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Rapid, efficient, versatile, easy-to-use, and non-expensive analytical approaches are globally demanded for food analysis. Many ambient ionization approaches based on electrospray ionization (ESI) have been developed recently for the rapid molecular characterization of food products. However, those approaches mainly suffer from insufficient signal duration for comprehensive chemical characterization by tandem MS analysis. Here, a commercially available disposable gel loading tip is used as a low-cost emitter for the direct ionization of untreated food samples. The most important advantages of our approach include high stability, and durability of the signal (> 10 min), low cost (ca. 0.1 USD per run), low sample and solvent consumption, prevention of tip clogging and discharge, operational simplicity, and potential for automation. Quantitative analysis of sulfapyridine, HMF (hydroxymethylfurfural), and chloramphenicol in real sample shows the limit-of-detection 0.1 μg mL−1, 0.005 μg mL−1, 0.01 μg mL−1; the linearity range 0.1–5 μg mL−1, 0.005–0.25 μg mL−1, 0.01–1 μg mL−1; and the linear fits R2 ≥ 0.980, 0.991, 0.986. Moreover, we show that tip-ESI can also afford sequential molecular ionization of untreated viscous samples, which is difficult to achieve by conventional ESI. We conclude that tip-ESI–MS is a versatile analytical approach for the rapid chemical analysis of untreated food samples. [ABSTRACT FROM AUTHOR]

A triangular-shaped flat plastic substrate probe was prepared for direct electrospray ionization mass spectrometry (ESI–MS) for analysis of untreated chemical and biological samples including liquids (Met-Arg-Phe-Ala peptide, reserpine, and dodecyl aldehyde), solids (biological samples, traditional Chinese medicine), and powders (roasted coffee, rhizoma coptidis, lotus plumule, and Schisandra sphenanthera). Quantitative analysis of reserpine in water yielded a detection limit of 1 ng mL−1, dynamic response range within 1–500 ng mL−1, and linearity of signal response ˃0.9925. Compared to the conventional capillary ESI, this plastic probe ESI offers lower cost of analysis (US $0.0056 per probe), higher sensitivity, lower sample consumption, longer signal duration (>6 min), better reproducibility, signal stability, and higher speed of analysis (<10 s per sample, including sample loading). Overall, the results indicate the potential of ESI–MS based on flat plastic probes as a versatile method for simple, sensitive, and stable analysis of untreated biological sample analysis. [ABSTRACT FROM AUTHOR]

The mechanisms of volatile species formation for hydroperoxylated metabolites of unsaturated fatty acids in grass carp oil were investigated. All oil samples were heated at 110 °C for 8 various durations. The hydroperoxylated metabolites were evaluated by ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry, solid-phase microextraction gas chromatography mass spectrometry and conventional chemical indicators. Compared to fresh fish oil, the content of monounsaturated fatty acids and saturated fatty acids with higher oxidation stability in the heating samples was significantly increased (P < 0.05), while the content of polyunsaturated fatty acids was significantly reduced (P < 0.05). A total of 35 triglycerides were determined, of these, the relative content of carbon numbers (CNs) 54, 56 and 58 was dramatically decreased, while CN50 and CN52 were gradually increased. Partial least-squares discriminant analysis indicated that continuous heating had different effects on volatile substances and twelve volatile species variables associated with lipid oxidation from the eight various heating periods were identified. In addition, sixteen oxidized metabolites were identified and their content was significantly increased (P < 0.05), except the 13-HODE, 9-HOTrE, 5-HETE and 12-HETE. The metabolic pathways of grass carp oil under continuous heating were clarified based on critical volatile components and oxidized metabolites, intending to reveal the oxidation paradigm of oil exposed to high temperatures. [ABSTRACT FROM AUTHOR]

Despite growing work on the positive outcomes resulting from ambidextrous leadership, limited research has examined whether ambidextrous leadership always has desirable consequences on followers. In order to achieve explorative and exploitative innovation, ambidextrous leaders are required to perform two styles of leadership behaviors, namely opening and closing leadership behaviors. The present study argues that as followers are reliant on their leaders to provide them with information and clarification about the tasks, by engaging in ambidextrous leadership behaviors to try and foster innovative behaviors amongst their followers, the leader may unintendedly increase the follower's job stress and role ambiguity. Drawing on a sample of 416 leader–follower dyads, we established that while ambidextrous leadership contributes to the innovative behaviors of followers, it also increases followers' job stress and role ambiguity, which subsequently reduces innovative behaviors. The results suggest that ambidextrous leadership has two faces, enabling and burdening, which can both enhance and stifle innovative behaviors. [ABSTRACT FROM AUTHOR]

More than 200 toxic substances (including narcotic drugs, psychotropic drugs, organic phosphorus compounds, carbamates, pyrethroids and other pesticides, veterinary drugs, rodenticides, natural toxins, and other drugs) were identified and quantified using an ion-trap mass spectrometer. The advantages of this technique—its selectivity, accuracy, precision, utilization of only small amounts of the sample, and short analysis time for a single sample (less than 30s)—render it a rapid and accurate methodology for toxin screening. Subsequently, an extractive electrospray ionization (EESI) mass spectrometry database was established by combining the Xcalibur data processing system with NIST database software. This allowed unknown toxicants in urine and blood samples, stomach contents, and liver samples, as provided by the Jiangxi Provincial Public Security Department, to be analyzed and identified. This EESI methodology and databank has the potential for widespread application to the large-scale analysis of practical samples. [ABSTRACT FROM AUTHOR]