Analyst has no control on random errors but systemic errors can be reduced by following methods.
Calibration of apparatus: By calibrating all the instruments, errors can be minimized and appropriate corrections are applied to the original measurements.
Control determination: standard substance is used in experiment in identical experimental condition to minimize the errors.
Blank determination: By omitting sample, a determination is carried out in identical condition to minimize the errors occurs due to impurities present in reagent.
Independent method of analysis: It is carried out to maintain accuracy of the result e. g. Iron (III) is first determined gravimetrically by precipitation method as iron (III) hydroxide and then determined titrimetrically by reduction to the iron (II) state.
Parallel determination: Instead of single determination, duplicate or triplicate determination is carried out to minimize the possibilities of accidental errors.
Standard edition: This method is generally applied to physico-chemical procedures such as polarography and spectrophotometry.
Internal standards: It is used in spectroscopic and chromatographic determination.
Amplification methods: It is used when a very small amount of material is to be measured which is beyond the limit of the apparatus.
Isotopic dilution: It is used for the compound containing radio-active isotope.