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Notice of Public Lecture: Zoya Dobrusin

Faculty of Graduate Studies 

Graduate Programme in Chemistry 
A Candidate for the Degree of 

Master of Science.  

Title of Thesis: 
Quantitative Methods for the Analysis of Hydrocarbon Oxidation Products: 
A Smog Chamber Study

August 17, 2012 @ 9:30 am – 10:15 am
121 Chemistry Building
York University

Abstract: The oxidation products from the reaction of beta-pinene with the hydroxyl (HO) radical were studied using the York University smog chamber. The main focus of this study was to look into methods of quantifying products with the API-365 APCI-MS/MS instrument. Being able to obtain quantitative information with this instrument would allow us to determine product yields and gain a better understanding of the instrument’s sensitivity towards different classes of compounds. Linear calibrations were achieved through the use of analyte signals relative to the protonating reagent(s) (protonated water and its clusters) in the chemical ionization process.

Individual compound calibrations using analyte introduction via syringe pump were performed for reaction relevant products: nopinone and pinic acid. Nopinone calibrations, which were representative of gas phase products, were successful. On the other hand, pinic acid calibrations, meant to be more indicative of low volatility products, could not be properly achieved. The second type of calibration approach targeted to evaluate general instrument sensitivity towards classes of functional groups and to also reduce the dependence on commercially available standard compounds. This was done by deriving a relationship between instrument sensitivity and gas phase basicity (GB). This relationship was tested first by developing calibration curves (sensitivity/GB calibrations) using a few simple ketones and alcohols. The ketone calibration curve, showing good linearity, was then used to estimate the sensitivity of a reaction relevant ketone (nopinone).

Both calibration approaches were tested for their accuracy by using their measured sensitivities to estimate the concentration of a known amount of nopinone injected into the chamber. They were also both used to calculate the yield of nopinone in the beta-pinene/HO chamber experiment. The syringe pump calibrations showed good accuracy and were used to calculate a yield of 24 ± 5 %; a value in general agreement with other literature reported data. However, the sensitivity/GB calibrations did not show sufficiently accurate results. The sensitivity/GB calibrations were still fully evaluated and several problem areas were identified for future research.

Updated on April 4th, 2014.