Tips about fentanyl's, their analogs and how to clean up samples

There has been a large increases in cases of suspected heroin samples which later turns out to be a case of fentanyl's or their analogs.  Some of the time we receive cases which contains a mixture of heroin mixed into the samples along with mannitol and inositol.  Some of these mixtures have also included dimenhydrinate, caffeine and procaine.  Because drug dealers are aware of the potential death due to fentanyl's they have been cutting it heavily.  So the results from the Gas-Chromatograph-Mass Spectrometry (GC-MS) will reveal a baseline loaded with sugars and other cutting agents.  The peaks for the fentanyl are rather small and does not give good baseline resolution.  The most obvious way to see this is if you have a broad peak with a mass spec ion of 73.  My suggestion is to try to clean up the sample using a solvent which should work with all fentanyl's and heroin without deleterious effects.  I have mentioned this type of method for cleaning up samples in previous posts.  One particular concern of mine is the presence of a larger 93 ion in the fentanyl sample compared to adjacent 91 and 96 ions.  This is probably attributed to phenylamine.  This may be due to a weak sample and this is where cleaning your sample might be important.  I am going to repeat this for those who might be hesitant about cleaning with fear of loss of sample.  The following is the approach to the method.

1.  Prepare a solution of an ANOR mixture containing 2-3 mL of CH(2)Cl(2) in a small test tube (75 mm x 10 mm).  Add about 1/2 mL of ammonium hydroxide (fresh is better) and vortex for about 15 - 20 seconds.  Discard the top (ammonium layer) so that you are left with just the basified dichloromethane (DCM).
2. In a new small test tube, add your sample, (0.01 g if possible or more), add about 100 uL to 500 uL of 0.5 N HCl or 0.1 M H(2)SO(4).  The goal here is to dissolve your sample as much as possible in the weak acid.  Vortex it for about 10 seconds.
3. To the sample tube, using an automatic pipettor or be aware of using a transfer pipet since DCM does not pipet very well.   Add about 0.5 mL to a 1 mL of the DCM solution from step 1 to your sample tube.  Don't worry about some ammonium hydroxide being present in your solvent.  Vortex this carefully for about 20-30 seconds.  If you have an emulsion, don't worry, just centrifuge for about 30 seconds.
4. To your sample tube, the upper layer is the remaining aqueous sample from step 2.  Using a transfer pipet remove all of this layer and place into another tube or discard this.  Don't lose the sample tube since this is were the sample is.  There should only be the ANOR-DCM mixture left.
5. Place an aluminum pan on a hot plate at a very low setting (like 2) and the aluminum pan is near the edge of the hot plate.  Do this under a hood.  Decant or carefully pipet out the sample tube (step 1) into the aluminum pan.  Boil down so that you will end up with a residue.  If you have a small amount of liquid don't worry.  Take the pan off the hot plate and add methanol in a small amount to your residue (100-200 uL).  Gently mix by swirling pan and transfer this to a GC-MS vial containing an insert or liner.  Run your GC-MS.

Notes: ANOR -Alternate Non-aqueous Organic Ratio extraction procedure-published in DEA Microgram  1/1983