Model 3700 Macroduct® Sweat Collection System. Sweat is stimulated with the Webster sweat inducer by pilocarpine iontophoresis. The Macroduct Anaerobic sweat collector is used to collect sweat for analysis for the laboratory diagnosis of cystic fibrosis. Macroduct produces an error-free sample of undiluted pure sweat for electrical conductivity analysis using the Sweat-Chek® Sweat Conductivity Analyzer, for osmolality assay using the Vapro® Vapor Pressure Osmometer, or for chloride analysis by various methods.