Analytica Chimica ActaThis is an RSS file. You can use it to subscribe to this data in your favourite RSS reader, such as GoogleReader, or to display this data on your own website or blog. Subscribe to this data using MyMedWorm.Subscribe to this data using GoogleReader.Subscribe to this data using Bloglines.Subscribe to this data using MyYahoo.

Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources.

• Contents
• Discussions

Pages: 1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  

On-line monitoring of nine haloacetic acid species at the microgL(-1) level using post-column reaction-ion chromatography with nicotinamide fluorescence.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A laboratory-built automated instrument is reported for on-line, near real-time monitoring of nine haloacetic acids species (HAA9) in drinking water. The device uses anion-exchange chromatography to separate the HAA9 species, followed by post-column reaction with nicotinamide in basic solution with fluorescence detection. Method detection limits for HAA9 species ranged from 0.6 to 10.1microgL(-1), mean % recovery values ranged from 58 to 161%, and % relative standard deviation ranged from 3.5 to 32% while operating within a factor of 2.5-5 of the method detection limit. The bias between the proposed method and United S...
Source: Analytica Chimica Acta - November 5, 2009 Category: Chemistry Authors: Simone PS, Ranaivo PL, Geme G, Brown MA, Emmert GL Tags: Anal Chim Acta Source Type: journals

Glyphosate and glufosinate detection at electrogenerated NiAl-LDH thin films.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
An amperometric sensor based on Ni(1-x)Al(x)(OH)(2)NO(3x).nH(2)O layered double hydroxide (LDH) has been developed for the electrochemical analysis in one step of two herbicides: glyphosate (N-(phosphonomethyl)glycine, Glyp) and glufosinate ((DL-homoalanine-4-yl)-methylphosphinic acid, Gluf). NiAl-LDH was prepared by coprecipitation or by electrodeposition at the Pt electrode surface. Inorganic films were fully characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Adsorption isotherms of Glyp onto this inorganic lamellar material have been established. Electrocatalytic oxidation of Gl...
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Khenifi A, Derriche Z, Forano C, Prevot V, Mousty C, Scavetta E, Ballarin B, Guadagnini L, Tonelli D Tags: Anal Chim Acta Source Type: journals

Surface modification of polyacrylonitrile fiber for immobilization of antibodies and detection of analyte.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Pendent nitrile groups of multifilamentous polyacrylonitrile (PAN) fibers were reduced to amino groups using lithium aluminum hydride for different time of reduction and amine content was estimated by performing acid-base titrations. Attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR) and Differential Scanning Calorimetry (DSC) were used for the characterization of the generated amino groups and thermal properties of the reduced fibers, respectively. The surface morphology of the fibers after reduction and immobilization was characterized using Scanning Electron Microscope (SEM). The newly fo...
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Jain S, Chattopadhyay S, Jackeray R, Singh H Tags: Anal Chim Acta Source Type: journals

Benzimidazole carbamate residues in milk: Detection by Surface Plasmon Resonance-biosensor, using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method for extraction.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A surface plasmon resonance (SPR) biosensor screening assay was developed and validated to detect 11 benzimidazole carbamate (BZT) veterinary drug residues in milk. The polyclonal antibody used was raised in sheep against a methyl 5(6)-[(carboxypentyl)-thio]-2-benzimidazole carbamate protein conjugate. A sample preparation procedure was developed using a modified QuEChERS method. BZT residues were extracted from milk using liquid extraction/partition with a dispersive solid phase extraction clean-up step. The assay was validated in accordance with the performance criteria described in 2002/657/EC. The limit of detectio...
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Keegan J, Whelan M, Danaher M, Crooks S, Sayers R, Anastasio A, Elliott C, Brandon D, Furey A, O'Kennedy R Tags: Anal Chim Acta Source Type: journals

Single crystal WO(3) nanoflakes as quartz crystal microbalance sensing layer for ultrafast detection of trace sarin simulant.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Tungsten oxide (WO(3)) nanoflakes were synthesized, and characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Thermogravimetry and X-ray photoelectron spectroscopy demonstrate the existence of strongly bound surface water molecules on the surface of tungsten oxide nanoflakes. WO(3) nanoflake functionalized quartz crystal microbalance sensors were fabricated, and firstly used for detection of trace sarin simulant, dimethyl methylphosphonate (DMMP). The sensors have better reproducibility and stability as well as much shorter response (30s) and recovery time (73s) than tho...
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Zhao Y, He J, Yang M, Gao S, Zuo G, Yan C, Cheng Z Tags: Anal Chim Acta Source Type: journals

A multidimensional high performance liquid chromatography method coupled with amperometric detection using a boron-doped diamond electrode for the simultaneous determination of sulfamethoxazole and trimethoprim in bovine milk.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The development and validation of a multidimensional HPLC method using an on-line clean-up column coupled with amperometric detection employing a boron-doped diamond (BDD) electrode for the simultaneous determination of sulfamethoxazole (SMX) and trimethoprim (TMP) in bovine milk are presented. Aliquots of pre-prepared skim-milk samples were directly injected into a RAM octyl-BSA column in order to remove proteins that otherwise would interfere with milk analysis. After exclusion of the milk proteins, SMX and TMP were transferred to the analytical column (an octyl column) and the separation of the compounds from one an...
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Andrade LS, de Moraes MC, Rocha-Filho RC, Fatibello-Filho O, Cass QB Tags: Anal Chim Acta Source Type: journals

On-line monitoring of nine haloacetic acid species at the mugL(-1) level using post-column reaction-ion chromatography with nicotinamide fluorescence.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A laboratory-built automated instrument is reported for on-line, near real-time monitoring of nine haloacetic acids species (HAA9) in drinking water. The device uses anion-exchange chromatography to separate the HAA9 species, followed by post-column reaction with nicotinamide in basic solution with fluorescence detection. Method detection limits for HAA9 species ranged from 0.6 to 10.1mugL(-1), mean % recovery values ranged from 58 to 161%, and % relative standard deviation ranged from 3.5 to 32% while operating within a factor of 2.5-5 of the method detection limit. The bias between the proposed method and United Stat...
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Simone PS, Ranaivo PL, Geme G, Brown MA, Emmert GL Tags: Anal Chim Acta Source Type: journals

Development and validation of an HPLC method for the determination of process-related impurities in pridinol mesylate, employing experimental designs.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A simple high performance liquid chromatographic method for the determination of process-related impurities in bulk drug of the central anticholinergic compound pridinol mesylate, has been developed and validated. Spectroscopically characterized synthetic impurities were used as standards. The chromatographic separation was optimized employing an experimental design strategy, and was achieved on a C(18) column with a mobile phase containing 50mM potassium phosphate buffer (pH 6.4), MeOH and 2-propanol (20:69:11, v/v/v), delivered at a flow rate of 1.0mLmin(-1). UV detection was performed at 245nm. The optimized method ...
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Bianchini RM, Castellano PM, Kaufman TS Tags: Anal Chim Acta Source Type: journals

Screening of salbutamol residues in swine meat and animal feed by an enzyme immunoassay in Taiwan.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, a sensitive, specific salbutamol polyclonal antibody-based ELISA has been developed that could serve as a rapid screening assay, and the detection of positive samples at the place of sampling can result in more effective control of the illegal use of beta-agonists. PMID: 19854346 [PubMed - in process] (Source: Analytica Chimica Acta)
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Sheu SY, Lei YC, Tai YT, Chang TH, Kuo TF Tags: Anal Chim Acta Source Type: journals

High-performance liquid chromatographic method for determination of amino acids by precolumn derivatization with 4-chloro-3,5-dinitrobenzotrifluoride.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This work presents an high-performance liquid chromatography method for the determination of amino acids after precolumn derivatization with 4-chloro-3,5-dinitrobenzotrifluoride (CNBF) which can readily react with both primary and secondary amines. The precolumn derivatization conditions, including the CNBF concentration, reaction pH, temperature and reaction time were investigated for method optimization. In pH 9.0 borate buffer, the reaction of amino acids with CNBF was carried out at 60 degrees C for 30min, the optimized concentration of CNBF was 70mmolL(-1) and the molar ratio of amino acids to CNBF was 1:5.25. The...
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Shi T, Tang T, Qian K, Wang F, Li J, Cao Y Tags: Anal Chim Acta Source Type: journals

Solid-phase extraction followed by liquid chromatography-tandem mass spectrometry for the determination of hydroxylated benzophenone UV absorbers in environmental water samples.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A procedure for the determination of six derivatives of 2-hydroxybenzophenone, used as UV absorbers, in water samples is presented. Compounds were first concentrated using a solid-phase extraction (SPE) cartridge and then selectively determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using electrospray ionization (ESI). The effect of different parameters on the performance of concentration and determination steps is discussed. The highly polar and acidic 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP-4) required the use of ammonium acetate as modifier during desorption of SPE cartridges and al...
Source: Analytica Chimica Acta - October 28, 2009 Category: Chemistry Authors: Negreira N, Rodríguez I, Ramil M, Rubí E, Cela R Tags: Anal Chim Acta Source Type: journals

Preface.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19850160 [PubMed - in process] (Source: Analytica Chimica Acta)
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Schoenmakers P, Smits R Tags: Anal Chim Acta Source Type: journals

Comparative analysis of the electrostatics of the binding of cationic proteins to vesicles: Asymmetric location of anionic phospholipids.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The role of electrostatics is studied in the adsorption of cationic proteins to zwitterionic phosphatidylcholine (PC) and anionic PC/phosphatidylglycerol (PG) mixed small unilamellar vesicles (SUVs). For model proteins the interaction is monitored vs. PG content at low ionic strength. The adsorption of lysozyme and myoglobin (isoelectric point, pI 7-11) is investigated in SUVs, along with changes of the fluorescence emission spectra of the cationic proteins, via their adsorption on SUVs. In the Gouy-Chapman formalism, the activity coefficient goes with the square of charge number. Deviations from the ideal model could ...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Torrens F, Castellano G Tags: Anal Chim Acta Source Type: journals

Characterization of the morphology of co-extruded, thermoplastic/rubber multi-layer tapes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Tapes with alternating semi-crystalline thermoplastic/rubber layers with thicknesses varying from 100nm up to several mum were prepared by multi-layer co-extrusion. The variation in layer thickness was obtained by varying the thermoplastic/rubber feed ratio. A systematic study on the use of various microscopy techniques to visualize the morphology of the layered systems is presented. The relatively large length scales and the sample preparation make optical microscopy (OM) unsuitable to study the morphology of the multi-layer tapes. Although excellent contrast between the thermoplastic and rubber layers can be obtained...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: L'abee RM, Vissers AM, Goossens JG, Spoelstra AB, van Duin M Tags: Anal Chim Acta Source Type: journals

Rapid methods of polymer and polymer additives identification: Multi-sample solvent-free MALDI, pyrolysis at atmospheric pressure, and atmospheric solids analysis probe mass spectrometry.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Polymer manufacturers add antioxidants, waxes, dyes, and other materials to enhance polymer utility or processing. Numerous analytical methods are available to characterize various chemical aspects of polymers including methods interfaced with mass spectrometry (MS) such as pyrolysis (Py), gas chromatography (GC), liquid chromatography (LC), and thermogravimetric analysis (TGA). Current methods work well, but because of the necessity of extraction, chromatography, or thermal methods, most are too time consuming for high throughput analyses which might be necessary in, for example, regulatory laboratories. Here we discu...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Trimpin S, Wijerathne K, McEwen CN Tags: Anal Chim Acta Source Type: journals

Characterisation of archaeological waterlogged wood by pyrolytic and mass spectrometric techniques.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Two techniques based on analytical pyrolysis and mass spectrometry, direct exposure-MS (DE-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), were used to characterise waterlogged archaeological wood and to study degradation patterns of wood in aqueous environments. The two techniques were applied to samples from the excavation of the Site of the Ancient Ships of Pisa San Rossore in Pisa (Italy), and data were compared to those relative to native sound wood of the same species (pine, elm, beech). Both the methods result valuable in the analysis of ancient wood artefacts, avoiding the long wet-chemical p...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Lucejko JJ, Modugno F, Ribechini E, Del Río JC Tags: Anal Chim Acta Source Type: journals

Non-invasive analysis of swelling in polymer dispersions by means of time-domain(TD)-NMR.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this contribution, we discuss the potential of low-field time-domain(TD)-NMR to study the swelling of (aqueous) polymer dispersions by a volatile solvent. Due to the sensitivity of transverse relaxation times (T(2)) to swelling-induced changes in the molecular dynamics of the polymer component, the effects of swelling can be measured without spectral resolution. The measurement is performed on polymer dispersions in native state with solids contents around 50% in a non-invasive way without separating the polymeric phase and the water phase from each other. Using acetone in two polyurethane (PU) dispersions with diff...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Nestle N, Häberle K Tags: Anal Chim Acta Source Type: journals

Identification and quantification of polycarboxylates in detergent products using off-line size exclusion chromatography-nuclear magnetic resonance.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The performance of many contemporary detergent products critically depends on polymers. Water-soluble polycarboxylates represent an important class of detergent polymers, and their quantitative assessment in detergent matrices stands as a considerable challenge. The presence of high levels of surfactants is a major complication, due to the strong tendency of surfactants to form micelles and to interact with the polymers. First, we addressed critical steps in the subsequent combined use of liquid extraction and off-line size exclusion chromatography-nuclear magnetic resonance (SEC-NMR) for identification and quantificat...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Visser I, Klinkenberg M, Hoos P, Janssen HG, van Duynhoven J Tags: Anal Chim Acta Source Type: journals

Improved compositional analysis of block copolymers using Diffusion Ordered NMR Spectroscopy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Block copolymers constitute a fascinating class of polymeric materials that are used in a broad range of applications. The performance of these materials is highly coupled to the physical and chemical properties of the constituting block copolymers. Traditionally, the composition of block copolymers is obtained by (1)H NMR spectroscopy on purified copolymer fractions. Specifically, the integrals of a properly selected set of (1)H resonances are compared and used to infer the number average molecular weight (M(n)) of one of the block from the (typically known) M(n) value of the other. As a corollary, compositional deter...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Viel S, Mazarin M, Giordanengo R, Phan TN, Charles L, Caldarelli S, Bertin D Tags: Anal Chim Acta Source Type: journals

Structural characterization of a poly(methacrylic acid)-poly(methyl methacrylate) copolymer by nuclear magnetic resonance and mass spectrometry.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Mass spectrometry (MS) and nuclear magnetic resonance (NMR) have been combined to achieve the complete microstructural characterization of a poly(methacrylic acid)-poly(methyl methacrylate) (PMAA-PMMA) copolymer synthesized by nitroxide-mediated polymerization. Various PMAA-PMMA species could be identified which mainly differ in terms of terminaisons. (1)H and (13)C NMR experiments revealed the structure of the end-groups as well as the proportion of each co-monomer in the copolymers. These end-group masses were further confirmed from m/z values of doubly charged copolymer anions detected in the single stage mass spect...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Giordanengo R, Viel S, Hidalgo M, Allard-Breton B, Thévand A, Charles L Tags: Anal Chim Acta Source Type: journals

Identification and quantitation of trace impurities in fatty alcohol ethoxylates using HPLC and MALDI-TOF mass spectrometry.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A two-step HPLC separation that combines isocratic and gradient elution has been developed for the analysis of trace impurities in fatty alcohol ethoxylates (FAEs). Quantitative estimates of the early eluting impurities were obtained from a calibration curve based on the responses of an evaporative light scattering detector (ELSD). Isocratic conditions were used to elute the impurities and gradient conditions for the main FAE components. In this manner, an acceptable compromise was obtained between resolution and analysis time. Fractions were collected and the impurities identified using MALDI-TOF mass spectrometry. ...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Lee D, Rumbelow S, Williams SK Tags: Anal Chim Acta Source Type: journals

Enzymatic determination of cholesterol and triglycerides in serum lipoprotein profiles by asymmetrical flow field-flow fractionation with on-line, dual detection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Alterations of lipoproteins (LPs) and related lipid levels in blood serum are correlated to the risk of coronary artery disease (CAD). Fast, possibly automated methods to obtain complete, multi-parametric LP profiles are therefore welcome to be developed for routine, clinical analysis practice. In this work, asymmetrical flow field-flow fractionation (AF4) with on-line, dual post-fractionation reaction detection (PFRD) is applied to develop a method for single-run, simultaneous quantification of cholesterol (CHOL) and triglycerides (TGs) in each fractionated LP class. The enzymatic reagents used for the post-fractionat...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Rambaldi DC, Reschiglian P, Zattoni A, Johann C Tags: Anal Chim Acta Source Type: journals

Comparison of adsorption equilibrium of fructose, glucose and sucrose on potassium gel-type and macroporous sodium ion-exchange resins.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Adsorption equilibrium of fructose, glucose and sucrose was evaluated on sulfonated poly(styrene-co-divinylbenzene) cation-exchange resins. Two types of resins were used: potassium (K(+)) gel-type and sodium (Na(+)) macroporous resins. Influence of the cation and effect of the resin structure on adsorption were studied. The adsorption isotherms were determined by the static method in batch mode for mono-component and multi-component sugar mixtures, at 25 and 40 degrees C, in a range of concentrations between 5 and 250gL(-1). All adsorption isotherms were fitted by a linear model in this range of concentrations. Sugars ...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Nobre C, Santos MJ, Dominguez A, Torres D, Rocha O, Peres AM, Rocha I, Ferreira EC, Teixeira JA, Rodrigues LR Tags: Anal Chim Acta Source Type: journals

Optimal gradient operation in comprehensive liquid chromatographyxliquid chromatography systems with limited orthogonality.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A novel strategy is described for designing optimal second dimension ((2)D) gradient conditions for a comprehensive two-dimensional liquid chromatography system where the two dimensions are not fully orthogonal. Using the approach developed here, the initial and final organic modifier content values resulting in the highest coverage of separation space can be derived for each (2)D gradient run. Theory indicates that these values can be determined by adapting (2)D gradient operation to the degree of orthogonality. The new method is tested on a comprehensive two-dimensional liquid chromatography system that uses reversed...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Bedani F, Kok WT, Janssen HG Tags: Anal Chim Acta Source Type: journals

Fractionation of human serum lipoproteins and simultaneous enzymatic determination of cholesterol and triglycerides.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A method based on Asymmetric Flow Field-Flow Fractionation (AF4) was developed to separate different types of lipoproteins from human serum. The emphasis in the method optimization was on the possibilities to characterize the largest lipoprotein fractions (LDL and VLDL), which is usually not possible with the size-exclusion chromatography methods applied in routine analysis. Different channel geometries and flow programs were tested and compared. The use of a short fractionation channel was shown to give less sample dilution at the same fractionation power compared to a conventional, long channel. Different size select...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Qureshi RN, Kok WT, Schoenmakers PJ Tags: Anal Chim Acta Source Type: journals

A rapid separation method for gel content determination in pressure sensitive adhesive dispersions and acrylic-based latices for an industrial setting.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A rapid method has been developed for determining gel content in industrial samples such as water-borne pressure sensitive adhesives (PSAs) and acrylic-based latices. The method is based on thermal field-flow fractionation (ThFFF) and evaporative light scattering detection (ELSD). Results are compared to those obtained using a centrifugation-based gravimetric method. Sample preparation was an important aspect of the developed analysis. Although the latices and PSA are similar in chemistry, they required different handling and sample preparation procedures. The PSA sample, with its sub-ambient glass transition temperatu...
Source: Analytica Chimica Acta - October 25, 2009 Category: Chemistry Authors: Lohmann CA, Haseltine WG, Engle JR, Williams SK Tags: Anal Chim Acta Source Type: journals

Maize kernel hardness classification by near infrared (NIR) hyperspectral imaging and multivariate data analysis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The use of near infrared (NIR) hyperspectral imaging and hyperspectral image analysis for distinguishing between hard, intermediate and soft maize kernels from inbred lines was evaluated. NIR hyperspectral images of two sets (12 and 24 kernels) of whole maize kernels were acquired using a Spectral Dimensions MatrixNIR camera with a spectral range of 960-1662 nm and a sisuChema SWIR (short wave infrared) hyperspectral pushbroom imaging system with a spectral range of 1000-2498 nm. Exploratory principal component analysis (PCA) was used on absorbance images to remove background, bad pixels and shading. On the cleaned ima...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Williams P, Geladi P, Fox G, Manley M Tags: Anal Chim Acta Source Type: journals

Improving the detection of significant factors using ANOVA-PCA by selective reduction of residual variability.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Selective elimination of residual error can be used when applying Harrington's ANOVA-PCA in order to improve the capabilities of the method. ANOVA-PCA is sometimes unable to discriminate between levels of a factor when sources of high residual variability are present. In some cases this variability is not random, possesses some structure and is large enough to be responsible for the first principal components calculated by the PCA step in the ANOVA-PCA. This fact sometimes makes it impossible for the interesting variance to be in the first two PCA components. By using the proposed selective residuals elimination proced...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Climaco-Pinto R, Barros AS, Locquet N, Schmidtke L, Rutledge DN Tags: Anal Chim Acta Source Type: journals

Extraction of multiple pure component 1H and 13C NMR spectra from two mixtures: novel solution obtained by sparse component analysis-based blind decomposition.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sparse component analysis (SCA) is demonstrated for blind extraction of three pure component spectra from only two measured mixed spectra in (13)C and (1)H nuclear magnetic resonance (NMR) spectroscopy. This appears to be the first time to report such results and that is the first novelty of the paper. Presented concept is general and directly applicable to experimental scenarios that possibly would require use of more than two mixtures. However, it is important to emphasize that number of required mixtures is always less than number of components present in these mixtures. The second novelty is formulation of blind NM...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Kopriva I, Jerić I, Smrecki V Tags: Anal Chim Acta Source Type: journals

Determination of sub-micromolar amounts of sulfide by standard free anodic stripping voltammetry and anodic stripping voltammetric titration.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A novel electrochemical methods namely standard free anodic stripping voltammetry and anodic stripping voltammetric titration are proposed for determination of dissolved sulfide concentration. 2Ag(+) + S(2-) --> Ag(2)S reaction is used to provide the information. The anodic stripping voltammetric response of unreacted silver-ions at the glassy carbon electrode is used as analytical signal. Results reliability and accuracy are confirmed by analysis of model solutions, spiked natural and tap waters and recovery study, with a recovery of 100 +/- 5% (n=7) obtained. The approaches show the detection limit (3sigma(blank))...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Titova TV, Borisova NS, Zakharchuk NF Tags: Anal Chim Acta Source Type: journals

Comparative studies of praseodymium(III) selective sensors based on newly synthesized Schiff's bases.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Praseodymium ion selective polyvinyl chloride (PVC) membrane sensors, based on two new Schiff's bases 1,3-diphenylpropane-1,3-diylidenebis(azan-1-ylidene)diphenol (M(1)) and N,N'-bis(pyridoxylideneiminato) ethylene (M(2)) have been developed and studied. The sensor having membrane composition of PVC: o-NPOE: ionophore (M(1)): NaTPB (w/w; mg) of 150: 300: 8: 5 showed best performances in comparison to M(2) based membranes. The sensor based on (M(1)) exhibits the working concentration range 1.0x10(-8) to 1.0x10(-2) M with a detection limit of 5.0x10(-9) M and a Nernstian slope 20.0+/-0.3 mV decade(-1) of activity. It exh...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Gupta VK, Goyal RN, Pal MK, Sharma RA Tags: Anal Chim Acta Source Type: journals

Electrochemical immunoassay using magnetic beads for the determination of zearalenone in baby food: an anticipated analytical tool for food safety.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this work, electrochemical immunoassay involving magnetic beads to determine zearalenone in selected food samples has been developed. The immunoassay scheme has been based on a direct competitive immunoassay method in which antibody-coated magnetic beads were employed as the immobilisation support and horseradish peroxidase (HRP) was used as enzymatic label. Amperometric detection has been achieved through the addition of hydrogen peroxide substrate and hydroquinone as mediator. Analytical performance of the electrochemical immunoassay has been evaluated by analysis of maize certified reference material (CRM) and se...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Hervás M, López MA, Escarpa A Tags: Anal Chim Acta Source Type: journals

Ligandless-dispersive liquid-liquid microextraction of trace amount of copper ions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the present work, a new ligandless-dispersive liquid-liquid microextraction (LL-DLLME) method has been developed for preconcentration trace amounts of copper as a prior step to its determination by flame atomic absorption spectrometry. In the proposed approach 1,2-dicholorobenzene and ethanol were used as extraction and dispersive solvents, respectively. Some factors influencing on the extraction efficiency of copper and its subsequent determination were studied and optimized, such as the extraction and dispersive solvent type and volume, pH of sample solution, extraction time and salting out effect. Under the optim...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Mohammadi SZ, Afzali D, Baghelani YM Tags: Anal Chim Acta Source Type: journals

Extraction and mechanism investigation of trace roxithromycin in real water samples by use of ionic liquid-salt aqueous two-phase system.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The ionic liquid, as a green solvent, has several advantages over the organic solvents in traditional liquid-liquid extraction. Aqueous two-phase system (ATPS) consisting of a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoraborate, [Bmim]BF(4)) and Na(2)CO(3), which is a novel, simple, non-toxic and effective sample pretreatment technique coupled with molecular fluorescence spectrophotometry, was developed for the simultaneous separation, enrichment and rapid analysis of roxithromycin. The extraction yield of roxithromycin in [Bmim]BF(4)-Na(2)CO(3) aqueous two-phase system is influenced by the types of...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Li CX, Han J, Wang Y, Yan YS, Xu XH, Pan JM Tags: Anal Chim Acta Source Type: journals

HPLC determination of ibuprofen, diclofenac and salicylic acid using hollow fiber-based liquid phase microextraction (HF-LPME).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper describes an extraction method using a polypropylene membrane supporting dihexyl ether (three-phase hollow fiber-based liquid phase microextraction (HF-LPME)) for the analysis of several pharmaceuticals (salicylic acid (SAC), ibuprofen (IBU) and diclofenac (DIC)) followed by a HPLC determination using a monolithic silica type HPLC column, that allows lower retention times than the usual packed columns with adequate resolution. Detection was realized by means of a coupled in series diode array (DAD) and fluorescence (FLD) detectors. HF-LPME is a relatively new technique employed in analytical chemistry for sa...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Ramos Payán M, Bello López MA, Fernández-Torres R, Pérez Bernal JL, Callejón Mochón M Tags: Anal Chim Acta Source Type: journals

Comparison of digestion methods for ICP-MS determination of trace elements in fish tissues.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A comparison is presented of six methods involving nitric acid in conjunction with other reagents to digest three certified marine biological samples (DOLT-3, DORM-3, IAEA-407) and a fish bone homogenate (prepared from Merluccius australis). An inductively coupled plasma-mass spectrometer with an octopole collision cell was used to determine up to 40 elements (Li, B, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Ag, Cd, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Pb, Th, U) in the digests. These results were assessed in terms of their accuracy and precision, and a flow chart was d...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Ashoka S, Peake BM, Bremner G, Hageman KJ, Reid MR Tags: Anal Chim Acta Source Type: journals

Determination of glucose and ethanol after enzymatic hydrolysis and fermentation of biomass using Raman spectroscopy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Raman spectroscopy has been used for the quantitative determination of the conversion efficiency at each step in the production of ethanol from biomass. The method requires little sample preparation; therefore, it is suitable for screening large numbers of biomass samples and reaction conditions in a complex sample matrix. Dilute acid or ammonia-pretreated corn stover was used as a model biomass for these studies. Ammonia pretreatment was suitable for subsequent measurements with Raman spectroscopy, but dilute acid-pretreated corn stover generated a large background signal that surpassed the Raman signal. The backgroun...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Shih CJ, Smith EA Tags: Anal Chim Acta Source Type: journals

A sensitive resonance light scattering spectrometry of trace Hg2+ with sulfur ion modified gold nanoparticles.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A new resonance light scattering (RLS) spectrometric method for mercury ions (Hg(2+)) in aqueous solutions with sulfur ion (S(2-)) modified gold nanoparticles (Au-NPs-S) has been developed in this contribution. It was found that S(2-) at the surface of Au-NPs resulting from the surface modification can interact with Hg(2+) to form very stable S-Hg-S bonds when Hg(2+) concentration is lower than that of S(2-), resulting in the aggregation of Au-NPs-S and causing enhanced RLS signals. The enhanced RLS intensities (DeltaI(RLS)) characterized at 392 nm were found to be proportional to the concentration of Hg(2+) in the ran...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Fan Y, Long YF, Li YF Tags: Anal Chim Acta Source Type: journals

Zinc oxide-potassium ferricyanide composite thin film matrix for biosensing applications.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Thin film of zinc oxide-potassium ferricyanide (ZnO-KFCN) composite has been deposited on indium tin oxide (ITO) coated corning glass using pulsed laser deposition (PLD). The composite thin film electrode has been exploited for amperometric biosensing in a mediator-free electrolyte. The composite matrix has the advantages of high iso-electric point of ZnO along with enhanced electron communication due to the presence of a redox species in the matrix itself. Glucose oxidase (GOx) has been chosen as the model enzyme for studying the application of the developed matrix to biosensing. The sensing response of the bio-electr...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Saha S, Arya SK, Singh SP, Sreenivas K, Malhotra BD, Gupta V Tags: Anal Chim Acta Source Type: journals

Chiral salen Mn(III) complex-based enantioselective potentiometric sensor for L-mandelic acid.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A new enantioselective potentiometric sensor containing chiral salen Mn(III) as the chiral selector was designed for the assay of L-mandelic acid (L-MA). Optimized membrane electrodes displayed linear dynamic range from 1x10(-5) to 1x10(-1) mol L(-1) with a detection limit of 7.2x10(-6) mol L(-1) and a Nernstian response of -58.1+/-0.5 mV decade(-1) towards L-MA within pH range 7.0-10.2. The potentiometric enantioselectivity coefficient (logK(L,D)(Pot)) of this sensor was -4.0, indicating that the chiral salen Mn(III) complex-based electrode exhibited fairly good discrimination toward L-MA over counter isomer D-MA. The...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Xu L, Yang Y, Wang Y, Gao J Tags: Anal Chim Acta Source Type: journals

Simultaneous evaluation of toxicities using a mammalian cell array chip prepared by photocatalytic lithography.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A prototype of a mammalian cell array chip was developed on a flat glass surface. A superhydrophilic (water contact angle=5 degrees)/highly hydrophobic (120 degrees) pattern was prepared on a fluorinated polymer-coated glass surface by means of photocatalytic lithography, and A549 (a human alveolar epithelial cell line), Hep G2 (a human hepatoma cell line) and mouse fibroblast 3T3 cells were inoculated onto the superhydrophilic regions. The cell populations were confined in the superhydrophilic regions for at least 24 h and separated from each other for at least one week. Organ-specific toxicity of aflatoxin B(1) and n...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Komori K, Nada J, Nishikawa M, Notsu H, Tatsuma T, Sakai Y Tags: Anal Chim Acta Source Type: journals

Capillary electrochromatography with contactless conductivity detection for the determination of some inorganic and organic cations using monolithic octadecylsilica columns.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A fast separation of alkali and alkaline earth metal cations and ammonium was carried out by capillary electrochromatography on monolithic octadecylsilica columns of 15 cm length and 100 microm inner diameter using water/methanol mixtures containing acetic acid as mobile phase. On-column contactless conductivity detection was used for quantification of these non-UV-absorbing species. The method was also extended successfully to the determination of small amines as well as of amino acids, and the separation selectivity was optimized by varying the composition of the mobile phase. Detection limits of about 1 microM were ...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Mai TD, Pham HV, Hauser PC Tags: Anal Chim Acta Source Type: journals

Rapid LC-MS detection of cyanobacterial hepatotoxins microcystins and nodularins--comparison of columns.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Eight reversed-phase columns intended for rapid HPLC were assessed for the separation of thirteen microcystins and nodularins, cyclic peptidic hepatotoxins. The instrumentation consisted of an Agilent Technologies 1200 Rapid Resolution high performance liquid chromatography system coupled to a mass spectrometer, Bruker Daltonics Ultra Performance High Capacity Ion Trap MS (HCT Ultra) with electrospray ionisation (RRLC-ESI-IT-MS). The columns tested were 2-2.1 mm x 50 mm in diameter and length, and contained small particles (1.8-2.7 microm), or monolithic silica supports for fast performance. The shortest total run time...
Source: Analytica Chimica Acta - October 8, 2009 Category: Chemistry Authors: Neffling MR, Spoof L, Meriluoto J Tags: Anal Chim Acta Source Type: journals

Review of recent advances in analytical techniques for the determination of neurotransmitters.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Methods and advances for monitoring neurotransmitters in vivo or for tissue analysis of neurotransmitters over the last five years are reviewed. The review is organized primarily by neurotransmitter type. Transmitter and related compounds may be monitored by either in vivo sampling coupled to analytical methods or implanted sensors. Sampling is primarily performed using microdialysis, but low-flow push-pull perfusion may offer advantages of spatial resolution while minimizing the tissue disruption associated with higher flow rates. Analytical techniques coupled to these sampling methods include liquid chromatography, c...
Source: Analytica Chimica Acta - October 6, 2009 Category: Chemistry Authors: Perry M, Li Q, Kennedy RT Tags: Anal Chim Acta Source Type: journals

Review: Microfluidic applications in metabolomics and metabolic profiling.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Metabolomics is an emerging area of research focused on measuring small molecules in biological samples. There are a number of different types of metabolomics, ranging from global profiling of all metabolites in a single sample to measurement of a selected group of analytes. Microfluidics and related technologies have been used in this research area with good success. The aim of this review article is to summarize the use of microfluidics in metabolomics. Direct application of microfluidics to the determination of small molecules is covered first. Next, important sample preparation methods developed for microfluidics a...
Source: Analytica Chimica Acta - October 6, 2009 Category: Chemistry Authors: Kraly JR, Holcomb RE, Guan Q, Henry CS Tags: Anal Chim Acta Source Type: journals

Recent developments in electrochemical flow detections--a review: part I. Flow analysis and capillary electrophoresis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Recent years have provided numerous new examples of applying flow-through electrochemical detectors in chemical analysis. This review, based on about 250 original research papers cited from the current analytical literature, presents their application in flow analysis and capillary electrophoretic methods. Example applications are also given for arrays of electrochemical sensors in flow analysis and electrochemical detection in microfluidic systems. Potentiometric detection with ion-selective electrodes predominates in flow analysis carried out mostly in a flow-injection system, while amperometric and conductivity dete...
Source: Analytica Chimica Acta - October 6, 2009 Category: Chemistry Authors: Trojanowicz M Tags: Anal Chim Acta Source Type: journals

Grab vs. composite sampling of particulate materials with significant spatial heterogeneity--a simulation study of "correct sampling errors".Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sampling errors can be divided into two classes, incorrect sampling and correct sampling errors. Incorrect sampling errors arise from incorrectly designed sampling equipment or procedures. Correct sampling errors are due to the heterogeneity of the material in sampling targets. Excluding the incorrect sampling errors, which can all be eliminated in practice although informed and diligent work is often needed, five factors dominate sampling variance: two factors related to material heterogeneity (analyte concentration; distributional heterogeneity) and three factors related to the sampling process itself (sample type, s...
Source: Analytica Chimica Acta - October 6, 2009 Category: Chemistry Authors: Minkkinen PO, Esbensen KH Tags: Anal Chim Acta Source Type: journals

Improving the detection of hydrogen peroxide of screen-printed carbon paste electrodes by modifying with nonionic surfactants.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Nonionic surfactants, such as Triton X-100 and Tween-20, were shown in this study to improve the electrocatalytic activity of screen-printed carbon paste electrodes (SPCE). The electrochemical response of SPCE to hydrogen peroxide increased 8-10-fold with the modification of nonionic surfactants. In addition, the glucose biosensors fabricated from nonionic surfactant-modified SPCE exhibited 6.4-8.6-fold higher response to glucose than that fabricated from unmodified SPCE. A concentration effect is proposed for nonionic surfactant to bring neutral reactants to the surface of electrode. Moreover, nonionic surfactant-modi...
Source: Analytica Chimica Acta - October 6, 2009 Category: Chemistry Authors: Yuan CJ, Wang YC, Reiko O Tags: Anal Chim Acta Source Type: journals

Study of the Hg2+ binding with chelation therapy agents by differential pulse voltammetry on rotating Au-disk electrode and electrospray ionization mass-spectrometry.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A recently proposed electroanalytical method, using differential pulse voltammetry (DPV) on the rotating Au-disk electrode, and electrospray ionization mass-spectrometry (ESI-MS) has been applied to study the binding of the pharmaceutical chelating agents meso-2,3-dimercaptosuccinic acid (DMSA), sodium 2,3-dimercaptopropanesulfate (DMPS) and D-penicillamine (D-Pen) with Hg(2+). From the use of voltammetric titrations it was possible to obtain a detailed picture of the complexation processes at concentrations much lower than in previous studies. Predominant species were Hg(Pen)(2), Hg(2)(DMSA)(2) and Hg(DMPS)(2). For Pe...
Source: Analytica Chimica Acta - October 6, 2009 Category: Chemistry Authors: Chekmeneva E, Díaz-Cruz JM, Ariño C, Esteban M Tags: Anal Chim Acta Source Type: journals

Determination of trace impurities in high-purity iron using salting-out of polyoxyethylene-type surfactants.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
To an iron sample solution was added polyoxyethylene-4-isononylphenoxy ether (PONPE, nonionic surfactant, average number of ethylene oxides 7.5) and the surfactant was aggregated by the addition of lithium chloride. The iron(III) matrix was collected into the condensed surfactant phase in >99.9% yields, leaving trace metals [e.g., Ti(IV), Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II), and Bi(III)] in the aqueous phase. After removing the surfactant phase by centrifugation, the remaining trace metals were concentrated onto an iminodiacetic acid-type chelating resin. The trace metals were desorbed wi...
Source: Analytica Chimica Acta - October 6, 2009 Category: Chemistry Authors: Matsumiya H, Sakane Y, Hiraide M Tags: Anal Chim Acta Source Type: journals