Showing papers on "Calibration curve published in 1980"

Quantitative secondary ion mass spectrometry: A review

Abstract: Quantitative analysis in general aims at determining the value of a selected physical or chemical property of a given sample. With SIMS, in particular, the parameters to be determined are the concentration of a given element and also its distribution, both in depth and along the surface. Every measurement is affected by a given overall uncertainty due to statistical fluctuations in the measured signal and to systematic errors related to the experimental conditions. A discussion is devoted to the experimental conditions which influence the reproducibility of the measured signal and give rise to systematic errors, e.g. charging effects, matrix effects, selective sputtering and mass-dependent transmission, etc. The various methods used to derive the desired elemental concentration and its distribution in the sample from the raw measured data are evaluated, namely the use of calibration curves, relative sensitivity factors, fitting parameter methods and first-principle methods. Finally, the question is considered of how representative is the value determined from the (usually small) volume with respect to the composition of the bulk of the sample (sampling error).

Density Independent Moisture Meter at X-Band

Abstract: A new method of density independent moisture determination at one single frequency is developed. It is based on the two-parameter-measurement of the complex dielectric constant being composed to a density independent calibration curve A(?) which is a function of the moisture content ? only. The feasibility of this principle is demonstrated by an industrial moisture meter at 9 GHz for different materials and sensing heads.

Release wave calibration of manganin gauges

Abstract: A calibration curve for the response of commercial Manganin gauges upon unloading in plane dynamic experiments is presented. The data obtained from 18 plane impact experiments cover shock stresses in the 1.5–15 GPa range and involves various materials. The calibration curve was drawn through normalized data points. The normalization is based on the assumption that the ratio between resistances of the gauge at the shock and unloading states depends on the ratio of the respective stresses.

Kit for calibrating pipettes

Abstract: A pipette calibration kit containing a plurality of solutions, each of a predetermined concentration, which are used for plotting a calibration curve, and at least one reagent of a predetermined concentration which is used to replace an identical quantity of diluent in a predetermined volume of the diluent. The concentration of the reagent-diluent mixture is measured and the quantity of the reagent substituted for diluent in the reagent-diluent mixture, i.e., the volume of the pipette used to add the reagent to the diluent, is determined from the calibration curve.

Simple and specific high performance liquid chromatographic method for the routine monitoring of clonazepam in plasma.

Abstract: A simple, specific, and sensitive high performance liquid chromatographic (HPLC) method for the determination of clonazepam in plasma is described. The drug was extracted with chloroform at an alkaline pH using flunitrazepam as internal standard. The HPLC analysis was performed using a column packed with Spherisorb C6 reverse phase, the mobile phase being a solution of acetonitrile sodium acetate 0.1 M (40/60, v/v); the ultraviolet detector was set at 306 nm. The calibration curve was linear for plasma concentrations between 2 and 200 ng/ml-1 when 1 ml of sample was analyzed. Diazepam, its metabolites, and the most common antiepileptics did not interfere with the analysis. The coefficient of variation at the lowest concentration was 14%. With this method, clonazepam can also be used as internal standard for the determination of flunitrazepam. The performance of the column was still satisfactory after the analysis of more than 500 plasma samples.

Rate measurement analyzer

Abstract: A method and apparatus for the detection of the magnitude of selected chemical substances in a biological fluid by fixed rate analysis. Photometric analysis is performed sequentially upon a standard solution and then upon an unknown sample to determine the rate reaction in each. The method and apparatus minimize or eliminate error in equipment drift and calibration. The rate reaction is manually initiated in a standard solution carrying a known amount of a chemical substance. The standard is then placed into a photodetector circuit to produce a voltage representing optical density which increases at a constant but unknown rate during the reaction. The time required for the voltage to change from a base-line level to a selected and pre-set value is then measured and stored as a calibration reference time. Then, the rate reaction in the sample carrying an unknown amount of the chemical substance is initiated and the standard is replaced by the sample in the same photodetector circuit to produce a voltage representing optical density of the unknown sample. The voltage representing the optical density of the unknown sample increases at a constant but unknown rate and the rate is proportional to the amount of chemical substance in the sample. The voltage level at the end of the calibration reference time represents the change in the optical density of the unknown sample which, in turn, indicates the amount of chemical substance in the sample with respect to the standard sample. The voltage level is then provided to a display which indicates the amount of the chemical substance in the sample.

Trace element determination by capacitive discharge atomic absorption spectrometry

Abstract: Conventional instrumental analytical techniques require careful calibration of the instrument with chemically analysed standards or synthetic standards of known composition. When analyses of miscellaneous materials are required, providing the required range of standards becomes impossible. As a way to an absolute method of atomic absorption analysis, L'vov1 suggested using a capacitive bank as a source of electrothermal energy for heating graphite atomizers. We describe here a new analytical technique which uses a capacitor bank for electrothermal heating of an anisotropic pyrolytic tube atomizer in atomic absorption spectrometry producing very fast rates of heating and an isothermal condition, both in space and in time1,2, and uses a direct relationship: peak absorbance = constant × mass of analyte, thereby dispensing with analytical calibration curves. Sensitivity is almost independent of the matrix and matrix interferences are greatly reduced. Background correction is not required.

Simplified Determination of Cadmium, Lead and Chromium in Estuarine Waters by Flameless Atomic Absorption

Abstract: A simplified, sensitive and rapid method for determining low concentrations of cadmium, lead and chromium in estuarine waters is described. To minimize matrix interferences, nitric acid and ammonium nitrate are added for cadmium and lead; nitric acid only is added for chromium. Then 10, 20 or 50 μ1 of the sample or standard (the amount depending on the sensitivity desired) is injected into a heated graphite atomizer, and specific atomic absorbance is measured. Analyte concentrations are calculated from calibration curves for standard solutions in demineralized water for chromium or an artificial seawater medium for lead and cadmium. Analytical ranges (μg1−1) with two instruments were linear at 0.1-1.0 and 1.G10 for cadmium, 4-20 and lCb-100 for lead. and 0.2-5 and 5-100 for chromium. Detection limits (μg−1) were 0.1 for cadmium, 4 for lead and 0.2 for chromium. For cadmium (0.5 and 5 μg −1), lead (4 and 50 μgl−1) and chromium (1 and 10 μgl−1) in half-strength artificial seawater, the relative sta...

Optimized Mathematical Approximation of Calibration Curve for Size Exclusion Chromatography

Abstract: Calibration curves for several column systems were approximated by the first to fourth order polynomials and the errors arised from the misuse of the calibration equation were discussed. Approximation of the calibration curve for a linear column system as a straight line caused serious errors in the calculated molecular weight averages, especially of the polymers of narrow molecular weight distribution. Errors have also been arisen from the manual construction of a calibration curve. Most of calibration curves were approximated by the third order polynomial and some by the second and the fourth or the combination of the first and the second polynomials.

Method and device for the automatic calibration of an analog-to-digital converter

Abstract: For the automatic calibration of an analog-to-digital converter an analog calibration quantity is measured and the digital signal is compared with a digital calibration signal associated with the calibration quantity. A digital difference signal is applied to a register for influencing its counting capacity, while the register contents of pulses counted during the measurement also represents one of the parameters involved in the analog-to-digital conversion. Because of the fully digital character of the calibration, this calibration can be performed very rapidly and accurately.

Design Aspects of Scheffe's Calibration Theory Using Linear Splines.

Abstract: The measurement process uncertainty is propagated through the use of a calibration curve. The magnitude and direction of this uncertainty depends on the choice of the controllable variable in producing the calibration curve; in other words, the design of the calibration experiment. In this paper this design is discussed in the context of Scheffe's approach to the uncertainties of a calibration curve and in particular for the case in which the calibration curve is a linear spline. A class of appropriate designs is given, which depend on the location of the knots and the slopes of the segments. One of these designs is quickly calculable and can be found without a computer. Based on these results, a design approach is suggested for the case in which the knots are not known exactly.

Application of 14 MeV neutron activation analysis to the determination of Ce and Sm markers in biological materials

Abstract: The rare-earth elements are very suitable multiple particulate markers for the investigation of matter flow in the gastro-intestinal tract of animals by means of the indicator activation method. A rapid determination of cerium and samarium in biological samples is possible with the aid of a 14 MeV neutron generator. The activity of139mCe has to be corrected for the interferences of28Al and143mSm. For the determination of samarium the radionuclides155Sm and153Sm are used. In order to increase the specific activity of these nuclides, which are produced mainly by means of nuclear reactions with thermal neutrons, the samples are irradiated inside a polyethylene moderator block. The deviation from the linearity of the calibration curve for samarium is discussed.

Method for absorptiometric analysis analyzing

Abstract: PURPOSE:To measure the target element with good accuracy by using the standard solution containing the analysis target element and the contrast element of the concentrations at which the linear relations of the concentrations and absorbancies are always maintained when diluted, and subsequently diluting this and making the colibration curve CONSTITUTION:The standard solution containing 10ppm of A and 1ppm of B in the case when the relations between absorbancies and concentrations are shown by figure (a) and figure (b) respectively with respect to, for example, analysis target element A (Zn) and contrast element B(Ag) is prepared and while this is subsequently diluted, their respective absorbancies DA, DB are measured to obtain the calibration curve such as the one shown in figure (c) Next, the specimen solution containing A of an unknown amount (0-10ppm) is measured and from the absorbancy DA1 thus obtained, the imaginary absorbancy DB1 of the corresponding B is obtained by using the calibration curve Next, the concentration CA1 of A in the specimen solution is obtained by using the relations shown by general formula II [k is the concentration ratio of A to B (10 times) in the standard solution; m is the conversion coefficient of the concentration of B with respect to the absorbancy of B]