Application of Ni(II)-imprinted cross-linked poly(methacrylic acid) synthesised through double-imprinting method for the on-line preconcentration of Ni(II) ions in aqueous media

The present paper describes the feasibility of on-line preconcentration of nickel ions from aqueous medium on Ni(II)-imprinted cross-linked poly(methacrylic acid) (IIP) synthesised through a double-imprinting method and their subsequent determination by FAAS. The proposed method consisted in loading the sample (20.0 mL, pH 7.25) through a mini-column packed with 50 mg of the IIP for 2 min. The elution step was performed with 1.0 mol L^?1 HNO₃ at a flow rate of 7.0 mL min^?1. The following parameters were obtained: quantification limit (QL) – 3.74 µg L^?1, preconcentration factor (PF) – 36, consumption index (CI) – 0.55 mL, concentration efficiency (CE) – 18 min^?1, and sample throughput – 25 h^?1. The precision of the procedure assessed in terms of repeatability for ten determinations was 5.6% and 2.5% for respective concentrations of 5.0 and 110.0 µg L^?1. Moreover, the analytical curve was obtained in the range of 5.0–180.0 µg L^?1 (r = 0.9973), and a 1.64-fold increase in the method sensitivity was observed when compared with the analytical curve constructed for the NIP (non-imprinted polymer), thus suggesting a synergistic effect of the Ni(II) ions and CTAB on the adsorption properties of the IIP. The practical application of the adsorbent was evaluated from an analysis of tap, mineral, lake and river water. Considering the results of addition and recovery experiments (90.2–100 %), the efficiency of this adsorbent can be ensured for the interference-free preconcentration of the Ni(II) ions.     

Separation of Hydrocarbon Mixtures in the Microgram Range by Inclusion in a Urea-packed Mini Column

Abstract

The use of classical urea inclusion techniques for the separation of straight chain hydrocarbons from branched and cyclic compounds is satisfactory when applied to mixtures in the milligram to gram ranges, but leads to low separation efficiencies when quantities in the microgram to milligram range are involved. In this study, a modified inclusion technique using an urea-packed milli-bore column and a catalytic eluent is described. Examples of its use for the separation of mixtures of linear and cyclic hydrocarbons from 30μg up to a few milligrams are given. The versatility of this technique for the analyses of low amounts of environmental samples is described, and an application to the hydrocarbon fraction of surface sediment from lake Leman (Switzerland) is presented.     

Structural and transport properties of Sn–Mg alloys

In this work, the structural and transport properties of Mg-doped Sn-based alloys have been investigated. The temperature-dependent transport and structural properties of Sn–Mg alloys were investigated for five different samples (Pure Sn, Sn-1.0 wt% Mg, Sn-2.0 wt% Mg, Sn-6.0 wt% Mg and Pure Mg). Scanning electron microscopy (SEM), X-ray diffraction and energy dispersive X-ray analysis measurements were carried out in order to clarify the structural properties of the samples. It was found that the samples had tetragonal crystal symmetry, except for pure Mg which had hexagonal crystal symmetry. We also found that the cell parameters changed slightly with the addition of Mg element. The SEM micrographs of the samples showed that they had smooth surfaces with a clear grain boundary. The electrical and thermal conductivity of the samples were measured by four-point probe and the radial heat flow method, respectively. The electrical resistivity of the samples increased almost linearly with the increasing temperature. The thermal conductivity values ranged between 0.60 and 1.00 W/Km, while they decreased slightly with temperature and increased with Mg composition. The thermal conductivity values of the alloys were in between the values of pure Sn and Mg. The thermal conductivity results of the alloys were compared with other available results, and a good agreement was seen between the results. In addition, the temperature coefficients of electrical resistivity and thermal conductivity were determined; these were independent of the composition of the alloying elements.     

Synthesis of 4-Benzidinyl Butyric Acid: A Key Intermediate for Antibodies Production Against Benzidin

a four-step synthesis of monoalkylated benzidin is reported for immunogen preparation against benzidin dye. Use of 10% H₂SO₄/ dioxan for N-Boc cleavage avoids the cyclisation of 4-benzidinyl butyric acid into the corresponding lactam observed with the classical TFA/ CH₂Cl₂ system.     

Automated DBS Extraction Prior to Hilic/RP LC–MS/MS Target Screening of Drugs

This article describes a rapid LC–MS/MS target screening method based on an automated extraction of 5 μL dried blood spots (DBS), two 5 min chromatographic runs on orthogonal phase columns (RP and Hilic) and a data dependent acquisition (DDA) of product ions spectra for the reliable identification of the detected compounds. The extraction step was performed in 2 min by using the LC autosampler itself in 96-well plates. This procedure was evaluated using 22 model compounds frequently encountered in forensic investigations, i.e., cocaine, benzodiazepines, amphetamines, opioids, antidepressants and antipsychotics. These investigations showed that even if the extraction step was reduced to a minimum, the extraction recoveries were satisfactory (median value of 40 %) and allowed for the detection of the model compounds in their therapeutic ranges, with the exception of morphine. Moreover, the use of two different chromatographic columns broadened the number of screening targets to those that behaved poorly under RP conditions, such as amphetamines or glucuronides, while keeping chromatographic gradients very short. This procedure was applied to 34 authentic post-mortem cases. It allowed the detection of 89 % of the compounds that were quantified in the routine procedures and the formal identification of 77 % of the compounds using their product ions spectra. These results were considered more than satisfactory compared to routine screening alone (GC–MS and LC-DAD, 55 % compound identification). The method described in this article is therefore a powerful approach for a fast, reliable and efficient target screening of drugs in forensic and clinical investigations.     

Application of FTIR Spectroscopy for Identification of Blood and Leukemia Biomarkers: A Review over the Past 15 Years

Abstract

Fourier transform infrared (FTIR) spectroscopy is an effective and nondestructive method for monitoring cellular alterations. Combining the advantages of FTIR spectroscopy with the challenge of cellular characterization, the main objective of this review is to collect information related to the spectroscopic identification of blood cells, focusing on specific biochemical features of leukemia cells detected through FTIR spectral analysis. Some interesting results obtained by different authors regarding human promyelocytic leukemia, white blood cells, chronic lymphocytic leukemia, and human peripheral blood mononuclear cells are presented. In addition, the characterization of two types of cells, namely, leukemia T and a healthy human blood cells, is reported and the identification of biochemical markers provides important information that, associated with clinical examination, can assist in the diagnosis of diseases.     

13C NMR quantification of mono and diacylglycerols obtained through the solvent‐free lipase‐catalyzed esterification of saturated fatty acids

In the present investigation, we studied the enzymatic synthesis of monoacylglycerols (MAG) and diacylglycerols (DAG) via the esterification of saturated fatty acids (stearic, palmitic and an industrial residue containing 87% palmitic acid) and glycerol in a solvent‐free system. Three immobilized lipases (Lipozyme RM IM, Lipozyme TL IM and Novozym 435) and different reaction conditions were evaluated. Under the optimal reaction conditions, esterifications catalyzed by Lipozyme RM IM resulted in a mixture of MAG and DAG at high conversion rates for all of the substrates. In addition, except for the reaction of industrial residue at atmospheric pressure, all of these products met the World Health Organization and European Union directives for acylglycerol mixtures for use in food applications. The products were quantified by ¹³C NMR, with the aid of an external reference signal which was generated from a sealed coaxial tube filled with acetonitrile‐d3. After calibrating the area of this signal using the classical external reference method, the same coaxial tube was used repeatedly to quantify the reaction products. Copyright © 2012 John Wiley & Sons, Ltd.