The Konelab measures:
- Na, K and Cl in serum and plasma,
- Na and K in urine,
- Li, which is offered as an option, in serum
– Ca and pH in Konelab PRIME 60 and 30, which are offered as an option, in serum and plasma.

The measurement is done with the direct ISE technique. The measured sample activity is compared to the activity of calibrators, which are adjusted to mimic activity normally found in serum samples.The electrode block is comprised of the measurement electrodes and the reference electrode. The potentials produced at each membrane are measured once every second.

One dispensing arm, one pump and one 500 micro liters syringe are provided for the ISE measurement in Konelab PRIME 60 and 30. In Konelab 20 and 20XT one dispensing arm and FMI pump perform the ISE measurement. A sample is aspirated through the needle from the sample cup. The sample is moved to the electrode block where the measurement takes place.

Sample measurement is followed by ISE Calibrator solution 1 measurement. The ISE dispensing pump transfers ISE Calibrator solution 1 from the bag to the block. At the same time the sample is discarded. After the measurement ISE Calibrator solution 1 is pumped through the needle to the waste.