1. Hair analysis for cocaine: Factors in laboratory contamination studies and their relevance to proficiency sample preparation and hair testing practices 
Virginia Hill, Thomas Cairns, Michael Schaffer 
Forensic Science International 
Volume 176, Issue 1, Pages (March 2008)
DOI: /j.forsciint
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2. Fig. 1
An example of methylene blue dye uptake by a hair sample before and after laboratory perm treatment (50× magnification). Sample (A) untreated in the lab, took up 28.3ng cocaine/10mg hair when soaked for an hour in 10μg/mL cocaine, while the permed Sample (B) took up 2126ng cocaine/10mg hair. Both samples were determined negative by the wash criterion.
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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3. Fig. 2
Total cocaine on two hair samples in the in-house contamination experiment after rubbing with Cocaine–HCl (1), applying sweat (2) and weekly after shampooing five times per week (3–6).
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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4. Fig. 3
Wash profiles of cocaine-contaminated Sample #1 of in-house contamination experiment after being rubbed with cocaine, after sweat was applied to the contaminated sample, after shampooing daily for 1 week, and after shampooing daily for 4 weeks. Only the sample before exposure to sweat has most of the cocaine on the surface of the hair where it is readily removed by isopropanol (IP).
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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5. Fig. 4
Wash profiles of cocaine-contaminated Sample #2 of in-house contamination experiment after being rubbed with cocaine, after sweat was applied to the contaminated sample, after shampooing daily for 1 week, and after shampooing daily for 4 weeks. Only the sample before exposure to sweat has most of the cocaine on the surface of the hair where it is readily removed by isopropanol (IP).
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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6. Fig. 5
Hair Sample #1 of in-house contamination experiment (50× magnification). (A) Not stained with methylene blue. (B) Stained with methylene blue. The low dye uptake indicates the hair was not porous.
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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7. Fig. 6
Hair Sample #2 of in-house contamination experiment (50× magnification). (A) Not stained with methylene blue. (B) Stained with methylene blue. The low dye uptake indicates the hair was not porous.
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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8. Fig. 7
Total cocaine on the five samples contaminated in the RTI-cooperative experiment, before washing. These samples were then washed and analyzed in our laboratory, sampling times during the experiment as shown in the legend.
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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9. Fig. 8
Sample #1 of the RTI-cooperative study (A) before staining and (B) after methylene blue staining (50× magnification). The uptake of dye by strands of Sample #1 was variable, ranging from very little blue to very intense color.
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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10. Fig. 9
Sample #2 of the RTI-cooperative study (A) before staining and (B) after methylene blue staining (50× magnification). The uptake of dye by strands of Sample #2 was more uniform than for #1, and most of the strands show very intense stain.
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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11. Fig. 10
Sample #3 of the RTI-cooperative study (A) before staining and (B) after methylene blue staining (50× magnification). The uptake of dye by strands of Sample #3 was variable and those strands that did take up dye took up little. The hair sample is relatively nonporous.
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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12. Fig. 11
Sample #4 of the RTI-cooperative study (A) before staining and (B) after methylene blue staining (50× magnification). No uptake of dye is seen in Sample #4. The hair sample is nonporous.
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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13. Fig. 12
Sample #5 of the RTI-cooperative study (A) before staining and (B) after methylene blue staining (50× magnification). No uptake of dye is seen in Sample #5. The hair sample is nonporous.
Forensic Science International  , 23-33DOI: ( /j.forsciint )
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