Na-2 Operator’s Manual – OPTI CCA-TS2
SODIUM ANALYTES
Interferences
The OPTI CCA Na
+
sensor has no measurable interference from K
+
variation within the range 0.8-10
mmol/L.
The OPTI CCA Na
+
sensor does exhibit a small interference from Li
+
. Li
+
levels of 1.0, 2.5, and 6.4
mmol/L will cause a positive Na
+
bias of 0.9, 1.2, and 1.3 mmol/L, respectively. A syringe sample
anticoagulated with typical amounts of lithium heparin has 1-4 mmol/L of lithium, which offsets the
measured Na
+
by less than 1%.
To minimize the interference from lithium, use syringes containing the lowest acceptable heparin level.
Carefully follow the syringe manufacturer’s recommendation regarding proper lling of the syringe.
A partially lled syringe results in excessive lithium concentration.
The OPTI CCA Na
+
results include an appropriate correction for pH at all values of pH.
This correction may introduce an extra source of variability at the extreme values.
Heparin salts are the only acceptable anticoagulants. Other anticoagulants such as citrate, EDTA, oxalate,
and uoride cause signicant interferences to the electrolyte sensors.
The following exogenous interferents were quantied in tonometered plasma, showing interferences to
dyes which typically have short half-lives within the body before being metabolized by the liver.
This
testing was done on the OPTI CCA
platform, with a standard OPTI style Sodium sensor. No changes were
made to the sensor or the measurement principle, so the interference of the OPTI CCA-TS2 is equivalent
to the OPTI CCA.
Substance Amount Na
+
change (mmol/L)
Sodium uorescein 26 mg/dL unstable
Cardio (indocyanine) green 0.5 mg/dL -18.0
Methylene blue 25 mg/dL -2.0
Only clear, uncolored quality control materials, such as OPTI CHECK or OPTI CHECK PLUS brand
aqueous controls should be used with the OPTI CCA-TS2 system. Colored materials, including
prociency testing materials, may interfere with the sodium measurement, or fail to be properly aspirated.
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