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Showing papers on "Calibration curve published in 1979"


Book
01 Jan 1979
TL;DR: In this article, the potential-determining Ions were determined using the Nernst Equation and the Salt Bridge Electrolyte/Sample Solution Contact Zone (SBE).
Abstract: 1 Fundamentals of Potentiometry.- 1.1 Electrode Processes.- 1.2 The Nernst Equation.- 1.3 Potential-Determining Ions.- 1.4 Ion-Selective Electrode Materials.- 1.5 The Potentiometric Selectivity Coefficient as a Quantitative Indication of the Electrode Selectivity.- 2 Electrode Potential Measurements.- 2.1 Reference Electrodes.- 2.2 The Standard Hydrogen Electrode as a Primary Reference Electrode.- 2.2.1 Preparation.- 2.2.2 Characteristics.- 2.3 The Liquid Junction Potential.- 2.3.1 Origin.- 2.3.2 Calculation.- 2.3.3 Salt Bridge Electrolytes.- 2.3.4 Construction of the Salt Bridge Electrolyte/Sample Solution Contact Zone.- 2.3.5 Cells Without Liquid Junction.- 2.4 Secondary Reference Electrodes.- 2.4.1 Silver/Silver Chloride.- 2.4.1.1 Preparation.- 2.4.1.2 Characteristics.- 2.4.2 Thallium Amalgam/Thallium (I) Chloride (Thalamid(R)).- 2.4.2.1 Characteristics.- 2.4.3 Mercury/Mercury (I) Chloride (Calomel).- 3 Ion-Selective Electrodes.- 3.1 General Construction Principles.- 3.2 Solid-State Membrane Electrodes.- 3.2.1 Glass Membrane Electrodes For Li+, Na+, K+, Rb+, Cs+, NH4+, NR4+, Ag+, Tl+ Ions.- 3.2.1.1 Construction.- 3.2.1.2 Characteristics.- 3.2.1.3 Handling.- 3.2.1.4 Sample Preparation.- 3.2.2 Homogeneous Solid-State Membrane Electrodes For Ag+, Cd2+, Cu2+, Pb2+, S2-, F-, Cl-, Br-, I-, SCN-, CN- Ions.- 3.2.2.1 Principles.- 3.2.2.2 Construction.- 3.2.2.3 Preparation of Solid-State Membrane Electrodes Based on Ag2S.- 3.2.2.4 Characteristics.- 3.2.2.5 Handling.- 3.2.2.6 Sample Preparation.- 3.2.3 Heterogeneous Solid-State Membrane Electrodes For Ag+, Cl-, Br-, I-,CN-, SCN-, S2- Ions.- 3.2.3.1 Construction.- 3.2.3.2 Preparation.- 3.2.3.3 Characteristics.- 3.2.3.4 Handling.- 3.3 Porous and Nonporous Supported Ion Exchanger and Neutral Carrier Membrane Electrodes.- 3.3.1 Ion-Exchangers For Ca2+, Me2+ Cations and Cl-, ClO4-, NO3-, BF4- Anions.- 3.3.2 Neutral Carrier Compounds For Li+, Na+, K+, Rb+, Cs+, NH4+, NR4+, Ca2+ and Ba2+ Cations.- 3.3.3 Construction.- 3.3.4 Preparation of PVC Membrane Electrodes.- 3.3.5 Characteristics.- 3.3.6 Handling.- 3.3.7 Further Electro-Active Phases.- 3.4 Solid State Electrodes with Electroactive Coatings.- 3.5 Gas Sensors For CO2, NH3, SO2, NO2, HF, H2S, HCN, etc..- 3.5.1 Principles.- 3.5.2 Construction.- 3.5.3 Characteristics of Gas-Sensitive Electrodes.- 3.5.4 Handling.- 3.5.5 Sample Preparation.- 3.6 Bio-Sensors.- 3.6.1 Principles.- 3.6.2 Construction.- 3.6.3 Preparation of Enzyme Electrodes.- 3.6.4 Characteristics of Bio-Sensors.- 3.6.5 Sample Preparation with Bio-Sensors.- 4 Measuring Techniques with Ion-Selective Electrodes.- 4.1 Equivalent Circuit for a Cell with Liquid Junction.- 4.2 Measuring the EMF of an Electrochemical Cell.- 4.3 Choosing an EMF Measuring Device.- 4.4 Characteristics of Electrometer Amplifiers.- 4.4.1 Resolving Power.- 4.4.2 Insulation Problems.- 4.4.3 Charging Phenomena.- 4.4.4 Ground Loops.- 5 Analysis Techniques Using Ion-Selective Electrodes.- 5.1 Calibration Curves.- 5.1.1 Determination of Activity Using an Activity Calibration Curve.- 5.1.2 Determination of Concentration Using a Concentration Calibration Curve.- 5.2 Direct Indication on the pH or plon Scale of an Instrument.- 5.3 Titration Procedures for Determining Concentrations.- 5.3.1 Prerequisites.- 5.3.2 Titration Errors.- 5.3.3 Sample Preparation for Titrations.- 5.3.4 Titration to a Pre-determined EMF Value.- 5.3.4.1 On the Basis of a Titration Curve.- 5.3.4.2 On the Basis of a Concentration Cell Set-Up.- 5.3.5 "Chemically Linearized" Titration Curves (One Point Titration).- 5.4 Concentration Determinations with the Help of a Standard Addition with a Known Electrode Slope S.- 5.4.1 Measuring the Change in EMF upon Addition of a Standard Solution to the Sample Solution.- 5.4.2 Measuring the Change in EMF upon Addition of the Sample Solution to a Standard Solution.- 5.5 Concentration Determinations with the Help of a Standard Addition with an Unknown Electrode Slope S.- 5.5.1 Method of Double Standard Addition.- 5.5.2 Method of Standard Addition with Subsequent Dilution.- 5.6 Practical Example of the Addition Method: Sodium and Potassium Determination in Blood Serum.- 5.7 Concentration Determinations with the Help of a "Mathematically Linearized" Titration Curve.- 5.8 Practical Example of the Gran Extrapolation Method: Determination of Chloride in the ppm Range.- 5.8.1 Principles.- 5.8.2 Preparatory Work.- 5.8.3 Blank Determination.- 5.8.4 Chloride Content Determination of the Sample Solution.- 5.9. Determination of Some Characteristic Electrode Parameters.- 5.9.1 Determination of the Detection Limit.- 5.9.2 Determination of the Selectivity Coefficient.- 6 Applications of Ion-Selective Electrodes.- 6.1 Physiology, Biology, Medicine.- 6.1.1 Measurements in Extracellular Fluids.- 6.1.1.1 In-vitro Measurements.- 6.1.1.1.1 Sample Preparation.- 6.1.1.1.2 The Indicating Electrode.- 6.1.1.1.3 The Reference Electrode.- 6.1.1.2 In-vivo Measurements.- 6.1.2 Measurements of Intracellular Ion Activities.- 6.1.2.1 Preparation of Ion-Selective Microelectrodes.- 6.1.2.2 Guarded Signal Wires for Extremely High Ohmic Electrodes.- 6.1.2.3 Reference Microelectrodes.- 6.1.2.4 Special Amplifiers for Microelectrode Applications.- 6.2 Continuous Measurements in Industry and Environmental Research.- 6.2.1 Flow-thru Cells.- 6.2.1.1 Influence of Grounding.- 6.2.1.2 Influence of Temperature.- 6.2.1.3 Analysis Techniques with Flow-thru Measurements.- 6.2.1.4 Flow-thru Measurements without Reference Electrodes.- 6.2.1.4.1 Direct Potentiometry.- 6.2.1.4.2 Concentration Determination through Standard Solution Addition.- 6.2.1.4.3 Indirect Concentration Determination.- 6.2.1.4.4 The Cyanide Monitor as an Example of Industrial On-Line Measurements.- 6.2.2 Concentration Determination Via a Continuous Titration.- Outlook.- A.1 Concentration, Activity and Activity Coefficient.- A.1.1 Preparing Accurate Activity Calibration Solutions.- A.2 Survey of the Temperature Dependence of Commonly Used Reference Electrodes.- A.3 Table for Evaluation Using Analysis Technique 5.4.1.- A.4 Table for Evaluation Using Analysis Technique 5.4.2.- A.5 Table for Evaluation Using Analysis Technique 5.5.1.- A.6 Table for Evaluation Using Analysis Technique 5.5.2.- A.7 Evaluation Table for Standard Addition + 1:1 Dilution.- A.8 Ion-Selective Electrode Manufacturers and/or Dealers.- Literature.- Index of Symbols Used.

179 citations


Journal ArticleDOI
TL;DR: In this paper, finite element analysis procedures are utilized to provide theoretical calibration curves for the electrical potential crack-monitoring system as applied to single-edge-notch (SEN) and compact tension (CT) fracture specimens.
Abstract: Finite element analysis procedures are utilized to provide theoretical calibration curves for the electrical potential crack-monitoring system as applied to single-edge-notch (SEN) and compact tension (CT) fracture specimens. The results are compared to existing calibrations for such test piece geometries derived using experimental, electrical analog and analytical (conformal mapping) procedures.

113 citations


Journal ArticleDOI
TL;DR: A rapid and sensitive method for the measurement of nicotine in plasma, urine, saliva and breast milk is described and a micro‐method is described which requires only 100 μl of sample and yields an accurate result in 5 min.
Abstract: A rapid and sensitive method for the measurement of nicotine in plasma, urine, saliva and breast milk is described. An internal standard (quinoline) is added to the samples and these are made alkaline and extracted with diethyl ether. The solvent is evaporated to small bulk and extracted with dilute acid which is then made alkaline. The nicotine is finally extracted into butyl acetate and an aliquot of this extract is injected onto a gas-chromatograph fitted with a nitrogen detector. Quantitation relies on comparison of peak areas and the calibration curve is linear over the concentration range 0.5 to 100 ng ml-1. Nicotine concentrations as low as 0.1 ng ml-1 can be measured. In addition, a micro-method is described which requires only 100 microliter of sample and yields an accurate result in 5 min.

89 citations


Journal ArticleDOI
TL;DR: In this paper, a calibration curve is constructed using microporous silica beads whose mean diameters (4.4, 6.4 and 12.1 μm) are accurately determined by electron microscopy.

65 citations



Journal ArticleDOI
TL;DR: In this article, a flow injection procedure is described for the Spectrophotometric determination of aluminium in plant and soil material with eriochrome cyanine R. This system utilizes merging zones and sequential addition of pulsed reagents.

57 citations


Journal ArticleDOI
TL;DR: Measurements of trace quantities of chromium in samples of NBS standard reference steel, doped skim milk powder, and doped flour have been undertaken and suggest the possibility of a universal calibration curve for all elements irrespective of the substrate matrix in which they are contained.
Abstract: Trace element analysis based on laser ablation and selectively excited radiation (TABLASER) is proposed as a new and reliable microultratrace technique for quantitative in situ element analysis. Measurements of trace quantities of chromium in samples of NBS standard reference steel, doped skim milk powder, and doped flour have been undertaken. A linear 45 degrees slope dependence of signal vs concentration that extends beyond 1% in the case of chromium was observed. Although the present sensitivity limit is in the ppm range, improved overlap between the probing dye laser beam and the wave of atomized material combined with a better design of the optical system could reduce the detection limit of the TABLASER to the ppb range. This would correspond to an absolute detection limit of about 10(-16) g. An important feature of this new technique is its relative freedom from chemical matrix effects, which suggests the possibility of a universal calibration curve for all elements irrespective of the substrate matrix in which they are contained. This technique is also adaptable to multielement analysis.

47 citations


Journal ArticleDOI
TL;DR: An approach to the analysis of RIA data which incorporates robust estimation methods is described and an algorithm is presented for obtaining the M-estimates of nonlinear calibration curves.
Abstract: The minute concentrations of many biochemically and clinically important substances are currently estimated by radioimmunoassay (RIA). Traditionally, the most popular approaches to the statistical analysis of RIA data have been to linearize the data through transformation and fit the calibration curve using least squares or to directly fit a nonlinear calibration curve using least squares. Estimates of the hormone concentration in patients are then obtained using this curve. Unfortunately, the transformation is frequently unsuccessful in linearizing the data. Furthermore, the least squares fit can lead to erroneous results in both approaches since the many sources of error which exist in the RIA process often result in outlier observations. In this paper, an approach to the analysis of RIA data which incorporates robust estimation methods is described. An algorithm is presented for obtaining the M-estimates of nonlinear calibration curves. The curves to be fitted are modified hyperbolae based on 12 to 16 observations. A procedure, based on the application of the Bonferroni Inequality, is presented for obtaining tolerance-like interval estimates of the concentration of the hormone of interest in the patients. Results of simulations are cited to support the method of construction of confidence bands for the fitted calibration curve. Data obtained from the Veteran's Hospital, Buffalo, New York are used to illustrate the application of the algorithm which is presented.

42 citations



Journal ArticleDOI
TL;DR: A highly sensitive and specific method for hydrocortisone determination in plasma is described and a linear calibration curve was found from 5 to 150 ng/ml with the precision estimated to be ±7% (CV).

24 citations


Journal ArticleDOI
W. Huda1
TL;DR: In this paper, a thin Kapton foil was used to extract the proton beam into air by means of a thin kapton cover and the results were in good agreement with theoretical predictions for the variation of K X-ray yields with proton energy and atomic number of the element Z.

Journal ArticleDOI
TL;DR: In this paper, a theoretical method for constructing a quantitative calibration curve for AES signal versus deposit film thickness has been developed, which can be easily obtained by only measuring secondary electron coefficients from the pure deposit and substrate materials.

Journal ArticleDOI
TL;DR: In this article, the effects of four gravel concentrations (0, 20, 40, and 60 percent by weight) and three gravel size fractions (4-8 mm, 8-15 mm, and 15-40 mm) on the calibration of a neutron moisture meter and density probe was investigated for a beach sand and a clayey tropical Alfisol (Oxic Paleustalf).
Abstract: The effects of four gravel concentrations (0, 20, 40, and 60 percent by weight) and three gravel size fractions (4–8 mm, 8–15 mm, and 15–40 mm) on the calibration of a neutron moisture meter and density probe was investigated for a beach sand and a clayey tropical Alfisol (Oxic Paleustalf). The slope of the regression line of the calibration curve relating neutron count ratio with volumetric moisture content of gravel-free sand was statistically significantly different from that of three gravel-sand mixtures. The calibration curve of three gravel-sand mixtures was statistically identical. For the gravel-soil mixtures, the slope of the calibration curve generally decreased with increased gravel concentration. The statistical comparison of the regression lines for the 4–8 mm gravel size fraction indicated that the slope coefficient of the calibration curve of only 60 percent gravel-soil mixture was significantly lower than that of 0, 20, and 40 gravel percentages. For the 8–15 mm gravel size fraction, the slopes of the regression lines of 40 and 60 percent gravel-soil mixtures were similar and significantly lower than that of 0 and 20 percent gravel concentrations. Gravel size had no effect on the calibration curve in the gravel-sand mixtures. In the gravel-soil mixtures, for 20 and 40 percent gravel concentrations, 4–8 mm gravel size had a significantly higher slope coefficient of the regression equations, compared with the 8–15 mm size fraction. The slope of the regression equation relating density count ratio with dry density significantly decreased with an increase in gravel concentration for 40 and 60 percent, compared with 0 and 20 percent gravels for gravel-soil mixtures. Heterogeneity of tropical soils, with regard to variations in texture and gravel concentrations, may necessitate a detailed calibration of the neutron moisture meter prior to its use on large watersheds.

Journal ArticleDOI
TL;DR: The two methods were found to exhibit good correlation but the spectrofluorimetric method proved to be more amenable to the analysis of a large number of samples.

Journal ArticleDOI
TL;DR: In this article, the quantum yield of self-activated neodymium materials for a mini-laser is correlated to the photoacoustiv spectrum obtained in the near infrared region (⋍ 0.9 μm).

Journal ArticleDOI
TL;DR: In this paper, the Benoit universal calibration method has been tested for evaluation of GPC data of polydimethylsiloxane (PDMS) in toluene at 60°C.
Abstract: The Benoit universal calibration method has been tested for evaluation of GPC data of polydimethylsiloxane (PDMS) in toluene at 60°C. For the conversion of the calibration curve for polystyrene to the PDMS calibration curve, the Mark–Houwink equation for PDMS in toluene at 60°C was derived: [η] = 9.77 × 10−5M0.725. The applicability of this universal calibration was proved by the experimental results on five PDMS model samples. For the correct evaluation of the PDMS elution curve, the use of the true calibration is inevitable, because the hydrodynamic volume of PDMS molecular weight unit is somewhat different from the polystyrene one.

Journal ArticleDOI
01 Jan 1979-Analyst
TL;DR: In this article, a simple method for determining low concentrations of oxygen in power station waters has been developed, based on the reaction of dissolved oxygen with the leuco-base of methylene blue to give a soluble blue oxidation product the absorbance of which is a function of the oxygen concentration.
Abstract: A simple, fast method for determining low concentrations of oxygen in power-station waters has been developed, based on the reaction of dissolved oxygen with the leuco-base of methylene blue to give a soluble blue oxidation product the absorbance of which is a function of the oxygen concentration.A special glass cell has been devised, which acts sequentially as a sample-collection vessel, a reaction vessel and a spectrophotometric cuvette. The cell design permits the easy addition of the leuco-base and also the air-saturated water used for calibration. A novel technique of “zero-time extrapolation” for the determination of the reagent/cuvette blank circumvents the difficulty of making this measurement with oxygen-free water.The calibration graph is linear up to 50 µg l–1, but satisfactory measurements may be made up to 100 µg l–1. The criterion of detection is approximately 1.0 µg l–1 with standard deviations ranging between 0.4 and 1.7 µg l–1, depending on the concentration. The analysis time is 5–10 min for a single determination.Iron(II) and copper(II) ions are the only ions likely to be present in boiler waters that cause serious interference and these must be removed before analysis by passing the water sample through a cation-exchange column.

Journal ArticleDOI
TL;DR: In this article, X-ray fluorescence analysis under high vacuum (∼10−6 torr) was applied to the determination of fluorine in slags and the calibration curve has excellent linearity and accuracy.
Abstract: X-ray fluorescence analysis under high vacuum (∼10−6 torr) was applied to the determination of fluorine in slags. Slag samples are converted into glass beads using a fusion method and the fluorescent X-ray intensity of characteristic X-ray F Kα (1.83 nm) is measured to determine fluorine. The calibration curve has excellent linearity and accuracy; σd is 0.18% for 11 kinds of samples involving fluorine of 0.10% to 16.78% (mean: 6.96%).

Journal ArticleDOI
TL;DR: In this article, two radioanalytical methods, characterized by high selectivity, were developed to determine micro amounts of one element in the presence of macro amounts of other elements with similar chemical properties.

Journal ArticleDOI
TL;DR: In this article, a critical evaluation of common methods of column of column calibration in gel permeation chromatography is reported for a range of well characterised polymer standards, namely the Q factor method and the universal calibration method.

Journal ArticleDOI
TL;DR: In this article, the accuracy of chemical analysis by flame atomic emission spectrometry is influenced by the methods used to obtain the calibration plots, which are then used to determine the accuracy.
Abstract: The accuracy of chemical analysis by flame atomic emission spectrometry is influenced by the methods used to obtain the calibration plot. Experimental data are treated by several different methods to obtain calibration plots, which are then used to determine the accuracy of each method. In general, log-log plots are shown to be more accurate than are linear plots, especially at the higher analyte concentrations where the emission is no longer directly proportional to concentration.

Journal ArticleDOI
TL;DR: In this article, the authors derived a mathematical expression for the emulsion calibration curve used in optical emission spectroscopy, and employed a two-step preliminary curve method to obtain an approximation of the first derivative of the calibration curve.
Abstract: The Federal Bureau of Mines has derived a mathematical expression for the emulsion calibration curve used in optical emission spectroscopy. Employing a two-step preliminary curve method, an approximation of the first derivative of the calibration curve is formed and integrated. The final equation is I = (1 + βS)−α where I is the line intensity, S is the transform that linearizes the preliminary curve, and α and β are constants.

Journal ArticleDOI
TL;DR: A calibration curve and a pressure scale for the manometer are developed which will allow convenient application in other laboratories and an experiment which utilizes the technique is briefly disscussed.
Abstract: A method of accurately manipulating the pressure of helium gas in the range P=10−1 to 10−20 Torr, T<5 K is presented. The method requires only a very modest apparatus and makes use of thermodynamic measurements on the 4He–Grafoil system. A calibration curve and a pressure scale for the manometer are developed which will allow convenient application in other laboratories. An experiment which utilizes the technique is briefly disscussed.

Journal ArticleDOI
TL;DR: In this paper, a Laboratory Automation System (Hewlett-packard 3354 B) minimizes systematic errors in quantification problems when detector responses are not linear, using linear segmental interpolation.

Journal ArticleDOI
TL;DR: A method for quantitative determination of the major constituents in laterites and bauxites by x-ray fluorescence using fused Na2B4O7 glass discs is presented in this paper.
Abstract: A method for the quantitative determination of the major constituents in laterites and bauxites by x-ray fluorescence using fused Na2B4O7 glass discs is presented. The calibration curves were set up employing synthetic mixtures of oxides of Si, Al, Ti, and Fe. The interelement effects were corrected using a multiple regression analysis programed on a PDP 11/45 computer. The precision was determined by preparation and analysis of five synthetic pellets; the accuracy was ascertained by analysis of five international standards.

ReportDOI
01 Mar 1979
TL;DR: In this paper, a rotating electric field technique is employed to achieve real-time response and uniform cross-sectional measurement of the conductivity of the component in a two-phase flow.
Abstract: An instrument has been evaluated which permits volume fraction measurement of the conductivity of the component in a two-phase flow. A unique rotating electric field technique is employed to achieve real-time response and uniform cross-sectional measurement. A spool-piece sensor replaces a short pipeline section and causes no additional pressure drop. A reference conductivity measurement is incorporated to compensate for changes in the bulk conductivity of the conductive component caused by changes in temperature and the concentration of impurities in the flow medium. Testing of the instrument was performed over the full range (0-100%) of void fractions, in both horizontal and vertical attitudes, and instrument readings during steady state flow conditions were compared with directly measured liquid-fraction values, obtained using a quick-closing valve calibration method. The resulting calibration curves proved to be nearly linear. An error analysis indicates a +-5% variation in the mid-rance test results which can be attributed to unavoidable quick-closing valve sampling error, due to the existence of a high level of slug flow during testing at high velocity. In later tests, at lower velocities, th data scatter varied less than 1%. This instrument has been demonstrated to be an effective means for measuring relative volume fraction inmore » conductive two-phase flow.« less

Patent
28 Aug 1979
TL;DR: In this article, a method of least squares using more than two calibration points was proposed to find stable point (s) in the low energy region besides those two points of calibration.
Abstract: PURPOSE:To determine the gamma ray energy spectrum automatically, by using the output of multiple pulse height analyzer as the monitor. CONSTITUTION:When gamma rays are measured by Nal (Tl) scintillation detector and analyzed by a multiple pulse height analyzer, photo peaks of K-40 and Tl-208 appear clearly. However, if a channel to energy calibration curve is obtained from these two points alone, instability may be caused in the low energy region, the when the dose rate is determined by using the calibration curve, an error in the low energy region increases particularly. Instead, therefore, finding stable point (s) in the low energy region besides those two points of calibration, the channel to energy calibration is achieved by the method of least squares using more than two calibration points. Accordingly, a channel to energy calibration device is provided, and noticing that the channel to energy calibration curves A to D are all converged in one point E in the low energy region, this point E is used as the calibration point.

Journal ArticleDOI
TL;DR: In this paper, methyl stearate was used as an internal standard for the mass spectrometric quantitation of six structurally different compounds because of the limited availability of sample-like standards (labelled analogues, etc.).
Abstract: Methyl stearate was tested as an internal standard for the mass spectrometric quantitation of six structurally different compounds because of the limited availability of sample-like standards (labelled analogues, etc.). Based on the selected ion monitoring and integrated ion current techniques, satisfactory (correlation coefficient >0.99) calibration curves were obtained in all cases by plotting the log ratio of evaporated weights vs the log ratio of integrated ion currents (sample to standard). This indicates that the use of sample-independent standards instead of compounds closely related to the sample, provides a versatile and generally applicable quantitation technique with a precision better than ± 15% at the ng level.