ASTM E1968-1998(2003) Standard Guide for Microcrystal Testing in the Forensic Analysis of Cocaine《法医检定法中微晶体试验的标准指南》.pdf

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1、Designation: E 1968 98 (Reapproved 2003)Standard Guide forMicrocrystal Testing in the Forensic Analysis of Cocaine1This standard is issued under the fixed designation E 1968; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year

2、 of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONMicrocrystal tests are primarily chemical-precipitation tests in which a light microscope is used toobserve and d

3、istinguish the different types of crystals formed. These tests require skill and expertiseon the part of the analyst that can be gained adequately only through appropriate training andexperience in their use. These tests should not be attempted by those who are unfamiliar with themfor use in the ana

4、lysis of cocaine.1. Scope1.1 This guide describes some standard procedures appli-cable to the analysis of cocaine using multiple microcrystaltests.1.2 These procedures are applicable to cocaine, which ispresent in solid dosage form or an injectable liquid form. Theyare not typically applicable to th

5、e analysis of cocaine inbiological samples.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 aggregation, nthe collecting of units or parts into amass or whole.2.1.2 birefringence, nproperty of some crystals, havingmore than one refractive index. This property will result ininte

6、rference colors, which are viewed through a polarized lightmicroscope.2.1.3 cocaine, neither d- or l- cocaine. It should be notedthat l-cocaine is the naturally occurring isomer found in thecoca plant.2.1.4 dendritic, adjmultibrachiate or branching crystals,growing in a tree-like manner. Each branch

7、 of the crystal iscontiguous structurally.2.1.5 habit, nthe external morphology of the crystal.2.1.6 microdrop, na small drop of liquid that would fit onthe end of a standard size, flattened toothpick. The approximatevolume of this drop would be 10 to 25 L.2.1.7 needles (acicular), nlong, thin cryst

8、als with pointedends.3. Summary of the Technique3.1 A small sample of the material containing the suspectedcocaine is dissolved in a dilute acid and the appropriateprecipitating reagent is added. The crystals that are formed areobserved and distinguished utilizing a light microscope.4. Significance

9、and Use4.1 This technique produces a chemical-precipitation reac-tion between cocaine and the precipitating reagent. The habitand the aggregation of the crystals formed may be used todistinguish cocaine from other drugs.4.2 This technique can be utilized on cocaine present ineither the salt or free

10、base form.4.3 This technique does not distinguish between the salt andfree base forms.5. Interferences5.1 Diluents/AdulterantsDiluents/adulterants, such aslidocaine or benzocaine, present in combination with cocainein the sample to be tested may inhibit crystal formation or mayresult in crystals tha

11、t are distorted or otherwise renderedunidentifiable. In these instances, it will be necessary toseparate the cocaine from the diluents/adulterants or to useother testing methods to analyze for cocaine.6. Apparatus6.1 Standard Light Microscope, capable of varying magni-fications including 1003 is nee

12、ded for viewing the crystals. Apolarized light attachment is not essential, but is desirable,because the heavy metal crystals of cocaine are birefringent.7. Reagents and Materials7.1 10 % Solution of Acetic Acid.7.2 Authenticated Cocaine Standard.1This guide is under the jurisdiction of ASTM Committ

13、ee E30 on ForensicSciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.Current edition approved Nov. 10, 1998. Published January 1999.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.3 5 % Solution of G

14、old Chloride (HAuCl4), in reagentgrade water.7.4 10 % Solution of Hydrochloric Acid.7.5 5 % Solution of Platinum Chloride (H2PtCl6), in reagentgrade water.8. Calibration and Standardization8.1 The reagents utilized for these microcrystal tests are tobe tested for reliability using an authenticated c

15、ocaine stan-dard. Only when it is determined that the reagents are produc-ing the expected response, may the reagents be used in thisprocedure.9. Procedure9.1 Gold Chloride:9.1.1 Place a small sample, a few particles of powder, lessthan 1 mg of the suspected cocaine on a microscope slide.9.1.2 Disso

16、lve the sample in a few microdrops of 10 %hydrochloric acid or 10 % acetic acid.9.1.3 Add a few microdrops of 5 % gold chloride to theedge of the acid solution on the microscope slide.9.1.4 Observe the formation of the crystals using a properlyaligned and adjusted light microscope. This observation

17、can bedone between crossed polars if desired. If crossed polars are tobe used, orient the polarizer in the east-west direction and theanalyzer in the north-south direction, verified by a blackbackground.9.1.5 Formation of crystals in a habit corresponding to thoseobtained with authenticated standard

18、s is indicative of thepresence of cocaine. The shape of these crystals may varyslightly depending on the concentration of the cocaine in theacid solution.9.1.6 If a dense cloud of precipitate is formed upon theaddition of the precipitating agent, the crystals may not bereadily visible. It may be nec

19、essary to repeat the test reducingthe concentration of suspected cocaine in the acid solution.This reduction is done by either decreasing the sample size orincreasing the volume of solvent.9.2 Platinum Chloride:9.2.1 Place a small sample, a few particles of powder, lessthan 1 mg of the suspected coc

20、aine on a microscope slide.9.2.2 Dissolve the sample in a few microdrops of 10 %hydrochloric acid or 10 % acetic acid.9.2.3 Add a few microdrops of 5 % platinum chloride to theedge of the acid solution on the microscope slide.9.2.4 Observe the formation of the crystals using a properlyaligned and ad

21、justed light microscope. This observation can bedone between crossed polars if desired. If crossed polars are tobe used, orient the polarizer in the east-west direction and theanalyzer in the north-south direction, verified by a blackbackground.9.2.5 Formation of crystals in a habit corresponding to

22、 thoseobtained with authenticated standards is indicative of thepresence of cocaine. The shape of these crystals may varyslightly depending on the concentration of the cocaine in theacid solution.9.2.6 If a dense cloud of precipitate is formed upon theaddition of the precipitating agent, the crystal

23、s may not bereadily visible. It may be necessary to repeat the test reducingthe concentration of suspected cocaine in the acid solution.This reduction is done by either decreasing the sample size orincreasing the volume of solvent.10. Interpretation of Results10.1 Gold chloride is capable of disting

24、uishing cocainefrom its diastereoisomers.10.2 If crystals structurally similar to those formed by anauthenticated cocaine standard are formed by both precipitat-ing reagents, the test results may be considered positive for thepresence of cocaine.10.3 All observed crystalline precipitates must be doc

25、u-mented and included in the analysts notes for each itemanalyzed.11. Precision and Bias11.1 No information is presented about either the precisionor bias of this technique.12. Keywords12.1 cocaine; microcrystalline testingREFERENCES(1) Fulton, C., “Modern Microcrystal Tests for Drugs,” Wiley-Inters

26、cience, New York, NY, 1969.(2) Clarke, E.G.C., “Isolation and Identification of Drugs,” Pharmaceuti-cal Press, London, England, 1971, pp. 139141.(3) Allen, A. C., Copper, D. A., Kiser, W. O., Cottrell, R. C., “The CocaineDiastereoisomers,” Journal of Forensic Sciences, Vol 26, No. 1, Jan.1981, pp. 1

27、226.(4) Cunniff, P., (ed.) A.O.A.C. Offcial Methods of Analysis, 16th edition,1995, Chapter 18, p. 45.(5) Chamot, E. and Mason, C., Handbook of Chemical Microscopy: Vol I,John Wiley, New York, NY, 1930.(6) Chamot, E. and Mason, C., Handbook of Chemical Microscopy: Vol II,John Wiley, New York, NY, 19

28、31.(7) Nichols, R., “Drug Proficiency Test False Positives: A Lack of CriticalThought,” Science and Justice, Vol 37, No. 3, pp. 191196.E 1968 98 (2003)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Us

29、ers of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed ever

30、y five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible techni

31、cal committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E 1968 98 (2003)3