Heroin detection by raman spectroscopy from impure compositions comprising an interfering fluorescent contaminant
A method of identifying the presence of heroin in an impure heroin composition which contains heroin and at least one fluorescent contaminant which interferes with a Raman signal from the heroin. The method may include contacting the mixture with a solvent such as an alcohol, then contacting the resulting alcohol composition with a SERS surface. The surface may then be exposed to laser light from a hand-held Raman spectrometer to detect a Raman signal from the heroin. An apparatus for performing the method is also provided.
1. A method of identifying the presence of heroin in a mixture comprising an impure heroin composition which contains heroin and at least monoacetyl morphine fluorescent contaminant which interferes with a Raman signal from the heroin, the method comprising:
contacting the mixture with ethanol;
then contacting the resulting composition with a SERS surface;
then exposing the surface to laser light from a hand-held Raman spectrometer; and
detecting the Raman signal from the heroin in the mixture comprising the impure heroin composition which contains heroin and at least monoacetyl morphine fluorescent contaminant which interferes with the Raman signal from the heroin in the hand-held Raman spectrometer.
2. A method according to claim 1 wherein the composition contains between 5 to 95 weight % of the fluorescent contaminant.
3. A method according to claim 1 wherein the surface comprises gold, silver or copper.
4. A method according to claim 3 wherein the surface is textured.
5. A method according to claim 4 wherein the surface is an exposed surface of a silver layer which overlays a silicon substrate.
6. A method according to claim 5 wherein the silicon substrate is textured.
7. A method according to claim 1 wherein the resulting Raman signal from the heroin is detected using a wavelength anywhere between 500-2000 cm −1 .
8. A method according to claim 1 wherein the resulting Raman signal from the heroin is detected using a wavelength anywhere between 600-650 cm −1 .
9. A method according to claim 7 where a Raman spectra is obtained between 250-2500 cm −1 .
10. A method according to claim 1 where the laser light from the Raman spectrometer is used to accelerate evaporation of the solvent on the SERS substrate.