Huanwen Chen

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Desorption electrospray ionization mass spectrometry (DESI-MS) and nuclear magnetic resonance (NMR) spectroscopy are used to provide data on urine examined without sample preparation to allow differentiation between diseased (lung cancer) and healthy mice. Principal component analysis (PCA) is used to shortlist compounds with potential for biomarker(More)
Urine metabolic profiles of patients with inborn errors of metabolism were examined with nuclear magnetic resonance (NMR) and desorption electrospray ionization mass spectrometry (DESI-MS) methods. Spectra obtained from the study of urine samples from individual patients with argininosuccinic aciduria (ASA), classic homocystinuria (HCY), classic(More)
On-line droplet-droplet extraction occurs when a sample spray intersects a reagent electrospray; this allows continuous analysis of trace amounts of compounds directly in complex matrices including undiluted urine, milk and polluted water over extended periods of time.
Desorption electrospray ionization (DESI) allows mass spectrometry to be used for on-line high-throughput monitoring of pharmaceutical samples in the ambient environment, without prior sample preparation. Positive and negative ion DESI are used to characterize the active ingredients in pharmaceutical samples formulated as tablets, ointments, and liquids.(More)
The effect of diet on metabolites found in rat urine samples has been investigated using nuclear magnetic resonance (NMR) and a new ambient ionization mass spectrometry experiment, extractive electrospray ionization mass spectrometry (EESI-MS). Urine samples from rats with three different dietary regimens were readily distinguished using multivariate(More)
In metabolomics studies and clinical diagnosis, interest is increasing in the rapid analysis of exhaled breath. In vivo breath analysis offers a unique, unobtrusive, non-invasive method of investigating human metabolism. To analyze breath in vivo, we constructed a novel platform of extractive electrospray ionization (EESI) ion trap mass spectrometry (ITMS)(More)
Desorption electrospray ionization (DESI), an ambient mass spectrometry technique, is used for trace detection of the explosives trinitrohexahydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 2,4,6-trinitrotoluene (TNT), Pentaerythritol tetranitrate (PETN), and their plastic compositions (Composition C-4, Semtex-H,(More)
Ambient mass spectrometry, pioneered with desorption electrospray ionization (DESI) technique, is of increasing interest in recent years. In this study, a corona discharge ionization source is adapted for direct surface desorption chemical ionization of compounds on various surfaces at atmospheric pressure. Ambient air, with about 60% relative humidity, is(More)
A novel air-tight neutral desorption enclosure has been fabricated to noninvasively sample low picograms of explosives 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazocine (HMX), triacetone triperoxide (TATP), and nitroglycerin (NG) from human skin using a neutral nitrogen gas beam.(More)