The focus of our laboratory is to develop analytical methods to detect organic compounds at very low (sub-picomole, 10-12 mol) concentrations. The samples we analyze are liquids or gases that are directed toward medical diagnostics, industrial hygiene and analysis of air toxics. The testing methodologies that we currently are developing use chromatographic separation techniques (gas (GC) or liquid chromatography (LC)) and various mass spectrometric (MS) methods for identification and quantitative analysis, often requiring the construction of new or modification of existing equipment. Students in my research group acquire a thorough understanding of how to use instruments to their optimum capacity, how to modify and repair them, and how to develop analytical methods using them.
The detection of endogenous volatile organic compounds (VOCs) in human breath has been used for over 200 years to diagnose specific disorders and disease states in humans such as diabetes, liver disease, kidney malfunctions, duodenal ulcers and vitamin E deficiency. We have developed methods to broaden the applicability of this analysis to breath condensates (moisture laden breath) and to provide reliability to the analysis not previously known. We have developed a breath collection device and sample concentrators that can detect all VOCs in breath to 0.02 ppb concentration from a single sample. It is the first collector that provides contaminant free breath samples from subjects over extended periods of time. Some of the VOCs are endogenous compounds are body metabolites expelled via breath from the blood, and some have been implicated in the progression of asthma and other lung disorders, tissue degeneration and cardiovascular disease. We have used it to monitor exposure to toxic chemicals, to identify endogenous biomarker compounds in healthy subjects, and to determine effects from fasting.
The measurement of chemicals in the blood has been used as the “gold standard” in medical diagnosis of health and of disease states. Because of the risk and need for trained personnel to collect blood, alternate non-invasive methods of sample collection are being sought so that patients may test themselves at home using easy to use diagnostics kits. Parotid saliva collection is an ideal candidate for home diagnostic use because patients can collect it within a few minutes. Whole saliva has been used for some time to monitor many compounds such as steroids, drugs and drug metabolites, and metabolites produced from oxidative stress, periodontal disease, gingivitis, HIV disease, diabetes, and cancer. Parotid saliva is a sterile serous exocrine secretion exuded in the mouth that contains many of the compounds found in blood serum, as thus may be an alternate method for diagnostic purposes. Our simple parotid collection test kit is being evaluated by a clinical laboratory for the monitoring of testosterone, cortisol, and other metabolites. With it we have measured the VOC constituents of normal parotid, metabolites of nicotine, monitored toxic substances in the workplace, and examined the effects of fasting. We are cataloging all normal VOC constituents to determine what compounds present are from endogenous sources and not from environmental sources. We are analyzing the higher molecular weight constituents (> 104) of parotid saliva using matrix assisted laser desorption ionization (MALDI) MS.
W. Wu, T. B. Weber, D. A. Chatfield, J. Cornejo-Bravo, Parotid saliva as biomarker to monitor environmental exposure, 221st Nat. Meet. Amer. Chem. Soc., San Diego, CA, Apr 4, 2001, papers 443912 and 443915.
B. I. Roman, D. A. Chatfield, and T. B. Weber, Analysis of volatile endogenous compounds in parotid saliva, breath and breath condensates by mass spectrometry, 2002 Rocky Mtn. Regional Conf., Amer. Chem. Soc., Oct 12-15, 2002, Albuquerque, N.M., paper 149.