Showing papers on "Calibration curve published in 1983"

Determination of linear fluorescence intensities from flow cytometric data accumulated with logarithmic amplifiers.

Abstract: Logarithmic amplifiers are useful in accumulating flow cytometric data with a large dynamic range. However, quantitative comparison of fluorescence intensities for different samples or different subpopulations within a sample is simplified by the conversion of data from log space back to linear space. A method is described in which fluorescent polystyrene spheres of differing intensities are used to construct a calibration curve for the logarithmic intensity scale. This allows calculation of relative linear intensity for each channel of the logarithmically accumulated data and determination of linear fluorescence means and coefficients of variation for comparative purposes. Fluorescent spheres of appropriate intensity may also be used as internal standards to monitor instrument and/or stain stability for samples accumulated using logarithmic amplifiers.

Random error in the CCS (cells connected in series) potentiometric method

Abstract: The dependence of the relative standard deviation (RSD) on the number of cells connected in series in the CCS potentiometric method [1] is discussed in detail. An example concerns the determination of Cu2+ ions with the use of the copper ion-selective electrode. Four cells have been applied. A significant decrease in RSD has been obtained as compared with conventional single cell potentiometry.

Cold Vapor Atomic Absorption determination of mercury by Flow Injection Analysis using a Teflon membrane phase separator coupled to the absorption cell

Abstract: A Flow Injection Analysis (FIA) procedure for the determination of trace amounts of mercury by the Cold Vapor Atomic Absorption (CVAA) method is presented. In order to make efficient use of the FIA technique, a new flow cell was developed to permit a rapid separation of elemental mercury from the carrier solution. The design of this device is based on the permeability of Hg 0 in commercially available Teflon (PTFE) tape, which acts as a membrane phase separator. The calibration curve is linear up to 70 ng.ml −1 ( A = 0.005 + 0.008 Hg(ng.ml −1 ); r = 0.9996) using a 15-cm open cell approach, with a detection limit of 1.4 ng. ml −1 (0.66 ng of mercury), considering a signal to noise ratio of three. The standard deviation is s = ±0.004 absorbance units, calculated at a level of 50 ng.ml −1 of Hg 2+ . The sampling rate was 110 samples per h.

Statistical evaluation of calibration curve nonlinearity in isotope dilution gas chromatography/mass spectrometry

Abstract: Instead of artificially transforming the data to a linear model for the isotope dilution mass spectrometry (IDMS) curve, a polynomial regression was desired to describe the relationship between isotope ratios and mole ratios. The described calculation procedure was tested by applying it to synthetic data generated by the basic IDMS equation and was compared with actual data from an IDMS study of Bromhexine, a mucolytic drug (C/sub 14/H/sub 22/N/sub 2/Br/sub 2/), and its trideuterated analog. The model was found to approximately describe the curvature of the calibration curve.

Modified calibration technique of a five-hole probe for high flow angles

Abstract: A new method is described for calibrating a five-hole probe for extending the useful measurement range up to flow angularities of 85°. The calibration method involves adjustment of the calibration coefficients to allow valid calibration at larger flow angles. The extended range calibration curves for flow angularity, total and static pressures are presented. The present range is valid in pitch only when the yaw ports are nulled.

Tissue photometry method and device, in particular for quantatively determining the blood oxygen saturation from photometric measurements

Abstract: The invention relates to a tissue photometry method and device, in particular for quantitatively determining the blood oxygen saturation from photometric measurements periodically obtained using a photometer having a monochromator. Hitherto it was possible to draw essentially only qualitative conclusions from photometric spectra. According to the invention, a first spectrum is extracted from the periodic signal sequence, a specified number of further spectra are chosen on the basis of a selectable quality criterion, a Fourier transformation of the spectr into the frequency space is undertaken and, on the basis of signals in the Fourier spectrum, the characteristic value of a test sample, in particular the blood oxygen saturation, is determined by comparison with a given calibration curve. The associated device and its evaluation circuit comprise at least one selection unit, a Fourier transformation unit and a signal selector.

Precision-dependent calibration in instrumental analysis

Abstract: Calibration as a basic operation for instrumental analysis has to provide the calibration function through which by mathematical inversion the analytical function is indirectly accessible. Generally, the precision of measurements is not constant in the entire measuring range, but dependent on the measuring quantity I. The corresponding variance is frequently described by s 0 2 (I) = β 0 2 + 1 2 I + 2 2 I 2, where the β-coefficients can be obtained by a so-called noise analysis. The calibration function has to be determined by a weighted regression with factor 1/s 0 2 . Admitted for selection are simple, but also non-linear functions with a few coefficients only, which are calculated so that the least possible scatter is to expect in the entire measuring range. For ‘wellfitting ’ functions, the ‘residual scatter’ is proportional to s 0(I) and not distinctly greater. — The weighting is demonstrated by way of two examples of elemental analysis: for the determination of La in aqueous solution by ICP-OES and for the determination of Zn in brass by XRF. Even if the weighting merely affects the calibration curve itself, its omission results partly in considerably large and partly in illusorily small analytical errors.

Quantitative Determination of Catalytic Surface Adsorption Sites by Fourier Transform Infrared Photoacoustic Spectroscopy

Abstract: The use of Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) as a method for quantitative analysis of surface adsorption site is demonstrated. Mid-IR information about the amount of adsorption is available with the sampling advantages of PAS: ability to analyze opaque materials with minimal sample preparation, qualitative information about both gas [CO(g)] phase and adsorbed [CO(ads)] species, a sealed sample environment for control of the gas phase in contact with the sample, and the ability to monitor in situ reaction kinetics. In this study a calibration curve is constructed for the amount of CO(g) in the sample cell with a silica internal reference. This calibration curve is utilized to calculate the amount of CO(ads) by subtraction on a catalytic surface where both CO(g) and CO(ads) exist at equilibrium. Using standard parameters from gas titration/volume uptake studies, the surface covered and the percentage of active sites on the surface are determined. This analysis combines the qualitative analytical capabilities of PAS with quantitative analysis, thus demonstrating another facet of the usefulness of FT-IR/PAS in addressing unusual problems.

Flow Injection Analysis of Mercury/Cold Vapor Atomic Fluorescence Spectrophotometry

Abstract: A new flow injection system for the determination of mercury by the cold vapor atomic fluorescence method is described. A sample solution (64 μ1) is injected into a stream of 0.1 M hydrochloric acid, which is mixed with a stream of 3% tin (II) chloride solution in a mixing joint. The combined stream is carried through a reaction coil for reduction of Hg (II) to Hg (0) and subsequently introduced into a specially designed gas-liquid separation vessel. Then the vaporized mercury is swept into a flow type fluorescence cell with a continuous flow of argon after removal of water in the gas phase through a condenser. Mercury is excited with an electrodeless discharge lamp as a source and the mercury fluorescence at both 184.9 and 253.7 nm is measured with a solar-blind photomultiplier. This method allows about 35 determinations of mercury in aqueous samples per hour. The calibration curve is linear over the 0–20 ppb range of mercury. The limit of detection (S/N = 3) is 0.008 ng (0.12 ppb × 64 μ1) and t...

Comments on calibration and design of a heat flow meter

Abstract: After a review of the calibration of two heat flow meter (HFM) transducers, the HFM has been redesigned. The new design produces a calibration independent of the characteristics of the material being tested; that is, it produces the same calibration curve for thick, low-density specimens as for thin, high-density ones. Calibration within +-1% of transfer standard accuracy is discussed; the HFM precision for thick specimens of low-density glass fiber appears to be higher than that of a guarded hot plate under the same testing conditions.

Diffraction Correction in Pulse-Echo Attenuation Measurements

Abstract: In the estimation of ultrasound attenuation in biological tissue, diffraction phenomena introduce bias due to their depth dependent filtering effect. The spectral h igh frequency c omposition is enhanced around the focal zone of a focused transducer (or in the far field of a plane transducer). this effect two approaches have been developed and compared: 1) The numerical calculation of the power spectrum of the roundtrip impulse response integrated over an i sochronous volume. The result gives the mean filter introduced by diffraction at a given roundtrip time. 2) An experimental calibration of diffraction is obtained by measuring a gated back-scattered signal coming from a narrow slice s lightly below the surface of a scattering test object, immersed in water. Calibration curves have been used to correct the running spectral moments and result in an important u nbiasing of the attenuation estimate. In order to understand, measure and correct

Quantitative examination of polyester-cotton by near-infrared photoacoustic spectroscopy

Abstract: Quantitative analysis of polyester - cotton has been conducted using near-infrared photoacoustic spectroscopy. Linear calibration graphs were obtained for mixtures of cotton and polyester; the linear regression coefficient for the cotton calibration graph was calculated to be 0.990 and that for polyester was 0.998.

Method of measuring consistency of viscous substance in small quantity

Abstract: PURPOSE:To easily permit measurement of consisting even with a small quantity of viscous substances by a method wherein the calibration curve is obtained by measuring reference samples with known consistency, a sample is put between two sheets of plates at least one of which is transparent, and then a given load is applied thereon for a predetermined time. CONSTITUTION:A small quantity of sample grease 3 to be measured is put on the center of a lower glass plate 2 using a microspatula or the like. An upper glass plate 1 is placed on the sample and then a weight 4 of ca. 1kg is put thereon. After holding them in this state motionless for a predetermined time, the weight 4 is removed and the diameter of a spread 6 of the sample grease on the glass plate 1 is immediately measured at two or more points. The average value of thus measured results is calculated. In this way, using several kinds of greases having different consistency, the reference curve is obtained based on the relationship between the average diameter of the spread and the consistency. Next, similar operation is carried out on a sample with not yet known consistency to measure the average diameter of spread of the sample. The consistency of the sample can be attained by comparing thus measured result with the calibration curve.

Method and apparatus for measuring partial pressure of oxygen and combustible gas

Abstract: PURPOSE:To enable the simultaneous measurement of oxygen and a combustible gas by providing a measuring electrode provided on one side of a solid electrolyte with a plurality of electrodes which attain a different equilibrium in a combustion reaction between oxygen and the combustible gas in a gas to be measured. CONSTITUTION:A standard comparison gas contacts the inside of a solid electrolyte 1 while a reference electrode 2 is provided on the surface thereof on the closed end side. A gas to be measured contacts the outside of the solid electrolyte 1 while electrodes 3 and 4 are provided independently. Signals from these electrodes are inputted into a potential measuring devices 5 and 6 to detect an electromotive force E1 and an electromotive force E2 between the electrodes 2 and 3 and 2 and 4 respectively. A calibration curve is prepared from electromotive forces obtained when the composition of the gas being measured is varied and set on an arithmetic unit 7 to compute the electromotive force obtained form unknown gas based on the calibration curve. Thus, partial pressures of oxygen and the combustible gas are obtained and shown on displays 8 and 9.

Determination of composition distribution of acrylonitrile-styrene copolymers by thin-layer chromatography

Abstract: Determination of chemical composition distribution of acrylonitrile-styrene copolymers was carried out by thin-layer chromatography (TLC). A mixture of benzene and methyl ethyl ketone gave the most suitable calibration curve of Rf values versus acrylonitrile (AN) contents, where a concentration gradient technique was applied for development. Average AN contents obtained by TLC are coincident with those found by elemental analysis. The copolymers extracted from ABS resins are sufficiently arranged in the order of breadth of composition distribution by using the data from TLC. The agreement between the composition distribution curve and that from the theory of copolymerization is good.

Method and apparatus for determination of sample homogeneity in scintillation counting

Abstract: A method for ascertaining radiochemical homogeneity in a liquid scintillation sample reliably identifies inaccurate geometries is disclosed so that meaningful activity counts can be determined. The novel method involves measuring the activity level of a set of homogeneous quench standard to obtain quench indicating parameter, or the Spectral Index of the External standard (SIE). The endpoint of each standard sample is computed allowing the formation of a table so that a calibration curve for each radionuclide of interest can be computed. The activity level of the unknown sample is then measured and the SIE determined so that an endpoint can be calculated. Finally, the theoretical endpoint obtained from a calibration curve is compared to the computed endpoint; if the computed endpoint of the sample deviates by more than 4% for tritium and 5% for higher energy radionuclides from the theoretical endpoint, the sample is considered to be nonhomogeneous or heterogeneous. An external standard-type liquid scintillation counting system is disclosed which automatically determines sample homogeneity, and it includes a microprocessor in its control system. The steps of the present invention and incorporated into the programmed steps for the microprocessor such that nonhomogeneous or heterogeneous samples are automatically identified on the readout of the system for an investigator.

Method and apparatus for measuring concentration of substance in liquid

Abstract: PURPOSE:To readily measure the concentration of a nonvaporizing substance in a liquid, by utilizing the fact that the vapor pressure of a vaporizing component in a liquid changes owing to the presence of a nonvaporizing substance. CONSTITUTION:Liquids containing a nonvaporizing substance at various concentrations are prepared, and a vaporizing component is added thereto until a predetermined concentration by volume is obtained, thereby to prepare test liquids. The vaporizing component concentration of the test liquids is measured under predetermined conditions by employing a tube method to obtain the calibration curve between the concentration and the vapor pressure of the vaporizing component beforehand. When the concentration of a nonvaporizing substance in a liquid 7 to be measured is actually measured, a vaporizing components is supplied into the liquid 7 from a supply device 11. By a system 1-6 for a tube method employing a carrier gas, the sensitivity to the vaporizing component is calculated in an arithmetic unit 23 from an output signal with respect to the concentration of the vaporizing component in the liquid 7, thereby allowing the concentration of the nonvaporizing substance in the liquid 7 to be made known from the calibration curve and the like stored in a memory 24.

Compensating method of calibration curve

Abstract: PURPOSE:To compensate simply a calibration curve with high precision, by comparing the measured value of absorbance of a sample having known concentration with the absorbance to the concentration obtained from the calibration curve in case a compensation is given to the calibration curve of the absorbance to the density. CONSTITUTION:A compensation is given to a calibration curve A which is formed by absorbances y1-y6 obtained by measuring 6 samples having known concentrations x1-x6. For this purpose, a sample of concentration x6, for example, is measured to obtain absorbance y'6. Then a ratio alpha=y'6/y6 is obtained to the absorbance y6 and then multiplied by absorbances y1-y5 to obtain absorbances y'1-y'5. These absorbances y'1-y'5 are connected to each other to form a compensated calibration curve B. Just one measuring frequency suffices to simplify the compensation of the calibration curve with high accuracy.

Total Body Potassium Determination Using a Whole-Body Counter

Abstract: A scanning bed whole-body counter with two NaI(Tl) scintillation detectors was used for total body potassium determination with 40K for clinical application. For the calibration an in vivo dilution technique with 42K was used. The present counting method effectively minimised effects of redistribution and body build. For routine use the (W/H)1/2 calibration curve is suggested instead of the more complicated individual 42K calibration.

Optimal multicomponent analysis using the generalized standard addition method

Abstract: The authors present a commonly used undergraduate experiment in multicomponent analysis which has been modified to include the standard addition method, thereby eliminating the need for multiple calibration curves.

Fluorine in Twenty‐Two International Reference Rock Samples and a Compilation of Fluorine Values for the USGS Reference Samples

Abstract: Fluorine in 22 international reference samples has been determined with an ion selective electrode following fusion with a Na2bCO3-ZnO mixture To eliminate the effect of fluorine complexes in the solutions, the results presented are means of fluoride determinations from a standard calibration curve and from the method of standard addition Together with these new determinations an updated compilation of USGS-I reference samples is presented

Novel static cold vapour atomic-absorption method for the determination of mercury

Abstract: A static cold vapour procedure for the determination of mercury by atomic-absorption spectrometry using a very simple and inexpensive apparatus is described. The mercury-laden air is forced into the absorption cell by water displacement. Maximum sensitivity is obtained when the volume of the displaced air is equal to the internal volume of the absorption cell, and the mercury solution is 9 M in sulphuric acid. The peak absorbance exhibited a marked decline for hydrochloric acid concentrations above 1.5 M and for nitric acid concentrations above 3 M. The calibration graph obtained for mercury(II) in 9 M sulphuric acid is linear from 0 to 17 ng ml–1, and the sensitivity is 0.08 ng ml–1. A windowless absorption cell can also be used with a narrower linear calibration range. The detection limit was found to be 0.08 ng ml–1 for both cells with and without end windows.

Development and performance of an automatic hydride/mercury system

Abstract: All operations of this system are automatically and sequentially controlled by a programmer. The calibration curve is obtained by using only one standard solution. The optimal operating parameters were found for arsenic, bismuth, lead, antimony, selen, tin and mercury. The sensitiveties and detection limits of these elements are 0.15, 0.04, 0.24, 0.05, 0.05, 0.10, 0.11 and 0.1, 0.01, 0.1, 0.02, 0.04, 0.03, 0.03 ng/ml respectively. The RSDs are lower than 4% for all elements. This system was evaluated with 35 samples of various marine products, sediment and effluent.