Preparation of Mixed-mode Chromatography Supports Based on Gigaporous Polymer Microspheres

Discrimination of hazardous bacteria with combination laser-induced breakdown spectroscopy and statistical methods

Real-time biohazard detectors must be developed to facilitate the rapid implementation of appropriate protective measures against foodborne pathogens. Laser-induced breakdown spectroscopy (LIBS) is a promising technique for the real-time detection of hazardous bacteria (HB) in the field. However, distinguishing among various HBs that exhibit similar C, N, O, H, or trace metal atomic emissions complicates HB detection by LIBS. This paper proposes the use of LIBS and chemometric tools to discriminate Staphylococcus aureus, Bacillus cereus, and Escherichia coli on slide substrates. Principal component analysis (PCA) and the genetic algorithm (GA) were used to select features and reduce the size of spectral data. Several models based on the artificial neural network (ANN) and the support vector machine (SVM) were built using the feature lines as input data. The proposed PCA-GA-ANN and PCA-GA-SVM discrimination approaches exhibited correct classification rates of 97.5% and 100%, respectively.

Recent advances in mixed-mode chromatographic stationary phases

Mixed-mode phases have become very popular in the last decade, and the number of new mixed/multi-mode sorbents is growing fast. Unlike single-mode stationary phases, perfectly suited for the separation of the analytes possessing similar physicochemical properties, for instance reversed-phase chromatography for hydrophobic solutes, mixed-mode sorbents providing multimodal interactions can render better separation selectivity for complex mixtures of solutes differing significantly in their physicochemical characteristics. The most frequent modern mixed-mode stationary phases are di/tri-mode sorbents embracing the following interactions, hydrophobic, electrostatic (coulombic), and hydrophilic. According to their structures, it is possible to distinguish silica-based, polymer-based, hybrid, and monolithic mixed-mode stationary phases. Herewith, newly synthesized mixed-mode sorbents developed within the last two and half years are categorized, discussed, and summarized. The main attention is devoted to the description of the synthetic routes and characterization methods applied for the new stationary phases.

An arylboronate locked fluorescent probe for hypochlorite

An unusual arylboronate based fluorescent probeR1was synthesized for the selective and sensitive detection of ClO⁻.