Selective determination of chloride and bromide ions in serum by cyclic voltammetry

Voltammetric determination of chloride and bromide ions in serum was made using a one-body type Ag electrode, whose surface was covered with a dialysis membrane for preventing interference from proteins. This determination was based on measurement of the charge of the reduction wave of silver halide formed on the Ag electrode surface in a halide ion solution during a cathodic potential sweep. In this method, depending on the potential sweep range, the charge of the reduction wave of AgI, AgI + AgBr, or AgI + AgBr + AgCl can be measured. Here, the method was used to determine the chloride and bromide ions in artificial serum. Linear concentration ranges were 1.0 x 10(-2)-2.4 x 10(-1) M for chloride ions and 5.0 x 10(-3)-1.8 x 10(-2) M for bromide ions. The correlation coefficient was 0.999 in each case. The relative standard deviation for chloride ion (1.0 x 10(-1) M) was 1.9% (n = 10), and that for bromide ion (1.5 x 10(-2) M) was 2.5% (n = 10). Bromide ions at a relatively high concentration as the component of serum had no effect on the determination of the chloride ion in the serum. This method is thus useful for the selective determination of chloride and bromide ions in serum.