Page 23 - Quality control of pharmaceuticals (07-PA 704)
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Fe3+ impurity, the error will be proportional to the sample size as the
impurity will increase by the sample size.
Example Proportional Error
Analyzing sample with impurities:
(1) Analyte conc is 50 ppm (true value), calculated amount is 55 ppm.
(2) Analyte conc is 500 ppm (true value), calculated amount is 550 ppm
For first case,
Absolute error = 55-50= 5 mg
Relative Error = (5 / 50) × 100 = 10%
For second case,
Absolute error = 550-500= 50 mg
Relative Error = (50 / 500) × 100 = 10%
relative error is constant
Random Errors in Chemical Analysis
Examination of the curve indicates the following facts:
Very large errors are unlikely to occur; while smaller errors occur with
great frequency.
Positive & negative errors are equally probable.
