Showing papers on "Calibration curve published in 1977"
TL;DR: Measurements of parotid saliva showed that it was possible to analyze fluoride concentrations as low as 4 ng F/ml with good reproducibility and that a 150 μl sample is sufficient for fluoride determination with high accuracy.
Abstract: A simple and accurate technique for the determination of fluoride (F-) in capillary-sampled blood is presented. The method is based on the known addition-slope determination technique using the fluoride electrode. No calibration curve or calibration of the electrode is required. A standard deviation of 1.3-5.6% in the range 300-10 ng F/ml was given by 259 duplicate determinations on human plasma. Measurements of parotid saliva showed that it was possible to analayze fluoride concentrations as low as 4 ng F/ml with good reproducibility. The results also show that a 150 microliter sample is sufficient for fluoride determination with high accurary. This method can easily be used in clinical laboratory.
79 citations
TL;DR: In this paper, the applicability of differential pulse anodic stripping voltammetry to thin-layer electrodes is demonstrated with PbZ+, CdZ+, Zn2+, CuZf, and TI'.
Abstract: The applicability of differential pulse anodic stripping voltammetry to thin-layer electrodes is demonstrated with PbZ+, CdZ+, Zn2+, CuZf, and TI'. Typical calibration curves are linear over a range of 30 to 600 ng/mL with a detection limit of 10 ng/mL. Samples of blood, soybean, and oyster were analyzed for lead. The elimination of interferences in anodic stripping due to the Cu-Zn intermetallic compound is illustrated using a twin-electrode thin-layer cell in which Cu and Zn are deposited on separate electrodes. The utility of differential pulse voltammetry of drugs is shown with diazepam for which the calibration curve is linear over a range of 1 to 60 pg/rnL with a detection limit of 0.1 pg/mL. Measurements were performed on 60 1L of solution.
50 citations
TL;DR: In this article, a Varian AA-6 spectrophotometer was used to evaluate the precision of atomic absorption measurements and applied to 8 elements, and it was shown that there are many similarities in the precision characteristics of different elements.
Abstract: Procedures for evaluating the precision of atomic absorption measurements have been improved and applied to 8 elements. Measurements on a Varian AA-6 spectrophotometer indicate that there are many similarities in the precision characteristics of different elements. For instance, analyte absorption flicker noise limits the measurement precision of most elements at moderate absorbances. The actual value of the measurement precision at a given absorbance and the dependence of measurement precision on absorbance depend upon the calibration curve, the wavelength of analysis, the integration time, and the type of flame employed.
39 citations
TL;DR: In this article, the uncertainties resulting from the use of the gravimetric method, with a linear correlation between count rates and water content of soil samples, are considered first, and the determination of errors in the values of water content and count rates, and to the difficulties arising from the choice of the correlation technique are given.
37 citations
TL;DR: In this paper, a method for developing a GPC calibration curve for a polymer where only broad molecular weight distribution samples are available is described, and results of applying the procedure to poly(n-lauryl methacrylate) are presented.
Abstract: A novel, precise, and simple method is described for developing a GPC calibration curve for a polymer where only broad molecular weight distribution samples are available. The method demands a GPC calibration curve for another polymer (e.g., polystyrene) and measurement of the intrinsic viscosity and an average molecular weight for each of several samples of the broad molecular weight distribution polymer in addition to GPC measurements on those samples. Results of applying the procedure to poly(n-lauryl methacrylate) are presented.
33 citations
TL;DR: In this article, a new quantitative X-ray diffraction technique was developed by examining the theoretical basis of X ray diffraction originally outlined by Alexander and Klug, which is based on the assumption that all components are identifiable and are to be analyzed for, and avoids the use of internal standards, calibration curves, or mass absorption coefficient measurements.
Abstract: A new quantitative X-ray diffraction technique has been developed by examining the theoretical basis of X-ray diffraction originally outlined by Alexander and Klug. The new technique is based on the assumption that all components are identifiable and are to be analysed for, and avoids the use of internal standards, calibration curves, or mass absorption coefficient measurements.
32 citations
TL;DR: Gel permeation chromatography (GPC) was combined with flow time measurements on the eluent to provide both the distribution of hydrodynamic volumes and distribution of intrinsic viscosities in linear polymers.
Abstract: Gel permeation chromatography (GPC) was combined with flow time measurements on the eluent to provide both the distribution of hydrodynamic volumes and the distribution of intrinsic viscosities in linear polymers. Standard polystyrene samples were used to establish a universal hydrodynamic volume calibration as well as the zone spreading and viscometer transfer line tailing parameters. Viscometry data are particularly helpful in establishing the zone spreading parameters and the calibration curve at very high molecular weights. The results were applied to measurements on samples of linear polybutadiene and polyvinyl acetate. Agreement between values of Mw from GPC with those obtained by light scattering confirmed the universal calibration principle.
30 citations
26 citations
Patent•
01 Feb 1977
TL;DR: In this article, an improved multiple ratio single particle counter is presented, where the intensities of scattered radiation are measured at more than two angles and ratios of these intensities are derived.
Abstract: The present invention is an improved multiple ratio single particle counter. Intensities of scattered radiation are measured at more than two angles and ratios of these intensities are derived. These ratios are compared with calibration curves to determine an unambiguous measure of the particle parameter.
24 citations
TL;DR: A novel approach to sample deposition in furnace atomization is suggested, which obviates the need for skilled application of microvolumes by syringe and Precision approaching that of flame atomization systems is achieved and concentrational sensitivity may be increased simply by extending the deposition time.
23 citations
TL;DR: In this article, five approaches to the determination of trace amounts of lead, bismuth, thallium, selenium, tellurium, and silver in iron and nickel-based alloys were investigated.
TL;DR: In this paper, the effects of externally applied pressure on the analytical characteristics of absorbance signals derived from analyte atomization in a heated graphite atomizer have been examined, and a specially constructed graphite furnace fitted with a pressurizable housing allowed studies to be carried out under pressures up to 13 atm of inert gas.
TL;DR: A method for calculating radioimmunoassay standard curves, based on the theory of Ekins et al., is described, and it could be shown that the model gave significantly better results than did two simpler ones.
Abstract: A method for calculating radioimmunoassay standard curves, based on the theory of Ekins et al., is described. Because a four-parameter model is used, nonlinear standard curves are the result. The calibration curve is fitted to the measured standard points by means of a weighted least-squares method. The program based on this model can be easily processed on a desk-top calculator. For all 250 runs of six different assays, very good standard curves could be obtained. The mean deviation between the concentrations of the standard points and the corresponding calculated values was about 6%. In 26% of the cases it could be shown that the model we describe gave significantly better results than did two simpler ones.
TL;DR: In this paper, a pH-dependent electrode obtained by thermomoulding a mixture of powdered antimony and a thermoplastic polymer is shown to be highly reproducible and reliable.
TL;DR: In this paper, PIXE is applied to the sera of nephritic patients in order to perform a study of changes in concentrations of trace elements in their sera.
TL;DR: In this paper, it was shown that with sufficiently long column lengths and flow rates, accurate molecular weights of both narrow and broad molecular weight distribution samples are directly calculable from the chromatogram without the need for peak spreading corrections.
Abstract: Using general-purpose multicolumn sets, it was found that separations could be increased by increasing analysis time, either by decreasing flow rate or increasing column length. Several examples are shown illustrating the influence of these system variables. The generation of linear calibration curves over extended molecular weight ranges is discussed. In particular, the desirability of using high molecular weight standards to extend the calibration curve and eliminate extrapolation of the curve is shown. Not using all available gel porosities, i.e., gapped column sets, is shown to be detrimental to the resolution of molecular species. It was found that with the use of sufficiently long column lengths and flow rates, accurate molecular weights of both narrow and broad molecular weight distribution samples are directly calculable from the chromatogram without the need for peak spreading corrections.
12 Sep 1977-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: In this paper, an electron microprobe is used to analyze single particles to determine their chemistry and identify them, and the bulk chemistry of the dust can be obtained in a similar manner by analysing large numbers of particles simultaneously.
Abstract: Information is also required as rapidly as possible from a single preparation so that many samples may be analysed on a routine basis. This paper will outline how this information can be obtained by using an electron microscope analysis system. With such an instrument, dust particles of all sizes may be observed and their size and shape obtained, while the electron microprobe may be used to analyse single particles to determine their chemistry and identify them. The bulk chemistry of the dust may be obtained in a similar manner by analysing large numbers of particles simultaneously. By using the chemical data obtained from single particles and also the bulk chemistry of the sample, the mineral composition of the dust may be computed. A measure of the mass of dust being analysed can be obtained from a measurement of the X-ray count rate obtained during bulk analysis, measurement of the incident electron-beam intensity and reference to an instrument calibration curve.
TL;DR: In this article, a method for the determination of ammonia and hydrogen sulfide in aqueous solution is presented, which involves the use of a gas-permeable membrane which isolates the piezoelectric crystal device from the solution yet allows the desired gases to pass.
TL;DR: The approach described may be used to characterize the specificity of an analytical method when the calibration curve is linear and the presence of an interferent causes a parallel shift of the curve or changes its slope but not its shape.
TL;DR: In this article, the design and operating characteristics of a circuit suitable for accurate calibration of the frequency dependence of marginal oscillator detectors used in ion cyclotron resonance spectroscopy is discussed.
Abstract: The design and operating characteristics of a circuit suitable for accurate calibration of the frequency dependence of marginal oscillator detectors used in ion cyclotron resonance spectroscopy is discussed. The results of calibration curves determined from this ’’Q‐spoiler’’ circuit are compared with an empirical ’’chemical’’ calibration of the marginal oscillator. The excellent agreement between these two methods indicates the Q‐spoiler circuit can give accurate relative frequency calibration of the marginal oscillator over the frequency range 100–1000 kHz.
TL;DR: An ion micro-analyzer (Cameca IMS 300 with a TD 1000 computer unit) has been calibrated for quantitative point determination of fluorine in apatites, including tooth and bone material, and is effective down to about 20 ppm F.
Abstract: An ion micro-analyzer (Cameca IMS 300 with a TD 1000 computer unit) has been calibrated for quantitative point determination of fluorine in apatites, including tooth and bone material. Samples with macroscopically measured F concentrations were used as external standards. The samples were bombarded with O− primary ions. Secondary positive ion currents were registered as mass spectra containing mass numbers 19, 20, 31, 44, 59, 60 and 61. The latter mass numbers were used in isotopic correction to subtract oxide and hydroxide contributions from the fluoride 59 peak. For each bombarded spot, the ratios19F+/40Ca2+, respectively59CaF+/44Ca+, were plotted in a log-log graph against40Ca2+/44Ca+, the abscissa providing a measure of ionization efficiency. The plots yielded two sets of parallel straight lines, with ordinate values proportional to the respective F/Ca concentration ratios, in agreement with earlier theory. Each set of lines constitutes a calibration graph, where the fluorine concentration at an investigated spot is obtained when substituting the measured ion current ratios. With biological apatites, account must also be taken of effects due to, among other things, adsorbed humidity, other contaminations, and non-stoichiometry. When all precautions are taken, the accuracy of the determined F contents in the point analysis of an area some 100 μm in diameter can be expected to be better than 6% at 1500 ppm F, and better than 25% at 100 ppm F. The calibration is effective down to about 20 ppm F. Applications have been carried out on samples of human tooth enamel.
TL;DR: In this paper, a simple method to calculate average molecular weights and D (≡Mw/Mn) value from the GPC chromatogram of copolymerization products, especially for ethylene and polypropylene copolymers, was investigated by simulation technique.
Abstract: A simple method to calculate average molecular weights and D (≡Mw/Mn) value from the GPC chromatogram of copolymerization products, especially for ethylene–propylene copolymerization products, was investigated by simulation technique. The method is based on the use of the calibration curve determined by the average ethylene content of the products. In addition to this method, the calibration curve prepared for polypropylene was also applied to determined the D value. Average molecular weights and D values were determined, with small errors, for narrow distribution samples with respect to molecular weight and chemical composition.
IBM1
TL;DR: In this paper, a precise and rapid method of measuring the mass thickness of pure element films using the LAMA Program to generate calibration curves by the fundamental parameters method is described, where only thick (bulk) pure element standards are required thereby eliminating the necessity of preparing thin film standards.
Abstract: A precise and rapid method of measuring the mass thickness of pure element films using the LAMA Program to generate calibration curves by the fundamental parameters method is described. Only thick (‘bulk’) pure element standards are required thereby eliminating the necessity of preparing thin film standards. The accuracy is comparable to routine interferometry. A table giving the intensity ratios of the thin film to the corresponding thick standard is given for eighteen common elements and a thickness range of 500–100 000 A, making it possible to apply the method without use of a computer.
TL;DR: A computer method for calculating the calibration curve for emulsion-covered glass plates used to interpret densities of lines for quantitative spectrographic work is reported.
TL;DR: In this paper, a universal calibration curve for polystyrene, polydimethylsiloxane and polymethylphenylsiloxide was obtained by means of a combination of the GPC and viscometric methods.
Abstract: An universal calibration curve for polystyrene, polydimethylsiloxane and polymethylphenylsiloxane has been obtained by means of a combination of the GPC and viscometric methods. The MWD of polydimethylsiloxane has been determined by use of the universal calibration curve and this is compared with the MWD obtained by high speed sedimentation in the ultracentrifuge.
TL;DR: In this article, the absorbance of different contents of Li, Be, Sr, Ba, Ti, V, Cr, Co, Ni, Cu, and Zn in four artificial matrices representing ultrabasic, basic, intermediate, and granitic rock composition was measured and compared with a calibration curve of the respective element dissolved in H 2 O + HCl only.
TL;DR: In this article, a simple, simple, sensitive, and reliable determination of parts per billion (ppB) levels of chloride ion is described for high purity water or heavy water of pressurized and high temperature reactors, steam generators, and cooling systems by mercurous chloride-mercuric sulfide ion selective electrode.
Abstract: A rapid, simple, sensitive, and reliable determination of parts per billion (ppB) levels of chloride ion is described for high purity water or heavy water of pressurized and high temperature reactors, steam generators, and cooling systems by mercurous chloride-mercuric sulfide ion selective electrode. The method has been applied to heavy water samples of CANDU-type nuclear reactors as well as to the water of conventional steam generators. The manual method consists of treating 100 ml aliquots of standard solutions and water samples with 1 ml 2M HNO/sub 3/. A calibration curve is constructed from the millivolt readings obtained in the standard solutions, and chloride ion concentration of the samples is determined by comparing the mv reading of the sample with the calibration graph. The automated and computerized version provides all operations automatically, together with a direct printout of the concentration and indexing. The electrode displays near-Nernstian response for the range 0.05-3.500 ppM chloride and can be used for concentrations as low as 0.02 ppM. Comparative tests and coefficients of variation are highly satisfactory.
TL;DR: In this article, a field calibration procedure for the AGA 680 Thermovision system is described, which is necessary because there are numerous uses of a thermovision systems for which the standard calibration curves supplied by the manufacturer are inadequate.
Abstract: In this paper a field calibration procedure for the AGA 680 Thermovision system is described The procedure is necessary because there are numerous uses of a thermovision system for which the standard calibration curves supplied by the manufacturer are inadequate These uses include measurements with bandpass filtered optics, as well as measurements of radiance In effect, the system may be calibrated so that it serves as a field radiometer