Under the alkaline condition, the sodium tetraphenylborate reacts with the potassium ions in the sample to form the potassium tetraphenylborate which is white and small particles with small solubility. Potassium tetraphenylborate particles are in a stable suspension state in the solution. The turbidity is proportional to the potassium ion concentration in the sample and potassium content can be calculated indirectly by measuring the OD value at 450 nm.

1. Prevent the formulation of bubbles when adding the liquid to the microplate.

2. Hemolysis samples should not be adopted since red blood cells contain high concentrations of potassium ions.

3. Ammonia, mercury, chlorine can interfere with the determination of potassium ion.

4. It is recommended to use deionized water to prepare tissue homogenate and avoid potassium ion pollution.

5. It is suggested to measure the total protein content when detecting the potassium content in tissue or cells (E-BC-K165, E-BC-K168 and E-BC-K318).

                                              [Note]: A-H, standard wells; S1-S80, sample wells.

1)   Standard tube: Take 50 μL of Standard solution with different concentrations to the wells.

Sample tube: Take 50 μL of supernatant (pretreated Sample) to the wells.

2)   Add 200 μL of Chromogenic agent into the wells of Step 1.

3)   Mix fully and stand for 5 min at room temperature.

4)   Measure the OD value at 450 nm with Microplate Reader.

For Rat liver tissue, take 0.1 g of fresh rat liver sample, add 0.9 mL of 2-8℃ deionized water, then homogenize treat the sample in ice water bath, centrifuge at 10000 g for 10 min at 4℃, then dilute the supernatant with deionized water for 2 times and carry the assay according to the operation table.

The results are as follows:

standard curve: y = 0.77073 x – 0.00139, the average OD value of the sample well is 0.404, the average OD value of the blank well is 0.045, the concentration of protein in sample is 9.23 gprot/L, and the calculation result is:

K+content (mmol/gprot)=0.404-0.045+0.00139÷0.77073×10×2÷9.23=1.01mmol/gprot