title: Sensitivity enhancement in the determination of volatile biomarkers in saliva using a mass spectrometry-based electronic nose with a programmed temperature vaporizer.
abstract: With a view to improving the sensitivity of direct coupling of a headspace sampler (HS) with a mass spectrometer (MS), here we propose the use of a programmed temperature vaporizer (PTV) in solvent-vent injection mode before the sample is introduced into the MS. This preconcentration scheme has been used for some time in many methods based on gas chromatography (GC), but to the best of our knowledge it has not yet been used in an electronic nose based on MS. The increase in the S/N ratio with the proposed instrumental configuration (HS-PTV/MS) lies between 6.9- and 22-fold. The main advantage of using this injector lies in the fact that it does not involve time-consuming steps. To check the possibilities of this methodology, saliva samples from healthy volunteers and patients with different types of illnesses (including some types of cancer) were analyzed. None of the compounds studied was detected in the samples corresponding to the healthy volunteers. One or more biomarkers, at levels ranging from 13 to 500 μg/L, were found in five of the samples from the patients. Additionally, separative analysis by HS-PTV-GC/MS was performed for confirmatory purposes and both methods provided similar results. The main advantage of the proposed methodology is that no prior chromatographic separation and no sample manipulation are required.
authors.affiliation: Departamento de Química Analítica, Nutrición y Bromatología, Facultad de Ciencias Químicas, Universidad de Salamanca , 37008 Salamanca, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: del Nogal Sánchez
authors.forename: Pedro Ángel
authors.initials: PÁ
authors.lastname: Callejo Gómez
authors.forename: José Luis
authors.initials: JL
authors.lastname: Pérez Pavón
authors.forename: Bernardo
authors.initials: B
authors.lastname: Moreno Cordero
authors.forename: Angel Pedro
authors.initials: AP
authors.lastname: Crisolino Pozas
authors.forename: Angel
authors.initials: A
authors.lastname: Sánchez Rodríguez
mesh_terms: D015415:Biomarkers / Q000032:analysis*; D004581:Electronics; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006358:Hot Temperature; D057230:Limit of Detection; D012463:Saliva / Q000737:chemistry*; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: D015415:Biomarkers; D055549:Volatile Organic Compounds