Test to presumptively identify alkaloids and other compounds
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]
^ abcdefghijklmnopqr"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.
^ abcdefghijklmnopqr"Controlled Substances Procedures Manual" (PDF). Virginia Department of Forensic Science. 2013. Archived from the original (PDF) on 2013-08-13. Retrieved 2013-08-06.
^ abcdEMCDDA (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.
^ abcdefghijklmnopqrstuvwxyzaaabac"Clarke's Analysis of Drugs and Poisons". Pharmaceutical Press. 2011. doi:10.1080/00450618.2011.620006. ISBN 978-0-85369-711-4. S2CID 71790993.
^ abcdefToole 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.
^ abcdefghijklmnopqrstuvw"Color Tests and Analytical Difficulties With Emerging Drugs of Abuse" (PDF). Johnson County Sheriff’s Office Criminalistics Laboratory. 2012. Retrieved 2013-07-16.
^"Modafinil reaction with the Froehde reagent and others". Reagent Tests UK. 13 December 2015. Retrieved 18 December 2015.
The Froehdereagent is used as a simple spot-test to presumptively identify alkaloids, especially opioids, as well as other compounds. It is composed...
Retrieved December 18, 2015. "Modafinil reaction with the Froehdereagent and others". Reagent Tests UK. December 13, 2015. Archived from the original on...
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