Volatile compounds (VCs) hold the potential to diagnose and monitor disease states in a cost effective, rapid, and most importantly non-invasive manner. Gas chromatography mass spectrometry (GC-MS) has been in use since the 1960s and remains the gold standard for qualitative VC analysis. Within this thesis three novel methods and/or utilisations of mass spectrometry are described. Chapter 2 describes and benchmarks a metal oxide sensor (MOS) coupled to a standard GC-MS instrument. Testing this system to the headspace of 12 stool samples the sensor detected a mean 1.6 more peaks per sample then the MS. This superior sensitivity exhibited by the MOS sensor should allow for greater discriminatory abilities to differentiate samples into clinically relevant groups. It has become increasingly important to qualitatively and quantitatively assess the VCs for use in monitoring health. Chapter 3 describes a novel method for the quantification of VCs from the headspace of stool samples analysed using GC-MSis presented. Using 13C labelled carbon compounds as internal standards a method has been designed which quantifies the compounds withinin the stool; 15 compounds were quantified. The EDX110 dressing has been developed by Edixomed Ltd; uses hydrogel technology to generate nitric oxide (NO) to enhance wound healing. A series of experiments first allowed for the development of a robust and reproducible method of real-time quantification. The effect of pH was assessed using citric acid buffered with sodium citrate, pH values3, 3.6, 4.2, 4.8, 5.4, and 6.2 were all analysed. NO production showed an inverse correlation; pH 3 producing 81 μg of NO and pH 6.2 only producing 7μg. With the exception of pH 3 HONO and NO2 remained relatively consistent across the pH values with a median 3 and 0.9μg respectively.
Gould, O. The detection of trace volatiles from complex matrices using gas chromatography mass spectrometry (GCMS) techniques and selected ion flow tube mass spectrometry (SIFT-MS) assessment of volatiles produced from nitric oxide producing smart dressings. (Thesis). University of the West of England. Retrieved from https://uwe-repository.worktribe.com/output/3807511