Abstract
The analytical performances of needle trap micro-extraction (NTME) coupled with gas chromatography-tandem mass spectrometry were evaluated by analyzing a mixture of twenty-two representative breath volatile organic compounds (VOCs) belonging to different chemical classes (i.e. hydrocarbons, ketones, aldehydes, aromatics and sulfurs). NTME is an emerging technique that guarantees detection limits in the pptv range by pre-concentrating low volumes of sample, and it is particularly suitable for breath analysis. For most VOCs, detection limits between 20 and 500 pptv were obtained by pre-concentrating 25 ml of a humidified standard gas mixture at a flow rate of 15 ml min−1. For all compounds, inter- and intra-day precisions were always below 15%, confirming the reliability of the method. The procedure was successfully applied to the analysis of exhaled breath samples collected from forty heart failure (HF) patients during their stay in the University Hospital of Pisa. The majority of patients (about 80%) showed a significant decrease of breath acetone levels (a factor of 3 or higher) at discharge compared to admission (acute phase) in correspondence to the improved clinical conditions during hospitalization, thus making this compound eligible as a biomarker of HF exacerbation.
Highlights
Needle trap micro-extraction (NTME) coupled with gas chromatography-mass spectrometry (GC-MS) represents an emerging and promising technique that guarantees detection limits in the pptv range by preconcentrating a volume of breath less than 50 ml [1]
Application to real samples: heart failure (HF) patients The optimized NTME procedure was applied to monitor the chemical composition of breath samples collected from forty patients suffering from HF
This paper reports a validated analytical procedure for the determination of volatile organic compounds (VOCs) in exhaled breath samples by NTME followed by GC-MS/MS analysis
Summary
Needle trap micro-extraction (NTME) coupled with gas chromatography-mass spectrometry (GC-MS) represents an emerging and promising technique that guarantees detection limits in the pptv range by preconcentrating a volume of breath less than 50 ml [1]. A needle trap device (NTD) consists of a stainless-steel needle (22 or 23 gauge) packed with few milligrams of different types of stationary phases. Such devices, introduced for the first time in the late nineties [2], allows combining the sample collection and the analyte pre-concentration in a single step requiring less than 3 min to be accomplished. The simplest method to transfer the adsorbed analytes to the capillary column is the expansive flow technique, which exploits the gas flow generated by the thermal expansion of air inside the needle [7]. As recently reported [8], the presence of water does not represent a significant problem for the GC column and for the MS due to the very low amount retained by hydrophilic sorbents [8, 9]
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