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Analytical Performance (analytical + performance)
Selected AbstractsA food safety control low mass-range proteomics platform for the detection of illicit treatments in veal calves by MALDI-TOF-MS serum profilingBIOTECHNOLOGY JOURNAL, Issue 11 2009Lorenza Della Donna Abstract Performance enhancing agents (PEAs) are illegally used in cattle and other meat producing species to increase food conversion and lean meat production. Due to the very short breeding cycle, veal calves represent the meat producing bovine category mostly subjected to illicit treatments. These chemical agents are difficult to detect by conventional analytical approaches due to the employment of synergistic formulations at very low dosage and given the use of uncharacterized novel compounds. Such a scenario has fostered a strong interest in the discovery of functional molecular biomarkers for the detection of growth promoting agents in meat producing species. A multivariate MALDI-TOF-MS proteomics platform has been developed using bovine serum samples. Analytical performances have been thoroughly evaluated in order to enable reproducible profiles from 10 ,L sera samples. We propose univariate and multivariate discrimination models capable to identify calves undergoing illicit treatments. In particular, we found a strong discrimination power associated with a polypeptide fragment from ,2-glycoprotein-I. We provide a fundamental proof of concept in the potential application of MALDI-TOF-MS proteomics profiling in the food safety control. [source] Glassy Carbon Electrodes Modified with Multiwall Carbon Nanotubes Dispersed in PolylysineELECTROANALYSIS, Issue 15 2008Yamile Jalit Abstract We report the analytical performance of glassy carbon electrodes (GCE) modified with a dispersion of multiwall carbon nanotubes (MWCNT) in polylysine (Plys) (GCE/MWCNT-Plys). The resulting electrodes show an excellent electrocatalytic activity towards different bioanalytes like ascorbic acid, uric acid and hydrogen peroxide, with important decrease in their oxidation overvoltages. The dispersion of 1.0,mg/mL MWCNT in 1.0,mg/mL polylysine is highly stable, since after 2 weeks the sensitivity for hydrogen peroxide at GCE modified with this dispersion remained in a 90% of the original value. The MWCNT-Plys layer immobilized on glassy carbon electrodes has been also used as a platform to build supramolecular architectures by self-assembling of polyelectrolytes based on the polycationic nature of the polylysine used to disperse the nanotubes. The self-assembling of glucose oxidase has allowed us to obtain a supramolecular multistructure for glucose biosensing. The influence of glucose oxidase concentration and adsorption time as well as the effect of using polylysine or MWCNT-Plys as polycationic layers for further adsorption of GOx is also evaluated. [source] Differential Pulse Voltammetric Determination of Uric Acid on Carbon-Coated Iron Nanoparticle Modified Glassy Carbon ElectrodesELECTROANALYSIS, Issue 10 2008Shengfu Wang Abstract A carbon-coated iron nanoparticles (CIN, a new style fullerence related nanomaterial) modified glassy carbon electrode (CIN/GCE) has been developed for the determination of uric acid (UA). Electrochemical behaviors of UA on CIN/GCE were explored by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that the voltammetric response of UA on CIN/GC was enhanced dramatically because of the strong accumulation effect of CIN and the large working area of the CIN/GC electrode. The parameters including the pH of supporting electrolyte, accumulation potential and time, that govern the analytical performance of UA have been studied and optimized. The DPV signal of UA on CIN/GCE increased linearly with its concentration in the range from 5.0×10,7 to 2.0×10,5 M, with a detection limit of 1.5×10,7 M (S/N=3). The CIN/GCE was used for the determination of UA in samples with satisfactory results. The proposed CIN/GCE electrochemical sensing platform holds great promise for simple, rapid, and accurate detection of UA. [source] Amperometric Glucose Biosensing of Gold Nanoparticles and Carbon Nanotube Multilayer MembranesELECTROANALYSIS, Issue 9 2007Ying Liu Abstract A novel multilayer gold nanoparticles/multiwalled carbon nanotubes/glucose oxidase membrane was prepared by electrostatic assembly using positively charged poly(dimethyldiallylammonium chloride) to connect them layer by layer. The modification process and membrane structures were characterized by atomic force microscopy, scanning electron microscopy and electrochemical methods. This membrane showed excellent electrocatalytic character for glucose biosensing at a relatively low potential (,0.2,V). The Km value of the immobilized glucose oxidase was 10.6,mM. This resulting sensor could detect glucose up to 9.0,mM with a detection limit of 128,,M and showed excellent analytical performance. [source] Carbon Nanotubes Paste Electrodes.ELECTROANALYSIS, Issue 7-8 2007A New Alternative for the Development of Electrochemical Sensors Abstract In this work we summarize the recent activities of our group regarding the analytical performance of a new composite material, the so-called carbon nanotubes paste electrode (CNTPE) obtained by dispersion of multiwall carbon nanotubes in mineral oil. The electrocatalytic properties towards different redox systems, especially those involved in important enzymatic reactions are discussed. Significant shifting in the overpotentials for the oxidation and/or reduction of hydrogen peroxide, NADH, phenol, catechol, dopamine, ascorbic acid, uric acid and hydroquinone are obtained at CNTPE in comparison with the analogous graphite paste electrode (CPE). The usefulness of the electrode as a matrix for immobilizing enzymes is also demonstrated. Highly sensitive and selective glucose quantification is accomplished even without using permselective films or redox mediators. Enzymatic biosensors obtained by incorporation of lactate oxidase, polyphenol oxidase and alcohol dehydrogenase/NAD+ within the composite material have allowed the successful quantification of lactate, phenol, dopamine, catechin and ethanol. The sensitive quantification of traces of oligonucleotides and double stranded calf thymus DNA by adsorptive stripping is reported. The confined DNA layer demonstrated to be stable either in air, acetate or phosphate buffer. The advantages of incorporating copper particles for the quantification of amino acids and albumin is also discussed. [source] Electrooxidation of DNA at Glassy Carbon Electrodes Modified with Multiwall Carbon Nanotubes Dispersed in ChitosanELECTROANALYSIS, Issue 7-8 2007Soledad Bollo Abstract We report on the analytical performance of glassy carbon (GCE) electrodes modified with a dispersion of multiwall carbon nanotubes (CNT) in chitosan (CHIT) for the quantification of DNA. The electroanalytical response of the resulting electrodes was evaluated using differential pulse voltammetry, while the electrochemical reactivity of the film surface was characterized using scanning electrochemical microscopy. Different treatments of the modified GCE were evaluated to improve the stability of the film and the accumulation of DNA. The guanine oxidation signal of double stranded calf-thymus DNA after 3-min accumulation was 20 times higher at GCE/CHIT-CNT cross-linked with glutaraldehyde (GTA) than at bare GCE, while the peak potential was around 45,mV less positive. The guanine oxidation signal demonstrated to be highly reproducible, with 3.4% RSD for 5 different electrodes. The treatment with sodium hydroxide demonstrated to be not effective since the resulting films were less stable and the guanine oxidation signal was ten times smaller compared to electrodes prepared with the GTA treated films. The effect of chitosan molecular weight used to prepare the dispersion and the amount of carbon nanotubes dispersed were evaluated. The response of single stranded DNA and oligo(dG)15 is also discussed. [source] Electrochemical Sensing of ExplosivesELECTROANALYSIS, Issue 4 2007Joseph Wang Abstract This article reviews recent advances in electrochemical sensing and detection of explosive substances. Escalating threats of terrorist activities and growing environmental concerns have generated major demands for innovative field-deployable tools for detecting explosives in a fast, sensitive, reliable and simple manner. Field detection of explosive substances requires that a powerful analytical performance be coupled to miniaturized low-cost instrumentation. Electrochemical devices offer attractive opportunities for addressing the growing explosive sensing needs. The advantages of electrochemical systems include high sensitivity and selectivity, speed, a wide linear range, compatibility with modern microfabrication techniques, minimal space and power requirements, and low-cost instrumentation. The inherent electroactivity of nitroaromatic, nitramine and nitroester compounds makes them ideal candidates for electrochemical detection. Recent activity in various laboratories has led to the development of disposable sensor strips, novel electrode materials, submersible remote sensors, and electrochemical detectors for microchip (,Lab-on-Chip') devices for on-site electrochemical detection of explosive substances. The attractive behavior of these electrochemical monitoring systems makes them very promising for addressing major security and environmental problems. [source] Study of Factors Affecting the Performance of Voltammetric Copper Sensors Based on Gly-Gly-His Modified Glassy Carbon and Gold ElectrodesELECTROANALYSIS, Issue 12 2006Guozhen Liu Abstract This paper reports a study of the factors affecting the analytical performance of gold and glassy carbon electrodes modified with the tripeptide Gly-Gly-His for the detection of copper ions. Gly-Gly-His is attached to a glassy carbon (GC) surface modified with 4-carboxyphenyl moieties or a gold surface modified with 3-mercaptopropionic acid by the reaction of the N-terminal amine group of the peptide with the carboxylic acid groups of the monolayer via carbodiimide activation. X-ray photoelectron spectroscopy was used to characterize the steps in the biosensor fabrication. It was found that the analytical performance of a sensor prepared with Gly-Gly-His on a GC electrode was similar to that on a gold electrode under the same conditions. The performance was greatly enhanced at higher temperature, no added salt during copper accumulation and longer accumulation time within a pH range of 7,9. Interference studies and investigations of stability of the Gly-Gly-His sensor are reported. Analysis of natural water samples show that the sensors measure only copper ions that can complex at the sensor surface. Strongly complexed copper in natural water is not measured. Despite greater stability of diazonium salt derived monolayers on carbon surfaces compared with alkanethiols self-assembled monolayers on gold, the stability of the sensors was essentially the same regardless of the modification procedure. [source] Conducting Polymer-Based Solid-State Ion-Selective ElectrodesELECTROANALYSIS, Issue 1 2006Johan Bobacka Abstract Conducting polymers, i.e., electroactive conjugated polymers, are useful both as ion-to-electron transducers and as sensing membranes in solid-state ion-selective electrodes. Recent achievements over the last few years have resulted in significant improvements of the analytical performance of solid-contact ion-selective electrodes (solid-contact ISEs) based on conducting polymers as ion-to-electron transducer combined with polymeric ion-selective membranes. A significant amount of research has also been devoted to solid-state ISEs based on conducting polymers as the sensing membrane. This review gives a brief summary of the progress in the area in recent years. [source] Amperometric Nitrite Sensor Based on PVP-Os Entrapped in Titania Sol-Gel MatrixELECTROANALYSIS, Issue 19 2004Yancai Li Abstract A novel nitrite sensor was developed based on the immobilization of a partially quaternized poly(4-vinylpyridine) complexed with [Os(bpy)2Cl]+/2+ (PVP-Os) in a porous TiO2 sol-gel matrix by a vapor deposition method. The preparation process simplified the traditional sol-gel process and prevented the cracking of conventional sol-gel derived glasses. Electrochemical behavior of the sensor was characterized by cyclic voltammetry and shows excellent electrocatalytic response for the reduction of nitrite. Effect of operating potential on electrochemical responses of the sensor was explored for optimum analytical performance by using the amperometric method. The stability of the sensor was also evaluated. [source] Amperometric detection in microchip electrophoresis devices: Effect of electrode material and alignment on analytical performanceELECTROPHORESIS, Issue 19 2009David J. Fischer Abstract The fabrication and evaluation of different electrode materials and electrode alignments for microchip electrophoresis with electrochemical detection is described. The influences of electrode material, both metal and carbon-based, on sensitivity and LOD were examined. In addition, the effects of working electrode alignment on analytical performance (in terms of peak shape, resolution, sensitivity, and LOD) were directly compared. Using dopamine (DA), norepinephrine, and catechol (CAT) as test analytes, it was found that pyrolyzed photoresist electrodes with end-channel alignment yielded the lowest LOD (35,nM for DA). In addition to being easier to implement, end-channel alignment also offered better analytical performance than off-channel alignment for the detection of all three analytes. In-channel electrode alignment resulted in a 3.6-fold reduction in peak skew and reduced peak tailing by a factor of 2.1 for CAT in comparison to end-channel alignment. [source] Carbon nanotube disposable detectors in microchip capillary electrophoresis for water-soluble vitamin determination: Analytical possibilities in pharmaceutical quality controlELECTROPHORESIS, Issue 14 2008Agustín G. Crevillén Abstract In this work, the synergy of one mature example from "lab-on-chip" domain, such as CE microchips with emerging miniaturized carbon nanotube detectors in analytical science, is presented. Two different carbon electrodes (glassy carbon electrode (GCE) 3,mm diameter, and screen-printed electrode (SPE) 0.3,mm×2.5,mm) were modified with multiwalled carbon nanotubes (MWCNTs) and their electrochemical behavior was evaluated as detectors in CE microchip using water-soluble vitamins (pyridoxine, ascorbic acid, and folic acid) in pharmaceutical preparations as representative examples. The SPE modified with MWCNT was the best electrode for the vitamin analysis in terms of analytical performance. In addition, accurate determination of the three vitamins in four different pharmaceuticals was obtained (systematic error less than 9%) in only 400,s using a protocol that combined the sample analysis and the methodological calibration. [source] Performance evaluation of the PENTRA 60C+ automated hematology analyzer and comparison with the ADVIA 2120INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 2 2009K. GUERTI Summary The PENTRA 60C+ hematology analyzer provides a complete blood cell (CBC) count, including a five-part differential (5-DIFF) count and two leukocyte subpopulations, i.e. large immature cells (LIC's) and atypical lymphocytes (ALY's). We evaluated its analytical performance and assessed agreement with the ADVIA 2120, in order to install the analyzer in a small satellite hematology laboratory. First we assessed repeatability, reproducibility and carry-over to evaluate the analytical performance. Then we used Pearson correlation coefficients, Passing and Bablok regression analysis and a graphical approach (n = 209) to evaluate agreement with the ADVIA 2120. Repeatability and reproducibility were excellent for the majority of CBC and 5-DIFF count parameters. Carry-over was negligible. Our data showed very good correlation for most CBC count parameters. Lower correlation coefficients were observed for red cell distribution width, mean corpuscular volume and mean platelet volume. As compared to the ADVIA 2120, the 5-DIFF count performed very well. Agreement was poorer for low-level eosinophils and basophils. Furthermore, the PENTRA 60C+ was equally able to identify pathological blood samples through the determination of LIC's and ALY's. Therefore, the PENTRA 60C+ is an eligible blood cell counter to be operational in a satellite laboratory setting. [source] Adaptation and evaluation of the Randox full-range CRP assay on the Olympus AU2700®JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 1 2007A.M. Dupuy Abstract The implementation of a high-sensitivity CRP (hs-CRP) assay as a routine laboratory parameter may be necessary. A single CRP method that could yield reliable results for the whole concentration range (0.1,200 mg/L) would be the most practical solution for the laboratory setting. The aim of this study was to assess the Randox full-range CRP assay on the Olympus AU2700® biochemistry analyzer and evaluate its analytical performance on serum and heparin plasma samples. The Randox CRP turbidimetric assay was compared with the existing CRP assay used routinely on the Olympus AU2700®. The analytical performance of the Randox CRP with both Olympus CRP reagents (CRP for normal application andhs-CRP) was good. We found that the Randox CRP method in the range of 0.5,160 mg/L was closely correlated to the Olympus CRP and hs-CRP for serum samples. According to a Bland-Altman analysis, the serum and heparinized samples showed an excellent agreement in CRP concentrations throughout the entire range (mean difference = ,0.035 ± 1.806 mg/L) as well as in CRP levels <10 mg/L. Our data indicate that Randox full-range CRP measurements using an immunoturbidimetry assay on Olympus systems perform as well for routine diagnostics as other high-sensitivity applications using serum or heparin plasma. J. Clin. Lab. Anal. 21:34,39, 2007. © 2007 Wiley-Liss, Inc. [source] Evaluation of the Sysmex Xe-2100® hematology analyzer in hospital useJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2003Daničle Nakul-Aquaronne Abstract The Sysmex XE-2100® (Sysmex Corp. Kobe, Japan) is a latest-generation hematology analyzer. Its optical and electrical measuring technology is improved by the addition of flux cytometry, fluorescence, and differential lysis. Its analytical performance in terms of precision, reproducibility, linearity, carryover, and time stability was found to be entirely satisfactory. In addition, the results of 500 complete blood counts and differentials correlated perfectly with those obtained by the Coulter STKS® (Beckman Coulter, Villapointe, France). The comparison of 500 leukocyte differential count results analyzed in parallel with optical microscopy and the XE-2100® were surprising, and favorable to the XE-2100®. This analyzer provides the user with an undeniable feeling of security concerning its reliability in detecting and identifying anomalies in the automated leukocyte differential count. With a sensitivity of 96%, a negative predictive value (NPV) of 98%, and a false-negative (FN) rate of 4%, the XE-2100® has perhaps reached the technological limits for a machine performing morphological recognition of normal and pathological blood cells. J. Clin. Lab. Anal. 17:113,123, 2003. © 2003 Wiley-Liss, Inc. [source] Mass spectrometric analysis of the marine lipophilic biotoxins pectenotoxin-2 and okadaic acid by four different types of mass spectrometersJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2008Arjen Gerssen Abstract The performances of four different mass spectrometers [triple-quadrupole (TQ), time-of-flight (ToF), quadrupole ToF (Q-ToF) and ion trap (IT)] for the detection of the marine lipophilic toxins pectenotoxin-2 (PTX2) and okadaic acid (OA) were investigated. The spectral data obtained with the different mass spectrometric analyzers were used to propose fragmentation schemes for PTX2 in the positive electrospray mode and for OA in the negative electrospray mode. TQ data were used to obtain product ions, while ToF and Q-ToF-MS produced accurate mass data of the precursor ion and product ions, respectively. IT data provided a better understanding of the fragmentation pathways using MSn experiments. With respect to analytical performance, all four mass analyzers showed a good linearity (R2 > 0.97) and repeatability (CV < 20%). Detection limits (LoDs) (S/N = 3) were the lowest on triple-quad MS: 12.2 and 2.9 pg on-column for PTX2 and OA, respectively. Copyright © 2008 John Wiley & Sons, Ltd. [source] Analytical characterization of microfabricated SU-8 emitters for electrospray ionization mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2008Tiina Sikanen Abstract We present a detailed optimization and characterization of the analytical performance of SU-8-based emitters for electrospray ionization mass spectrometry (ESI/MS). The improved SU-8 fabrication process presented here enhances patterning accuracy and reduces the time and cost of fabrication. All emitters are freestanding and enable sample delivery by both pressure-driven and spontaneous flows. The optimized emitter design incorporates a sharp, double-cantilevered tip implemented to the outlet of an SU-8 microchannel and provides highly sensitive ESI/MS detection. Moreover, the optimized design allows the use of relatively large microchannel dimensions (up to 200 × 50 µm2, w × h) without sacrificing the detection sensitivity. This is advantageous with a view of preventing emitter clogging and enabling reproducible analysis. The measured limits of detection for the optimized emitter design were 1 nM for verapamil and 4 nM for Glu-fibrinopeptide B with good quantitative linearities between 1 nM and 10 µM (R2 = 0.9998) for verapamil and between 4 nM and 3 µM (R2 = 0.9992) for Glu-fibrinopeptide B. The measured tip-to-tip repeatability for signal intensity was 14% relative standard deviation (RSD) (n = 3; 5 µM verapamil) and run-to-run repeatability 4,11% RSD (n = 4; 5 µM verapamil) for all individual emitters tested. In addition, long-term stability of < 2% RSD was maintained for timescales of 30 min even under free flow conditions. SU-8 polymer was also shown to be chemically stable against most of the tested electrospray solvents. Copyright © 2008 John Wiley & Sons, Ltd. [source] Evaluation of use of a very short polar microbore column segment in high-speed gas chromatography analysisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2008Peter Quinto Tranchida Abstract Very fast GC analyses are commonly carried out by using 10 m×0.1 mm id capillaries. In order to achieve rapid elution times (1,3 min), the latter are operated under suboptimum conditions. The present research is focused on the evaluation of use of a 0.1 mm id polar column segment (2 m), operated under near-to-optimum conditions, in very fast GC analysis. The results attained are compared with those derived from using a 10 m microbore column in very fast GC experiments. Prior to method development, the effects of gas velocity, temperature program rate, and sample amounts on analytical performance were evaluated. Following these preliminary applications, a complex lipidic sample, cod liver oil, was subjected to rapid separation (,2.1 min) on the 10 m capillary through the application of a 50°C/min temperature rate and a 130 cm/s gas velocity. The same matrix was analyzed on the 2 m capillary using the same temperature program rate and range, but with a close-to-ideal linear velocity. The results observed were of interest, as the separation was achieved in less time (1.45 min) with improved peak resolution. Finally, both methods were validated in terms of retention time and peak area repeatability, LOQ, and linearity. [source] Noncovalent Assembly of Picket-Fence Porphyrins on Nitrogen-Doped Carbon Nanotubes for Highly Efficient Catalysis and BiosensingCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2010Wenwen Tu Abstract A water-insoluble picket-fence porphyrin was first assembled on nitrogen-doped multiwalled carbon nanotubes (CNx MWNTs) through FeN coordination for highly efficient catalysis and biosensing. Scanning electron micrographs, Raman spectra, X-ray photoelectron spectra, UV/Vis absorption spectra, and electrochemical impedance spectra were employed to characterize this novel nanocomposite. By using electrochemical methods on the porphyrin at low potential in neutral aqueous solution, the presence of CNx MWNTs led to the direct formation of a high-valent iron(IV),porphyrin unit, which produced excellent catalytic activity toward the oxidation of sulfite ions. By using sulfite ions, a widely used versatile additive and preservative in the food and beverage industries, as a model, a highly sensitive amperometric biosensor was proposed. The biosensor showed a linear range of four orders of magnitude from 8.0×10,7 to 4.9×10,3,mol,L,1 and a detection limit of 3.5×10,7,mol,L,1 due to the highly efficient catalysis of the nanocomposite. The designed platform and method had good analytical performance and could be successfully applied in the determination of sulfite ions in beverages. The direct noncovalent assembly of porphyrin on CNx MWNTs provided a facile way to design novel biofunctional materials for biosensing and photovoltaic devices. [source] Amperometric Algal Chlorella vulgaris Cell Biosensors Based on Alginate and Polypyrrole-Alginate GelsELECTROANALYSIS, Issue 11 2006Rodica Abstract The successful development and analytical performances of two biosensor configurations based on the entrapment of algal cells of Chlorella vulgaris into either a regular alginate gel or a newly synthesized pyrrole-alginate matrix are reported. These biosensors were compared in terms of their amperometric current measurements to p -nitrophenyl phosphate when used as substrate for the detection of an algal alkaline phosphatase activity. The high stability of the pyrrole-alginate gel when compared to that of the alginate coating is herein demonstrated. [source] Highly Sensitive Electrogenerated Chemiluminescence Detecting Ranitidine Based On Chemically Modifying Microenvironment of the Chemiluminescence ReactionELECTROANALYSIS, Issue 11 2005Xingwang Zheng Abstract Using a graphite electrode modified with vaseline and NiO, ranitidine showed a strongly ECL enhancing effect for the weak ECL signal of electrooxidation of luminol. Based on this finding, a more sensitive ECL method for ranitidine was firstly proposed. Under the optimum experimental conditions, the ranitidine hydrochloride concentration in the range of 3.0×10,8,9.0×10,6,mol/L was proportional to the enhancing ECL signal and offered a 9×10,9,mol/L detection limit for ranitidine hydrochloride. At the same time, based on the investigation on this ECL reaction mechanism, a new concept, to improve the suitable ECL reaction micro-environment with chemically modified electrode technique for the better analytical performances of ECL analysis was also firstly proposed. [source] Total analysis of endocrine disruptors in a microchip with gold nanoparticlesELECTROPHORESIS, Issue 18 2010Hui-Bog Noh Abstract The development of a simple, sensitive, and direct method for the total analysis of certain endocrine disruptors was performed by integrating preconcentration steps to a separation step on a microchip through the modification of the field-amplified sample stacking and field-amplified sample injection steps. To improve the preconcentration and separation performances, the preconcentration and separation buffers were modified with citrate-stabilized gold nanoparticles (AuNPs). For the detection of the separated samples, cellulose-dsDNA/AuNPs-modified carbon paste electrodes were used at the channel end. The experimental parameters affecting the analytical performances, such as the buffer concentration, water plug length, SDS concentration in the separation buffer, AuNPs concentration, preconcentration time, detection potential and electrode to channel distance, were examined. The detection limits of the test compounds were between 7.1 and 11.1,fM and that for 4-pentylphenol was 7.1 (±1.1) fM. Dynamic ranges were in the range from 0.15 to 600.0,pM. The experiments with real samples were performed to evaluate the reliability of the proposed method. [source] An improved microalbumin method (µALB_2) with extended analytical measurement range evaluated on the ADVIA® chemistry systemsJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 5 2009Pradip Datta Abstract Quantitative determination of albumin (ALB) in human urine is important to assess kidney functions in a variety of diseases. Recently, Siemens released an improved Microalbumin assay (µALB_2) to measure urinary ALB on the automated, random access ADVIA 1650/1800, ADVIA 2400, and ADVIA 1200 Chemistry Systems. We evaluated analytical performances of this new method. All ADVIA Chemistry Systems use the same microalbumin reagent packs, µALB_2 calibrators, and commercial controls. The within-run and total CVs of the improved method with two-level BioRad Liquichek Urine Chemistry controls (,2 and 9,mg/dl ALB) and a urine pool (,29,mg/dl ALB) on all ADVIA Chemistry systems were <4.1 and <6.1%, respectively (40 replicates per sample). The analytical range/linearity of the method (all ADVIA systems) was from 0.3,mg/dl to theALB concentration in the highest level of calibrator (,38,42,mg/dl). The improved method (µALB_2) on the ADVIA 1650/1800 (y) correlated well with both the Beckman DXC 800 Microalbumin and the old microalbumin method on the ADVIA 1650/1800 analyzers. The improved method showed <10% interference with 16 chemicals from acetaminophen to uric acid that may be present in urine. The improved method has a minimum of 60 days' on-system stability on all systems with the calibration frequencies of (with/without a Reagent Container insert) 20/30 days (ADVIA1200), 50/60 days (ADVIA1650/1800), and 20/60 days (ADVIA2400). No prozone was observed with the method on any platform up to the highest ALB concentration tested in a sample (4,000,mg/dl). J. Clin. Lab. Anal. 23:314,318, 2009. © 2009 Wiley-Liss, Inc. [source] Evaluation of stratus® CS Stat fluorimetric analyser for measurement of cardiac markers Troponin I (cTnI), creatine kinase MB (CK-MB), and myoglobinJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 6 2001Bénédicte Bénéteau-Burnat Abstract Myoglobin, CK-MB, and Troponin I (cTnI) are cardiac muscle necrosis markers that are useful for detecting acute myocardial infarction (AMI). The Stratus® CS (Dade Behring, Inc.) is a discrete fluorimetric immunoassay analyser designed for the determination of the three cardiac markers from a single sample of whole blood or plasma. Overall analytical performances of the Stratus® CS provided by Dade Behring were evaluated according to the French Society of Clinical Biology guidelines. Within-run imprecision (n = 20) for the three parameters at three levels gave values under 5%, whereas CVs for between-run imprecision (n = 20) were under 6%. The sensitivities were 0.03 ,g/L for cTnI and 0.4 ,g/L for CK-MB. Linearities extended from 0,50 ,g/L for cTnI, 0,140 ,g/L for CK-MB, and 1,900 ,g/L for myoglobin. The results, particularly those obtained on whole-blood samples, correlated well with those obtained on Stratus® II. We did not find any interference with haemolysis, icterus, or lipemia. The system was very easy to use, and fulfills the requirements for the analysis of the three cardiac markers in patients with acute chest pain in emergency situations. J. Clin. Lab. Anal. 15:314,318, 2001. © 2001 Wiley-Liss, Inc. [source] Comparison of inductively coupled plasma mass spectrometry techniques in the determination of platinum in urine: quadrupole vs. sector fieldRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2005Sandro Spezia In recent years the increasing use of platinum (Pt) both in medical and in industrial applications has caused its growing anthropogenic emission and spread in the environment. Pt is released into the atmosphere by exhaust catalytic converters, and Pt compounds are often used in antitumour therapies. As a consequence, significant amounts of Pt can be detected in hospital wastewaters. This can lead to an increase in the exposure levels to Pt, especially in urban areas. It is therefore necessary to determine Pt reference values in the general population, by using suitable procedures able to achieve adequate analytical performances. Several measurements of Pt in biological fluids have been reported, but the analytical methods used for the determination of Pt often lack information about the uncertainty of the results, especially for low concentrations of urinary Pt in non-occupationally exposed subjects. The present paper considers the measurement of urinary Pt levels in a general population group from central Italy, by both quadrupole (Q) and sector field (SF) inductively coupled plasma mass spectrometry (ICP-MS). The two procedures were validated and their expanded uncertainties were evaluated. The limits of detection (LODs), calculated taking into account dilution factors, were 0.18 and 0.05,ng L,1 of Pt for the Q and SF procedures, respectively. The median value observed was 4.13,ng L,1 of Pt in urine, while the relative combined uncertainty at 5,ng L,1 was below 20% with both ICP-MS techniques. These data are in good agreement with those reported in the literature for similar studies. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||||||||