U.S. Department of Justice

Federal Bureau of Investigation

April 1999   Volume 1   Number 1

Chapter 4 of Forensic Fiber Examination Guidelines

Appendix D:
Composition of Eluents

Table 1: Eluent Systems
The following list summarizes eluent systems that have been recommended in the relevant forensic literature. This list is not meant to be totally inclusive or exclusive.

Eluent	Solvents	Proportions (v/v)	Reference
1	n-Butanol, acetone, water, ammonia	5:5:1:2	8, 16
2	Pyridine, amyl alcohol, 10% ammonia	4:3:3	8, 10, 16
3	n-Butanol, ethanol, ammonia, pyridine, water	8:3:4:4:3	8, 10, 16
4	Methanol, amyl alcohol, water	5:5:2	10, 16
5	Toluene, pyridine	4:1	8, 16
6	Chloroform, ethyl acetate, ethanol	7:2:1	10
7	n-Hexane, ethyl acetate, acetone	5:4:1	8, 16
8	Toluene, methanol, acetone	20:2:1	8, 16
9a	n-Butanol, acetic acid, water	2:1:5	8
10	n-Butanol, ethanol, ammonia, pyridine	4:1:3:2	8, 16
11	Chloroform, butanone, acetic acid, formic acid	8:6:1:1	8
12a	n-Butanol, acetic acid, water	4:1:5	8, 16

The ethanol used is 99%. The ammonia is 0.880 SG unless otherwise stated.

Table 2: Eluents Recommended for Certain Dye Classes
Certain fiber type or dye class combinations have been found to give better separation in certain eluents. These are shown in the following table and are recommended as a first choice.

Fiber Type Dye Class Eluent Number Wool Acid or Metalized 1.2 Cotton and Viscose Direct 1, 4, 3 Acrylic Basic 11, 12, 1 Polyester Disperse 6, 7, 8, 5 Polyamide Acid 9, 10  Polypropyleneb

a Dyes rarely extract from polypropylene, but if they do, they are most likely to be acidic.
^b Polypropylene rarely contains an extractable dye. If the dye can be extracted, an eluent appropriate to the dye class is used.

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FORENSIC SCIENCE COMMUNICATIONS   APRIL 1999   VOLUME 1   NUMBER 1