Impact of LC-MS/MS quantification methods on analytical results by example of nationwide U.S. environmental samples.

Although different quantification methods are extensively used in environmental chemistry, the impact of the choice of method on the quality and range of analytical results is understudied. This two-part study consists of (a) in-lab evaluation and (b) a traditional meta-analysis (n = 66) of commonly used quantification methods): (i) external calibration; (ii) isotope dilution method with authentic target analogs; (iii) isotope dilution with non-target standards; and (iv) standard addition prior to LC-MS/MS in liquid chromatography tandem mass spectrometry (LC-MS/MS) by example of antibiotics in sewage sludge from across the U.S.

Volatile profiling of cacti: a preliminary assessment of the taxonomic and evolutionary significance of volatile compounds in Cylindropuntia, Grusonia, Consolea, Opuntia, Quiabentia, and Tacinga.

Volatile analyses of cacti have previously been performed on the flowers, fruits, and consumed stems. During our own investigations, we and others have observed that the cut stems of certain species of the Graveolens clade of Cylindropuntia emitted odors similar to those of rancid butter or cyanoacrylate. Some species of Consolea, Opuntia, Quiabentia, and Tacinga were found to produce similar odors.

Retrospective nationwide occurrence of fipronil and its degradates in U.S. wastewater and sewage sludge from 2001 - 2016.

The insecticide fipronil is under regulatory scrutiny worldwide for its toxicity to pollinators and aquatic invertebrates. We conducted the first U.S.

U.S. nationwide reconnaissance of ten infrequently monitored antibiotics in municipal biosolids.

Ten infrequently monitored antibiotics in biosolids were examined in archived American sewage sludges (n = 79) collected as part of the 2006/2007 U.S. Environmental Protection Agency (EPA) Targeted National Sewage Sludge Survey.

Ion Mobility Spectrometry-Mass Spectrometry Coupled with Gas-Phase Hydrogen/Deuterium Exchange for Metabolomics Analyses.

Ion mobility spectrometry-mass spectrometry (IMS-MS) in combination with gas-phase hydrogen/deuterium exchange (HDX) and collision-induced dissociation (CID) is evaluated as an analytical method for small-molecule standard and mixture characterization. Experiments show that compound ions exhibit unique HDX reactivities that can be used to distinguish different species. Additionally, it is shown that gas-phase HDX kinetics can be exploited to provide even further distinguishing capabilities by using different partial pressures of reagent gas.

Ion Mobility, Hydrogen/Deuterium Exchange, and Isotope Scrambling: Tools to Aid Compound Identification in 'Omics Mixtures.

Liquid chromatography tandem mass spectrometry (LC-MS/MS), a widely used method for comparative 'omics analysis, experiences challenges with compound identification due to matrix effects, difficulty in separating isomer and isobaric ions, and long analysis times. Ion mobility spectrometry (IMS) has proven to be useful in separating isomer and isobar ions; however, IMS-MS suffers from decreased peak capacity due to the correlation in ion size and mass. In proof-of-principle experiments, the use of gas-phase hydrogen/deuterium exchange (HDX) combined with IMS-MS/MS techniques is demonstrated to offer advantages for compound identification.

Comparative plasma proteomic studies of pulmonary TiO2 nanoparticle exposure in rats using liquid chromatography tandem mass spectrometry.

Mounting evidence suggests that pulmonary exposure to nanoparticles (NPs) has a toxic effect on biological systems. A number of studies have shown that exposure to NPs result in systemic inflammatory response, oxidative stress, and leukocyte adhesion. However, significant knowledge gaps exist for understanding the key molecular mechanisms responsible for altered microvasculature function.

Advances in ion mobility-mass spectrometry instrumentation and techniques for characterizing structural heterogeneity.

Over the last decade, the field of ion mobility-mass spectrometry (IM-MS) has experienced dramatic growth in its application toward ion structure characterization. Enabling advances in instrumentation during this time period include improved conformation resolution and ion sensitivity. Such advances have rendered IM-MS a powerful approach for characterizing samples presenting a diverse array of ion structures.

Huntingtin N-Terminal Monomeric and Multimeric Structures Destabilized by Covalent Modification of Heteroatomic Residues.

Early stage oligomer formation of the huntingtin protein may be driven by self-association of the 17-residue amphipathic α-helix at the protein's N-terminus (Nt17). Oligomeric structures have been implicated in neuronal toxicity and may represent important neurotoxic species in Huntington's disease. Therefore, a residue-specific structural characterization of Nt17 is crucial to understanding and potentially inhibiting oligomer formation.

An improved UHPLC-UV method for separation and quantification of carotenoids in vegetable crops.

Carotenoid identification and quantitation is critical for the development of improved nutrition plant varieties. Industrial analysis of carotenoids is typically carried out on multiple crops with potentially thousands of samples per crop, placing critical needs on speed and broad utility of the analytical methods. Current chromatographic methods for carotenoid analysis have had limited industrial application due to their low throughput, requiring up to 60 min for complete separation of all compounds.

Survey of regional health care providers on selection of treatment for bulimia nervosa.

Objective: To determine which treatments clinicians currently recommend for patients with bulimia nervosa (BN), to find out if they recommended evidence-based treatments, and to assess availability and clinician satisfaction with treatment options.

Methods: Surveys were sent to 1,263 health care providers in Minnesota, Iowa, and Wisconsin who were likely to encounter patients with BN. These health care providers comprised all primary care clinicians, physician assistants, advanced practice nurses, and all mental health/chemical dependency clinicians (MDs, Clinical Nurse Specialist (CNS), social workers, doctoral and masters-level therapists, and chemical dependency (CD) counselors) affiliated with the Mayo Clinic in Rochester, Minnesota.

Decisional capacity of severely depressed patients requiring electroconvulsive therapy.

Objective: The decisional capacity of severely depressed people frequently comes into question. The ability to improve this decisional capacity through educational efforts alone is not known. Our study aimed to determine the decisional capacity of severely depressed people requiring electroconvulsive therapy (ECT), and whether educational interventions improve their ability to provide informed consent for ECT.

Effect of "ionized" wrist bracelets on musculoskeletal pain: a randomized, double-blind, placebo-controlled trial.

Objective: To assess objectively the perceived benefits of wearing an "ionized" wrist bracelet to treat muscle or joint pain.

Subjects And Methods: This study was performed at the Mayo Clinic in Jacksonville, Fla, in 2000 and 2001. In a randomized, double-blind design, 305 participants wore an ionized bracelet and 305 wore a placebo bracelet for 4 weeks.

Papillary thyroid carcinoma managed at the Mayo Clinic during six decades (1940-1999): temporal trends in initial therapy and long-term outcome in 2444 consecutively treated patients.

It is uncertain whether more extensive primary surgery and increasing use of radioiodine remnant ablation (RRA) for papillary thyroid carcinoma (PTC) have resulted in improved rates of cause-specific mortality (CSM) and tumor recurrence (TR). Details of the initial presentation, therapy, and outcome of 2444 PTC patients consecutively treated during 1940-1999 were recorded in a computerized database. Patients were followed for more than 43,000 patient-years.