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A direct mass spectrometry method utilizing reactive paper spray ionization was developed for sensitive cannabinoid quantitation in biofluid matrices. The ca. 2-minute sample measurements used on-paper derivatization to significantly increase paper spray mass spectrometry (PS-MS) positive ion mode sensitivity while minimizing sample preparation steps. Calibrations demonstrate high linearity, with R2 > 0.99 for (−)-trans-Δ9-tetrahydrocannabinol (THC) in oral fluid and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) in urine. The limit of detection and lower limit of quantitation were 0.78 and 10 ng mL−1 for THC in oral fluid and 1.3 and 10 ng mL−1 for THC-COOH in urine, respectively. THC-COOH levels measured by reactive PS-MS in seven spiked human urine samples showed bias of −9.4 to 5.9%, and percent difference values of −16.8 to 9.8% in comparison with a reference LC-MS method. Based upon the method simplicity, validation experiments, sensitivity, and rapidity, we conclude that reactive PS-MS has potential applications for rapid cannabinoid drug testing in urine and oral fluid. [ABSTRACT FROM AUTHOR]

Cationized birch xylan was prepared and its use as a papermaking chemical was evaluated. The focus was on studying the effects of cationized birch xylan on the wet and dry strength of fine paper. The results of the laboratory experiments show that the addition of 3 percent of cationized birch xylan to birch kraft pulp improved the initial wet strength of the web by 30 percent compared to base stock at a solids content of 55%. Furthermore, the tensile stiffness of the wet web increased by approximately a third and the dry tensile strength improved by 26%, while the dry elastic modulus was not changed. The improvements in the strength properties were clear when compared to the base stock, but not as high as achieved with conventionally used cationized starch. The difference between the xylan and starch is most likely due to the shorter polymer chain length of the cationized xylan. [ABSTRACT FROM AUTHOR]

Highlights: [•] Improvement of the direct quantification with analytical pyrolysis. [•] Optimization of the chromatographic parameters after pyrolysis of cationic starch. [•] Quantification of cationic starches in cellulose matrixes. [•] Validation of the cationic starch quantification in paper samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • GQD-DDT and GQD-MPA was synthesized using novel hydrothermal protocol. • GQD-DDT and GQD-MPA was used for the identification of cations using colorimetric and spectrophotometric assay. • GQD-DDT and GQD-MPA have well activity for ion sensing in aqueous solution. This study describes the synthesis of various types of thiolated-graphene quantum dots (GQDs) for the simultaneous multi-sensing of heavy metal ions using one-droplet microfluidic paper-based analytical devices (OD- µ PADs). For the first time, functionalized GQDs were synthesized and stabilized on the surface of hydrophobic fiber-glass with simple manufacturing and assembly strategy towards colorimetric chemosensing of ions including iron, copper, cobalt, mercury, chrome, manganese, and nickel. For this purpose, GQDs are functionalized by various organic species including cysteamine, decanethiol, and mercaptopropionic acid (MPA) towards specific electrostatic interaction with metal ions of Fe (II), Cu (II), Co(II), Hg (II), Mn (II), and Ni (II). Therefore, an innovative GQDs-based miniaturized chemo-system was proposed for the environmental analysis. Additionally, the results were confirmed using fluorescence spectrometry as an optical detection method. Finally, this simple and efficient colorimetric platform was used for facile metal ions detection in human urine models, and environmental fluids, which can provide a commercial device for sensing contaminants by non-professional users in biomedical/environmental mixture. As an economical technique, this platform presents a "mix-and-sense" system without dye (as a side substance) or chemical treatments. The low instrumental requirements, the color uniformity, and the disposability of OD- μ PADs approve the commercial application of the engineered ion-chemosensor. [ABSTRACT FROM AUTHOR]

A new approach for the chemical modification of the surface of paper based on the application of colloidal mixtures containing cationic starch and polyoxometalates on uncoated base paper is presented. Polyoxometalates with the Keggin-type structure and physical properties similar to those presented by coating pigments, namely H3PW12O40∙23H2O, H4SiW12O40∙24H2O, and K7PW11O39∙9H2O, have been used in order to improve the quality of inkjet printing. The analysis of the different samples by FTIRATR spectroscopy showed the presence of the polyoxometalates (and the cationic starch) on the top surface of the paper. In addition, the determination of surface energy parameters, namely the polar component (σsp) and the dispersive component (σsd) of the surface energy, by contact angle measurements revealed that, for the new samples, the polar component level was much higher than that of the uncoated base paper. The quality of inkjet printing, evaluated by parameters such as the gamut area and the optical density, was considerably improved by these surface treatments. [ABSTRACT FROM AUTHOR]

Rationale: Smoking is responsible for one in five deaths around the world. Thus, governments have been trying to reduce the number of active smokers by increasing taxes on products. This scenario creates a new problem by raising the consumption of illegally traded cigarettes, which are often seized and analyzed by police forces. Methods: Legal and illegal cigarette samples were extracted and analyzed using paper spray ionization mass spectrometry (PS-MS). The mass spectrometer was set to operate in full-scan positive ion mode to yield representative chemical profiles of each sample. The results were used to build a chemometric model using partial least squares discriminant analysis (PLS-DA) to discriminate between both sets of samples, i.e. legal and illegal. Results: The PS-MS procedure was fast, simple and efficient, yielding high-quality and reproducible mass spectra with a very good signal-to-noise ratio. Even though all samples displayed visually indistinguishable mass spectra, the PS-MS data handled by the PLS-DA approach furnished a model that reached sample classification with rates of 100% and 80% for the training and validation sets, respectively. Conclusions: A novel methodology was successfully developed associating the PSMS technique with chemometric analysis to differentiate between legal and illegal cigarettes. The PS-MS technique proved to be adequate for obtaining fingerprints of such types of samples despite high complexity, and a PLS-DA model was successfully constructed achieving 82.1% accuracy. [ABSTRACT FROM AUTHOR]

Oat β-D glucan was treated with 3-chloro-2-hydroxypropyl-trimethyl ammonium chloride (10%, 20%, 30%, or 50% of beta glucan) to obtain a range of cationic β-D glucan samples. The derivatization was confirmed by the results of Fourier transform infrared (FTIR) tests and elemental analysis. Addition of 1% cationic β-D glucan based on the mass of unbleached pine kraft fiber increased burst, tensile, and folding endurance properties of the resulting paper. Similar effects were observed at pH 5 and pH 8.5, showing that the system can be considered robust relative to typical acidic and alkaline papermaking conditions. The strength benefits were also observed in recycled sheets made by reslurrying paper prepared with cationic β-D glucan, even when the initial drying conditions had been severe. The beneficial results of cationization, which can be explained by a more hydrophilic nature and better retention, hold promise as a means of improving the strength properties of virgin paper. The treatment of the initial paper also can enhance the dry-strength performance when the fibers are recovered and used again. Application: Treating a hemicellulosic byproduct of oat processing to give it a positive charge can improve its effectiveness as a dry-strength agent for wet-end addition. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the synthesis of zeolites from paper sludge ash, and to evaluate their applications for water purification to simultaneously remove NH4+ and PO43- in aqueous solution. Paper sludge ash had a low abundance of Si and a significant Ca content, due to the presence of calcite that was used as paper filler. Na2SiO3 was added to the NaOH solution to increase Si content in order to synthesize zeolites with high cation exchange capacity. The original ash without addition of Si yielded hydroxysodalite with a cation exchange capacity of ca. 50 cmol/kg. Addition of Si to the solution yielded Na-P1 (zeolite-P) with a higher cation exchange capacity (ca. 120 cmol/kg). The observed concentrations of Si and Al in the solution during the reaction explain crystallizations of these two phases. The product with Na-P1 could simultaneously remove NH4+ and PO43- from the solution between pH 4 and 9. [ABSTRACT FROM AUTHOR]

Accumulation of interfacial space charge in oil-paper interface is a critical issue in insulation diagnostics of transformers. This interfacial charge mainly accumulates due to the conductivity difference of oil and paper. Accumulation of interfacial charge leads to localized field enhancement, which further leads to partial discharges and acceleration in the aging of insulation. Therefore, from the point of view of transformer insulation diagnostics, assessment of interfacial charge is very important. However, it is not easy to estimate interfacial space charge behavior from the transformer diagnostics methods currently in use. In case of Polarization-Depolarization Current (PDC) measurement, a well known method for transformer condition monitoring, the effect of interfacial charge is reflected in the non-linearity of current response during polarization and de-polarization. During de-polarization process, a part of the interfacial charge accumulated during polarization period is absorbed by the electrodes producing a current, which is difficult to separate using conventional linear dielectric theory. In this paper, an attempt has been made to separate this current component from de-polarization current through considering charge de-trapping mechanism. Terming this current component as de-trapping current, its relationship with other parameters of transformer insulation is discussed. The developed methodology has been applied on several practical transformers. It was observed that the time constant of de-trapping current is related to the paper conductivity, oil conductivity, dissipation factor and age of the insulation. [ABSTRACT FROM PUBLISHER]

Here, we report a highly water‐soluble colorimetric and fluorescent pH probe that works in the pH range 0.2–3.0. The probe showed a rapid response, high stability, and excellent reversibility to acidity. Moreover, the fluorescence of probe was not influenced by the existence of high concentration of cations. The pKa of probe was calculated to be 2.25 ± 0.06. Furthermore, the pH test papers coated with the probe exhibited a distinct color change in acidic conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Depending on xylan source, a different effect on paper strength was observed. [•] Cationization of xylan improved the strength enhancement. [•] A main influence on the paper strength was the absorption of cationic xylan. [•] Optimal absorption and strength were observed at a medium degree of cationization. [ABSTRACT FROM AUTHOR]

The non-stick properties of parchment papers are achieved by polydimethylsiloxane (PDMS) coatings. During baking, PDMS can thus be extracted from the silicone-coated parchment into the baked goods. Positive-ion direct analysis in real time (DART) mass spectrometry (MS) is highly efficient for the analysis of PDMS. A DART-SVP source was coupled to a quadrupole-time-of-flightmass spectrometer to detect PDMS on the contact surface of baked goods after use of silicone-coated parchment papers. DART spectra from the bottom surface of baked cookies and pizzas exhibited signals because of PDMS ions of the general formula [(C2H6SiO)n + NH4]+ in the m/z 800-1900 range. [ABSTRACT FROM AUTHOR]

Abstract: This study examines and quantifies the effect of cationic polyacrylamide (CPAM) dissolution kinetics and charge density on the adsorption and aggregation state of gold nanoparticles (AuNPs) on paper and the resulting Surface Enhanced Raman Scattering (SERS) performance. Dissolution kinetics of CPAM of different charge density was studied by monitoring their viscosity and hydrodynamic diameter over regular intervals of time. It was found that the degree of dissolution of CPAM greatly affected the surface coverage and aggregation of AuNPs on the CPAM pre-adsorbed paper substrate and their SERS reproducibility. CPAM of higher charge density dissolves faster and produced a more uniform aggregation and higher surface coverage of AuNPs on paper for a higher and more reproducible Raman EF. Understanding the CPAM dissolution process enables the optimization of SERS performance of the AuNPs-paper as a bio-diagnostic platform. [Copyright &y& Elsevier]

Abstract: This study examines and quantifies the effect of cationic polyelectrolyte adsorption on paper on the aggregation and retention of gold nanoparticles (AuNPs) to optimize their Surface Enhanced Raman Scattering (SERS) enhancement factor and sensitivity. Aggregation of metallic nanoparticles is known as a key factor for intense SERS enhancement. Paper substrates were treated with aqueous solutions of cationic polyacrylamide (CPAM) varying in concentration, charge density, and molecular weight to control the AuNPs’ aggregate size distribution and surface coverage on paper. The Raman Enhancement Factor of AuNPs-CPAM paper was almost an order of magnitude greater than for the untreated AuNPs paper. The high loading and uniform distribution of AuNPs aggregates on CPAM pre-treated paper contributed toward the excellent SERS reproducibility, sensitivity, and high enhancement factor. This configuration of AuNP on paper was favoured by treating the substrate with CPAM solutions of higher concentrations, higher charge density, and greater molecular weight. [Copyright &y& Elsevier]

The outcomes of this work highlight the development and validation of a rapid and simple manifold for determination of exchangeable cations [calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K)] and cation exchange capacity (CEC) in soil. First, the performance of the manifold was evaluated to determine the best conditions to use: filter assembly, volume and number of aliquots of extracting solution, and the use of vacuum. Second, the analytical performance was study from trueness and precision analysis. For that, soil samples with assigned values, an in house reference material and unknown soil samples, were used, comparing their results with those obtained using the classical extraction method (agitation, centrifugation, and filtration). The performance study showed that a filter system assembled with S&S Nº859 type filter paper, cotton, and plastic piece is better to the other studied options. Four aliquots of 10 mL extracting solution and a few seconds of vacuum between additions is recommended to achieve the best recovery. The extraction procedure proposed using the manifold demonstrated to be accurate, and so can effectively replace the classical method for the extraction of exchangeable cations and CEC in soils. Regarding simplicity, rapidity, and simultaneity, the manifold method could be the method of choice for extraction up to 24 samples. Moreover, the manifold method significantly reduces the laboratory supplies and instrument used in the extraction steps in the classical method, attaining better efficiency and reducing costs associated to this stage of the analysis. [ABSTRACT FROM AUTHOR]