts and Sciences: Chemistry.
Selenium (Se) is an essential micronutrient required by many organisms but in a narrow beneficial range. Due to its role as an antioxidant and anti-inflammatory agent, much research has been conducted on this element for possible use in cancer treatment and other diseases. In addition to these drug development studies, accurate Se quantification and speciation is also needed by regulatory agencies as it can be toxic after consuming large quantities. Inductively-couple plasma mass spectrometry (ICP-MS) is an important technique for elemental analysis, especially Se. Due to isobaric interferences for Se in ICP-MS, the addition of the collision-reaction cell in previous decades has increased detection capabilities; however, introduction of the commercial ICP tandem MS instrument (ICP-QQQ) in 2012 using reaction gases, such as oxygen, has lowered background interferences formed in the argon plasma increasing detecting power. With this instrument, the most naurally abundant Se isotopes (78, 80 m/z) are selected by the first quadrupole, reacted with oxygen gas in the octopole reaction cell, and a product ion (SeO+ at 94, 96 m/z) is selected by the second quadrupole. While this advancement in trace Se detection comes with many advantages, previous methodologies, such as internal standardization, need to be updated. In this work, method development of sample preparation and instrumental considerations were completed using oxygen mass-shift interference removal technology for the ICP-QQQ. An evaluation of internal standardization for SeO+ was completed using this instrument to determine if Se reactivity with oxygen was a critical factor in selecting an internal standard (ISTD) to compensate for matrix effects and instrumental drifts in sensitivity. In this manuscript, solid sample preparation strategies for total Se determination was also developed using microwave digestions; however, Se is known to be species-dependent for supplementation and toxicity. Therefore, species extraction protocols and chromatographic separation methods were also developed and combined with ICP-QQQ detection. These methods were applied to the environmentally sustainable food production system, aquaponics. Following ISTD assessments, tellurium oxide (TeO+) was recommended as the most adequate universal ISTD to compensate for sensitivity fluctuations in the SeO+ depending on matrix enhancements or suppressions, instrumental drift, or differences in instrumental configurations. This was unsurprising as Te shares similarities in ionization potential and reactivity with oxygen. Microwave digestions and enzymatic extractions were developed and validated as solid sample preparations procedures for total Se determination and speciation, respectively, using certified reference materials. A reverse-phase ion-pairing chromatographic method capable of separating six Se species was developed and coupled to the ICP-QQQ. These methods were applied to commercial cattle and aquaculture feeds as well as foodstuffs (tilapia fillets, vegetables) produced from Se supplemented aquaponics systems. Since Se determination of total content and species type are important considerations for human and animal health, these methods are a worthy contribution to scientific literature. Evaluating SeO+ internal standardization for the ICP-QQQ and discussing the effect of Se supplementation in aquaponics systems were the first studies completed on these subject matters. Hopefully, the results provided here will be used and expanded on in future research endeavors.
William Heineman, Ph.D. (Committee Chair)
Julio Landero Figueroa, Ph.D. (Committee Chair)
Edward Merino, Ph.D. (Committee Member)
Allan Pinhas, Ph.D. (Committee Member)
168 p.
Analytical Chemistry
Selenium Speciation; ICP-MS; Oxygen Mass-shift; Internal Standards; Aquaponics

Recommended Citations

Citations

  • Smith, S. W. (2018). Selenium Determination using Oxygen Mass-Shift Interference Removal Technology with LC-ICP-MS/MS [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535701577136671

    APA Style (7th edition)

  • Smith, Skyler. Selenium Determination using Oxygen Mass-Shift Interference Removal Technology with LC-ICP-MS/MS. 2018. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535701577136671.

    MLA Style (8th edition)

  • Smith, Skyler. "Selenium Determination using Oxygen Mass-Shift Interference Removal Technology with LC-ICP-MS/MS." Doctoral dissertation, University of Cincinnati, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535701577136671

    Chicago Manual of Style (17th edition)

ucin1535701577136671
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This open access ETD is published by University of Cincinnati and OhioLINK.