title: Measurement of exhaled volatile organic compounds from patients with chronic obstructive pulmonary disease (COPD) using closed gas loop GC-IMS and GC-APCI-MS.
abstract: Due to its high sensitivity, compact size and low cost ion mobility spectrometry (IMS) has the potential to become a point-of-care breath analyzer. Therefore, we developed a prototype of a compact, closed gas loop IMS with gas chromatographic (GC) pre-separation and high resolving power of R  =  90. In this study, we evaluated the performance of this GC-IMS under clinical conditions in a COPD study to find correlations between VOCs (10 ppbv to 1 ppmv) and COPD. Furthermore, in order to investigate possible correlations between ultra-low concentrated breath VOCs (0.1 pptv to 1 ppbv) and COPD, a modified mass spectrometer (MS) with atmospheric pressure chemical ionization (APCI) and GC pre-separation (GC-APCI-MS) was used. The GC-IMS has been used in 58 subjects (21 smokers with moderate COPD, 12 ex-smokers with COPD, 16 healthy smokers and 9 non-smokers). GC-APCI-MS data were available for 94 subjects (21 smokers with moderate COPD, 25 ex-smokers with COPD, 25 healthy smokers and 23 non-smokers). For 44 subjects, a comparison between GC-IMS and GC-APCI-MS data could be performed. Due to service intervals, subject availability and corrupt data, patient numbers were different for GC-APCI-MS and GC-IMS measurements. Using GC-IMS, three VOCs have been found showing a significant difference between healthy controls and patients with COPD. In the GC-APCI-MS data, we only observed one distinctive VOC, which has been identified as 2-pentanone. This proof-of-principle study shows the potential of our high-resolution GC-IMS in the clinical environment. Due to different linear dynamic response ranges, the data of GC-IMS and GC-APCI-MS were only comparable to a limited extent.
authors.affiliation: Institute of Electrical Engineering and Measurement Technology, Leibniz Universität Hannover, Hannover, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Allers
authors.forename: J
authors.initials: J
authors.lastname: Langejuergen
authors.forename: A
authors.initials: A
authors.lastname: Gaida
authors.forename: O
authors.initials: O
authors.lastname: Holz
authors.forename: S
authors.initials: S
authors.lastname: Schuchardt
authors.forename: J M
authors.initials: JM
authors.lastname: Hohlfeld
authors.forename: S
authors.initials: S
authors.lastname: Zimmermann
mesh_terms: D000328:Adult; D000368:Aged; D001944:Breath Tests / Q000379:methods*; D002849:Chromatography, Gas / Q000379:methods*; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D008875:Middle Aged; D019095:Point-of-Care Systems; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D055549:Volatile Organic Compounds / Q000032:analysis*; D055815:Young Adult
chemical_list: D055549:Volatile Organic Compounds