ASTM E1969-98

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Designation: E 1969 – 98
Standard Guide for
Microcrystal Testing in the Forensic Analysis of
Methamphetamine and Amphetamine
This standard is issued under the fixed designation E 1969; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Microcrystal tests are primarily chemical-precipitation tests in which a light microscope is used to
observe and distinguish the different types of crystals formed. These tests require skill and expertise
on the part of the analyst that can be gained adequately only through appropriate training and
experience in their use. These tests should not be attempted by those who are unfamiliar with them
for use in the analysis of methamphetamine or amphetamine.
1. Scope 2.1.11 tablets, n—plates with appreciable thickness but less
than the length or breadth.
1.1 This guide describes some standard procedures appli-
cable to the analysis of methamphetamine and amphetamine
3. Summary of the Technique
using microcrystal tests.
3.1 A small sample of the material containing the suspected
1.2 These procedures are applicable to methamphetamine
methamphetamine or amphetamine is dissolved in an appro-
and amphetamine, which are present in solid dosage form or an
priate acid and the appropriate precipitating reagent is added.
injectable liquid form. These procedures are not typically
The crystals that are formed are observed and distinguished
applicable to the analysis of methamphetamine and amphet-
utilizing a light microscope.
amine in biological samples.
3.2 If the proper formation of crystals is inhibited by the
2. Terminology presence of diluents, a purification of the sample based on the
volatility of methamphetamine and amphetamine may be
2.1 Definitions of Terms Specific to This Standard:
performed.
2.1.1 aggregation, n—the collecting of units or parts into a
mass or whole.
4. Significance and Use
2.1.2 birefringence, n—property of some crystals, having
4.1 This technique produces a chemical-precipitation reac-
more than one refractive index. This property will result in
tion between methamphetamine or amphetamine and the pre-
interference colors, which are viewed through a polarized light
cipitating reagent. The habit and the aggregation of the crystals
microscope.
formed may be used to distinguish methamphetamine and
2.1.3 blades, n—broad, flat, elongated crystals.
amphetamine from other drugs.
2.1.4 grains, n—thick tablets having nearly equal width,
breadth and thickness.
5. Interferences
2.1.5 habit, n—the external morphology of the crystal.
5.1 Diluents/Adulterants—Diluents/adulterants present in
2.1.6 microdrop, n—a small drop of liquid that would fit on
combination with methamphetamine or amphetamine in the
the end of a standard size, flattened toothpick. The approximate
sample to be tested may inhibit crystal formation or result in
volume of this drop would be 10 to 25 μL.
crystals that are distorted or otherwise rendered unidentifiable.
2.1.7 needles (acicular), n—long, thin crystals with pointed
In these instances, it will be necessary to separate the meth-
ends.
amphetamine or amphetamine from the diluents or to use other
2.1.8 plates, n—blades with nearly equal length and breadth
testing methods to analyze the methamphetamine or amphet-
and of a thickness substantially less than the width.
amine.
2.1.9 rods, n—long, thin crystals with squared off ends.
2.1.10 skeletal crystal, n—a crystal characterized by re-
6. Apparatus
peated branching.
6.1 A standard light microscope capable of varying magni-
fications including 1003 is needed for viewing the crystals. A
This guide is under the jurisdiction of ASTM Committee E 30 on Forensic
polarized light attachment is not essential, but is desirable,
Sciences and is the direct responsibility on Subcommittee E30.01 on Criminalistics.
because the heavy metal crystals of methamphetamine and
Current edition approved Nov. 10, 1998. Published January 1999.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 1969
amphetamine are birefringent. If these crystals are broken gently by scratching with a probe,
they will break apart into smaller rods, which are open on both
7. Reagents and Materials
ends, having an appearance of the letter “X.”
9.1.6 If a dense cloud of precipitate is formed upon the
7.1 10 % Solution of Hydrochloric Acid.
addition of the precipitating agent, the crystals may not be
7.2 Concentrated Phosphoric Acid.
readily visible. It may be necessary to repeat the test reducing
7.3 1.0 N to 10.0 N Sodium Hydroxide.
the concentration of suspected methamphetamine or amphet-
7.4 Gold Chloride (HAuCI ) Solution, approximately 5 %,
amine in the acid solution. This is done by either decreasing the
in reagent grade water. Gold chloride in phosphoric acid also is
sample size or increasing the volume of solvent.
suitable.
9.1.7 The following procedure to separate the methamphet-
7.5 Platinum Chloride (H PtC1 ) Solution, approximately
2 6
amine or amphetamine from diluents may be used.
5 %, in reagent grade water. Platinum chloride in phosphoric
9.1.7.1 Place a small amount of the sample into a spot well.
acid also is suitable.
Sample size should be approximately 2 to 3 mg.
7.6 Authenticated Amphetamine Standard.
9.1.7.2 Add a small volume of 1.0 N to 10.0 N sodium
7.7 Authenticated Methamphetamine Standard.
hydroxide, such that the powder is just covered.
8. Calibration and Standardization
9.1.7.3 Place a microdrop of concentrated phosphoric acid,
or gold chloride reagent containing phosphoric acid, on a slide
8.1 The reagents utilized for these microcrystal tests are to
and invert the slide over the sample such that the microdrop is
be tested for reliability using authenticated amphetamine and
over the spot well containing the sample.
methamphetamine standards and negative controls following
9.1.7.4 Any amine present, including methamphetamine
the prescribed procedure. Only when it is determined that the
and amphetamine, will be converted to the free base form.
reagents are producing the expected response may the reagents
Many free bases are volatile at room temperature, and as they
be used in the testing procedure.
leave the solution, they will collect in the microdrop of
9. Procedure phosphoric acid.
9.1.7.5 After a period of time has elapsed, approximately 1
9.1 Gold Chloride:
to 3 min, remove the slide and observe the crystals formed
9.1.1 Place a small sample, a few particles of powder, less
directly if gold chloride is used in the hanging drop, or perform
than 1 mg, of the suspected methamphetamine or amphetamine
the testing procedure described in 9.1.3-9.1.5 on the microdrop
on a microscope slide.
of phosphoric acid. The appropriate period of time is variable
9.1.2 Dissolve the sample in a few microdrops of 10 %
and will depend on the concentration of methamphetamine or
hydrochloride acid or concentrated phosphoric acid.
amphetamine in the sample, the diluents present, as well as the
NOTE 1—The crystals tend to precipitate faster from the phosphoric
room temperature. It may be necessary to repeat the test for a
acid. There also tends to be less interference when using the concentrated
shorter or longer duration or utilize more sample if adequate
phosphoric acid.
recovery of amines is not accomplished during initial attempts.
9.1.3 Add a few microdrops of 5 % gold chloride to the
9.2 Platinum Chloride:
edge of the acid solution on the microscope slide.
9.2.1 Place a small sample, a few particles of powder, less
...