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DISCRETPAK™ REAGENTS - Carbon Dioxide (CO2)

Intended Use

For IN VITRO diagnostic use in the quantitative determination of Carbon Dioxide (CO2)  in serum using manual or automated applications.

Method Principle

In the presence of bicarbonate, phophoenolpyruvate carboxylase (PEPC) catalyzes the carboxylation of PEP to form oxalacetate. Oxalacetate is then quantitated via the MDH-NADH reaction with concomitant oxidation of NADH to NAD. The decrease of the NADH absorbance is monitored at 380nm and it is directly proportional to the concentration of bicarbonate in the sample. The reaction scheme illustrates the reactions that occur in this method.

                PEPC
Phosphoenolpyruvate + HCO ────────>Oxalacetate + Pi
                    Mg2+

                 MDH
Oxalacetate + NADH + H ────────>Malate NAD


Preparation Of Working Reagent

Catachem CO2 Reagent is prepared by adding exactly the volume of distilled or deionized water stated on the label.

Reagent Storage And Stability

Catachem CO2 Reagent is stored at 2-8°C. When stored as directed, the reagent is stable until the expiration date stated on the label. Store the CO2 Working Reagent at 2-8°C. When prepared and stored as directed, the Working Reagent is stable for 30 days in a tightly capped container and for 8 hours in an opened container.

Method Performance Characteristics

Sensitivity: The sensitivity of this method is 0.01 - 0.05 absorbance units per mEq/L.
Linear Range: In this method there is no significant nonlinearity over the range of 0.0 - 50 mEq/L.
Precision: Within-run and day-to-day precision is summarized below.

CO2

Within-Run Precision

Total Precision

MEAN

SD

CV

SD

CV

mg/dL

mg/dL

%

mg/dL

%

16.0

0.11

0.71

0.15

0.96

23.5

0.27

1.15

0.50

2.14

29.8

0.21

0.70

0.49

1.67


Correlation

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

Correlation Data

Parameter

Data Observed

N

122

Range

9.0 - 36

Regression

Y = 1.05x + 0.38

Correlation

  r = 0.977

Sy,x

1.23