Comparison and evaluation of the specificity and binding capacity of commercial and in house affinity columns used in sample preparation for analysis of growth-promoting drugs

Immunoaffinity chromatography (IAC) and affinity chromatography (AC:) are widely used for extraction of drugs from biological samples. Fifteen column types were purchased from five different manufacturers and;their ability to bind specific drugs including beta-agonists and anabolic steroids over a range of analyte concentrations in fortified bovine urine samples was assessed. The performance data obtained from these columns were compared with columns produced in this laboratory (in house columns). The in house columns gave the highest recoveries, ranging from 92 to 100% at the 1 ng spiking concentration, for five of the seven analytes assessed. Forty percent (11 of 27) of all the commercial column assessments recorded recoveries of less than 50% even when the lowest spiking concentration was applied (1 ng). For one manufacturer, only one of seven different columns purchased delivered extraction efficiencies greater than 50%. The extraction efficiencies of the clenbuterol columns were the highest with all commercially prepared columns showing at least 50% binding of radiolabelled tracer. Recoveries of alpha-nortestosterone were the lowest. The variability of these products with respect to quality control requires constant monitoring.

Investigation of the effect of the preparation method on the activity and stability of Au/CeZrO4 catalysts for the low temperature water gas shift reaction

The impact of the preparation method on the activity and stability of gold supported on ceria-zirconia low temperature water-gas shift (WGS) catalysts have been investigated. The influence of the gold deposition method, nature of the gold precursor, nature of the washing solution, drying method, Ce: Zr ratio of the support and sulfation of the support have been evaluated. The highest activity catalysts were obtained using a support with a Ce: Zr mole ratio 1: 1, HAuCl4 as the gold precursor deposited via deposition precipitation using sodium carbonate as the precipitation agent and the catalyst washed with water or 0.1 M NH4OH solution. In addition, the drying used was found to be critical with drying under vacuum at room temperature found to be most effective.

Monoclonal antibody-based ELISA for the quantification of nitrofuran metabolite 3-amino-2-oxazolidinone in tissues using a simplified sample preparation

A sensitive and specific monoclonal ELISA for the determination of tissue bound furazolidone metabolite 3-amino-2-oxazolidinone (AOZ) is described. The procedure enables the detection of AOZ in matrix supernatant after homogenisation, protease treatment, acid hydrolysis and derivatisation of AOZ released from the tissue by o-nitrobenzaldehyde. The formed p-nitrophenyl 3-amino-2-oxazolidinone (NPAOZ) is determined by ELISA calibrated with matrix-matched standards in the concentration range of 0.05-5.0 mu g l(-1). The assay was validated according to criteria set down by Commission Decision 2002/657/EC for the performance and validation of analytical methods for chemical residues. Detection capability, set on the basis of acceptance of no false negative results, was 0.4 mu g kg(-1) for shrimp, poultry, beef and pork muscle. This sensitivity approaches the established confirmatory LC-MS/MS able to quantify tissue-bound AOZ at levels as low as 0.3 mu g kg(-1). An excellent correlation of results obtained by ELISA and LC/MS-MS within the concentration range 0-32.1 mu g kg(-1) was found in the naturally contaminated shrimp samples (r = 0.999, n = 8). A similar con-elation was found for the incurred poultry samples within the concentration range of 0-10.5 mu g kg(-1) (r = 0.99, n = 8). (c) 2005 Elsevier B.V All rights reserved.

Sample preparation and heavy metal determination by atomic spectrometry /

Microwave digestions of mercury in Standards Reference Material (SRM) coal samples with nitric acid and hydrogen peroxide in quartz vessels were compared with Teflon® vessel digestion by using flow injection cold vapor atomic absorption spectrometry. Teflon® vessels gave poor reproducibiUty and tended to deliver high values, while the digestion results from quartz vessel show good agreement with certificate values and better standard deviations. Trace level elements (Ag, Ba, Cd, Cr, Co, Cu, Fe, Mg, Mn, Mo, Pb, Sn, Ti, V and Zn) in used oil and residual oil samples were determined by inductively coupled plasma-optical emission spectrometry. Different microwave digestion programs were developed for each sample and most of the results are in good agreement with certified values. The disagreement with values for Ag was due to the precipitation of Ag in sample; while Sn, V and Zn values had good recoveries from the spike test, which suggests that these certified values might need to be reconsidered. Gold, silver, copper, cadmium, cobalt, nickel and zinc were determined by continuous hydride generation inductively coupled plasma-optical emission spectrometry. The performance of two sample introduction systems: MSIS™ and gas-liquid separator were compared. Under the respective optimum conditions, MSIS^"^ showed better sensitivity and lower detection limits for Ag, Cd, Cu, Co and similar values for Au, Ni and Zn to those for the gas-liquid separator.

Sample preparation: a crucial factor for the analytical performance of rationally designed MALDI matrices

Evidence is presented that the performance of the rationally designed MALDI matrix 4-chloro-α-cyanocinnamic acid (ClCCA) in comparison to its well-established predecessor α-cyano-4-hydroxycinnamic acid (CHCA) is significantly dependent on the sample preparation, such as the choice of the target plate. In this context, it becomes clear that any rational designs of MALDI matrices and their successful employment have to consider a larger set of physicochemical parameters, including sample crystallization and morphology/topology, in addition to parameters of basic (solution and/or gas-phase) chemistry.

Co catalysts supported on SiO(2) and gamma-Al(2)O(3) applied to ethanol steam reforming: Effect of the solvent used in the catalyst preparation method

Cobalt catalysts were prepared on supports of SiO(2) and gamma-Al(2)O(3) by the impregnation method, using a solution of Co precursor in methanol. The samples were characterized by XRD, TPR, and Raman spectroscopy and tested in ethanol steam reforming. According to the XRD results, impregnation with the methanolic solution led to smaller metal crystallites than with aqueous solution, on the SiO(2) support. On gamma-Al(2)O(3), all the samples exhibited small crystallites, with either solvent, due to a higher Co-support interaction that inhibits the reduction of Co species. The TPR results were consistent with XRD results and the samples supported on gamma-Al(2)O(3) showed a lower degree of reduction. In the steam reforming of ethanol, catalysts supported on SiO(2) and prepared with the methanolic solution showed the best H(2), CO(2) and CO selectivity. Those supported on gamma-Al(2)O(3) showed lower H(2) selectivity. (C) 2011 Elsevier Ltd. All rights reserved.

Dependence of the electrical conductivity and elastomeric properties on sample preparation of blends of polyaniline and natural rubber

Blend films (free-standing) containing 20% in volume of polyaniline (PANI) in 80% of natural rubber (NR) were fabricated by casting in three different ways: (1) adding PANI-EB (emeraldine base) dissolved in N-methyl-2-pyrrolidone (NMP) to the latex (NRL), (2) adding PANI-EB dissolved in in-cresol to NR dissolved in xylol (NRD), (3) overlaying the surface of a pure NR cast film with a PANI layer grown by in situ polymerization (NRO). All the films were immersed into HCl solution to achieve the primary doping (protonation) of PANI before the characterization. The main goal here was to investigate the elastomeric and electrical conductivity properties for each blend, which may be applied as pressure and deformation sensors in the future. The characterization was carried out by optical microscopy, dc conductivity, vibrational spectroscopy (infrared absorption and Raman scattering), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile stress-strain curves. The results suggest that the NRL blend is the most suitable in terms of mechanical and electrical properties required for applications in pressure and deformation sensors: a gain of conductivity without losing the elastomeric property of the rubber. (c) 2005 Wiley Periodicals, Inc.

The influence of preparation method of OC1OC6-PPV films on the photo-oxidation process

Poly(p-phenylene vinylene) (PPV) derivatives are well known for their applications in polymer light emitting diodes (PLEDs). PPV derivatives are highly susceptible to photo-oxidation though, which is mainly caused by the scission of the vinyl double bond on the polymer backbone. In this work, we show that Langmuir-Blodgett (LB) films are less degraded than cast films of a PPV derivative (OC1OC6-PPV). Both films had similar thickness (similar to 50 nm) to allow for a more realistic comparison. Degradation was monitored with UV-vis and FTIR spectroscopies. The results indicated that cast films were completely degraded in ca. 400 min, while LB took longer time, i.e. about four times the values for the cast films. The differences can be attributed to the more compact morphology in the LB than in the cast films. With a compact morphology the diffusion of oxygen in the LB film is hampered and this causes a delay in the degradation process. (c) 2006 Elsevier Ltd. All rights reserved.

The effect of preparation method and Sb content on SnO2-CuO sintering

The sintering behavior of SnO2-CuO system has been investigated for two preparation methods and as a function of antimony concentration. A chemical preparation (Pechini's method) resulted in powders with smaller particle sizes than for a conventional oxide mixture. This led to smaller grain sizes in Pechini's method ceramics. The microstructures were heterogeneous in both systems, showing grain coarsening. The densification was aided by liquid phase formation, due to copper, in both systems, but the temperature of maximum shrinkage rate was larger for the Pechini's method ceramic because copper had to diffuse to the grain surface. Independently of the preparation method, antimony did not aid densification, and increasing its concentration led to a higher densification temperature and lower shrinkage rate. (C) 2003 Kluwer Academic Publishers.

Influence of the preparation method and the support on H2O 2electrogeneration using cerium oxide nanoparticles

This work describes the influence of the preparation method and the carbon support using a low contentof cerium oxide nanoparticles (CeO2/C 4%) on H2O2electrogeneration via the oxygen reduction reac-tion (ORR). For this purpose, the polymeric precursor (PPM) and sol-gel (SGM) methods with Vulcan XC72R (V) and Printex L6 (P) supports were employed. The materials were characterized by X-ray diffrac-tion (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TheXRD analysis identified two phases comprising CeO2and CeO 2-x. The smallest mean crystallite size wasexhibited for the 4% CeO2/C PPM P material, which was estimated using the Debye-Scherrer equation tobe 6 nm and 4 nm for the CeO2and the CeO 2-xphases, respectively, and was determined by TEM to be5.9 nm. XPS analysis was utilized to compare the oxygen content of the 4% CeO2/C PPM P to Printex L6.The electrochemical analysis was accomplished using a rotating ring-disk electrode. The results showedthat the 4% CeO2/C specimen, prepared by PPM and supported on Printex L6, was the best electrocatalystfor H2O2production in 1 mol L -1NaOH. This material showed the highest ring current, producing 88%H2O2and transferring 2.2 electrons per O 2molecule via the ORR at the lowest onset potential. Addition-ally, the ring-current of the 4% CeO2/C PPM P material was higher than that of Vulcan XC 72R and PrintexL6, the reference materials for H2O 2production, indicating the highest electrocatalytic activity for the 4%CeO2/C PPM P material. © 2013 Elsevier Ltd. All rights reserved.