Automatic Method for the Determination of Calcium in the Presence of Magnesium and Phosphate Ions

[摘要] A direct spectrophotometric method for manual analysis of calcium using the indicator dye Eriochrome Blue S. E. was selected for automation. Most indicator dyes used have been somewhat unstable in solutions sufficiently alkaline to minimize the interference of magnesium. Eriochrome Blue S. E., when kept in an ice bath in the absence of light, permitted the use of sufficient alkali to remove interfering magnesium ions. Magnesium did not interfere in concentrations up to 12 mg./100 ml. when added to standards. The addition of 0.5% (w/v) citric acid removed interference of phosphate in concentrations up to 300 mg./100 ml.The automated method has the advantage of speed, yet retains the accuracy and precision of the conventional methods used for determining calcium.

[学科分类] 过敏症与临床免疫学