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Drug Analysis - PowerPoint PPT Presentation

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Drugs. Drug Analysis. General Principles. First test should be a visual examination naked eye low-power microscope especially important with plant materials & powders that do not appear to be uniform determine weight or volume of sample

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general principles
General Principles
  • First test should be a visual examination
    • naked eye
    • low-power microscope
      • especially important with plant materials & powders that do not appear to be uniform
      • determine weight or volume of sample
  • Examinations should proceed from general to the specific
    • each test should help narrow the number of possible substances that the sample could be
general principles1
General Principles
  • Analytical schemes and individual tests should conform to those already in general practice
general principles2
General Principles
  • When ever possible, at least one test should be specific for the drug in question
    • confirmatory test should be of a different type than those procedures used in the presumptive & separation phases of the examination
      • confirmatory tests
        • IR, GC-MS
      • presumptive or screening tests
        • “spot”tests, TLC
general principles3
General Principles
  • Try to conserve the drugs present as evidence
    • would allow for reanalysis
  • If the sample is too small to do a complete analysis
    • perform non-destructive tests before destructive tests
general principles4
General Principles
  • Tests should do double duty when possible
    • GC can be used for quantitative analysis as well as qualitative analysis
scheme of analysis
Scheme of Analysis
  • Preliminary visual examination of all samples
  • Weigh all samples
  • Select representative samples (if appropriate)
  • Screening tests (usually spot)
  • Separation tests
  • confirmatory tests
scheme of analysis1
Scheme of Analysis
  • Quantitative analysis if appropriate
  • Other tests if appropriate
preliminary examination
Preliminary Examination
  • If there are a large number of samples with similar packaging segregate the samples into groups
  • Determine if the mixture is homogeneous
  • See if crystals of a drug have been coated onto plant material (microscope)
    • PCP is often coated onto marijuana or parsley
  • Hygroscopic materials such as cocaine tend to aggregate & become discolored
screening tests
Screening Tests
  • Primary function to eliminate some drugs from consideration & indicate the identity of a drug
  • Categories
    • spot tests
    • microscopic tests
    • spectroscopic tests
spot tests color tests
Spot Tests (Color Tests)
  • Often done on a spot plate or sometimes in a test tube
  • Normally destroy the sample
  • No spot test is specific for a particular drug
    • negative test is a good indicator for the absence of the controlled substances that respond positively to it
  • Diluents may interfere with some spot tests
    • especially concentrated sulfuric acid
spot tests
Spot Tests
  • Marquis
    • 2% formaldehyde in sulfuric acid
      • turns purple in the presence of most opium derivatives
      • becomes orange-brown with amphetamines & methamphetamines
spot tests1
Spot Tests
  • Dillie-Koppanyi
    • 1% cobalt acetate in methanol followed by 5% isopropylamine in methanol
      • turns violet-blue in the presence of most barbiturates
spot tests2
Spot Tests
  • Duquenois-Levine
    • Reagent A: 2% vanillin & 1% acetaldehyde in ethanol
    • Reagent B: concentrated hydrochloric acid
    • Reagent C: chloroform
      • solutions are added sequentially to vegetation
        • purple color appears in the chloroform layer for marijuana
spot tests3
Spot Tests
  • Van Urk
    • 1% solution of p-dimethlaminobenzaldehyde in 10% concentrated hydrochloric acid and ethanol
      • turns purple in the presence of LSD
  • Difficult to conduct in field
    • LSD is present in very small amounts in illicit preparations
spot tests4
Spot Tests
  • Scott Test (cocaine)
    • solution A: 2% cobalt thiocayanate dissolve in water and glycerin (1:1)
    • solution B: concentrated hydrochloric acid
    • solution C: chloroform
      • powdered cocaine turns solution A blue
      • color turns pink on adding solution B
      • blue color appears in the chloroform layer on adding solution C
microscopic tests
Microscopic Tests
  • Two Types
    • morphology tests
    • microcrystal tests
  • Morphology
    • most commonly used with plant matter such as marijuana
      • look for botanical features
microcrystalline tests
Microcrystalline Tests
  • Involves dissolving the sample in a suitable solvent, filtering, and adding a precipitating agent to promote crystallization
  • The size & shape of the crystals are highly characteristic of the drug
  • TLC or GC
  • Comparison of Rf or retention-time values between questioned & known drugs
    • techniques accompanies and complements spot & crystal tests
separation tests
Separation Tests
  • Tests that separate controlled substances from the matrix of diluents and other substances in a mixture
    • TLC, GC, HPLC
confirmatory tests
Confirmatory Tests
  • A test that has the capability of identifying a drug after it has been presumptively identified by other techniques
    • individualization
    • generally spectroscopic
      • IR (method of choice in most forensic labs)
        • IR is unique for each compound (“fingerprint”)
        • substance should be as pure as possible
      • Mass Spectrometry
methods of analysis narcotics heroine
Methods of Analysis---Narcotics (Heroine)
  • Color Tests
    • Marquis (purple); Froehde’s reagent (purple changing to olive green on standing) Mecke’s (yellow, turning to green on standing)
  • Microcrystalline Tests
    • platinum chloride, sodium acetate, mercuric chloride
methods of analysis
Methods of Analysis
  • Separation---Heroine
    • easily separated from cutting agents by TLC
    • separated from quinine procaine, etc by a number of mobile phase systems
      • acetic acid:ethanol:water (30:60:10)
analysis meth
  • Spot tests
    • Marquis (orange)
  • Confirmation
    • IR spectroscopy on free bases (liquids) or hydrochloride or sulfate salts
      • salts give better spectra
analysis cocaine
  • Presumptive Tests
    • Spot Tests
      • Scott Test (blue;pink; blue)
    • TLC
    • Microcrystalline (gold chloride or lead iodide)
  • Quantitative analysis can be done by GC
  • Confirmatory Test
    • IR