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Showing papers on "Calibration curve published in 1996"


Journal ArticleDOI
TL;DR: It is expected that the use of this calibration method may help standardize flow cytometric measurements and will provide instrument-independent performance parameters to monitor quality control of instruments and reagents.
Abstract: Calibration of flow cytometers is becoming an increasingly important issue for both quality control of instrument performance and quantitation of antibody binding capacity of cells. Due to the numerous different instruments and analysis software currently available, a standardized method of calibration is necessary if interlaboratory comparison of instrument performance and antibody binding is to be achieved. This report describes a new methodology to obtain a standard calibration plot that can be derived from all instruments and from which specific instrument-independent performance parameters may be calculated that can be used to directly compare the performance and setup of these instruments. The requirements that the calibrated standards must meet are discussed, as well as the acceptable ranges proposed for the instrument-independent performance parameters. In addition, data are presented from standard calibration plots generated by different flow cytometers in numerous laboratories. The corresponding Primary Performance Parameters calculated from these plots are presented and compared. It is expected that the use of this calibration method may help standardize flow cytometric measurements and will provide instrument-independent performance parameters to monitor quality control of instruments and reagents. © 1996 Wiley-Liss, Inc.

139 citations


PatentDOI
TL;DR: A method and apparatus for measuring the concentration of an analyte present in a biological fluid is disclosed, which includes the steps of applying NIR radiation to calibration samples to produce calibration data and predicting analyte concentration of non-outliers from the calibration model.

137 citations


Journal ArticleDOI
TL;DR: In this article, the colorimetry of polymer-dispersed chiral nematic liquid crystal with different active temperature ranges were calibrated using four different trichromic representations of the liquid-crystal color.

128 citations


Journal ArticleDOI
TL;DR: The mass calibration remains accurate over a broad mass-to-charge ratio range (1–4 ku), even when the calibration curve is extrapolated several thousand mass units.

88 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used headspace solid phase microextraction (HS-SPME) for quantification of twenty chloro- and nitrobenzenes and -anilines spiked into soil samples.

82 citations


Journal ArticleDOI
TL;DR: In this article, the relationship between the precision of an analytical result and the analytical sensitivity and the linearity of the corresponding chemical calibration is established, and the simplified equation that is obtained makes it possible to rapidly estimate the standard deviation with a sufficient degree of freedom, even when few analysis replicates are available.
Abstract: The “in-line” and “on-line” linearity terms of a linear calibration are defined. “On-line” linearity, which is calculated from the standard deviation of the slope, is proposed as a performance characteristic for the analytical method. The relation between the precision of an analytical result, and the analytical sensitivity and “on-line” linearity of the corresponding chemical calibration is established. The simplified equation that is obtained makes it possible to rapidly estimate the standard deviation with a sufficient degree of freedom, even when few analysis replicates are available. An indication is also given of the suitable equation for a more accurate calculation. The use of the two linearities, both “in-line” and “on-line”, is discussed, concerning the determination of the linear calibration range, for those techniques with which curvatures are obtained when the concentration of the standard analyte exceeds a particular value.

69 citations


Patent
David E. Bockelman1
28 May 1996
TL;DR: In this paper, a set of calibration standards is used to solve for unknown network parameters of the calibration standards as well as error correction terms, and the network parameters are used to determine error terms for a network analyzer.
Abstract: A calibration technique (200) uses a set of calibration standards to solve for unknown network parameters of calibration standards as well as error correction terms. A set of standards provides an over-determined system of calibration equations having more calibration equations than unknown error terms (202). The additional calibration equations are used to solve for the unknown network parameters of the calibration standards (210). Once solved, the network parameters of the calibration standards provide a more accurate determination of error terms for a network analyzer (214).

66 citations


Journal ArticleDOI
TL;DR: In this paper, a tungsten coil atomizer, a miniature spectrometer/charge-coupled device combination mounted on a PC card, and a near-line background-correction method was used for lead detection.
Abstract: A compact, inexpensive atomic absorption spectrometer has been designed, constructed, and evaluated for the determination of lead at the μg/L level. The new device is made feasible by the combination of a reliable tungsten coil atomizer, a miniature spectrometer/charge-coupled device combination mounted on a PC card, and a near-line background-correction method. The finished spectrometer can be powered by a normal 12-V car battery, controlled with a laptop computer, and transported in any automobile. The overall dimensions of the original prototype system are 19 in. x 8 in. x 3 in. (excluding the computer), and it has no moving parts. The total estimated cost of the system including the computer is less than d6000. The limit of detection for Pb is 20 pg (20-μL sample volume), the linear dynamic range is two orders of magnitude, and the precision for the technique is 5% RSD at concentrations ten times greater than the detection limit. The accuracy of the technique was determined with the use of NIST SRM #1579a "Powdered Lead-Based Paint" containing 11.995 wt % Pb and NIST SRM 955a "Lead in Blood" containing 54.43 μg/dL Pb. The accuracy for the paint sample was 95.1% (11.41 wt % found) with the use of the calibration curve method (aqueous standards) and 97.2% (11.66 wt % found) with the method of standard additions. The accuracy for the blood sample was 93.5% (50.9 μg/dL found) with the calibration curve method and 96.6% (56.3 μg/dL found) with the method of standard additions. The limiting source of noise for the instrument is detector noise, so that the performance of the device can be improved by increasing the optical throughput of the system.

64 citations


Journal ArticleDOI
TL;DR: In this paper, a 12-bit analog-digital converter that receives analogue signals at −10 and +10 V and enables the electrical supply to the peristaltic pump to be interrupted is described.

62 citations


Journal ArticleDOI
TL;DR: In this article, W-coated diamond tips are used at a precisely controlled force of 70 μN, leading to a contact radius of 50 nm as determined from AFM analysis of the resulting imprints.
Abstract: Measurement of the carrier concentrations in silicon with lateral and in‐depth resolution on the sub‐100 nm scale has been demonstrated with an atomic force microscope (AFM) using conducting tips. The technique determines the local spreading resistance and hence inherits the attractive features of the conventional spreading resistance profiling (SRP) technique and will be referred to as nano‐SRP. For instance, the calibration curve established by measuring homogeneously doped substrates indicates a dynamic range of concentrations between 1014 and 1019 cm−3 and a monotonic relation between resistance and resistivity, similar to a conventional SRP calibration curve. In the present study, W‐coated diamond tips are used at a precisely controlled force of 70 μN, leading to a contact radius of 50 nm as determined from AFM analysis of the resulting imprints. The drastic reduction of the contact size implies that one can measure directly on a vertical cross section of the structure and overcome some limitations c...

60 citations


Journal ArticleDOI
TL;DR: In this paper, a new oxygen sensor has been developed based on luminescence quenching of cis-bis[2-(2-(thienyl)pyridine]platinum(II).
Abstract: The monitoring of the presence of oxygen in a variety of media has become of increasing interest, especially in relation to the modern necessity for effective and reliable environmental studies. With a view to extending the range of oxygen sensors available for this purpose, as well as reducing some of the problems inherent to the use of the existing ones, a new oxygen sensor has been developed based on luminescence quenching of cis-bis[2-(2′-thienyl)pyridine]platinum(II). This orthometallated complex has been selected as it displays a variety of desirable properties required for effective oxygen analysis. It is immobilized on a variety of polymer matrices and their suitability for this application then evaluated. A prototype sensor device has been constructed and calibrated and the signal-to-noise ratio (SNR) and power consumption optimized. With the objective of minimizing the number of reference points required for a reliable calibration plot, several different methods have been tested. One of these methods requires only two points and gives good calibration over the range (0–5) × 103 Pa oxygen partial pressure with a precision of 0.7% at 5 × 103 Pa. A precision of 0.3% at 21.2 × 103 Pa is achieved using a three-point calibration plot. The prototype construction also compensates to a certain extent for systematic instrumental drifts.

Journal ArticleDOI
TL;DR: In this article, the authors present practical and simple calibration procedures for the determination of major and trace elements that will allow one to adapt any mathematical model to any set of experimental data while producing the maximum accuracy in the final results.
Abstract: Different calibration procedures for the determination of major and trace elements by XRF analysis are presented and discussed. Empirical calibration curves comparing intensities with concentrations can be used for the analysis of samples with limited variations of the matrix composition. However, a general-purpose calibration procedure that is applicable to a larger variety of matrix types and covering wider ranges of the analyte concentration is usually more desirable. This paper presents practical and simple calibration procedures for the determination of major and trace elements that will allow one to adapt any mathematical model to any set of experimental data while producing the maximum of accuracy in the final results. It is also shown how to calculate from multi-element standards a practical intensity of the pure analyte, thus eliminating the requirement for a pure analyte specimen.

Journal ArticleDOI
TL;DR: In this article, the authors presented a new procedure for obtaining a full shear rate-shear stress flow curve for unstable slurries using the single bobbin Debex on-line viscometer, based on the use of a calibration algorithm which incorporates a correction for turbulent flow in the measurement vessel.

Journal ArticleDOI
TL;DR: In this article, a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI) method for quantification of cyclodextrins using 4-hydroxy-α-cyanocinnamic acid as a matrix was described.

Journal ArticleDOI
TL;DR: In this article, a calibration method for isotope dilution mass spectrometry is presented that fully accounts for nonlinearity of calibration functions, caused by the interference of the analyte on the m/z used for measurement of the internal standard and vice versa.
Abstract: A calibration method for isotope dilution mass spectrometry is presented that fully accounts for non-linearity of calibration functions, caused by the interference of the analyte on the m/z used for measurement of the internal standard and vice versa. In this way, it is also possible to use incompletely labelled molecules or analogues with a mass increment of only 1 u for isotope dilution, on condition that certain restrictions are respected. In addition, the proposed method is less time consuming than bracketing. The method works with the computer-stored full calibration curve and a single calibration point that is measured daily. The calibration curve is constructed from the experimentally determined mass spectral overlap between the unlabelled analyte and the labelled internal standard at the m/z values chosen for measurement. Measurement results for samples with unknown analyte concentration are calculated on the basis of a linear relationship between their ion abundance ratio and that of the daily single calibration point, but corrected by a factor derived from the theoretical calibration function. All calculations are performed with commonly available spreadsheet software. An application is presented for determining serum uric acid with a candidate gas chromatographic/ isotope dilution mass spectrometric reference method.

Journal ArticleDOI
TL;DR: In this paper, a preliminary data treatment was proposed to reduce the dependence on regression for multivariate calibration data, where a subset of samples from the calibration set that are closest to the unknown is selected for centering.
Abstract: Multivariate calibration models are constructed using measured responses of variables (e.g. spectra) on a set of calibration samples and values of a quantity of interest (e.g. concentration) measured by a reference method. The goal is to replace the reference method. Traditionally the calibration data are mean centered, which insures minimum average prediction error (for a prediction set having the same distribution as the calibration set). An alternative to this preliminary data treatment is presented. Instead of using the entire calibration set for centering, a subset of samples from the calibration set that are closest to the unknown is selected for centering. This preliminary data treatment reduces reliance on regression. Thus it is expected to perform well in cases where model errors are dominating or extrapolation occurs. The method is tested on data from near-infrared reflectance and infrared emission spectroscopy, showing that an average improvement of 20% in prediction accuracy is achievable. This method is fundamentally different from locally weighted regression because it uses the entire calibration set for the regression step.

Journal ArticleDOI
TL;DR: Although the structurally related codeine did not interfere significantly the results suggest that this method may be susceptible to matrix effects, dependent on the location of sampling from the process stream.
Abstract: A procedure for the determination of morphine in process streams by sequential injection analysis based on the chemiluminescence reaction of morphine with acidic potassium permanganate in the presence of sodium hexametaphosphate is presented. The chemiluminescence emission has been monitored using an in-house detection system which consisted of a fibre optic flowthrough cell and a sensitive, low dark current, photomultiplier tube. The calibration graph (range 2 × 10–8 to 1 × 10–4 mol/l) was not linear over the entire range of concentration, with a polynomial equation of best fit of y = 1.0 × 1015 x 3 – 2.2 × 1011 x 2 + 1.3 × 107 x – 8.3. The calibration function approximates linearity over the concentration range 2.5 × 10–6 to 3.0 × 10–5 mol/l where the slope of the log-log plot is 1.09 ± 0.16. The detection limit was estimated at about 10–8 mol/l from the response of the lowest calibration standard (2.5 × 10–8 mol/l) which gave a signal to noise ratio of 3 : 1. Although the structurally related codeine did not interfere significantly the results suggest that this method may be susceptible to matrix effects, dependent on the location of sampling from the process stream.

Journal ArticleDOI
TL;DR: A single capillary electrophoresis method was developed for both quantitative assay and determination of enantiomeric impurity in a pharmaceutical compound and found to give similar results.

Journal ArticleDOI
TL;DR: In this article, the authors discuss the validity of theoretical predictions, over a wide range of concentrations including high absorbance solutions, when a chopped continuous wave laser is used to irradiate the sample.


Patent
02 Oct 1996
TL;DR: In this article, a correction curve (fig. 19) is prepared by plotting 12 CO 2 concentrations and 13 CO 2/12 CO 2 concentration ratios, which are determined on the basis of a calibration curve and 13CO 2 and 12CO 2 absorbances of gaseous samples having the same 13 CO2 / 12 CO2 concentration ratio but known different 12CO2 concentrations.
Abstract: A correction curve (FIG. 19) is prepared by plotting 12 CO 2 concentrations and 13 CO 2 / 12 CO 2 concentration ratios which are determined on the basis of a calibration curve and 13 CO 2 and 12 CO 2 absorbances of gaseous samples having the same 13 CO 2 / 12 CO 2 concentration ratio but known different 12 CO 2 concentrations. A gaseous test sample containing 13 CO 2 and 12 CO 2 as component gases is introduced into a cell, and spectrometrically measured. A 12 CO 2 concentration of the gaseous test sample is determined by way of the spectrometric measurement. A concentration ratio correction value is obtained on the basis of the correction curve and the 12 CO 2 concentration of the gaseous test sample thus determined. A measured 13 CO 2 / 12 CO 2 concentration ratio is divided by the concentration ratio correction value thus obtained for correction of the 13 CO 2 / 12 CO 2 concentration ratio. Thus, the measurement accuracy of the concentration ratios of the component gases can be improved. A breath sampling bag and gas measuring system is also disclosed where each is configured such that breath inlets of the gas measuring apparatus are prevented from being respectively connected to the wrong breath introduction pipes of the breath sampling bag.

Journal ArticleDOI
01 Jan 1996-Analyst
TL;DR: In this paper, a method for the simultaneous determination of Cu, Ni and V in sea-water by HPLC is described, where the complexes of these metals with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)-phenol (5-Br-PAPS) are extracted with capriquat (trioctylmethylammonium chloride) in xylene and back-extracted into sodium perchlorate solution followed by separation and determination with an octade
Abstract: A method for the simultaneous determination of Cu, Ni and V in sea-water by HPLC is described. The complexes of these metals with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)-phenol (5-Br-PAPS) are extracted with capriquat (trioctylmethylammonium chloride) in xylene and back-extracted into sodium perchlorate solution followed by separation and determination by HPLC with an octadecylsilane column and spectrophotometric detection. The conditions of extraction and back-extraction such as, pH, concentration of 5-Br-PAPS or capriquat and concentration of sodium perchlorate are investigated. Linear calibration curve ranges, limits of detection and interferences owing to other ions in sea-water are presented. Application of this method to the trace analysis of Cu, Ni and V in sea-water is demonstrated.

Journal ArticleDOI
TL;DR: In this paper, a sensor calibration plan with the aim of reducing the calibration curve uncertainty is proposed, which is achieved by minimizing either the standard deviations of the regression curve coefficients or the standard deviation of the whole estimated calibration curve.

Journal ArticleDOI
01 Feb 1996-Talanta
TL;DR: In this article, a solid ion-pair material produced from ammonium tetraphenylborate (ATPB-naphthalene) provides a simple, rapid, economical and selective technique for preconcentrating iron from ≈ 500 ml of aqueous solution of standard alloys and biological samples.

Journal ArticleDOI
TL;DR: In this paper, organophosphorus, organochlorine and other electroncapture detection-sensitive pesticides were extracted from water in a single step using a C 18 solid-phase extraction cartridge, eluted with ethyl acetate and isooctane and determined by gas chromatography with electron-capture and flame photometric detection.

Journal ArticleDOI
TL;DR: In this paper, an automated method for the determination of carbendazim in water that combines high-performance immunoaffinity chromatography (HPIAC), highperformance liquid chromatography in the reversed phase mode, and detection by either UV-Vis diode array detector (DAD0 spectroscopy or mass spectrometry (MS) is presented.

Journal ArticleDOI
TL;DR: In this article, a fiber-optic sensor for oxygen gas and dissolved oxygen is reported. The sensor employs the quenching by oxygen of the fluorescence from a ruthenium complex trapped in a cage-like structure of a sol-gel derived porous thin film coated on a multimode optical fibre.
Abstract: A fibre-optic sensor for oxygen gas and dissolved oxygen is reported. The sensor employs the quenching by oxygen of the fluorescence from a ruthenium complex trapped in a cage-like structure of a sol-gel derived porous thin film coated on a multimode optical fibre. The light from a blue LED is modulated and used as the excitation source. The phase difference between the extremes of the measurement range (0 and 100% O2 in gas and ~0 ppm and water saturated with O2 (9 ppm) in liquid) is measured as a function of modulation frequency. The optimum frequency was experimentally found to be 75 kHz using a standard lock-in amplifier for phase detection. Using the optimum pulse frequency, the sensor calibration curves in gas and liquid toward oxygen were determined. The sensor exhibited excellent sensitivity and reversibility.

Patent
02 Oct 1996
TL;DR: In this article, a correction curve is prepared by plotting 12CO2 concentrations and 13CO2/12CO2 concentration ratios which are determined on the basis of a calibration curve and 13 CO2 and 12 CO2 absorbances of gaseous samples having the same 13 CO 2/12 CO2 concentration ratio but known different 12 CO 2 concentrations.
Abstract: A correction curve is prepared by plotting 12CO2 concentrations and 13CO2/12CO2 concentration ratios which are determined on the basis of a calibration curve and 13CO2 and 12CO2 absorbances of gaseous samples having the same 13CO2/12CO2 concentration ratio but known different 12CO2 concentrations. A gaseous test sample containing 13CO2 and 12CO2 as component gases is introduced into a cell, and spectrometrically measured. A 12CO2 concentration of the gaseous test sample is determined by way of the spectrometric measurement. A concentration ratio correction value is obtained on the basis of the correction curve and the 12CO2 concentration of the gaseous test sample thus determined. A measured 13CO2/12CO2 concentration ratio is divided by the concentration ratio correction value thus obtained for correction of the 13CO2/12CO2 concentration ratio. Thus, the measurement accuracy of the concentration ratios of the component gases can be improved.

Journal ArticleDOI
TL;DR: The proposed HPLC method with fluorometric detection for the analysis of granisetron in plasma is reproducible, selective, reliable, and sensitive, and its sensitivity is adequate for pharmacokinetic studies.

Journal ArticleDOI
TL;DR: The data indicate that this system is useful for rapid continuous-flow IRMS analysis of D/H ratios from organics in complex mixtures characteristic of geological and biological samples.
Abstract: Continuous-flow high-precision determination of D/H ratios from an organic mixture is described using gas chromatography coupled to a Pd filter system as an interface for isotope ratio mass spectrometry. A gas chromatograph and combustion and reduction furnaces are connected to a Pd filter via a postcolumn head pressure makeup gas to increase chromatographic sensitivity. This interface is evaluated using benzene as an internal standard in a mixture of ethylbenzene and cyclohexanone in hexane with analyte quantities of <3 ng (<300 pg of H). A calibration curve is constructed using four benzene samples over a range of −48 to 372‰ (δDSMOW), resulting in an average benzene D/H precision of SD <5‰ (δDSMOW) and deviations of <4‰ from the calibration curve. Ethylbenzene and cyclohexanone of a single D enrichment are analyzed as unknowns in three sample mixtures with varying D-enriched benzene and result in precisions of SD <5‰. No apparent memory is observed between peaks of differently enriched analytes within ...