Froehde reagent

The Froehde reagent is used as a simple spot-test to presumptively identify alkaloids, especially opioids, as well as other compounds. It is composed of a mixture of molybdic acid or a molybdate salt dissolved in hot, concentrated sulfuric acid, which is then dripped onto the substance being tested.

The United States Department of Justice method for producing the reagent is the addition of 100 ml of hot, concentrated (95–98%) sulfuric acid to 0.5 g of sodium molybdate or molybdic acid.[1]

The Virginia Department of Forensic Science method uses 0.5 g ammonium molybdate per 100 ml H2SO4 (conc.)[2]

Unheated sulfuric acid can be used to prepare the reagent in a less dangerous manner, but 2–4 hours must be allowed for the molybdate to dissolve.

Final colors produced by Froehde Reagent with various substances
Substance Color
AmphetamineNo reaction[3] or Red[4]
CathinoneNo reaction[5]
MethcathinoneNo reaction[5]
4-MMCNo reaction [5]
3-FMCNo reaction[5]
MDMABlack[3]
MethyloneBright yellow[5]
MDPVBright yellow[5]
ButyloneYellow > Green[6]
3,4-DMMCLight brown[6]
NaphyroneOrange[6]
PMAPale green[3]
PMMAPale green[3]
4-MeO-PCPLight yellow[6]
MethoxetamineYellow - Green[6]
3-HO-PCEBlack[6]
5-MeO-DALTYellow[6]
4-AcO-DALTYellow > Green[6]
4-HO-METYellow > Green[6]
4-HO-MIPTYellow > Green[6]
4-AcO-DETYellow > Green[6]
aMTYellow[6]
5-ITRed brown[6]
5-APBDark purple[6]
6-APBPurple[6]
CamfetamineTan > Dark yellow[6]
MethiopropamineLight brown[6]
MDAIGreen > Black[6]
5-IAIOrange[6]
AllylescalineGreen > Black (fast)[6]
2C-T-2Orange > Purple[6]
2C-BYellow[2]
2C-PGreen[6]
b-methoxy-2C-DRed[6]
AcetaminophenPale blue[2]
AspirinGreyish purple[1] or Blue > Purple[2]
AlimemazinePurple red[4]
ChlorphentermineGreen[4]
Chlorpromazine HClVery deep red[1][4]
Contac HClModerate olive brown[1]
Dimethoxy-meth HClVery yellow green[1]
DiphenhydramineOrange[4]
Doxepin HClDeep reddish brown[1][4]
DristanLight bluish green[1]
EphedrineBrown[4]
ExedrineBrilliant blue[1]
FlurazepamOrange[4]
LSDModerate yellow green,[1] Yellow Green[4]
MaceLight olive yellow[1]
MDA HClGreenish black[1][4]
MescalineGreen or brown or light yellow[4]
MeperidineGrey[2]
ModafinilDeep orange/red[7]
Morphine monohydrateDeep purplish[2] Red[1] > Slate[2]
Heroin HClDeep purplish red[1][4] > Green[2]
OpiumBrownish black[1][4]
Oxycodone HClStrong yellow[1][2] - Blue[4] or Green[4]
Codeine HClVery dark[1] Green[4] > Red - Brown[2]
HydromorphoneBlue > Purple[2]
HydrocodoneLight[2] Yellow[4]
PentazocineBlue[2][4]
PethidineYellow[4]
PhenoxymethylpenicillinBlue[2]
PhenyltoloxamineGreen[4]
PromazineOrange[4]
PromethazinePurple red[4]
Propoxyphene HClDark greyish red[1][4] or Brown[2]
PropylhexadrinePurple red[4]
SugarBrilliant yellow[1]
Salicylic acidPurple red[4]
TetracyclinePurple red[4]
ThioridazinePurple red[4]
GuaifenesinGreen with purple streaks[2]
MethapyrilenePurple[2]
PyrilaminePurple[2]
TrifluoperazineOrange[4]
TriflupromazineOrange[4]

See also

References
  1. "Color Test Reagents/Kits for Preliminary Identification of Drugs of Abuse" (PDF). Law Enforcement and Corrections Standards and Testing Program. July 2000. Retrieved 2011-07-24.
  2. "Controlled Substances Procedures Manual" (PDF). Virginia Department of Forensic Science. 2013. Archived from the original (PDF) on 2013-08-13. Retrieved 2013-08-06.
  3. EMCDDA (30 Mar 2011). EMCDDA Risk Assessment: Report on the Risk Assessment of PMMA in the Framework of the Joint Action on New Synthetic Drugs. Dictus Publishing. p. 54. ISBN 978-3-8433-2695-7. Retrieved 2012-01-25.
  4. "Clarke's Analysis of Drugs and Poisons". Pharmaceutical Press. 2011. doi:10.1080/00450618.2011.620006. ISBN 978-0-85369-711-4. S2CID 71790993.
  5. Toole KE, Fu S, Shimmon RG, Kraymen N (2012). "Color Tests for the Preliminary Identification of Methcathinone and Analogues of Methcathinone" (PDF). Microgram Journal. 9 (1): 27–32. Archived from the original (PDF) on 2013-11-26. Retrieved 2013-10-28.
  6. "Color Tests and Analytical Difficulties With Emerging Drugs of Abuse" (PDF). Johnson County Sheriff’s Office Criminalistics Laboratory. 2012. Retrieved 2013-07-16.
  7. "Modafinil reaction with the Froehde reagent and others". Reagent Tests UK. 13 December 2015. Retrieved 18 December 2015.
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