Instant Notes: Analytical Chemistry

Note that Nin the denominator is replaced by N-1, which is known as the number of degrees of freedomand is defined as the number ...

Where replicate samples are analyzed on a number of occasions under the same prescribed conditions, an improved estimate of the ...

confidence interval, CI, and the upper and lower limits of the range as confi- dence limits, CL. Confidence limits can be calcul ...

Chloride/ppm Mean Estimated standard deviation 346 351.67 ppm 6.66 ppm 359 350 Using equation (6), and at the 95% probability le ...

Section B – Assessment of data B3 SIGNIFICANCE TESTING Significance tests involve a comparison between a calculated experimental ...

Separate tabular values for some significance test factors have been compiled for what are described as one-tailedand two-tailed ...

Inspection of the data suggests that 0.380 mg dm-^3 is a possible outlier. Qexptl=0.380 -0.401/(0.410 -0.380) =0.021/0.03 =0.7 ...

The application of a two-tailed F-test is demonstrated by the following example. Example 3 A proposed new method for the determi ...

t= ×N (^1) ⁄ 2 (3) x dbeing the mean difference between paired values and sdthe estimated standard deviation of the differences ...

As texptlis greaterthan ttabat both the 95 and 99% probability levels, there is a significant difference between the means of th ...

● additional random effects, described as random-effect factors; ● specific effects from determinate sources, described as contr ...

Section B – Assessment of data B4 CALIBRATION AND LINEAR REGRESSION Many quantitative analytical procedures rely on instrumental ...

Calibration dataare generally used to construct a calibration graph, where detector response is plotted on the ordinate axis (y- ...

r= (2) where x 1 y 1 ; x 2 y 2 ; x 3 y 3 ;....xn,ynare the co-ordinates of the plotted points, x _ and y _ are the means of the ...

mass or concentration of the analyte, it is necessary to draw a line of best fit through the plotted points before they can be u ...

Example A calibration graph was prepared as part of a validation procedure for a new method to determine an active constituent o ...

the detector response and the mass or concentration of the analyte more complex curvilinearor logarithmic regressioncalculations ...

Detailed calculations of the correlation coefficient, r, and the slope and intercept values have not been given, but should be s ...

percentage or fraction of the total. Internal normalizationis of particular value in quantitative chromatography where several c ...

Section B – Assessment of data B5 QUALITY CONTROL AND CHEMOMETRICS Control charts The purpose of a control chartis to monitor da ...