Variation in gas and volatile compound emissions from human urine as it ages, measured by an electronic nose

Siavash Esfahani, Nidhi M. Sagar, Ioannis Kyrou, Ella Mozdiak, Nicola O'Connell, Chuka Nwokolo, Karna D. Bardhan, Ramesh P. Arasaradnam, James A. Covington*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Article number4
Number of pages11
Issue number1
Publication statusPublished - 25 Jan 2016

Bibliographical note

© 2016 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons by Attribution
(CC-BY) license (


  • Electronic nose
  • Headspace analysis
  • Ion mobility spectrometry
  • Storage
  • Urinary stability


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