The reasons for the non-linearity of the standard curve for the calcium-cresolphthalein complexone reaction have been investigated. Calcium forms both 1:1 and 2:1 complexes with cresolphthalein complexone; at low calcium concentrations the 1:1 complex predominates and causes non-linearity. At high calcium concentrations the cresolphthalein complexone concentration becomes limiting, resulting in flattening of the calibration curve. It is recommended that two-point calibration of the assay be performed using a low calcium standard rather than setting on the baseline.
No takes yet. Share an insight, caveat, or question.
Corns et al. (1987) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: