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Process-monitoring laboratories in the pulp and paper industry generally use a combination of wet chemical analyses and physical measurements to certify the fitness of a production pulp for a specific end-use. These laboratory tests require time and the effort of trained personnel, limiting their utility for real-time process control. Here we show that Raman probes of unrefined cellulosic pulps, well-suited to the online measurement of in-process materials, can predict the quality attributes of manufactured papers. The accuracy of prediction improves when the covariance is modelled in a reduced measurement space selected by a data-driven, feature-selection technique referred to as a Template Oriented Genetic Algorithm (TOGA). TOGA, combined with discrete wavelet transform (DWT), isolates functional-group features that correlate best with mechanical properties paper derived from refined pulp. Paper makers refine market pulps to build sheet strength using a beating process that decreases freeness as it increases fibre-fibre bonding. Methods demonstrated here predict manufactured sheet properties obtainable after any specified degree of refining from the Raman spectrum of an unrefined pulp. This analysis capacity will enable both vendors of market pulp and makers of sheet paper to specify in advance the amount of beating required to produce a desired product, thereby saving cost and conserving resources. [ABSTRACT FROM AUTHOR]

technique for solid-phase extraction utilizing pyridine-functionalized nanoporous silica (MCM-41, MCM-48 and SBA-15) was developed for the determination of gold in different samples using flame atomic absorption spectrometry. The effects of concentration and volume of eluent, pH of the solution, flow rate of extraction, sample volume and of potentially interfering ions on the efficiency of preconcentration and recovery was investigated. The limit of detection is lower than 45 pg mL. Under optimal conditions, the accuracy and precision (RSD%) of the method were calculated to be >99.5% and <0.7% for the two MCMs (41 and 48) and >89.5%, and <1.5% for SBA-15, respectively. The SPE technique was used to determine the concentration of gold in natural and industrial wastewater with satisfactory results. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A modified SBA-15 mesoporous silica was developed, as an adsorbent, for the removal of Cr(VI) ions from natural-water samples. The effects of experimental parameters, including pH of solution, sample and eluent flow rate, the eluent composition, the eluent volume, and the effect of coexisting ions on the separation and determination of Cr(VI), were investigated. It was shown that Cr(VI) was selectively adsorbed from aqueous solution at pH 3, but Cr(III) could be adsorbed from solution at alkaline pH range. The retained Cr(VI) was eluted with 0.5 mol L−1 KCl solution in 0.1 mol L−1 Na2CO3 subsequently. Under the optimum conditions, the modified mesoporous silica (py-SBA-15) with a high pore diameter exhibited an adsorption capacity of 136 mg g−1 and a lower limit of detection than 2.3 µg L−1 by using diphenylcarbazide as a chromophorous reagent for the determination of Cr(VI) ions. A preconcentration factor as high as 200 was calculated for Cr(VI). The loaded py-SBA-15 can be reactivated with recovery of more than 98.5% over at least eight cycles. The relative standard deviation (RSD) for Cr(VI) ion recovery was less than 1.8%. Validation of the outlined method was performed by analysing a certified reference material (BCR 544). The proposed method was applied to determine Cr(VI) value in natural and waste water samples successfully. [ABSTRACT FROM AUTHOR]

Aminopropyl-functionalized mesoporous silicas, NH2-MCM-41 and NH2-SBA-15, as absorbents were utilized for rapid extraction, preconcentration and determination of trace amounts of silver. Flow rates of sample and eluent, pH, eluent solution, type, concentration and the least amount of eluent for desorption of silver ions were optimized; moreover, break through volume and the effect of various cationic interferences on the sorption of silver were evaluated. The extraction efficiency of silver ions was greater than 95% for MCM-41-NH2 and 85% for SBA-15-NH2 and the limit of detection (LOD) was less than 4 ng mL−1 for both functionalized mesoporous silicas. The preconcentration factor was greater than 210 and the relative standard deviation (RSD) was <2%. The adsorption capacity of the mesoporous silicas is higher than 143 mg g−1 for NH2-MCM-41 and 137 mg g−1 for NH2-SBA-15. Under similar experimental conditions the results for these solid phases were compared with each other. NH2-SBA-15, in spite of larger pore size diameter and adsorption of silver ions in higher flow rates has lower recovery and a higher RSD compared to MCM-41. This method has been applied to determine silver in photographic emulsions and real samples. [ABSTRACT FROM AUTHOR]

The usage of tris(2-aminoethyl)amine-functionalized Fe3O4 nanoparticles as a novel magnetic sorbent for rapid extraction, preconcentration, and determination of trace amounts of silver and gold ions was investigated. The optimum conditions for sample pH, eluent parameters (type, concentration and volume) were obtained. The effect of various cationic interferences on the adsorption of silver and gold was evaluated. The analytical efficiency values of both silver and gold ions were higher than 98.0% in the optimum conditions. The limits of detection (LOD) were less than 0.8 and 0.5 ng ml-1 for silver and gold, respectively. The linear ranges for silver and gold were 1.5-1000 ng ml-1 and 1.0-1000 ng ml-1 respectively. The maximum capacity of the modified magnetic nanoparticles was more than 97.3 mg g-1 and 167 mg g-1 for silver, and gold ions, respectively. The presented method was used to determine silver and gold ions in real samples. Finally, the method accuracy was confirmed by standard reference materials. [ABSTRACT FROM AUTHOR]

A carbon paste electrode for determination of mercury (II) ions in real samples was prepared. The main objective of the present study was to evaluate the concentration of mercury ions in different soil, water, plant, and animal muscle samples by utilizing modified carbon paste electrode. Functionalized nanoporous MCM-48 and multi-walled carbon nanotubes material were used in order to increase the efficiency and selectivity of the electrode for mercury ions determination. The electrode composition material was optimized as graphite powder 57%, Paraffin 22%, modified MCM-48 16% and MWCNTs 5% (W/W). The linear range of the electrode was calculated 5.0×10-8 to 1.0×10-3 mol L-1, and a detection limit was obtained 1.5×10-8 mol L-1. The potential slope was achieved 29.7±1.0 mV, and lifetime for the electrode was investigated about 5 months. The proposed method was applied to a number of natural samples and the amount of mercury was determined. [ABSTRACT FROM AUTHOR]

Nanoporous silicas of the type SBA-15 (Santa Barbara Amorphous) and MCM-48 (Mobile Composition of Material) were modified with dipyridylamine (dipy) and used as solid phases for the extraction of Pd(II) ions. The experimental conditions (pH, sample and eluent flow rates, type and quantity of eluent) were optimized. The recovery values were ~ 99.7 and ~ 93.4% for dipy-MCM-48 and dipy-SBA-15, respectively, the limits of detection were <0.08 and <0.11 ng L, the pre-concentration factors were 725 and 550, and the adsorption capacity was >78 mg g. The procedure was applied to the preconcentration of Pd(II) in real samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Three-phase hollow fiber microextraction technique combined with high performance liquid chromatography-ultra violet (HPLC-UV) was applied for the extraction and determination of gabapentin in biological fluids. Gabapentin (GBP) was derivatized with 1-fluoro-2,4-dinitrobenzene, as a UV absorbent agent in borate buffer (pH 8.2) before extraction. The derivative product of GBP was extracted from the 8.5mL of acidic solution (source phase) into an organic phase (dihexyl ether) impregnated in the pores of a hollow fiber and finally back-extracted into 24μL of the basic solution (pH 9.1) located inside the lumen of the hollow fiber (receiving phase). The extraction took place due to pH gradient between the inside and outside of the hollow fiber membrane. In order to achieve maximum extraction efficiency, different parameters affecting the extraction conditions were optimized. Under the optimized conditions, preconcentration factor of 95 and detection limit (LOD) of 0.2μgL−1 were obtained. The calibration graph was linear within the range of 0.6–5000μgL−1. Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of GBP in human urine and plasma samples in the range of microgram per liter and suitable results were obtained (RSDs<6.3%). [Copyright &y& Elsevier]