A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:
Selected papers from the latest issue:
Effect of Nacl Additive on Properties of Aqueous Peg-Sodium Sulfate Two-Phase System
08 December 2011, 23:45:11
Publication year: 2011
Source: Journal of Chromatography A, Available online 8 December 2011
Luisa A. Ferreira, Pier Parpot, José A. Teixeira, Larissa M. Mikheeva, Boris Y. Zaslavsky
The concentrations of all components in the phases of aqueous two-phase polyethylene glycol-sodium sulfate system of a fixed composition with different concentrations of NaCl additive were determined. Solvatochromic solvent features of aqueous media in the phases of all the systems were characterized in terms of solvent dipolarity/polarizability, solvent hydrogen bond donor acidity and hydrogen bond acceptor basicity. Partitioning of a homologous series of dinitrophenylated amino acids with aliphatic alkyl side chain was examined in all the systems, and the differences between the relative hydrophobicity and electrostatic properties of the phases were quantified. These differences were described in terms of solvatochromic solvent features of the phases. The previously reported partition coefficients of twelve different nonionic compounds in all the systems were expressed in terms of solute descriptors. It is demonstrated that two solvatochromic solvent descriptors (solvent dipolarity/polarizability, and solvent hydrogen bond donor acidity) could adequately describe the partitioning of the solutes in all the systems employed.
Source: Journal of Chromatography A, Available online 8 December 2011
Luisa A. Ferreira, Pier Parpot, José A. Teixeira, Larissa M. Mikheeva, Boris Y. Zaslavsky
The concentrations of all components in the phases of aqueous two-phase polyethylene glycol-sodium sulfate system of a fixed composition with different concentrations of NaCl additive were determined. Solvatochromic solvent features of aqueous media in the phases of all the systems were characterized in terms of solvent dipolarity/polarizability, solvent hydrogen bond donor acidity and hydrogen bond acceptor basicity. Partitioning of a homologous series of dinitrophenylated amino acids with aliphatic alkyl side chain was examined in all the systems, and the differences between the relative hydrophobicity and electrostatic properties of the phases were quantified. These differences were described in terms of solvatochromic solvent features of the phases. The previously reported partition coefficients of twelve different nonionic compounds in all the systems were expressed in terms of solute descriptors. It is demonstrated that two solvatochromic solvent descriptors (solvent dipolarity/polarizability, and solvent hydrogen bond donor acidity) could adequately describe the partitioning of the solutes in all the systems employed.
Highlights
► Phase composition of PEG-Na2SO4–water system with different NaCl amounts determined ► Solvatochromic solvent features of aqueous media in the phases quantified ► Hydrophobic and electrostatic propertiers of phases described via solvent features ► Partition coefficients of nonionic solutes are expressed via solute descriptors ► Solvent dipolarity/polarizability and H-bond acidity govern partitioning of solutesDummy molecularly imprinted polymers on silica particles for selective solid-phase extraction of tetrabromobisphenol A from water samples
08 December 2011, 23:45:11
Publication year: 2011
Source: Journal of Chromatography A, Available online 8 December 2011
Yu-Min Yin, Yi-Ping Chen, Xiang-Feng Wang, Yuan Liu, Hai-Ling Liu, ...
Surface molecular imprinted polymers (MIPs) on silica gel particles for highly selective recognition of Tetrabromobisphenol A (TBBPA) were prepared by a sol–gel process. Diphenolic Acid (DPA) and Bisphenol A (BPA),whose structures were similar to that of TBBPA were selected as dummy template molecules, and 3-aminopropyltriethoxysilane (APTES) and tetramethoxysilane (TEOS) were chosen as functional monomer and cross-linker, respectively. The obtained materials were characterized by FTIR with diffuse reflectance accessory and the results indicated polymers were successfully grafted on the surface of silica gel supporters. The maximum static adsorption capacities for TBBPA of the DPA-MIPs, BPA-MIPs and non imprinted polymers (NIP) were 45, 38 and 22 mg grespectively, and the results of dynamic adsorption showed that the adsorption equilibrium can be achieved within 15 min for DPA- and BPA-MIPs. Both the DPA- and BPA-MIPs have higher selectivity for TBBPA than that of NIP when they are used as the sorbents for the solid phase extraction (SPE), while the adsorption property of DPA-MIPs was superior to that of BPA-MIPs at low concentration levels of TBBPA. The results indicated DPA-MIPs had more high affinity binding sites for TBBPA, which demonstrated that the strong interactions between the template and the functional monomer were favorable to form high affinity binding sites and improve the selectivity of the polymers. A corresponding analytical method for determination of the TBBPA residues in environmental samples was developed. The recoveries of TBBPA in tap water, river water and lake water were in the range from 85% to 97% with relative standard deviations below 7%, and its limit of detection can reach 2 ng mL.
Source: Journal of Chromatography A, Available online 8 December 2011
Yu-Min Yin, Yi-Ping Chen, Xiang-Feng Wang, Yuan Liu, Hai-Ling Liu, ...
Surface molecular imprinted polymers (MIPs) on silica gel particles for highly selective recognition of Tetrabromobisphenol A (TBBPA) were prepared by a sol–gel process. Diphenolic Acid (DPA) and Bisphenol A (BPA),whose structures were similar to that of TBBPA were selected as dummy template molecules, and 3-aminopropyltriethoxysilane (APTES) and tetramethoxysilane (TEOS) were chosen as functional monomer and cross-linker, respectively. The obtained materials were characterized by FTIR with diffuse reflectance accessory and the results indicated polymers were successfully grafted on the surface of silica gel supporters. The maximum static adsorption capacities for TBBPA of the DPA-MIPs, BPA-MIPs and non imprinted polymers (NIP) were 45, 38 and 22 mg grespectively, and the results of dynamic adsorption showed that the adsorption equilibrium can be achieved within 15 min for DPA- and BPA-MIPs. Both the DPA- and BPA-MIPs have higher selectivity for TBBPA than that of NIP when they are used as the sorbents for the solid phase extraction (SPE), while the adsorption property of DPA-MIPs was superior to that of BPA-MIPs at low concentration levels of TBBPA. The results indicated DPA-MIPs had more high affinity binding sites for TBBPA, which demonstrated that the strong interactions between the template and the functional monomer were favorable to form high affinity binding sites and improve the selectivity of the polymers. A corresponding analytical method for determination of the TBBPA residues in environmental samples was developed. The recoveries of TBBPA in tap water, river water and lake water were in the range from 85% to 97% with relative standard deviations below 7%, and its limit of detection can reach 2 ng mL.
Highlights
► Highly selective surface molecular imprinted polymers for TBBPA were prepared. ► Diphenolic Acid was selected as the dummy template molecule of the MIPs. ► Method for determination of the TBBPA residues in water samples was developed.A Liquid Chromatography-Tandem Mass Spectrometry Method for the Detection of Economically Motivated Adulteration in Protein-containing Foods
08 December 2011, 23:45:11
Publication year: 2011
Source: Journal of Chromatography A, Available online 8 December 2011
Shaun MacMahon, Timothy H. Begley, Gregory W. Diachenko, Selen A. Stromgren
A new analytical method was developed to determine the presence of six (6) compounds with the potential to be used in economic adulteration to enhance the nitrogen content in milk products and bulk proteins. Residues were extracted from the matrix with 2% formic acid, after which acetonitrile (ACN) was added to induce precipitation of the proteins. Extracts were analyzed by liquid chromatography using a ZIC-HILIC column with tandem mass spectrometry (LC-MS/MS) using electrospray ionization (ESI). Single-laboratory method validation data was collected in six matrices fortified at concentrations down to 1.0 μg/g (ppm). Average recoveries and average relative standard deviations (RSD) using spiked matrix calibration standard curves were the following: cyromazine (CY) 95.9% (7.5% RSD), dicyandiamide (DC) 98.1% (5.6% RSD), urea 102.5% (8.6% RSD), biuret (BU) 97.2% (6.6% RSD), triuret (TU) 97.7% (5.7% RSD), and amidinourea (AU) 93.4% (7.4% RSD). This method provides a rapid and effective approach to proactively combat economically motivated adulteration in protein-containing products.
Source: Journal of Chromatography A, Available online 8 December 2011
Shaun MacMahon, Timothy H. Begley, Gregory W. Diachenko, Selen A. Stromgren
A new analytical method was developed to determine the presence of six (6) compounds with the potential to be used in economic adulteration to enhance the nitrogen content in milk products and bulk proteins. Residues were extracted from the matrix with 2% formic acid, after which acetonitrile (ACN) was added to induce precipitation of the proteins. Extracts were analyzed by liquid chromatography using a ZIC-HILIC column with tandem mass spectrometry (LC-MS/MS) using electrospray ionization (ESI). Single-laboratory method validation data was collected in six matrices fortified at concentrations down to 1.0 μg/g (ppm). Average recoveries and average relative standard deviations (RSD) using spiked matrix calibration standard curves were the following: cyromazine (CY) 95.9% (7.5% RSD), dicyandiamide (DC) 98.1% (5.6% RSD), urea 102.5% (8.6% RSD), biuret (BU) 97.2% (6.6% RSD), triuret (TU) 97.7% (5.7% RSD), and amidinourea (AU) 93.4% (7.4% RSD). This method provides a rapid and effective approach to proactively combat economically motivated adulteration in protein-containing products.
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