The development and application of miniaturised FAIMS combined with mass spectrometry in bioanalysis

In this thesis, a miniaturised field asymmetric waveform ion mobility spectrometry (FAIMS) device is combined with mass spectrometry (MS), and liquid chromatography, for the development and application of bioanalytical methodologies. FAIMS is a highly orthogonal to MS and LC and has the potential to enhance both targeted and non-targeted bioanalytical applications. Chapter two demonstrates the capability of the FAIMS combined with mass spectrometry to reduce the complexity of the mass spectrum by separating species of different charge states and overlapping mass-to-charge ratios that are challenging to separate by MS. FAIMS selected transmission shows improvement in signal-to-noise ratios for low intensity species and enables visualisation of species undetectable without FAIMS. Chapter three describes the development of an LC-FAIMS-MS method for the rapid analysis of saliva for the identification of potential biomarkers as a result of oxidative stress. The combination of FAIMS showed a reduction in saliva matrix interferences resulting in improved discrimination and peak integration of two salivary oxypurine compounds in a rapid LC-FAIMS-MS method. Chapter four investigates the FAIMS separation of seven steroid metabolites with a range of cationic adducts, in order to develop a rapid screening LC-FAIMS-MS method for the determination of isobaric steroid metabolites in urine. LC-FAIMS-MS analysis of the steroid metabolites shows improved discrimination of co-eluting and isobaric steroid metabolites with improvements in signal-to-noise ratio with reductions in chemical noise, demonstrating the potential of combining FAIMS with LC-MS. Chapter five demonstrates the potential of FAIMS to increase peak capacity in non-targeted omics applications, by combining rapid compensation field scanning of the FAIMS with ultra-high performance LC-MS. The rapid scanning of the FAIMS allows acquisition of full scan FAIMS and MS nested data sets within the timescale of a UHPLC chromatographic peak, and is applied to the non-targeted profiling of human urine. Improvements in the number of features detected using LC-FAIMS-MS were as a result of reductions in chemical noise and separation of co-eluting isobaric species across the whole analytical space, demonstrating the potential of combining FAIMS with LC and MS

Increasing peak capacity in nontargeted omics applications by combining full scan field asymmetric waveform ion mobility spectrometry with liquid chromatography–mass spectrometry

Full scan field asymmetric waveform ion mobility spectrometry (FAIMS) combined with liquid chromatography and mass spectrometry (LC-FAIMS-MS) is shown to enhance peak capacity for omics applications. A miniaturized FAIMS device capable of rapid compensation field scanning has been incorporated into an ultrahigh performance liquid chromatography (UHPLC) and time-of-flight mass spectrometry analysis, allowing the acquisition of full scan FAIMS and MS nested data sets within the time scale of a UHPLC peak. Proof of principle for the potential of scanning LC-FAIMS-MS in omics applications is demonstrated for the nontargeted profiling of human urine using a HILIC column. The high level of orthogonality between FAIMS and MS provides additional unique compound identifiers with detection of features based on retention time, FAIMS dispersion field and compensation field (DF and CF), and mass-to-charge (m/z). Extracted FAIMS full scan data can be matched to standards to aid the identification of unknown analytes. The peak capacity for features detected in human urine using LC-FAIMS-MS was increased approximately threefold compared to LC-MS alone due to a combination of the reduction of chemical noise and separation of coeluting isobaric species across the entire analytical space. The use of FAIMS-selected in source collision induced dissociation (FISCID) yields fragmentation of ions, which reduces sample complexity associated with overlapping fragmentation patterns and provides structural information on the selected precursor ions

The determination of salivary oxypurines before and after exercise by combined liquid chromatography-field asymmetric waveform ion mobility spectrometry-time-of-flight mass spectrometry

© 2018 Springer-Verlag GmbH Germany, part of Springer Nature A method combining field asymmetric waveform ion mobility spectrometry with liquid chromatography-mass spectrometry (LC-FAIMS-MS) has been developed for the analysis of the oxypurine compounds hypoxanthine (HX) and xanthine (XA) in saliva. Separation of the oxypurines from interfering matrix components was investigated using FAIMS-MS. The selected FAIMS parameters were then applied to the rapid LC-FAIMS-MS analysis of HX and XA using a short chromatographic separation method (7 min). A comparison of the LC-MS method with and without FAIMS applied, resulted in improved discrimination from saliva matrix interferences and improved chromatographic peak integration for both HX and XA using a FAIMS separation. A quantitative evaluation of the LC-FAIMS-MS method was performed giving limits of detection of 2.0 ng mL −1 for HX and 1.8 ng mL −1 for XA, and limits of quantification of 6.6 ng mL −1 for HX and 6.0 ng mL −1 for XA. The developed LC-FAIMS-MS method was applied to the targeted analysis of the oxypurine metabolites in saliva collected from healthy male athletes (n = 11) before and after exercise designed to induce oxidative stress; post-exercise collection time-points included immediately after exercise, one hour and twenty-four hours’ post-exercise. The salivary concentrations of both HX and XA were lower after physical exercise, compared to the pre-exercise (rest) concentrations and returned to approximately pre-exercise levels after twenty-four hours. The method reported has the potential for monitoring the salivary oxypurines, HX and XA, as biomarkers of oxidative stress and in other clinical applications

Real-time monitoring of exhaled volatiles using atmospheric pressure chemical ionization on a compact mass spectrometer

© 2016 Future Science Ltd.Aim: Breath analyses have potential to detect early signs of disease onset. Ambient ionization allows direct combination of breath gases with MS for fast, on-line analysis. Portable MS systems would facilitate field/clinic-based breath analyses. Results & methodology: Volunteers ingested peppermint oil capsules and exhaled volatile compounds were monitored over 10 h using a compact mass spectrometer. A rise and fall in exhaled menthone was observed, peaking at 60-120 min. Real-time analysis showed a gradual rise in exhaled menthone postingestion. Sensitivity was comparable to established methods, with detection in the parts per trillion range. Conclusion: Breath volatiles were readily analyzed on a portable mass spectrometer through a simple inlet modification. Induced changes in exhaled profiles were detectable with high sensitivity and measurable in real-time

Real-time monitoring of exhaled volatiles using atmospheric pressure chemical ionization on a compact mass spectrometer

AIM: Breath analyses have potential to detect early signs of disease onset. Ambient ionization allows direct combination of breath gases with MS for fast, on-line analysis. Portable MS systems would facilitate field/clinic-based breath analyses. Results & methodology: Volunteers ingested peppermint oil capsules and exhaled volatile compounds were monitored over 10 h using a compact mass spectrometer. A rise and fall in exhaled menthone was observed, peaking at 60-120 min. Real-time analysis showed a gradual rise in exhaled menthone postingestion. Sensitivity was comparable to established methods, with detection in the parts per trillion range. CONCLUSION: Breath volatiles were readily analyzed on a portable mass spectrometer through a simple inlet modification. Induced changes in exhaled profiles were detectable with high sensitivity and measurable in real-time