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SECTION 1: INTRODUCTION
1.6 Macroduct Advanced Sweat Collector
The Macroduct Advanced Sweat Collector is a disposable plastic device with a shallow, elliptical
concave undersurface that covers the skin area that has been stimulated by pilocarpine
iontophoresis. The collection surface is contoured such that when firmly applied to the stimulated
area, the skin bulges into the concavity, leaving no air space. At the apex of the conical surface, a
tiny orifice leads to a small-bore plastic tube or duct, which is coiled into a spiral.
Sweat becomes visible in the spiral tube of the collector typically within one to four minutes,
depending upon the relative elasticity of the skin and the subject's sweating rate.
NOTE: Due to possible biological contamination and cross contamination of the sweat sample, the
Macroduct Advanced Sweat Collector is a single-use device.
NOTE: For best results, the stimulated skin area should cover reasonably deep flesh/musculature.
Thin skin sections overlaying palpable tendons or bony structures are not suitable as collection
sites.
The emergent sweat is turned blue by contact with a small amount (≤ 10 10
-9
mol) of blue water-
soluble dye (FD&C certified food color) applied to the Macroduct collector contoured surface
during the manufacturing process. This allows easy assessment of the volume produced at any
time during collection.
This dye does not interfere with sweat chloride assay by colorimetry, coulometric titration, or
sweat conductivity analysis. The dye contributes slightly to the osmolality and sodium content of
the sweat sample. Even with a low sweat yield of only 20 µL, this contribution will not exceed 1.5
mmol/kg and is negligible.
The spiral collection tube capacity is approximately 85 µL. This is adequate for average sweat
production levels (40 to 60 µL) in 30 minutes of collection. This volume is sufficient for all current
methods of sweat analysis (see Notes Regarding Sweat Rate on the following page).
The collector tubing has two black marks printed on the outside
surface of the tubing to gauge whether sweat rate is sufficient, based
on the 30 minute collection time. Sufficient sweat rate is defined as
1g/m
2
/min.
With the tubing extended from the collector (while the collector is
still attached to the limb), sweat below the first mark indicates an
insufficient sweat rate. Because of the tolerances of the tubing, this
mark can represent a maximum of 15 µL and a minimum of 10.4 µL
of sweat collected.
Sweat above the second mark indicates a sufficient sweat rate. Because of the tolerances of the
tubing, this second mark can represent a maximum of 22.7 µL and a minimum of 15 µL of sweat
collected. If the sweat is between the two marks, then it is indeterminate if a sufficient sweat rate
has been achieved and another means (e.g. weighing the sweat sample) must be used to confirm
sufficient sweat rate.
At the end of the collection period, the collector should remain on the limb until the sweat
specimen is removed by severing the plastic tube at its attachment point. See complete
instructions in Section 3 before attempting this procedure.
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