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Updated: Aug 12, 2026

Measurement of Total Calcium in Neurons by Electron Probe X-ray Microanalysis
Published on: November 20, 2013
Evaluation of a new method for determining the total calcium concentration using diluted plasma and an ion-selective
A K Boetefür1, O Müller-Plathe
1Zentrallaboratorium des Allgemeinen Krankenhaus Altona, Hamburg, Germany.
Abstract:
A newly developed method for determining the concentration of total calcium in plasma, using an ISE in diluted samples, was evaluated. This method is available on the CX3-Delta analyser (Beckman Instruments, Fullerton, CA, USA). Linearity, within-run imprecision and between-days imprecision were good. Inaccuracy was within appropriate limits. The correlation with results from atomic absorption spectrometry (AAS) was excellent. Reliable results were obtained in patients with hyper- and hypoproteinaemia, hypermagnesaemia and hyperphosphataemia. Citrate above 1 mmol/l caused a severe negative bias, so that citrate plasma cannot be used for calcium determinations with this method. The stability of the measuring system as well as the handling of the CX3-Delta were excellent. The preliminary reference interval for the concentration of total calcium determined with the present ISE method, using data from 124 healthy participants, was 2.18 to 2.51 mmol/l.
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