Comparison of standardization techniques for colorimetric analyses on a centrifugal analyzer

The influences of the mode of standardization and the type of standard on the precision of four mechanized methods performed on a centrifugal analyzer are described. Experimental results show that the mode of standardization -- variable, using a standard in each analytical batch, and constant, using a direct relationship between concentration and absorbance -- must be objectively selected. If the variable mode is chosen, the type and level of standard must be carefully chosen and absorbance of assays of the standard must be carefully monitored for good quality control. It is recommended that the optimum standardization technique and standard, where applicable, should be assessed and subsequently documented in evaluations of methods, kits and instruments.