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Determination of Mycotoxin and Mycotoxin Metabolites using LC/MS/MS |
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Mycotoxins are the secondary by-products of fungal mold metabolism. The toxicity and potential weaponization threat of mycotoxins demands the need for sensitive, robust and rugged analytical methodologies. Current methods used by agriculture and food laboratories are often unable to detect a suite of these toxins. In addition, these methods do not address exposure to these compounds, where detection of the metabolites would be necessary for clinical diagnosis and treatment. Our laboratories have developed both a GC/MS/MS and an LC/MS/MS protocol for the determination of a select group of mycotoxins and their metabolites (Figure 1) in both environmental and clinical matrices. |
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Analysis of Organophosphorous Nerve Agent Metabolites by LC/MS/MS |
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Nerve agents are the most well known and publicized chemical warfare agents. The chemical properties, lethality and history of these agents are well documented. Because of the potential use of nerve agents, methods for the detection and quantitation of these compounds are necessary. Of special interest is the development of methods to determine exposure levels to decrease the burden on the healthcare system. Our laboratory has developed and validated a method to measure the exposure to these agents by determination of the major metabolite the methyl phosphonic acids. This protocol uses solid phase extraction followed by electrospray negative ion LC/MS/MS analysis. |
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LC/MS/MS Determination of Urinary Concentrations of Insecticides and Herbicides in Professional Applicators |
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The objective of this work was the development of a robust, high-throughput, and sensitive method for the determination of specific pesticides in urine of professional turf applicators following occupational exposures. The compounds of interest in this study are: the herbicides dicamba, mecoprop (MCPP), 4-chloro-2-methylphenoxyacetic acid (MCPA), and 2,4-D; the insecticides imidacloprid and bifenthrin, and their urinary metabolites 6-chloronicotinic acid (6- CNA) and 2-methyl-3-phenylbenzoic acid (MPA), respectively. Quantitative analysis was performed using solid-phase extraction (SPE) followed by negative ion electrospray ionization HPLC/MS/MS from approximately 120 professional applicators. In 2003, twenty (20) applicators provided 19 consecutive 24-hour urine samples. In 2004, approximately 100 applicators will provide a total of six, 24 hour urine samples over three different time periods (spring, summer and fall). Measured concentrations of these analytes are to be used in conjunction with pesticide application information to predict the total absorbed dose following multiple exposures in a large occupational field study. This information, along with information collected from each subject by questionnaire, will be used to conduct an external validation of previously developed epidemiologic prediction models. Data obtained in this biomonitoring study will also be used to develop recommendations to reduce occupational exposure and for health risk assessments. |
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Rapid Sample Preparation and Identification of Infectious Microorganisms using Matrix-assisted Laser Desorption/Ionization and Time-of-flight Mass Spectrometry |
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The rapid detection of unknown infectious microorganisms in biological and environmental samples is a public health priority. The current Polymerase Chain Reaction (PCR) detection methods used in Public Health Laboratories are time consuming and results are not available for 24-48 hours after sample preparation. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) has been shown to be a much more powerful technology for the rapid screening for infectious microorganisms in biological samples. Previous work in this area has shown that it is possible to make distinctions at the strain level of microorganisms using a variety of MALDI-TOF/MS approaches. Studies have been performed to identify Escherichia coli strains based on ribosomal subunits obtained from whole cell lysates [1]. Whole cell approaches to differentiating between strains of microorganisms have been utilized with E. coli spp [2,3], Haemophilus spp[4], and Staphylococcus spp[5]. Screening for unknown infectious microorganisms is aided by the development of libraries of known microorganism spectra as well as pattern recognition software [6] and algorithm improvements [7] in recent years. The use of MALDI-TOF/MS is ideally suited for rapid screening of unknown infectious microorganisms due to the minimal amount of time needed for sample preparation prior to analysis. |