Evaluation of a kit for the colorimetric determination of inorganic phosphate.

An evaluation of a colorimetric kit method for the determination of inorganic phosphate (Pierce Phosphorus Auto/Stat Kit) is described. The within-batch and between-batch precisions were shown to fulfil current criteria, and recovery experiments, linearity studies, analyses of quality control materials, and studies of possible interfering substances evidenced good accuracy. Comparison of the results obtained on samples from patients with those obtained by the vanadate/molybdate continuous-flow method showed that the test method had a comparative positive bias. The use of a calibration reference serum as standard is recommended. The kit method is technically simple, requiring no protein precipitation, and analyses can be performed rapidly.