PRINCIPLE OF THE METHOD
Potassium ions in a protein-free alkaline medium react with sodium
tetraphenylboron to produce a finely dispersed turbid suspension of
potassium tetraphenylboron.(1,2) The turbidity produced is proportional to the
potassium concentration and read photometrically.
CLINICAL SIGNIFICANCE
Potassium (K+) is the major positive ion within cells and is particularly
important for maintaining the electric charge on the cell membrane. This
charge allows nerves and muscles to communicate and is necessary for
transporting nutrients into cells and waste products out of the cell. The
concentration of potassium inside cells is about 30 times that in the blood
and other fluids outside of cells.
Potassium levels are mainly controlled by the steroid hormone aldosterone.
Aldosterone is secreted from the adrenal gland when levels of potassium
increase. Aldosterone, in turn, causes the body to rid itself of the excess
potassium. Metabolic acidosis (for example, caused by uncontrolled
diabetes) or alkalosis (for example, caused by excess vomiting) can affect
blood potassium.
In normal people, taking potassium supplements or potassium-containing
drugs is of no consequences, because the kidneys efficiently dispose of
excess potassium.
PRECAUTIONS
R2: H314-Causes severe skin burns and eye damage.
R3 /CAL: H314-Causes severe skin burns and eye damage. H335- May
cause respiratory irritation. H411-Toxic to aquatic life with long lasting
effects.
Follow the precautionary statements given in MSDS and label of the
product.
PREPARATION (Note 4)
Working reagent (WR):
Mix equal volumes of R1 TPB-Na and R2 NaOH (Shake before to use).
Don’t use before 30 min. after its mixing. The working reagent must be
shaken before each use.
The working reagent is stable for 7 days at 15-25ºC and 30 days at 2-8ºC.
STORAGE AND STABILITY
All the components of the kit are stable until the expiration date on the label
when stored tightly closed at 2-8ºC, protected from light and contaminations
prevented during their use.
Do not use reagents over the expiration date.
ADDITIONAL EQUIPMENT
- Spectrophotometer or colorimeter measuring at 578 nm.
- Matched cuvettes 1.0 cm light path.
- General laboratory equipment (Note 1, 2, 3).
SAMPLES
- Serum and lithium heparin plasma
INTERFERENCES
No significant interfering effect has been up to following concentrations: Bilirubin
40 mg/dL, Hemoglobin 450 mg/dL, Triglycerides 2500 mg/dL and Ascorbate 20
mg/dL.
