|
| ||
|
|
||
Calibration Graph (calibration + graph)
Kinds of Calibration Graph Selected AbstractsFast Simultaneous Adsorptive Stripping Voltammetric Determination of Ni(II) and Co(II) at Lead Film Electrode Plated on Gold SubstrateELECTROANALYSIS, Issue 14 2007Katarzyna Tyszczuk Abstract A fast adsorptive stripping voltammetric procedure for simultaneous determination of Ni(II) and Co(II) in the presence of nioxime as a complexing agent at an in situ plated lead film electrode was described. The time of determination of these ions was shortened due to the application of gold as a substrate for lead film. At gold substrate lead film formation and accumulation of Ni(II) and Co(II) complexes with nioxime proceeds simultaneously. To obtain a stable signals for both ions a simple procedure of activation of the electrode was proposed. Calibration graphs for an accumulation time of 20,s were linear from 5×10,9 to 1×10,7 mol L,1 and from 5×10,10 to 1×10,8 mol L,1 for Ni(II) and Co(II), respectively. The procedure with the application of a lead film electrode on a gold substrate was validated in the course of Ni(II) and Co(II) determination in certified reference materials. [source] Analyzing and monitoring of phage,bacteria interaction using CEELECTROPHORESIS, Issue 20 2009Esra Acar Soykut Abstract The utilization of CE for monitoring bacteria,phage interaction was investigated in this study. Streptococcus thermophilus and Lactobacillus bulgaricus strains and their phages were used as model bacteria and phages for the purpose of validation in this study. CE with heterogeneous polymer polyethylene oxide was utilized for the separation of intact bacteria and investigation of phage,bacteria interaction. An intact phage detection was carried out with CZE by adding SDS in the running buffer. Calibration graphs of bacteria and phages were obtained with R2 values of 0.963 and 0.937, respectively. S. thermophilus strain was infected with its virulent phage B3-X18 for investigation of phage,bacteria interaction. It was observed in capillary electropherogram that the culture was lysed depending on the multiplicity of infection value and it showed to be completely lysed when the multiplicity of infection value was 10. The interaction of S. thermophilus strain with L. bulgaricus phage was also investigated by using a CE and a microbiological method and it was observed that the L. bulgaricus phage attached itself to the cell wall of S. thermophilus strain without damaging the cell. [source] Gas chromatography/negative-ion chemical ionisation mass spectrometry for the quantitative analysis of morphine in human plasma using pentafluorobenzyl carbonate derivativesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2002H. J. Leis A sensitive and specific method for the quantitative determination of morphine in human plasma is presented. Morphine was extracted from plasma by solid phase extraction on C18 and converted to its pentafluorobenzyl carbonate trimethylsilyl derivative. The derivatives were analysed without further purification. Using gas chromatography/negative ion chemical ionisation mass spectrometry, a useful diagnostic fragment ion at m/z 356 is obtained at high relative abundance. Deuterated morphine was used as internal standard. Calibration graphs were linear within the range 1.25 to 320,nmol/L. Intra-day precision was 3.82% (15,nmol/L), 2.85% (75,nmol/L) and 4.13% (225,nmol/L), inter-day variability was found to be 1.77% (15,nmol/L), 4.95% (75,nmol/L) and 9.88% (225,nmol/L). Inter-day accuracy showed deviations of 2.18% (15,nmol/L), ,0.72% (75,nmol/L) and ,0.13% (225,nmol/L). The method is rugged and robust and has been applied to the batch analysis of morphine during pharmacokinetic profiling of the drug. Copyright © 2002 John Wiley & Sons, Ltd. [source] Chiral Separation of Calcium (,)-2(S)-2-Benzyl-4-oxo-4-(cis -hexahydro-2-isoindolinyl)butyrate Enantiomers by High-performance Liquid Chromatography,CHINESE JOURNAL OF CHEMISTRY, Issue 1 2009Zhefeng ZHANG Abstract A chiral high-performance liquid chromatographic method was developed for the enantioseparation of a new insulinotropic drug of the glinide class with rapid onset. The chiral separation was performed on a Sumichiral OA-3300 column (250 mm×4.6 mm, 5 µm) with methanol containing 0.05 mol/L ammonium acetate as the optimized mobile phase at detection wavelengh 210 nm. Baseline separation of the two enantiomers was obtained in 22 min with a resolution of 3.01. Calibration graphs were constructed in a range of 0.028,5.6 µg·mL,1 for S - and 0.03,6.0 µg·mL,1 for R -(,)-enantiomer, respectively. The linear correlation equations are: y=1.32×103x,2.54 (r=0.9997) for S -enantiomer and y=1.15×103x,1.78 (r=0.9998) for R -enantiomer, respectively. The limits of detection obtained by S/N=3 were 0.15 ng for S - and 0.10 ng for R -enantiomer, respectively. RSD of the method was below 1.0% (n=5). [source] Photoelectrocatalytic Oxidation of NADH with Electropolymerized Toluidine Blue OELECTROANALYSIS, Issue 2-3 2007Yusuf Dilgin Abstract A poly(Toluidine Blue O) (poly-TBO) modified electrode was successfully prepared by repeated sweeping the applied potential from ,0.6 to +0.8,V (vs. SCE) on a glassy carbon electrode (GCE) in borate buffer solution at pH,9.1,containing 0.1,M NaNO3 and 0.4,mM Toluidine Blue O (TBO). The poly-TBO modified GCE shows electrocatalytic activity toward NADH oxidation in phosphate buffer solution at pH,7.0, with an overpotential of ca. 350,mV lower than that at the bare electrode. The photoelectrocatalytic oxidation of NADH at this electrode was also successfully investigated by using cyclic voltammetry and amperometry at constant potential. When the modified electrode surface was irradiated with a 250,W halogen lamp, a photoelectrocatalytic effect was observed for NADH oxidation and the current was increased about 2.2 times. The applied potential was selected at +100,mV for amperometric and photoamperometric detection of NADH. A linear calibration graph for NADH was obtained in the range between 1.0×10,5 and 1.0×10,3 M and between 5.0×10,6 and 1.0×10,3 M for amperometric and photoamperometric studies, respectively. The effect of some interfering compounds, such as ascorbic acid and dopamine on the electrocatalytic and photoelectrocatalytic oxidation of NADH was tested. [source] Arbutin determination in medicinal plants and creamsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2009W. Thongchai Synopsis A simple flow injection (FI) manifold with spectrophotometric detection was fabricated and tested for arbutin determination. It is based on the measurement of a red-coloured product at 514 nm formed by the complexation reaction between arbutin and 4-aminoantipyrine (4-AP) in the presence of hexacyanoferrate (III) in an alkaline medium. On injecting 300 ,L standard solutions at various concentrations of arbutin into the FI system under optimum conditions, a linear calibration graph over the range of 1.0,30.0 ,g mL,1 arbutin was established. It is expressed by the regression equation y = 0.2188 ± 0.0036x + 0.1019 ± 0.0366 (r2 = 0.9990, n = 5). The detection limit (3,) and the limit of quantitation (10,) were 0.04 ,g mL,1 and 0.13 ,g mL,1, respectively. The RSD of intraday and interday precisions were found to be 1.2,1.4% and 1.7,2.7%, respectively. The method was successfully applied in the determination of arbutin in four selected fruits and three commercial whitening cream extracts with the mean recoveries of the added arbutin over the range of 96.2,99.0%. No interference effects from some common excipients used in commercial whitening creams were observed. The method is simple, rapid, selective, accurate, reproducible and relatively inexpensive. Résumé Un collecteur simple pour injection en flux (FI) avec détection spectrométrique a été fabriqué et testé pour le dosage de l'arbutine. Son principe repose sur la mesure à 514 nm du produit rouge formé par la réaction de complexation entre l'arbutine et le 4-aminoantipyrine (4-AP) en présence d'hexacyanoferrate (III) en milieu alcalin. On procède à une injection de 300 ,L des solutions standards à diverses concentrations d'arbutine dans le système FI aux conditions optimales, puis on réalise un graphe de calibration linéaire dans l'intervalle de 1,0 à 30,0 ,g mL,1 d'arbutine. Le graphe correspond à l'équation de régression y = 0.2188 ± 0.0036x + 0.1019 ± 0.0366 (r2 = 0.9990, n = 5). La limite de détection (3,) et la limite de quantification (10,) sont respectivement de 0.04 ,g mL,1 et 0.13 ,g mL,1. La RSD des précisions intra et inter jours sont respectivement de 1.2,1.4% et 1.7,2.7%. La méthode a été appliquée avec succès à la mesure de l'arbutine dans 4 fruits sélectionnés et 3 extraits de crèmes de blanchiment commercialisées avec une recouvrance moyenne de l'arbutine ajoutée de 96.2 à 99%. Aucune interférence avec les excipients communément utilisés dans les crèmes de blanchiment commerciales n'a été observée. La méthode est simple, rapide, sélective, précise, reproductible et relativement bon marché. [source] Spectrophotometric determination of leukocytes in bloodJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 5 2002Huriye Kuzu-Karsilayan Abstract The determination of leukocyte concentration in human blood depending on the detection of oxidized o-dianisidine in acidic solution is studied. The oxidation of o-dianisidine was carried out by peroxidase enzymes found in leukocytes. The reaction was stopped by the addition of 4N H2SO4 to the solution, and a very stable, colored o-dianisidine derivative was obtained. The calibration graph was plotted with the recorded absorbance values at 400 nm assigned to the y-axis, and leukocyte counts in 1-mL blood samples to the x-axis. The equation of the calibration graph was y=0.0025x+0.0904, with a correlation coefficient of R=0.994. The coefficient of variation and P -value of the method were 4.00% and 0.05%, respectively. J. Clin. Lab. Anal. 16:233,236, 2002. © 2002 Wiley-Liss, Inc. [source] Analysis of flunarizine in the presence of some of its degradation products using micellar liquid chromatography (MLC) or microemulsion liquid chromatography (MELC) , Application to dosage formsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2005Dina T. El-Sherbiny Abstract The separation of flunarizine hydrochloride (FLZ) and five of its degradation products , 1-[bis(4-fluorophenyl)methyl]-4-(3-phenyl-2-propenyl)piperazine, 4-oxide (A), bis(4-fluorophenyl)methanone (B), bis(4-fluorophenyl)methanol (C), 1-(3-phenyl-2-propenyl)piperazine (D), and 1-[bis-4-fluorophenyl) methyl] piperazine (E) , could be accomplished by reversed phase liquid chromatography using either micellar or microemulsion mobile phases. Cyanopropyl-bonded stationary phase has been used with UV detection at 254 nm. Microemulsion mobile phase consisting of 0.15 M SDS, 10% n -propanol, 1% n -octanol, and 0.3% triethylamine in 0.02 M phosphoric acid of pH 7.0, has been used for the separation of FLZ and its degradation products (B, C, D, and E). Micellar mobile phases consisting of 0.15 M sodium dodecyl sulphate (SDS), 10% n -propanol, 0.3% triethylamine (TEA) in 0.02 M phosphoric acid of pH values either 4.0 or 6.8 have been used for the separation of FLZ from its degradation products, i.e. either from (B, C, D, and E) or from (A, B, C, and D), respectively. Micellar liquid chromatography (MLC) was applied to the determination of FLZ in pure form as well as in dosage forms; the calibration graph was linear over the concentration range of 0.15,50 ,g/mL with detection limit of 0.02 ,g/mL (4.19×10,8M). [source] An Electrochemical Robotic System for the Optimization of Amperometric Glucose Biosensors Based on a Library of Cathodic Electrodeposition PaintsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2004Sabine Reiter Abstract Summary: A library of 148 cathodic electrodeposition paints was synthesized and the properties of related amperometric glucose biosensors were evaluated. For this a novel automatic electrochemical robotic system was designed. The automatic biosensor fabrication and characterization sequence involves the electrochemically induced precipitation of the cathodic paint on the electrode surface in the presence of glucose oxidase, the conditioning of the obtained polymer layer, the recording of a glucose calibration graph and the quantitative dissolution of the polymer film and cleaning of the electrode surface. Schematic representation of the developed electrochemical robotic system for electrochemical screening in microtiter plates. [source] Cathodoluminescence as a tool to determine the phosphorus concentration in diamondPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2007J. Barjon Abstract In n-type diamond doped with phosphorus, exciton properties have been investigated by cathodoluminescence as a function of the phosphorus concentration. A series of homoepitaxial diamond layers were grown by microwave plasma-assisted chemical vapor deposition and doped with a liquid organic precursor of phosphorus (tertiarybutylphosphine). Their phosphorus concentration ranges from 5.2 × 1016 cm,3 to 3.3 × 1018 cm,3 as measured by secondary ion mass spectrometry. It is shown that the ratio between the luminescence intensities of the neutral phosphorus-bound exciton and the free exciton recombinations follows the donor concentration. A calibration graph is presented to determine the phosphorus contents in diamond with cathodoluminescence spectroscopy at 102 K. The influence of electrical compensation on the optical spectra is discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Validated capillary electrophoresis assay for the simultaneous enantioselective determination of propafenone and its major metabolites in biological samplesELECTROPHORESIS, Issue 8 2006Minoo Afshar Abstract A robust, inexpensive, and fully validated CE method for the simultaneous determination of the enantiomers of propafenone (PPF), 5-hydroxy-propafenone (5OH-PPF) and N -despropyl-propafenone (NOR-PPF) in serum and in in vitro media is described. It is based upon liquid,liquid extraction at alkaline pH followed by analysis of the reconstituted extract by CE in presence of a pH,2.0 running buffer composed of 100,mM sodium phosphate, 19% methanol, and 0.6% highly sulfated ,-CD. For each compound, the S -enantiomers are shown to migrate ahead of their antipodes, and the overall run time is about 30,min. Enantiomer levels between 25 and 1000,ng/mL provide linear calibration graphs, and the LOD for all enantiomers is between 10 and 12,ng/mL. The assay is shown to be suitable for the determination of the enantiomers of PPF and its metabolites in in vitro incubations comprising human liver microsomes or single CYP450 enzymes (SUPERSOMES). Incubations with CYP2D6 SUPERSOMES revealed, for the first time, the simultaneous formation of the enantiomers of 5OH-PPF and NOR-PPF with that enzyme. CE data can be used for the evaluation of the enzymatic N -dealkylation and hydroxylation rates. [source] Rapid Determination of Gallamine Triethiodide (Flaxedil®) and Pancuronium Bromide (Pavulon®) in Pharmaceutical and Urine Matrices by Means of Modified-Carbon-Paste Ion-Selective ElectrodesHELVETICA CHIMICA ACTA, Issue 4 2005A new analytical method for the determination of gallamine triethiodide (Flaxedil®; 1) and pancuronium bromide (Pavulon®; 2), two muscle relaxants used in surgical operations and in pain relief, has been developed. Our approach relies on rapid, precise, and sensitive potentiometric sensors based on modified-carbon-paste ion-selective electrodes (CP-ISEs). Linear calibration graphs in the working ranges of ca. 4.5,892 and 7.3,733,,g/ml (in H2O, pH,7.0, T=25°) were established for 1 and 2, respectively; and Nernst slopes corresponding to three- or two-electrons transfers, respectively, were obtained. The method works best in a pH range of 7,9. Average relative errors of 2.12 and 2.14%, with average standard deviations of 1.98,2.47 and 2.64,3.45, respectively, were obtained for urine samples of 1 and 2. The corresponding relative errors for the pharmaceutical samples were 1.59 and 1.64%, with standard deviations of 0.54,1.34 and 0.52,1.67, respectively. Statistical Student and F tests were applied to the data, and satisfactory results were obtained. [source] Determination of avoparcin in animal tissues and milk using LC-ESI-MS/MS and tandem-SPEJOURNAL OF SEPARATION SCIENCE, JSS, Issue 22 2008Koichi Inoue Abstract A highly sensitive and selective method using LC-ESI-MS/MS and tandem-SPE was developed to detect trace amounts of avoparcin (AV) antibiotics in animal tissues and milk. Data acquisition using MS/MS was achieved by applying multiple reaction monitoring of the product ions of [M + 3H]3+ and the major product ions of AV-, and -, at m/z 637 , 86/113/130 and m/z 649 , 86/113/130 in ESI(+) mode. The calculated instrumental LODs were 3 ng/mL. The sample preparation was described that the extraction using 5% TFA and the tandem-SPE with an ion-exchange (SAX) and InertSep C18-A cartridge clean-up enable us to determine AV in samples. Ion suppression was decreased by concentration rates of each sample solution. These SPE concentration levels could be used to detect quantities of 5 ppb (milk), 10 ppb (beef), and 25 ppb (chicken muscle and liver). The matrix matching calibration graphs obtained for both AV-, (r >0.996) and -, (r >0.998) from animal tissues and milk were linear over the calibration ranges. AV recovery from samples was higher than 73.3% and the RSD was less than 12.0% (n = 5). [source] High-performance liquid chromatography with sequential injection for online precolumn derivatization of some heavy metalsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 16 2007Rodjana Burakham Abstract HPLC was coupled with sequential injection (SI) for simultaneous analyses of some heavy metals, including Co(II), Ni(II), Cu(II), and Fe(II). 2-(5-Nitro-2-pyridylazo)-5-[N -propyl- N -(3-sulfopropyl)amino]phenol (nitro-PAPS) was employed as a derivatizing reagent for sensitive spectrophotometric detection by online precolumn derivatization. The SI system offers an automated handling of sample and reagent, online precolumn derivatization, and propulsion of derivatives to the HPLC injection loop. The metal,nitro-PAPS complexes were separated on a C18 -,Bondapak column (3.9×300 mm2). Using the proposed SI-HPLC system, determination of four metal ions by means of nitro-PAPS complexes was achieved within 13 min in which the parallel of derivatization and separation were processed at the same time. Linear calibration graphs were obtained in the ranges of 0.005,0.250 mg/L for Cu(II), 0.007,1.000 mg/L for Co(II), 0.005,0.075 mg/L for Ni(II), and 0.005,0.100 mg/L for Fe(II). The system provides means for automation with good precision and minimizing error in solution handling with the RSD of less than 6%. The detection limits obtained were 2 ,g/L for Cu(II) and Co(II), and 1 ,g/L for Ni(II) and Fe(II). The method was successfully applied for the determination of metal ions in various samples, including milk powder for infant, mineral supplements, local wines, and drinking water. [source] Determination of some hydroxybenzoic acids and catechins in white wine samples by liquid chromatography with luminescence detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2006Rafael Carlos Rodríguez-Díaz Abstract A liquid chromatographic method with luminescence detection for the determination of eight phenolic compounds is reported. The method involves postcolumn derivatization with terbium(III). This derivatization is based on the reaction between phenolics and terbium(III) to form luminescent chelates, which were determined at ,ex 295 and ,em 545 nm using the fluorescence mode. The long wavelength emission of lanthanide chelates can minimize interferences from background sample matrix, which usually emit at shorter wavelengths. Also, the chromatographic separation allows the individual determination of phenolics, which cannot be done using the direct measurement of the fluorescence of their corresponding terbium chelates. Dynamic ranges of the calibration graphs and detection limits, obtained with standard solutions of analytes were (,g/mL): gallic acid (0.9,40, 0.3), protocatechuic acid (0.05,7, 0.016), catechin (0.2,40, 0.07), vanillic acid (0.25,40, 0.08), p -hydroxybenzoic acid (0.8,40, 0.25), syringic acid (0.17,40, 0.05), epicatechin (0.3,40, 0.09) and salicylic acid (0.07,12, 0.02). The precision was established at two concentration levels of each analyte and expressed as the percentage of RSD with values ranging between 1.0 and 6.5%. The practical usefulness of the method was demonstrated by the analysis of white wine samples, which were diluted two-fold and directly injected into the chromatographic system. The recovery values obtained ranged between 93.3 and 108.0%. [source] Differential Kinetic Spectrophotometric Determination of Methamidophos and Fenitrothion in Water and Food Samples by Use of ChemometricsCHINESE JOURNAL OF CHEMISTRY, Issue 3 2010Na Deng Abstract A spectrophotometric method for simultaneous analysis of methamidophos and fenitrothion was proposed by application of chemometrics to the spectral kinetic data, which was based upon the difference in the inhibitory effect of the two pesticides on acetylcholinesterase (AChE) and the use of 5,5,-dithiobis(2-nitrobenzoic acid) (DTNB) as a chromogenic reagent for the thiocholine iodide (TChI) released from the acetylthiocholine iodide (ATChI) substrate. The absorbance of the chromogenic product was measured at 412 nm. The different experimental conditions affecting the development and stability of the chromogenic product were carefully studied and optimized. Linear calibration graphs were obtained in the concentration range of 0.5,7.5 ng·mL,1 and 5,75 ng·mL,1 for methamidophos and fenitrothion, respectively. Synthetic mixtures of the two pesticides were analysed, and the data obtained processed by chemometrics, such as partial least square (PLS), principal component regression (PCR), back propagation-artificial neural network (BP-ANN), radial basis function-artificial neural network (RBF-ANN) and principal component-radial basis function-artificial neural network (PC-RBF-ANN). The results show that the RBF-ANN gives the lowest prediction errors of the five chemometric methods. Following the validation of the proposed method, it was applied to the determination of the pesticides in several commercial fruit and vegetable samples; and the standard addition method yielded satisfactory recoveries. [source] | |||||||||||||