Microextraction by packed sorbent and liquid chromatography–tandem mass spectrometry as a tool for quantification of peptides in plasma samples: determination of sensory neuron‐specific receptors agonist BAM8‐22 and antagonist BAM22‐8 in plasma samples

Microextraction by packed sorbent (MEPS) is a miniaturized, solid‐phase extraction (SPE) technique that works online with gas chromatography (GC) and liquid chromatography (LC). Not only is the automation process with MEPS advantageous, but the much smaller volumes of the samples, solvents and dead space in the system also provide other significant advantages such as the speed and the simplicity of the sample preparation process. In this study MEPS has been evaluated for quantification of sensory neuron‐specific receptors agonist (BAM8‐22). Owing to the instability of BAMs, the focus was on fast extraction and determination of the peptide online using LC‐MS/MS. Sorbents such as C2, C8 and ENV+ (hydroxylated polystyrene–divinylbenzene copolymer) were investigated in the present study. MEPS‐C8 gave the best results compared with C2 and ENV and it was used for the method validation. The calibration curve was obtained within the concentration range of 20.0–3045 nmol/L in plasma. The regression correlation coefficients for plasma samples were ≥0.99 for all runs (n = 6). The between‐batch accuracy and precision for BAM8‐22 ranged from ?13 to ?2.0% and from 4.0 to 14%, respectively. Additionally, the accuracy and precision for BAM22‐8 ranged from ?13 to 7.0% and from 3.0 to 12%, respectively. The present method was used for pharmacokinetic studies for BAMs in plasma samples. Copyright © 2012 John Wiley & Sons, Ltd.     

Determination of RDX and Keto-RDX in High-Explosive Mixtures by High-Performance Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - High-performance thin-layer chromatography (HPTLC) has been used for separation and quantitation of components of high explosives...     

Complete order amenability of the Fourier algebra

We define complete order amenability and first complete order cohomology groups for quantized Banach ordered algebras and show that the vanishing of the latter is equivalent to the operator amenability for the Fourier algebra.     

Microextraction of Rosmarinic Acid Using CMK-3 Nanoporous Carbon in a Packed Syringe

CMK-3 nanoporous carbon was prepared and used as an efficient sorbent for microextraction in packed syringe of rosmarinic acid in Rosmarinus officinalis L. (rosemary). In the proposed method, only 2 mg of the nanoporous material, inserted between a syringe’s barrel and needle, was sufficient for the extraction with minimum consumption of organic solvents. Sample preparation was performed on the packed bed using a laboratory-made programmable apparatus. The apparatus was designed and used for automation of the conditioning, sampling, washing and elution steps of the method, and increasing the reproducibility of the experiments. For optimization of the experimental parameters, a central composite design method was used. Under the optimized conditions (i.e., number of adsorption cycles 14 times, number of elution cycles ten times and volume of elution 100 μL), an extraction recovery of 90 (±4.5) % was obtained for rosmarinic acid. The same packing bed could be used for at least 80 extractions without significant changes in its properties. The efficiency of the nanoporous sorbent was found to be superior to that of activated carbon, by a factor of about 17. The proposed method was successfully applied to the extraction of three rosemary samples before analysis by HPLC.

     

Synthesis and Evaluation of Technical Properties of Novel Cationic Mono‐s‐chloro Triazinyl (MCT) Reactive Dyes on Cotton

Two novel cationic mono‐s‐chloro triazinyl (MCT) reactive dyes together with their analogues were synthesized via reacting an N,N‐dimethyl dodecylamine with p‐nitrobenzyl bromide. The resultant was reduced using stannous chloride and hydrochloric acid to produce the primary amine. The quaternary ammonium salt containing primary amine was then diazotized and coupled to H‐acid/J‐acid reacted with cyanuric chloride and sulfanilic acid. The analogue dyes were prepared via the same route without quaternary ammonium salt making stage. The dyes were characterized using FTIR, ¹H NMR, UV‐Vis spectroscopy and elemental analysis. The substantivity, exhaustion and fixation of the dyes were investigated on cotton fabric. It was found that these functional dyes could be effectively introduced to cotton for achieving simultaneous coloration and functional finishing effects. All the dyed fabrics exhibited softening efficacy. The washing and light fastness of the dyed samples were further studied.     

Ion-selective carbon paste electrode based on new tripodal ligand for determination of cadmium (II)

A new chemically modified carbon paste electrode for Cd(II) ions based on 3,5-dinitro-N-(tri-2-pyridyl methyl) benzamide (DNTPMBA) as an ionophore was prepared. The electrode exhibits a Nernstian response for Cd(II) ions over a wide concentration range (2.16 × 10^?7–1.00 × 10^?1 mol L^?1) with a slope of 30 ± 1 mV per decade. It has a response time of about 50 s and can be used for a period of 3 months with good reproducibility. Detection limit obtained in the optimal conditions was 1.82 × 10^?7 mol L^?1. The electrode was successfully used for potentiometric determination of Cd(II) in well water. The pH influence and interference of some cations were also studied.     

Engineering of a <Emphasis Type="Italic">Bacillus</Emphasis> α-Amylase with Improved Thermostability and Calcium Independency

Successful industrial use of amylases requires that they are sufficiently stable and active at application conditions, e.g., at high temperature in starch-liquefaction process. In the present study, site-directed mutagenesis was used to enhance the thermal stability and calcium independency of a mesophilic α-amylase from Bacillus megaterium WHO. Mutations (A53S and H58I) were designed at the calcium-binding site based on the sequence alignment. Kinetic and thermostability parameters of the mutants were analyzed and compared with that of the wild type. In the presence of calcium, the affinity of the enzymes (wild type and mutants) toward starch was increased. In comparison to the wild type, calcium ion had more effect on the catalytic efficiency, k _cat/K _m, and half-life (at 60 °C) of A53S mutant. In A53S, the dependence of half-life on calcium concentration showed that the enhanced calcium binding is likely to be responsible for the increased stability. In contrast, calcium-independent mutant (H58I) possessed high thermostability. In addition, thermodynamic parameters of amylolytic reaction exhibited an increase in the activation energy and the entropy of the system. Kinetics of irreversible thermal inactivation suggests that the activation energy increased by 1.4-fold in the most stable variant.     

A New Family of Matrix Product States with Dzyaloshinski-Moriya Interactions

We define a new family of matrix product states which are exact ground states of spin 1/2 Hamiltonians on one dimensional lattices. This class of Hamiltonians contain both Heisenberg and Dzyaloshinskii-Moriya interactions but at specified and not arbitrary couplings. We also compute in closed forms the one and two-point functions and the explicit form of the ground state. The degeneracy structure of the ground state is also discussed.     

Lipid fluorination enables phase separation from fluid phospholipid bilayers

To probe the effect of lipid fluorination on the formation of lipid domains in phospholipid bilayers, several new fluorinated and non-fluorinated synthetic lipids were synthesised, and the extent of phase separation of these lipids from phospholipid bilayers of different compositions was determined. At membrane concentrations as low as 1% mol/mol, both fluorinated and non-fluorinated lipids were observed to phase separate from a gel-phase (solid ordered) phospholipid matrix, but bilayers in a liquid disordered state caused no phase separation; if the gel-phase samples were heated above the transition temperature, then phase separation was lost. We found incorporation of perfluoroalkyl groups into the lipid enhanced phase separation, to such an extent that phase separation was observed from cholesterol containing bilayers in the liquid ordered phase.     

A classification of spin 1/2 matrix product states with two dimensional auxiliary matrices

We classify the matrix product states having only spin-flip and parity symmetries, which can be constructed from two dimensional auxiliary matrices. We show that there are three distinct classes of such states and in each case, we determine the parent Hamiltonian and the points of possible quantum phase transitions. For two of the models, the interactions are three-body and for the other the interaction is two-body.