Watson, Thomas Harold
(2009)
THE FLOWING AFTERGLOW AS A CHEMICAL REACTIONMASS SPECTROMETER: ACCURACY DETERMINATIONS AND REAGENT IONDEVELOPMENT.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Henry's Law was utilized to determine the accuracy of the flowing afterglow at the University of Pittsburgh as a Chemical Reaction Mass Spectrometer (CR-MS). H3O+ and its first three hydrates were utilized as reagent ions in the CR-MS technique to quantify headspace concentrations over multiple series of dilute aqueous acetone, acetonitrile, and benzaldehyde/THF solutions. The temperature corrected Henry's Law constants, kHθ, of acetone, acetonitrile, benzaldehyde, and THF were calculated as 32.1+3.3, 45.2+6.5, 41.6+2.1, and 14.8+1.0 M atm-1, respectively. These values for acetone, acetonitrile, benzaldehyde, and THF are in agreement within error of the literature values of 28+3, 51+3, 39+3, and 14 M atm-1, respectively. These measurements suggest that our flowing afterglow can be utilized to accurately quantify multiple VOCs simultaneously via the CR-MS technique. H3O+ is the most commonly utilized reagent ion for the CR-MS technique due to its many advantages. This ion possesses two main limitations; it readily clusters with water and cannot decipher between isobaric (of the same mass) molecules. Due to its size and tendency to react like a proton, the trimethylsilyl group (TMS+) can be substituted for a proton to reduce clustering. Substitution of the nitrosyl cation for a proton creates a NO+ donor and an ion that can decipher between isobaric molecules. The preparation of R((CH3)3Si)ONO+, where R is a proton, trimethylsilyl, alkyl, or NO+ moiety, was attempted in order to make a reagent ion that can decipher between isobaric molecules, does not cluster, and, yet, maintains the advantages of H3O+ as a reagent ion. There were four different preparations attempted for ions of this type: NO+ + methoxytrimethylsilane, NO+ + hexamethyldisiloxane, ((CH3)3Si)2OH+ + methyl nitrite, and ((CH3)3Si)OH2+ + methyl nitrite. The clean production of R((CH3)3Si)ONO+ remains elusive. The reactions of NO+ and methoxytrimethylsilane and NO+ and hexamethyldisiloxane resulted in hydride and/or methide abstraction. No reaction occurred between protonated hexamethyldisiloxane and methyl nitrite. The reaction of protonated trimethysilanol with methyl nitrite did not produce an ion of the type R((CH3)3Si)ONO+ cleanly as it resulted in H(TMS)ONO+ (m/z 120) and (CH3)(TMS)ONO+ (m/z 134).
Share
| Citation/Export: |
|
| Social Networking: |
|
Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
| Creators | Email | Pitt Username | ORCID  |
|---|
| Watson, Thomas Harold | thw5@pitt.edu | THW5 | |
|
| ETD Committee: |
|
| Date: |
29 September 2009 |
| Date Type: |
Completion |
| Defense Date: |
11 August 2009 |
| Approval Date: |
29 September 2009 |
| Submission Date: |
3 August 2009 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Chemistry |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Mass Spectrometry |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-08032009-200225/, etd-08032009-200225 |
| Date Deposited: |
10 Nov 2011 19:56 |
| Last Modified: |
15 Nov 2016 13:48 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/8868 |
Metrics
Monthly Views for the past 3 years
Plum Analytics
Actions (login required)
 |
View Item |
![[feed]](/images/feed-icon-32x32.png){kind=icon}