Publications by authors named "Logan C Krajewski"

Background: Microcystins are an emergent public health problem. These toxins are secondary metabolites of harmful cyanobacterial blooms, with blooms becoming more prevalent with eutrophication of water. Exposure to microcystins can result in sickness, liver damage, and even death.

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Natural toxins present an ongoing risk for human exposure that requires a rapid, accurate diagnosis for proper response. In this study, a qualitative liquid chromatography high resolution mass spectrometry (LC-HRMS) method was developed and validated for the detection of a large, diverse selection of natural toxins. Data-dependent acquisition was performed to identify compounds with an in-house mass spectral library of 129 hazardous toxins that originate from plants, animals, and fungi.

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Microcystins are toxic chemicals generated by certain freshwater cyanobacteria. These chemicals can accumulate to dangerous levels during harmful algal blooms. When exposed to microcystins, humans are at risk of hepatic injury, including liver failure.

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To combat the ongoing opioid epidemic, our laboratory has developed and evaluated an approach to detect fentanyl analogs in urine and plasma by screening LC-QTOF MS/MS spectra for ions that are diagnostic of the core fentanyl structure. MS/MS data from a training set of 142 fentanyl analogs were used to select the four product ions and six neutral losses that together provided the most complete coverage (97.2%) of the training set compounds.

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Human exposures to fentanyl analogs, which significantly contribute to the ongoing U.S. opioid overdose epidemic, can be confirmed through the analysis of clinical samples.

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We report chemical characterization of natural oil seeps from the Gulf of Mexico by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and Gas Chromatography/Atmospheric Pressure Chemical Ionization Mass Spectrometry (GC/APCI-MS), to highlight how FT-ICR MS can also be employed as a means to determine petroleum connectivity, in addition to traditional GC/MS techniques. The source of petroleum is the Green Canyon (GC) 600 lease block in the Gulf of Mexico. Within GC600, two natural oil seepage zones, Mega Plume and Birthday Candles, continuously release hydrocarbons and develop persistent oil slicks at the sea surface above them.

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Here, we present atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance (FTICR) mass analysis of a volcanic asphalt sample by acquiring data for 20 Da wide mass segments across a 1000 Da range, stitched into a single composite mass spectrum, and compare to a broad-band mass spectrum for the same sample. The segmented spectrum contained 170 000 peaks with magnitude greater than 6σ of the root-mean-square (rms) baseline noise, for which 126 264 unique elemental compositions could be assigned. Approximately two-thirds of those compositions represent monoisotopic (i.

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Article Synopsis
  • As levels of natural organic matter (NOM) increase in surface water, it becomes crucial to minimize harmful disinfection by-products (DBPs) generated during chlorination.
  • Chromatographic prefractionation helps simplify the complex composition of NOM, making it easier to analyze how chlorination alters it.
  • The study found that highly oxidized NOM led to more diverse DBPs and significant changes that complicate detection, while less-oxidized materials formed fewer DBPs and maintained a more stable composition.
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