Standard deviation calibration plot

For internal quality control, urine from a known MPS patient and a solution containing chondroitin sulfate (50 pg/ml) are used. Results for urine and the artificial control should not exceed 3 standard deviations when plotted over time if it does, the test has to be repeated. In addition, absolute absorption values, the slope of the calibration curve, and the coefficient of variance (CV) of duplicates have to be within certain limits defined by the laboratory. 

Figure 3.166 Calibration function using the internal standard procedure. Plot area of the sample/area of the internal standard (ISTD) against concentration in the sample. The dotted lines indicate two standard deviations calibration precision.

For the basic evaluation of a linear calibration line, several parameters can be used, such as the relative process standard deviation value (Vxc), the Mandel-test, the Xp value [28], the plot of response factor against concentration, the residual plot, or the analysis of variance (ANOVA). The lowest concentration that has been used for the calibration curve should not be less than the value of Xp (see Fig. 4). Vxo (in units of %) and Xp values of the linear regression line Y = a + bX can be calculated using the following equations [28] ... 

Samples that are advanced to the next level of the screen are selected on the same basis as the calibration those inhibiting at least 80% of the tumor cells within two to three standard deviations from the mean for a one-run set. Figure 8.4 shows a typical "scatter plot" for 3680 compounds tested in a run set. The mean inhibition for all the compounds screened was 7.7%. The horizontal bars represent the standard deviations above and below that mean. The 105 compounds deemed "active" (shown by the bold bar in the... 

STL s quality-control programme includes the recovery of known additions of analyte, analysis of externally supplied standards, calibration, analysis of duplicates and control charting. Each analyte is monitored by analysing at least one AQC standard for every 20 samples. AQC results are plotted on control charts and action is taken if a point Hes outside +3 standard deviations (SD) or if two consecutive points He outside +2 SDs. 

The pure spectrum plot for component B with a 2 standard deviation uncertainty band is shown in Figure 5.35. The width of this band can be used to assess the quality of the estimated pure spectrum. The uncertainties are very small, indicating that the spectrum of pure component B is well determined by the calibration data. The same is observed with the other two components (not shown). 

DISCUSSION. Figure 10.11 shows the separation of a group of gases from blood. The procedure described depends on complete equilibration between the gas and liquid in the syringe. The period to achieve equilibration depends on the gas, and can be as little as 1 min for acetone and as much as 30 min for sulfur hexafluoride. Linear calibration curves can be obtained when peak height is plotted against gas concentration for either the flame ionization or electron capture detector. The reproducibility (n = 10) for ethane gave a standard deviation of 23% of the mean concentration while it was 2.3% for halothane and 1.8% for ether. 

Figure 7.3 represents the stripping curves and the corresponding calibration plot (inset) for lead obtained for a iacc of 60 s and a 7strip of 1 pA. Each point in the calibration curve corresponds to the mean of three parallel measurements performed consecutively in the same cell without polishing the electrode. The error bars are the standard deviations of these measurements. Possible changes of graphite-epoxy electrode surface in contact with solution should have the effect of repeatability of the response. A DL of approximately 200 ppb of lead was determined... 

A typical CC-measurement procedure (for a pH-sensitive LAPS structure) is depicted in Fig. 6.3. From the raw data material of the CC-mode measurement of all measurement spots under the pH-sensitive layer, a calibration plot can be derived. For example, for the above example, an average pH sensitivity of 54.2 mV/pH with a standard deviation of 0.5 mV/pH between the different measurement spots can be calculated. This initial calibration measurement allows furthermore the determination of different measurement parameters, e.g., the hysterisis, overall drift, stability, selectivity and the influence of external disturbances such as light and temperature. These parameters are important to evaluate the performance of the complete LAPS-based measurement system. 

Fig. 11 t-DLR-based pH imaging of several independent samples simultaneously, a Surface plot of a sensor array contained on the bottom of the wells of a microtiter plate (8 x 12 wells). The wells were filled with buffer of defined pH to obtain 12 independent data points for each pH. The acquisition time was 800 ms. b Calibration plot R versus pH of the f-Dl.R pH sensor. The error bars represent the standard deviation of the 12 wells [18]... 

As mentioned earlier, an appropriate constant amount of labeled compound is spiked to each of the calibration standards. The RR at each concentration is determined which is then plotted against the concentration to prepare a calibration curve. The RR of the analytes in the sample (or sample extract) are matched in the linearity range of the calibration curve to determine their concentrations. If the ratio of the RR to concentration is constant (<20% relative standard deviation) over the calibration range, an averaged ratio may alternatively be used instead of the calibration curve for that compound. 

Note that some of the instruments tested were pre-calibrated by the manufacturer, others were cahbrated on a standard procedure basis using fresh formazin calibration standards. The performances of the latter were consistently verified with fresh formazin standards. The instrumental mean and standard deviations of all turbidimeters tested compared with the nominal values of formazin standard solutions are plotted in Fig. 2. 

For the determination of nitrate, use a 1 dram vial with a polyethylene stopper (Kimble No. 60975-L) as a reaction vessel. Introduce a 0.20ml aliquot of aqueous sample into the vial, followed by 1.0ml of thiophen free benzene. Catalyse the reaction by addition of 1.0ml of concentrated sulphuric acid. Shake the vial for lOmin. Remove the benzene layer immediately from the reaction vial with a Pasteur pipette, place it in a separate vial and analyse by gas chromatography with electron capture detection for the nitrobenzene concentration generated. Treat standard solutions of potassium nitrate in the same manner to generate a standard calibration plot relating nitrobenzene concentration to peak height. If higher precision is desired (approximately 4% relative standard deviation), add 2,5-dimethylnitrobenzene to the benzene prior to reaction. 

Standards were prepared by injecting known amounts of freshly distilled vinyl acetate into 1.00 mL of solvent. Calibration curves were obtained by injecting 5.0-yL aliquots of standards and diluted standards into the gas chromatograph and plotting the peak areas versus concentrations. These calibration curves were linear over the range of 5-5000 yg/mL. The precision for replicate injections of a standard at 5 yg/mL was 3 relative standard deviation. 

In Figure 2, a composite calibration curve for seawater is reproduced. This curve is based on the response obtained for spike additions of 1.0, 2.5, 5.0, and 10 ng Hg to different 100-ml seawater samples analyzed over three weeks. The number of spikes making up this composite graph are 3, 19, 20, and 9, for the 1.0-, 2.5-, 5.0-, and 10-ng mercury additions, respectively. The average value for each addition was plotted, and the brackets indicate the standard deviation. The precision of analysis reported as a coefficient of variation for these spike additions is 30% at 5 ng Hg/L, 20% at 10 ng Hg/L, 15% at 25 ng Hg/L, and 10% at 50 ng Hg/L... 

Figure 8-11 Effect of calibration curve uncertainty. The dashed lines show confidence limits for concentrations determined by the regression line. Note that uncertainties increase at the extremities of the plot. Usually, we estimate the uncertainty in analyte concentration only from the standard deviation of the response. Calibration curve uncertainty can significantly increase the uncertainty in the analyte concentration from to. s, as shown.

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