Froehde reagent

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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
Amphetamine No reaction[3] or Red[4]
Cathinone No reaction[5]
Methcathinone No reaction[5]
4-MMC No reaction [5]
3-FMC No reaction[5]
MDMA Black[3]
Methylone Bright yellow[5]
MDPV Bright yellow[5]
Butylone Yellow > Green[6]
3,4-DMMC Light brown[6]
Naphyrone Orange[6]
PMA Pale green[3]
PMMA Pale green[3]
4-MeO-PCP Light yellow[6]
Methoxetamine Yellow - Green[6]
3-HO-PCE Black[6]
5-MeO-DALT Yellow[6]
4-AcO-DALT Yellow > Green[6]
4-HO-MET Yellow > Green[6]
4-HO-MIPT Yellow > Green[6]
4-AcO-DET Yellow > Green[6]
aMT Yellow[6]
5-IT Red brown[6]
5-APB Dark purple[6]
6-APB Purple[6]
Camfetamine Tan > Dark yellow[6]
Methiopropamine Light brown[6]
MDAI Green > Black[6]
5-IAI Orange[6]
Allylescaline Green > Black (fast)[6]
2C-T-2 Orange > Purple[6]
2C-B Yellow[2]
2C-P Green[6]
b-methoxy-2C-D Red[6]
Acetaminophen Pale blue[2]
Aspirin Greyish purple[1] or Blue > Purple[2]
Alimemazine Purple red[4]
Chlorphentermine Green[4]
Chlorpromazine HCl Very deep red[1][4]
Contac HCl Moderate olive brown[1]
Dimethoxy-meth HCl Very yellow green[1]
Diphenhydramine Orange[4]
Doxepin HCl Deep reddish brown[1][4]
Dristan Light bluish green[1]
Ephedrine Brown[4]
Exedrine Brilliant blue[1]
Flurazepam Orange[4]
LSD Moderate yellow green,[1] Yellow Green[4]
Mace Light olive yellow[1]
MDA HCl Greenish black[1][4]
Mescaline Green or brown or light yellow[4]
Meperidine Grey[2]
Modafinil Deep orange/red[7]
Morphine monohydrate Deep purplish[2] Red[1] > Slate[2]
Heroin HCl Deep purplish red[1][4] > Green[2]
Opium Brownish black[1][4]
Oxycodone HCl Strong yellow[1][2] - Blue[4] or Green[4]
Codeine HCl Very dark[1] Green[4] > Red - Brown[2]
Hydromorphone Blue > Purple[2]
Hydrocodone Light[2] Yellow[4]
Pentazocine Blue[2][4]
Pethidine Yellow[4]
Phenoxymethylpenicillin Blue[2]
Phenyltoloxamine Green[4]
Promazine Orange[4]
Promethazine Purple red[4]
Propoxyphene HCl Dark greyish red[1][4] or Brown[2]
Propylhexadrine Purple red[4]
Sugar Brilliant yellow[1]
Salicylic acid Purple red[4]
Tetracycline Purple red[4]
Thioridazine Purple red[4]
Guaifenesin Green with purple streaks[2]
Methapyrilene Purple[2]
Pyrilamine Purple[2]
Trifluoperazine Orange[4]
Triflupromazine Orange[4]

See also[edit]


  1. ^ a b c d e f g h i j k l m n o p q r "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. ^ a b c d e f g h i j k l m n o p q r "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. ^ a b c d 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. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac "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. ^ a b c d e f 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.
  6. ^ a b c d e f g h i j k l m n o p q r s t u v w "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.