Abstract
The collection and preservation of microtraces, such as fibers, using cellophane tape is generally accepted as being very practical and efficient. At the scene of a crime, for example, this means of sample collection is both easy and rapid, which explains in part its popularity. However, in addition to a very low specificity (high background), this technique suffers from one major disadvantage: the microtraces must undergo a long and tedious pretreatment before any detailed analysis is possible. This pretreatment involves the isolation and separation of the microtrace from the tape, followed by a solvent wash (usually with xylene) to remove all trace of the adhesive.
A recently commercialized product alleviates some of the problems associated with sample collection by this means: “Mask Plus II” (No. 5414, Scotch™, St-Paul, MN) is a new cellophane tape that is completely soluble in water. Microtrace collection can be performed with this tape by the conventional lifting procedure. In the laboratory, the microtraces may then be conveniently released from the tape by immersion in warm water (60°C) with continual agitation. After solubilization of the cellophane tape, the microtraces are isolated by membrane filtration then allowed to air dry.
The described technique has been thoroughly evaluated for fiber collection with comparison of the results with those obtained using conventional cellophane tape. Particular attention has been paid to operating conditions (temperature, humidity, conservation, etc.), collection efficiency, as well as possible alterations to the fibers themselves.
