Page 19 - Pharmaceutical Analytical Chemistry III

Example Constant Error

The effect of solubility losses: solubility loss of 0.5 mg of a
precipitate,
A precipitate of weight of 500 mg,
Absolute error = 499.5-500= - 0.5 mg
Relative Error (%Er) = (– 0.5 / 500) × 100 = – 0.1%
A precipitate of weight of 50 mg,
Absolute error = 49.5-50= - 0.5 mg
Relative Error (%Er) = (– 0.5 / 50) × 100 = – 1%

If the ppt amount is small, relative error is large