title: Variation in Gas and Volatile Compound Emissions from Human Urine as It Ages, Measured by an Electronic Nose.
abstract: The medical profession is becoming ever more interested in the use of gas-phase biomarkers for disease identification and monitoring. This is due in part to its rapid analysis time and low test cost, which makes it attractive for many different clinical arenas. One technology that is showing promise for analyzing these gas-phase biomarkers is the electronic nose--an instrument designed to replicate the biological olfactory system. Of the possible biological media available to "sniff", urine is becoming ever more important as it is easy to collect and to store for batch testing. However, this raises the question of sample storage shelf-life, even at -80 °C. Here we investigated the effect of storage time (years) on stability and reproducibility of total gas/vapour emissions from urine samples. Urine samples from 87 patients with Type 2 Diabetes Mellitus were collected over a four-year period and stored at -80 °C. These samples were then analyzed using FAIMS (field-asymmetric ion mobility spectrometry--a type of electronic nose). It was discovered that gas emissions (concentration and diversity) reduced over time. However, there was less variation in the initial nine months of storage with greater uniformity and stability of concentrations together with tighter clustering of the total number of chemicals released. This suggests that nine months could be considered a general guide to a sample shelf-life.
authors.affiliation: School of Engineering, University of Warwick, Coventry, CV4 7AL, UK. s.esfahani@warwick.ac.uk.
authors.forename: Siavash
authors.initials: S
authors.lastname: Esfahani
authors.affiliation: School of Medicine, University of Warwick, Coventry, CV4 7AL, UK. dr.nidhisagar@gmail.com.
authors.forename: Nidhi M
authors.initials: NM
authors.lastname: Sagar
authors.affiliation: Department of Metabolic Medicine, University Hospital Coventry and Warwickshire, Coventry, CV2 2DX UK. I.Kyrou@warwick.ac.uk.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kyrou
authors.affiliation: School of Medicine, University of Warwick, Coventry, CV4 7AL, UK. ella.mozdiak@nhs.net.
authors.forename: Ella
authors.initials: E
authors.lastname: Mozdiak
authors.affiliation: Department of Gastroenterology, University Hospital Coventry and Warwickshire, Coventry, CV2 2DX, UK. Nicola.Oconnell@uhcw.nhs.uk.
authors.forename: Nicola
authors.initials: N
authors.lastname: O'Connell
authors.affiliation: Department of Gastroenterology, University Hospital Coventry and Warwickshire, Coventry, CV2 2DX, UK. chukka.nwokolo@uhcw.nhs.uk.
authors.forename: Chuka
authors.initials: C
authors.lastname: Nwokolo
authors.affiliation: Rotherham General Hospital, Rotherham, S60 2UD, UK. bardhan.sec@rothegn.nhs.uk.|Clinical Sciences Research Institute, University of Warwick, Coventry, CV2 2DX, UK. bardhan.sec@rothegn.nhs.uk.
authors.forename: Karna D
authors.initials: KD
authors.lastname: Bardhan
authors.affiliation: Department of Gastroenterology, University Hospital Coventry and Warwickshire, Coventry, CV2 2DX, UK. R.Arasaradnam@warwick.ac.uk.|Clinical Sciences Research Institute, University of Warwick, Coventry, CV2 2DX, UK. R.Arasaradnam@warwick.ac.uk.
authors.forename: Ramesh P
authors.initials: RP
authors.lastname: Arasaradnam
authors.affiliation: School of Engineering, University of Warwick, Coventry, CV4 7AL, UK. j.a.covington@warwick.ac.uk.
authors.forename: James A
authors.initials: JA
authors.lastname: Covington
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D003924:Diabetes Mellitus, Type 2 / Q000652:urine*; D062609:Electronic Nose; D005260:Female; D005740:Gases / Q000032:analysis* / Q000652:urine; D006801:Humans; D008297:Male; D008875:Middle Aged; D013048:Specimen Handling; D013997:Time Factors; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000652:urine
chemical_list: D005740:Gases; D055549:Volatile Organic Compounds
keywords: electronic nose; headspace analysis; ion mobility spectrometry; storage; urinary stability
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