Use of a new sample-collection device (Macroduct) in anion analysis of human sweat

We compared concentrations of chloride and sulfate in sweat obtained by use of the Macroduct capillary-coil collection device with results obtained by the conventional absorbent filter pad technique. Samples obtained with the device weighed less than those obtained conventionally, but sweat chloride concentrations were not significantly different. To assess analysis of trace anions, we used inorganic sulfate as a prototype. Background contamination, a problem with the filter pads, was negligible with the Macroduct collector. However, with the Macroduct device, sulfate concentrations were nominally higher than with the conventional pads (105 +/- 6 vs 88 +/- 5 mumol/L) and showed no dependence of sulfate concentration on sweat rate. Subtraction of the significant "background" SO4 concentration obtained with blanks (i.e., unused filter pads) is a likely source of error in the conventional method. We consider the Macroduct device useful for study of trace constituents of human sweat.