Determination of the volume of sweat accumulated in a sweat-patch using sodium and potassium as internal reference

In the present work, we assessed the suitability of sodium and potassium physiologically present in sweat, as internal reference allowing to re-calculate the corresponding volume of sweat collected on a PharmChekTm Patch. A method using capillary electrophoresis with indirect ultraviolet detection was developed for the determination of sodium and potassium in sweat. The concentrations determined in specimens collected from 12 females and 10 males, using a home-made system composed of polypropylene copolymer bag, were 1039 +/- 89 mg/L and 711 +/- 45 mg/L for sodium, and 489 +/- 293 mg/L and 474 +/- 196 mg/L for potassium, respectively. In parallel, for seven females and eight males, the comparison of the volume of sweat collected in the same way to the re-calculated volume of sweat accumulated in a patch using sodium as internal standard, gave an average agreement of 98.4 +/- 15.0%. Results demonstrated the usefulness of sodium as internal standard to determine the volume of sweat accumulated in a patch, and confirm the suitability of PharmChek (TM) patch for the collection and determination of cations in sweat. (c) 2007 Elsevier B.V. All rights reserved.