Continuing calibration verification

Rule 3. Continuing calibration verification must take place at regular intervals during... 

A continuing calibration verification standard at a concentration that is close to the midrange of the calibration curve may be prepared either from the same stock solution as the initial calibration standard or from a standard of a different source. This CCV standard is analyzed at a certain frequency throughout sample analysis. 

Initial calibration Initial calibration verification with a second source standard Continuing calibration verification... 

Initial and continuing calibration verifications and acceptance limits Raw data for each sample (including reanalysis and second column confirmation), blanks, LCS/LCSD, MS/MSD, and calibration standards Sample preparation bench sheets Gel permeation chromatography clean-up logs / (Summary only) ... 

Initial and continuing calibration verifications and acceptance limits S S (Summary only) ... 

Chemical Abstract Service calibration check compounds continuing calibration verification California Code of Regulations... 

Curves used in Conjunction with Continuing Calibration Verification Standards ... 

The sensitivity and other parameters of a quantitative method can change with time. Such changes can be sudden (as a result of, e.g., an electrical surge or a switch to a new batch of solvent) or gradual (reflecting, e.g., a drift in room temperature or deterioration of a column or accumulation of crud in an atmospheric pressure ionization (API) interface. Section 5.3.3). A continuing calibration verification standard (CCVS) consists of either a QC sample (an aliquot of control matrix spiked with a known amount of analytical standard if the calibration... 

Before a suite of samples can be analyzed, a set of protocols, similar in design to other U.S. EPA ICP-MS analytical procedures such as Method 200.8, must be followed to ensure the instrument is working at its optimum performance. A summary of these protocols is shown in Table 20.2. The analytical run sequence outlined should be performed on a daily basis in order to meet all quality control requirements. (Note The samples shown in the top portion [sequence 1-19] must be run once per sequence, while the 10 samples [sequence 20-22] and the final continuing calibration verification [CCV] and continuing calibration blank [CCB] samples must be repeated.)... 

Method 200.8 specifies a variety of quality control standards. The first of these are the ICV and ICB (initial calibration verification and blank, respectively) samples. These must be run immediately after calibration and must be prepared from an alternative source to the calibration solutions. This test is designed to check the accuracy of the calibration. The CCV and CCB (continuing calibration verification and blank, respectively) samples are a similar check... 

The process of field validation and testing of models was presented at the Pellston conference as a systematic analysis of errors (6. In any model calibration, verification or validation effort, the model user is continually faced with the need to analyze and explain differences (i.e., errors, in this discussion) between observed data and model predictions. This requires assessments of the accuracy and validity of observed model input data, parameter values, system representation, and observed output data. Figure 2 schematically compares the model and the natural system with regard to inputs, outputs, and sources of error. Clearly there are possible errors associated with each of the categories noted above, i.e., input, parameters, system representation, output. Differences in each of these categories can have dramatic impacts on the conclusions of the model validation process. 

An initial calibration verification standard should be measured after calibration and before measuring any sample. A calibration verification standard is a standard solution or set of solutions used to check calibration standard levels. The concentration of the analyte should be near either the regulatory level of concern or approximately at the midpoint of the calibration range. These standards must be independent of the calibration solutions and be prepared from a stock solution with a different manufacturer or manufacturer lot identification than the calibration standards. An acceptance criterion is set, usually as a maximum allowable percentage variation (e.g., 5%, 10%). The calibration can be continually verified using either a calibration standard or the initial calibration verification standard. Acceptance criteria must be set and action taken when results fall outside the limits (i.e., stop the analysis, investigate, correct the problem and rerun samples run between the verification standards that were not limits). 

The continuing calibration consists of two parts evaluation of the chromatographic resolution and verification of the RRF values to be used for quantitation. At the beginning of each 12-hour period, the chromatographic resolution is verified in the same fashion as in the initial calibration through the analysis of the CC3 solution on the DB-5 (or equivalent) column or through the analysis of the column performance solution on the SP-2331 (or equivalent) column. 

Analytical sample Any solution or media introduced into an instrument on which an analysis is performed, excluding instrument calibration, initial calibration verification, initial calibration blank, continuing calibration blank. The following are all analytical samples undiluted and diluted samples, predigestion spike samples, duplicate samples, serial dilution samples, analytical spike samples, postdigestion spike samples, interference check samples, laboratory control samples, preparation or method blank, and linear range analysis samples. 

After installation and qualification the instrument requires regular maintenance and calibration. The instrument should be maintained on a preventive maintenance plan and calibrated periodically according to a documented schedule. The schedule for preventive maintenance and performance verification/recalibration will depend on the instrument, its environment, and its function. The proposed U.S.P. chapter on NIR spectrophotometry [6] suggests that The purpose of instrument qualification is to assure that an instrument is suitable for its intended application and, when requalified periodically, it continues to function properly over extended time periods. Performance verification includes a validation based on a quality of fit to an initial scan or group of scans included in the instrument qualification.. . . With such testing, it is expected that reference standard spectra collected on a new or newly repaired, properly operating instrument should be identical to spectra of those standards collected over... 

Continue to invest in high-quality mouitoriug programmes to provide early warning of future changes and to provide long-term data sets for model calibration and verification. 

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