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DISCRETPAK™ REAGENTS - Calcium (II)

Intended Use

For IN VITRO diagnostic use in the quantitative determination of Calcium in serum using manual or automated applications.

Method Principle

The serum sample is mixed with the Calcium Working Reagent. The total free Calcium reacts with Arsenazo III at 25 ˚C and a pH of 6.5 to form a purple-colored complex with maximum absorbance at 650 nm. The increase in absorbance of the purple-colored complex is directly proportional to the concentration of Calcium in the sample. The reaction scheme below illustrates the reaction that occurs in the method.

pH 6.5
2 Arsenazo III + Ca2+ ────────> Ca2+-Arsenazo Complex


Method Performance Characteristics

Sensitivity: The sensitivity of this method is 0.01 - 0.05 absorbance units per mg/Dl.
Linear Range: In this method there is no significant nonlinearity over the range of 2.0 - 20 mg/dL.
Precision: Within-run and day-to-day precision is summarized below.

Calcium

Within-Run Precision

Total Precision

MEAN

SD

CV

SD

CV

mg/dL

mg/dL

%

mg/dL

%

2.30

0.00

0.00

0.22

8.40

12.60

0.00

0.00

0.18

1.40

20.40

0.13

0.64

0.36

1.80


Correlation

A comparison of this method using an automated analyzer and a reference method based upon the Arsenazo III reaction resulted in the following regression statistics.

Correlation Data

Parameter

Data Observed

N

106

Range

7.5—15.3

Regression

Y = 0.965x + 0.35

Correlation

  r = 0.992

Sy,x

0.17