Rev. Date: 01-Aug-11 Art: 714181-00L pH - 3
Precision Data
Aqueous Control Mean SD %CV
Level 1 7.165 0.005 0.08
Level 3 7.656 0.003 0.04
Method Comparison
Radiometer Nova Radiometer
IL BGE ICA 1 STAT Profile 5 ABL500
n 62 47 57 45
Sxx 0.005 0.011 0.006 0.004
Syy 0.009 0.008 0.008 0.008
Slope 0.974 1.065 1.058 1.0265
Int't 0.196 -0.492 -0.436 -0.1857
Sy.x 0.012 0.008 0.010 0.0136
Xmin 7.210 7.050 7.050
Xmax 7.530 7.570 7.570
r 0.985 0.990 0.9920 .986
Factors Affecting Results*
Venous stasis (prolonged tourniquet application) and forearm exercise may decrease pH due to
localized production of lactic acid. Exposing the sample to air will cause an increase in pH due to the
loss of CO
2
. pH decreases on standing anaerobically at room temperature at a rate of 0.03 pH units
per hour.
3
Hemodilution of the plasma by more than 20% associated with priming cardiopulmonary bypass pumps,
plasma volume expansion or other fluid administration therapies using certain solutions may cause clinically
significant error on sodium, chloride, ionized calcium and pH results. These errors are associated with
solutions that do not match the ionic characteristics of plasma. To avoid these errors when hemodiluting by
more than 20%, use physiologically balanced multi-electrolyte solutions containing low-mobility anions (e.g.
gluconate) such as Normosol
®
-R (Abbott Laboratories), Plasma-Lyte
®
-A (Baxter Healthcare Corporation),
and Isolyte
®
-S (B Braun Medical) rather than solutions such as normal saline or Ringer’s Lactate.
*It is possible that other interfering substances may be encountered. These results are representative and your results may differ somewhat due to
test-to-test variation. The degree of interference at concentrations other than those listed might not be predictable.
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