Liquid-chromatographic determination of chloride in sweat from cystic fibrosis patients and normal persons.

Chloride concentrations in sweat were measured by "vacancy liquid chromatography," a technique in which anions eluting from an ion-exchange column in the presence of an elution buffer which absorbs at 280 nm cause a decrease in absorbance proportional to the concentration of the anion. Less than 1 microL of sweat suffices for this analysis, which takes 5 min per sample. Results were comparable to those obtained by conventional titrimetric determination of chloride. Sweat from cystic fibrosis patients had higher (104 +/- 26 mmol/L) chloride concentrations than sweat from normal persons (16 +/- 7 mmol/L). This technique can be used in the diagnosis of cystic fibrosis.