Calibration calibrator

Systematic error, as stated above, can be eliminated— not totally, but usually to a sufficient degree. This elimination process is called calibration. Calibration is simply a procedure where the result of measurement recorded by an instrument is compared with the measurement result of a standard. A standard is a measuring device intended to define, to represent physically, to conserve, or to reproduce the unit of measurement in order to transmit it to other measuring instruments by comparison. There are several categories of standards, but, simplifying a little, a standard is an instrument with a very high accuracy and can for that reason be... 

Calibration. In general, standards used for instrument calibration are physical devices (standard lamps, flow meters, etc.) or pure chemical compounds in solution (solid or liquid), although some combined forms could be used (e.g., Tb + Eu in glass for wavelength calibration). Calibrated lnstr iment parameters include wavelength accuracy, detection-system spectral responsivity (to determine corrected excitation and emission spectra), and stability, among others. Fluorescence data such as corrected excitation and emission spectra, quantum yields, decay times, and polarization that are to be compared among laboratories are dependent on these calibrations. The Instrument and fluorescence parameters and various standards, reviewed recently (1,2,11), are discussed briefly below. 

There are three imknowns, K, a and. One might question the availability of Mark-Houwink constants for the polymer in the open literature. Mark-Houwink constants in the literature differ widely for the same polymer and it is difficult to decide on the correct pair to employ. Another problem which can arise is that the universal molecular weight calibration curve may not apply exactly for the polymer in question. The use of the true Mark-Houwink constants would therefore introduce an error in the molecular weight calibration. Calibration with a broad MWD standard should eliminate this error. The Mark Houwink constants obtained in the calibration would in this instance be effective rather than true values. 

As part of maintenance, some equipment may need to be calibrated. SOPs must include calibration methods, and a report format needs to be available at the time of calibration. Calibration SOPs must include pass/fail specifications as well as corrective actions to be taken in the event of calibration failure. For quality calibration standards use National Institute of Standards and Technology (NIST) traceable standards or other intrinsic standards of known purity, quality, and stability. These standards should have certificates attesting to their performance properties. After calibration, the metrologist or other responsible person should review the calibration reports to identify any issues with the equipment that may need further attention. 

The application of PSA measurements for clinical monitoring of prostatic carcinoma requires fine tuning of PSA assays. One important aspect of this tuning is to have well-defined standards (primary calibrators). Calibrators or primary reference materials consisting of PSA complexed with ACT have been prepared and are available to sponsors of commercial immunoassays. As a result of this, some sponsors have studied calibration stability and have shown that calibration did not change within 14 to 90 days. Primary references of 90 percent PSA-ACT and 10 percent f-PS A have been shown to minimize differences in PSA measurements between different assays [NCCLS Document—Primary Reference Preparations Used to Standardize Calibration of Immunochemical Assays for Serum Prostate... 

A technique for the determination of free cupric ions in seawater has been described by Sunda and Hanson [332], The method is based on sorption of copper onto Sep-Pak Cis cartridges and internal free cupric ion calibration. Calibration is accomplished by adding cupric ion buffers and EDTA, which competes with natural organic ligands for copper complexation. The method was used to establish that 0-2% of the copper occurs as inorganic species and 98-100% occurs as organic complexes. 

The french standard makes no reference concerning the olfactometer calibration. Calibration will certainly be carried out with methane analyzed by a flame ionization detector. 

Quality controls are single procednres that are performed in conjnnction with an analysis to help assess the snccess of the analysis in a qnantitative manner. Examples of qnality controls are blanks, calibration, calibration verification. 

Step 7 On-line analyzer calibration Calibrating an analyzer entirely on-line is a last resort, for reasons discussed in Section 15.2.6. It is preferable to do at least the initial work to calibrate the analyzer off-line, or to transfer to the on-line analyzer a method developed on an off-line analyzer or on another on-line analyzer. However, sometimes this is not possible. On-line analyzer calibration is similar to standard analytical chemistry method development, except that getting sufficient variation in sample composition to build a robust calibration model may be difficult or may take a long time. (Ways to address the challenges involved in on-line calibration are discussed in Section 15.2.6 and in Chapter 14.)... 

Define Quality Control, Quality Assurance, sample, analyte, validation study, accuracy, precision, bias, calibration, calibration curve, systematic error, determinate error, random error, indeterminate error, and outlier. 

Bennet, A., Gartelmann, D., Mason, J.l. and Owen, J.A. (1970) Calibration, calibration drift and specimen interaction in autoanalyser systems. Clinica Chimica Acta 29, 161-180. 

Document metrological traceability. This requires identification of all CRMs used as calibrators, calibration certificates for equipment, and a statement of the measurement uncertainty of the measurement result. The metrological traceability chain is thus established. 

Mass Assignment. It is performed using specific MS calibrants. Calibrants should be well-characterized reference materials. Certification and handling of these... 

Resolution is also affected by the actual time that ions spend in the quadrupole. Ions that have higher kinetic energy have shorter residence time and lower resolution. Reducing the kinetic energy typically leads to an improvement in resolution. A dramatic change in resolution may cause a shift in the instrument calibration. After adjusting the resolution, it is necessary to check the calibration (calibration verification), and if it is noted that the difference between the predicted and actual mass values have shifted, the instrument should be recalibrated. 

The name of the calibrator, calibration date, and the date of the next calibration must be recorded. This information must be maintained by a designated individual(s) and must be readily retrievable for each piece of hardware requiring calibration. 

Before analysis may start, the instrument must be calibrated. Calibration is the process of standardizing an instrument s response in order to perform quantitative analysis. 

The calibration mode selected by the laboratory should also be carefully considered, i.e. standard additions, calibration curve and/or use of bracketing standards. All calibration methods suffer from typical sources of error or drawbacks, e.g. for standard additions non-linearity of the calibration curve, extrapolation difficulties, chemical form of calibrant added, etc. for external calibration (calibration curve) changes of the matrix affecting the linearity of the curve for bracketing standards time-consuming procedures for many routine laboratories, etc. (Quevauviller et al., 1996a Quevauviller, 1998b). 

Calibration Calibration entails the adjustment of a measurement device so that the value from the measurement device agrees with the value from a standard. The International Standards Organization (ISO) has developed a number of standards specifically directed to calibration of measurement devices. Furthermore, compliance with the ISO 9000 standards requires that the working standard used to calibrate a measurement device be traceable to an internationally recognized standard such as those maintained by the National Institute of Standards and Technology (NIST). 

In 1987, Chasseur assayed cimetidine granules. This was the first reported use of a synthetically produced extended range for calibration calibration samples were produced with a range of content from 70 to 130% of label. In 1987, Osbomet used NIR to assay for nicotinamide in vitamin premixes. 

Calibration. Calibration by three independent methods gave good agreement. The first calibration was made by the manufacturer of the crystal elements, by measuring the electric charge produced when the pressure on the element was suddenly reduced. A similar static calibration was made on the complete gage imits. 

Calibration Calibration solutions +/- Matrix effect, work outside linear range of the detector Reagents of suitable purity and stoichiometry where necessary verification of stoichiometry and purity of calibrants different calibration methods when possible calibration graphs, matrix-matched calibration solutions and standard additions. 

Type of calibrant +/- Calibrant not adapted Same remarks as for destructive methods additional care to be given to the stability on irradiation of the calibrant... 

A systematic difference was observed by one laboratory between two different sets of calibrants (calibrant solution made with a newer calibrant from the same producer). This highlighted the need to thoroughly verify the calibrant, i.e. not to rely on calibrants from one producer of which the quality could vary from one set to another. Most of the laboratories actually used their own calibrants, which were not verified for purity and stoichiometry. Only one laboratory used the calibrant previously verified and distributed in the first interlaboratory study [8]. It was stressed that calibration was an important issue and that more efforts should be put on the verification of calibrants in future exercises. It was agreed that the coordinator of the project would purchase calibrant from a chemical company and establish its purity sets of verified primary calibrants would then be made available to participants in a further exercise to characterise their own calibrants. 

A method performance study may also be used to evaluate the performance of a new analytical method or an automated form of an already existing method [1,19]. Under certain circumstances a method performance study may be called intercalibration study. This should only concern exercises where the calibration of methods is investigated e.g. studies on calibrants, calibrant solutions, calibration procedures etc. Such studies are more frequent in physical measurements for metrological purposes. 

Calibration is one of the oldest scientific activities. In order to measure something, a proper standard to measure against is needed. Even the ancient land surveyors in Babylonia and Egypt calibrated. Calibration is the use of empirical data and prior knowledge for determining how to predict unknown quantitative information Y from available measurements X, via some mathematical transfer function [Martens Naes 1989],... 

Multivariate calibration Calibration in which multiple independent variables are used to establish the calibration model. (Section 5.2) Nested factor In multiway ANOYA a factor that is varied separately for each level of another factor. (Section 4.8)... 

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