Lucidity GC-FID Does Cocaine

I decided to put a long standing rumor to rest that I heard when I was in middle school, and everyone I know believes.  That rumor is that all US dollars have trace amounts of cocaine on them. To test this I went around and collected dollar bills from various stores in the area.

These dollars were then either crumpled or folded and placed into a centrifuge tube.  The tubes were put into the Lucidity SimplePREP with a flat magnet. The SimplePREP then added 35 mL of methanol and mixed for 1 hour, then the samples sat for 24 hours in the methanol.

The samples were then placed into vials for GC-FID analysis.  The analysis was done first with a blank, then a cocaine standard of 1000 ppm in 1 mL of methanol purchased from Restek (catalogue number 34015) followed by the six samples.  The cocaine standard was run neat using the following conditions.

Figure 1. 1000ppm cocaine standard

The cocaine standard showed only one peak at 36 minutes and 38 seconds.  The samples were then analyzed to see if the peak was present.  Of the six samples, not one showed a peak at the same retention time as the cocaine standard. Figure 2 shows a representative sample of the 6.

Figure 2. Sample 2 of 6

Was the myth false?  Have I believed a lie this whole time?  Maybe the cocaine didn’t show up because the volume of solvent used to extract the cocaine was too much and the sample was too dilute to see by GC-FID.  So, I decided to evaporate one of the samples down to concentrate the compounds recovered from the dollar bill.  The solution was poured into an evaporating dish and allowed to evaporate down to 5 mL of solution.  The concentrated sample was then run using the same method.

Figure 3. Sample 2 concentrated

As you can see all of the peaks did get larger in the concentrated sample as expected, but again there was no peak at 36:38, meaning there isn’t any cocaine (or enough to be detected via our method of analysis) on my dollars.

To show that we can see cocaine on a dollar bill, I added cocaine to a new dollar bill that hadn’t been previously tested and allowed the cocaine to rest on the dollar for several hours.  The dollar was then added to a solution of methanol and agitated for an hour and then allowed to soak for 24 hours, the same prep method we used for the previous samples.  The solution was then poured into an evaporating dish and allowed to evaporate to about 5 mL and tested.

Figure 4. Sample 7 spiked with cocaine and concentrated

As you can see there is a peak at 36:35, a few seconds off from the cocaine but within the retention time window to show positive for cocaine.  This would be enough to warrant further testing with a GC-MS to be positive that this was indeed cocaine.

To show that this peak was the spiked peak of cocaine, I overlaid the cocaine dollar with a dollar from the earlier experiments.

Figure 5. Overlay of Sample 2 concentrated (red) and Sample 7 spiked and concentrated (blue)

The two chromatograms match very closely except for the peak labeled 4.  This is the only peak to change which makes us think this is the cocaine that was added to the dollar.

Further zooming in on peak number 4 shows that the base line of the plain dollar to be flat but the cocaine added dollar has a nice peak.

Figure 6. Closeup of peak 4 from Figure 5

This goes to show that none of the dollars that I tested showed positive for cocaine, but the sample that I deliberately put cocaine on did show a positive match for cocaine.  Again, I cannot say that there is or isn’t cocaine on US currency, just that there isn’t cocaine at a high enough level to be detected by the method I used on the 6 bills I tested.  Maybe I should test $10’s and $20 next time…