Testing calibration

Measuring surface crack depth is performed by calibration samples made of the same material like the object being tested. Calibration samples are the plates having narrow grooves like slits of various depth 0.2 mm, 0.5 mm, 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm and made by electric erosion method. The samples have dimensions 50 mm X 150 mm x 6 mm and 25 mmx 150 mm x 6 mm and are made of magnetic... 

The main purposes of the System of accreditation is to ensure reproducibility of measurements, harmonisation of rules and procedures of the National system of accreditation with guidelines of international organizations and national systems of different countries, creation of conditions for mutual recognition of the results of testing, calibration, attestation. 

We will explore the two major families of chemometric quantitative calibration techniques that are most commonly employed the Multiple Linear Regression (MLR) techniques, and the Factor-Based Techniques. Within each family, we will review the various methods commonly employed, learn how to develop and test calibrations, and how to use the calibrations to estimate, or predict, the properties of unknown samples. We will consider the advantages and limitations of each method as well as some of the tricks and pitfalls associated with their use. While our emphasis will be on quantitative analysis, we will also touch on how these techniques are used for qualitative analysis, classification, and discriminative analysis. 

To satisfy government agencies, instruments need to be adequately tested, calibrated, and/or standardized according to documented procedures. Current GLP standards state that equipment used in the generation, measurement, or assessment of data and equipment used for facility environmental control must be of appropriate design and capacity to function according to the protocol and shall be suitably located for operation, inspection, cleaning, and maintenance. 

J.L. Wise, P.K. Kammer, and J.A Murray, Post-test calibration of single-use, antimony, 24-hour ambulatory esophageal pH probes is necessary. Dig. Dis. Sci. 49, 688-692 (2004). 

It is always recommended that OQ is carried out after a service visit. Evidence of continued satisfactory performance during use (PQ) should be obtained from everyday method-related checks (e.g. system suitability testing, calibration and analytical quality control). It is advisable to set up thresholds outside of which the performance of an instrument is no longer acceptable. Each stage of the equipment qualification needs to be fully documented so that the evidence of performance at any given time can be checked. 

Accuracy is determined after a test calibration using one out of the four following ways. The difference between precision and accuracy is clearly shown in Figure 1. In the first case, if available, e.g., from the National Institute of Standards and Technology (NIST), reference samples (e.g., pharmaceutical in matrix) with defined true reference values are analyzed. Then true and measured values can directly be compared, but this case is rare. 

The second possibility is called cross-validation. The test samples are measured by a reference method. Howevep the reference method cannot provide true values because measurement error occurs here as well. Nevertheless, well-characterized methods can provide generally accepted values, which are then compared to the ones obtained using the test calibration. Note that this comparison must be done using particularly suited regression methods, because the error for both methods will be in the same order of magnitude. Especially, cross-validation of CE and HPLC has been frequently reported. 

What about the uncertainty of a measurement Are chents of the laboratories aware of quality issues and how they can interpret uncertainties given in a test/calibration report It seems that much more effort should be made to ensure an adequate understanding of such terms. 

Equipment used for the generation, measurement, or assessment of data shall be adequately tested, calibrated, and/or standardized."... 

Written records shall be maintained of all inspection, maintenance, testing, calibration, and/or standardizing operations."... 

The terms test, calibration, and standardization are interrelated. Each term has a special meaning, but there is some overlap of the terms. 

All aspects of a laboratory s program for the routine inspection, cleaning, maintenance, testing, calibration, and/or standardization of equipment must be in writing (i.e., SOPs, supplemented as necessary by equipment manuals). This would include a description of cleaning materials inspection, cleaning, and maintenance methods and schedules calibra-... 

Liddiard Jr, "The Small Scale Gap Test Calibration and Comparison with the Latge Scale Gap Test , NOLTR 66-87 (1966) 15) R.W. 

Donna Price T.P. Liddiard, Jr, "The Small Scale Gap Test Calibration and Comparison with the Large Scale Gap Test", NOLTR 66-87(1966), White Oak, Maryland [The SSGT, first described in 1952 by Dim-mock, Jr (Ref 26), has been used in its modified form, described in 1961 by Ayres (Ref... 

National Accreditation Board for Testing Calibration Laboratories... 

Equipment and its software used for testing, calibration and sampling should be capable of achieving the accuracy required and shall comply with specifications relevant to the testing and/or calibrations concerned. 

Written records shall be maintained of all inspection, maintenance, testing, calibrating and/or standardizing operations. These records, containing the date of the operation, shall describe whether the maintenance operations were routine and followed the written standard operating procedure. 

Finally, during the qualification of the facility, all systems are tested, calibrated, and cleaned. The mechanical and service infrastructure must be qualified. The operational qualification will involve practice runs. All documentation must be finalized. This includes standard operating procedures, batch records, and equipment logs. 

A certain mass flowmeter (see Section 6.2.3) was tested (calibrated) by comparing the readings given by the instrument G with true (known) values GT of the flow of a gas as measured by the instrument in a 0.15 m ID pipeline. True and measured values are compared in Fig. 6.61 and Table 6.17. Estimate the errors in the flowmeter due to bias and imprecision. Assume that variations in the input and output of the instrument are normally distributed. 

Testing/calibration equipment identification (e.g., traceable to national standards)... 

The pharmaceutical manufacturer is not normally represented at supplier factory calibrations but for critical items should consider an option to inspect instrumentation and witness tests. Calibration certificates referencing the test procedure and test equipment should be sought, particularly for the instruments and regulating devices directly associated with quality-related critical parameter measurements and control. 

Computer systems must be adequately inspected, tested, calibrated, and maintained. 

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