Simultaneous flow-injection analysis of three components with on-line dialyzers in series. Determination of sodium, potassium and chloride in blood serum.

A fast and reliable fully automated three-component flow-injection procedure for the simultaneous determination of sodium, potassium and chloride in blood serum is described. A single sample injection (100-mul blood serum) is directed to two different channels by using two dialyzers in series. To avoid interferences and blocking of the fine jet of the atomizer, sodium and potassium are dialyzed by the first dialyzer before measurement by AES with a flame photometer. A second dialyzer in series is used to eliminate interferences and for automated dilution before the dialyzed chloride is measured by UV/VIS spectrophotometry at 485 nm. The results obtained for the sodium, potassium and chloride in blood serum at a sampling rate of 106 samples per hour compared well with data obtained by standard methods.