Duplicate analysis

Construct a precision control chart using the following 20 ranges, each determined from a duplicate analysis of a 10-ppm calibration standard... 

The following data were obtained for the duplicate analysis of a 5.00-ppm N03 standard... 

Baurin, N., Baker, R., Richardson, C., Chen, I., Foloppe, N., Potter, A., Jordan, A., Roughley, S., Parratt, M., Greany, P., Morley, D., Hubbard, R. E. Drug-like annotation and duplicate analysis of a 23-supplier chemical database totalling 2.7 million compounds. J. Chem. Inf. 

Sample 3, duplicate analysis Treated sample, replicate 1 0.110... 

To establish the level of selenium on and in the peel of selenium-sprayed apples, samples were collected from five commercial Jonathan apple orchards and eight commercial Delicious apple orchards by representatives of the packing warehouses and submitted to the laboratory for analysis. The sampling and analytical procedure used for these samples was identical to that used for the samples reported in Table II. Sufficient fruit was available for duplicate analysis of most of the samples. 

Figure 6.24 compares the amounts of solvent required to analyze 24 compounds for solubility determination employing a four-point calibration and duplicate analysis when traditional HPLC and... 

FIGURE 6.24 Amount of solvent needed for solubility determinations employing HPLC and /iPLC (24 compounds, 4-point calibration curve, duplicate analysis). 

Standard deviation (based on duplicate analysis) are given in parentheses. 

Internal quality control (IQC) is one of a number of concerted measures that analytical chemists can take to ensure that the data produced in the laboratory are of known quality and uncertainty. In practice this is determined by comparing the results achieved in the laboratory at a given time with a standard. IQC therefore comprises the routine practical procedures that enable the analyst to accept a result or group of results or reject the results and repeat the analysis. IQC is undertaken by the inclusion of particular reference materials, control materials , into the analytical sequence and by duplicate analysis. 

Internal quality control is undertaken by the inclusion of particular reference materials, called control materials , into the analytical sequence and by duplicate analysis. The control materials should, wherever possible, be representative of the test materials under consideration in respect of matrix composition, the state of physical preparation and the concentration range of the analyte. As the control materials are treated in exactly the same way as the test materials, they are regarded as surrogates that can be used to characterise the performance of the analytical system, both at a specific time and over longer intervals. Internal quality control is a final check of the correct execution of all of the procedures (including calibration) that are prescribed in the analytical protocol and all of the other quality assurance measures that underlie good analytical practice. IQC is therefore necessarily retrospective. It is also required to be as far as possible independent of the analytical protocol, especially the calibration, that it is designed to test. 

Here the concept of statistical control is not applicable. It is assumed, however, that the materials in the run are of a single type. Carry out duplicate analysis on all of the test materials. Carry out spiking or recovery tests or use a formulated control material, with an appropriate number of insertions (see above), and with different concentrations of analyte if appropriate. Carry out blank determinations. As no control limits are available, compare the bias and precision with fitness-for-purpose limits or other established criteria. 

Mean area of chromatographic peaks for a duplicate analysis of the tablet extract ... 

SOZ, NO3, NH4 mass concentration - One-half of each Nuclepore filter was analyzed by Environmental Research and Technology, Inc. (ERT), Westlake Village, California. Their laboratory determined the masses of aerosol sulfate and nitrate on each filter by liquid ion chromatography and ammonium by colorimetry. Based on duplicate analysis of samples and standards the uncertainty in the various determinations per filter were ... 

Figure 4.11. Shewhart means plot of the duplicate analysis of a certified reference material, twice per day for 20 days. Each point is the mean of the day s four results. Warning limits (UWL and LWL) are at the global mean 2xs/i/4 and control (action) limits (UCL and LCL) at the global mean 3xs/ /4, where s is the standard deviation of all the data.

The entire process is made even more complex by the duplicate analysis of all positive samples and by the use of security measures that are necessary at all stages in order to avoid errors, particularly in view of the impact of such results. 

Each application allows the use of eight independent channels that depending on the procedure can be used to perform individual or duplicate analysis. For instance, in the OTA application the default setting of the software permit to dedicate two channels for the blank measurement and two channels for each of the three calibrators or samples whereas in the OPs protocol the user can utilize single channel or multiple channels. In each application, a check biosensor option is available to test the correct functioning and positioning of the sensors. 

USA Illinois Illinois No. 6 bituminous USA Illinois Illinois No. 6 bituminous duplicate analysis... 

In routine tests of environmental samples, many repeat analyses of a sample aliquots are not possible. Therefore, the precision of the test required is measured by a scale known as relative percent difference (RPD). This is determined from the duplicate analysis performed under identical conditions on two aliquots of one of the samples in a batch. It is calculated by dividing the difference of test results by the average of test results and expressing as percent. Thus,... 

Precision control charts may, alternatively, be constructed by plotting the RPDs of duplicate analysis measured in each analytical batch against frequency of analysis (or number of days). The mean and the standard deviation of an appropriate number (e g., 20) of RPDs are determined. The upper and lower warning limits and the uppper and lower control limits are defined at 2 and 3.v, respectively. Such a control chart, however, would measure only the quality of precision in the analysis. This may be done as an additional precision check in conjunction with the spike recovery control chart. 

Sometimes for convenience, and to enable homogeneity testing to be completed in a practical timeframe, one or two representative analytes are selected as markers for homogeneity and undergo full testing as described above. Spiking concentrations of the remaining analytes are checked by duplicate analysis. 

Thompson, M., and Howarth, R. J. (1976). Duplicate analysis in geochemical practice. Analyst 101, 690-709. 

The chemical analyses carried out are indicated in Table 15.1. Analytical results produced by the Bagnoli SpA underwent quality controls through use of internationally recognized control standards and duplicated analysis of 5% of the samples at random. Duplicate analysis of 5% of the samples were performed at the British Geological Survey Laboratories. 

In order to provide information on the precision of the analysis in the sample matrix, the laboratory must perform a duplicate analysis on one sample of each matrix in each SDG. The samples to be analyzed in duplicate may be specified by the Region in advance however, if no samples are so specified, the laboratory must select a sample of each matrix for duplicate analyses. The precision of the analysis is determined as the relative percent difference of the concentrations as specified in Section 14. 

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