Performance of an automatic calcium titrator for serum and urine calcium analysis

Abstract

For analysis of calcium, most clinical chemists choose either a kit method, an SMA 12/60 or an atomic absorption spectrophotometric (AAS) method. In this laboratory AAS is preferred but in routine screening, serum calciums are analysed on the SMA 12/60. A need exists in the clinical laboratory for a simple inexpensive instrument capable of analysing calcium quickly and accurately. Barnett (1973) considered that 14 out of 20 calcium kits studied were unsatisfactory. Recently, the Corning-EE1 Calcium Analyser Model 940 became available, and has been assessed in this laboratory. The method depends on the alkaline reaction of calcium and calcein to give a fluorescent product which is then titrated against EGTA. Titration stops automatically at a present level of fluorescence. Precision and accuracy compare well with SMA and AAS methods. Assay times are rapid: 60/h, or 5 min for a single test. The titrator is suitable for serum and urine. It is relatively cheap and simple to use. For analysis of calcium, most clinical chemists choose either a kit method, an SMA 12/60 or an atomic absorption spectrophotometric (AAS) method. In this laboratory AAS is preferred but in routine screening, serum calciums are analysed on the SMA 12/60. A need exists in the clinical laboratory for a simple inexpensive instrument capable of analysing calcium quickly and accurately. Barnett (1973) considered that 14 out of 20 calcium kits studied were unsatisfactory. Recently, the Corning-EE1 Calcium Analyser Model 940 became available, and has been assessed in this laboratory. The method depends on the alkaline reaction of calcium and calcein to give a fluorescent product which is then titrated against EGTA. Titration stops automatically at a present level of fluorescence. Precision and accuracy compare well with SMA and AAS methods. Assay times are rapid: 60/h, or 5 min for a single test. The titrator is suitable for serum and urine. It is relatively cheap and simple to use.