Evaluation of the Megaduct sweat collector for mineral analysis

Accurate measurement of sweat mineral loss is important for whole body mineral balance estimates and dietary reference intake formulation. Currently, common localized sweat collection methods such as the pouch and patch techniques may be limited by skin encapsulation and/or hidromeiosis, which may alter sweat mineral concentrations. The design of the newly developed Megaduct sweat collector may avoid these possible limitations. Therefore, the purpose of this study was to evaluate the utility of the Megaduct sweat collector for mineral analysis. Megaduct sweat collectors were affixed to ten volunteers on the final day of a heat acclimation protocol; collection time, sweat volume, and mineral concentrations of calcium, copper, iron, potassium, sodium, and zinc were measured. Megaduct filling required a collection period of 62 +/- 3 min due to a small collection surface (22.1 cm(2)). The mineral content of the sweat was 0.3 +/- 0.1 mmol L-1, 1.5 +/- 1.5 mu mol L-1, 8.5 +/- 2.1 mmol L-1, 43.2 +/- 15.0 mmol L-1, and 10.1 +/- 5.7 mu mol L-1 for Ca, Cu, K, Na, and Zn, respectively. The Megaduct sweat collector appears to avoid skin encapsulation and hidromeiosis, and captures sweat with similar mineral concentrations as reported in the literature for pouches. However, the filling time of the Megaduct (>60 min) may not capture possible changes in sweat mineral concentrations that are documented to occur in as little as 15 to 30 min.