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J Am Soc Mass Spectrom

Title:		Real-Time Quantitative Analysis of Valproic Acid in Exhaled Breath by Low Temperature Plasma Ionization Mass Spectrometry
Author(s):		Gong X; Shi S; Gamez G;
Address:		"Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79409-1061, USA. Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79409-1061, USA. gerardo.gamez@ttu.edu"
Journal Title:		J Am Soc Mass Spectrom
Year:		2017
Volume:		20161109
Issue:		4
Page Number:		678 - 687
DOI:		10.1007/s13361-016-1533-7
ISSN/ISBN:		1879-1123 (Electronic) 1044-0305 (Linking)
Abstract:		"Real-time analysis of exhaled human breath is a rapidly growing field in analytical science and has great potential for rapid and noninvasive clinical diagnosis and drug monitoring. In the present study, an LTP-MS method was developed for real-time, in-vivo and quantitative analysis of gamma-valprolactone, a metabolite of valproic acid (VPA), in exhaled breath without any sample pretreatment. In particular, the effect of working conditions and geometry of the LTP source on the ions of interest, protonated molecular ion at m/z 143 and ammonium adduct ion at m/z 160, were systematically characterized. Tandem mass spectrometry (MS/MS) with collision-induced dissociation (CID) was carried out in order to identify gamma-valprolactone molecular ions (m/z 143), and the key fragment ion (m/z 97) was used for quantitation. In addition, the fragmentation of ammonium adduct ions to protonated molecular ions was performed in-source to improve the signal-to-noise ratio. At optimum conditions, signal reproducibility with an RSD of 8% was achieved. The concentration of gamma-valprolactone in exhaled breath was determined for the first time to be 4.83 (+/-0.32) ng/L by using standard addition method. Also, a calibration curve was obtained with a linear range from 0.7 to 22.5 ng/L, and the limit of detection was 0.18 ng/L for gamma-valprolactone in standard gas samples. Our results show that LTP-MS is a powerful analytical platform with high sensitivity for quantitative analysis of volatile organic compounds in human breath, and can have potential applications in pharmacokinetics or for patient monitoring and treatment. Graphical Abstract »aΓ"
Keywords:		Breath Tests/instrumentation/*methods Cold Temperature Equipment Design Exhalation Humans Ions/chemistry Limit of Detection Reproducibility of Results Tandem Mass Spectrometry/instrumentation/*methods Valproic Acid/*analysis Ambient ionization Breath anal;
Notes:		"MedlineGong, Xiaoxia Shi, Songyue Gamez, Gerardo eng Evaluation Study 2016/11/11 J Am Soc Mass Spectrom. 2017 Apr; 28(4):678-687. doi: 10.1007/s13361-016-1533-7. Epub 2016 Nov 9"