Specimen Collection & Preservation

• Collect sample using standard sampling tube. Serum or heparinized plasma can be used. Do not use citrate, oxalate or EDTA as anticoagulants. Avoid venous stasis.
• Calcium in serum/plasma is stable for 7 days at 20- 25C and for 21 days at 2 8C and 8 months at -20 C. Centrifuge samples containing precipitate before performing assay.

Calculations 

• Fully automated system automatically calculates the Calcium concentration of each sample.
• Results in mmo1/1= Results in mg/di x 0.25

Application Sheet

Refer to the application sheet for details. For additional system applications, contact our local Accurex representative. 

Calibration

For calibration it is recommended to use C.f.a.s or any other suitable calibrator material. 

Calibration frequency

Re  calibration is recommended

• Whenever the reagent lot is changed.
• As per the requirement of quality control procedures 

Each batch of AutoPure Calcium Arsenazo III is assayed with atleast six quality control sera- Precinorm  Precipath  Biorad 1 , Biorad 11 ,Accutrol Normal and Accutrol Abnormal prior to release.

Expected Values

Serum/Plasma

Adults : 8.6 -10.2 mg/dl (2.15 -2.55 mmol/l)

Note:

Expected range varies from population to population. It is therefore recommended that each laboratory should establish its own normal range. For diagnostic purposes, the calcium results should always be assessed in conjunction with the patients medical history, clinical examinations and other findings.

Performance Characteristics 

Linearity

With AutoPure Calcium Arsenazo III, the assay is linear upto 15 mg/dl (3.75 mmo1/1). Determine samples with higher concentrations via the rerun function. On instruments without rerun function, manually dilute samples with higher concentrations using 0.9% NaCI or distilled/deionized water (e.g. 1 + 2). Multiply the result by the appropriate dilution factor (e.g. 3). 

Interference 

There is no significant interference in samples containing upto 40 mg/dl of bilirubin and 1000 mg/dl of haemoglobin

Precision 

Reproducibility was determined using quality control sera as shown below:

 Co   Relation Studies

A comparison of the calcium determination using AutoPure Calcium Arsenazo III and AutoZyme Calcium Arsenazo III reagent gave the following co relation (mg/dl):

Linear Regression

• y = 0.949x+ 0.574
• r= 0.941
• Sy.x = 0.33

No of samples measured : 72

The sample concentrations measured were between 9 mg/dl and 12 mg/dl.

References

• Thomas L., Clinical Laboratory Diagnostics, 1st ed. Frankfurt : TH - Books Verlagsgesellschaft.,1998 :192 -202.
• Endres, D.B., Rude, R.K., Mineral and Bone Metabolism. In : Burtis, CA., Ashwood, E.R., editors. Tietz Textbook of Clinical Chemistry, 3rd ed. philadelphia : W.B. Saunders Company ;1999 : 1395-1457.
• Michaylova V., Ilkova, P. Photometric determination of micro amounts of calcium with arsenazo III. Anal. Chem. Acta, 1971; 53 : 194 -198.
• Bauer, P.J. Affinity and Stoichiometry of calcium binding by arsenazo III. Anal. Biochem.1981; 110 : 61 - 72.