Froehde reagent

{{Short description|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.{{cite web|title=Color Test Reagents/Kits for Preliminary Identification of Drugs of Abuse|url=http://www.ncjrs.gov/pdffiles1/nij/183258.pdf|work=Law Enforcement and Corrections Standards and Testing Program|access-date=2011-07-24|date=July 2000}}

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

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.

class="wikitable sortable" |+ Final colors produced by Froehde Reagent with various substances
Substance !Color
Amphetamine	No reaction{{cite book | last1 = EMCDDA | title = EMCDDA Risk Assessment: Report on the Risk Assessment of PMMA in the Framework of the Joint Action on New Synthetic Drugs | publisher = Dictus Publishing | date = 30 Mar 2011 | page = 54 | url = http://www.emcdda.europa.eu/html.cfm/index33349EN.html | access-date = 2012-01-25 | isbn = 978-3-8433-2695-7}} or Red
Cathinone	No reaction{{cite journal | vauthors = Toole KE, Fu S, Shimmon RG, Kraymen N | title = Color Tests for the Preliminary Identification of Methcathinone and Analogues of Methcathinone | journal = Microgram Journal | volume = 9 | issue = 1 | pages = 27–32 | year = 2012 | url = http://www.justice.gov/dea/pr/microgram-journals/2012/mj9-1_27-32.pdf | access-date = 2013-10-28 | archive-date = 2013-11-26 | archive-url = https://web.archive.org/web/20131126123356/http://www.justice.gov/dea/pr/microgram-journals/2012/mj9-1_27-32.pdf | url-status = dead }}
Methcathinone	No reaction
4-MMC	No reaction
3-FMC	No reaction
MDMA	Black
Methylone	Bright yellow
MDPV	Bright yellow
Butylone	Yellow > Green{{cite web|title=Color Tests and Analytical Difficulties With Emerging Drugs of Abuse|url=https://www.nist.gov/oles/upload/Color-Tests-and-Analytical-Difficulties-with-Emerging-Drugs-Morris.pdf|work=Johnson County Sheriff’s Office Criminalistics Laboratory|access-date=2013-07-16|year=2012}}
3,4-DMMC	Light brown
Naphyrone	Orange
PMA	Pale green
PMMA	Pale green
4-MeO-PCP	Light yellow
Methoxetamine	Yellow - Green
3-HO-PCE	Black
5-MeO-DALT	Yellow
4-AcO-DALT	Yellow > Green
4-HO-MET	Yellow > Green
4-HO-MIPT	Yellow > Green
4-AcO-DET	Yellow > Green
aMT	Yellow
5-IT	Red brown
5-APB	Dark purple
6-APB	Purple
Camfetamine	Tan > Dark yellow
Methiopropamine	Light brown
MDAI	Green > Black
5-IAI	Orange
Allylescaline	Green > Black (fast)
2C-T-2	Orange > Purple
2C-B	Yellow{{cite web|title=Controlled Substances Procedures Manual|url=http://www.dfs.virginia.gov/manuals/controlledsubstances/procedures/221-d100%20controlled%20substances%20procedures%20manual.pdf|work=Virginia Department of Forensic Science|access-date=2013-08-06|year=2013|archive-url=https://web.archive.org/web/20130813124334/http://www.dfs.virginia.gov/manuals/controlledSubstances/procedures/221-D100%20Controlled%20Substances%20Procedures%20Manual.pdf|archive-date=2013-08-13|url-status=dead}}
2C-P	Green
b-methoxy-2C-D	Red
Acetaminophen	Pale blue
Aspirin	Greyish purple or Blue > Purple
Alimemazine	Purple red{{cite journal|title=Clarke's Analysis of Drugs and Poisons|journal=Pharmaceutical Press|year=2011|isbn=978-0-85369-711-4|doi=10.1080/00450618.2011.620006|s2cid=71790993}}
Chlorphentermine	Green
Chlorpromazine HCl	Very deep red
Contac HCl	Moderate olive brown
Dimethoxy-meth HCl	Very yellow green
Diphenhydramine	Orange
Doxepin HCl	Deep reddish brown
Dristan	Light bluish green
Ephedrine	Brown
Exedrine	Brilliant blue
Flurazepam	Orange
LSD	Moderate yellow green, Yellow Green
Mace	Light olive yellow
MDA HCl	Greenish black
Mescaline	Green or brown or light yellow
Meperidine	Grey
Modafinil	Deep orange/red{{cite web | url=http://www.reagent-tests.uk/blog/modafinil-reaction-with-the-froehde-reagent-and-others/ | title=Modafinil reaction with the Froehde reagent and others | publisher=Reagent Tests UK | date=13 December 2015 | access-date=18 December 2015}}
Morphine monohydrate	Deep purplish Red > Slate
Heroin HCl	Deep purplish red > Green
Opium	Brownish black
Oxycodone HCl	Strong yellow - Blue or Green
Codeine HCl	Very dark Green > Red - Brown
Hydromorphone	Blue > Purple
Hydrocodone	Light Yellow
Pentazocine	Blue
Pethidine	Yellow
Phenoxymethylpenicillin	Blue
Phenyltoloxamine	Green
Promazine	Orange
Promethazine	Purple red
Propoxyphene HCl	Dark greyish red or Brown
Propylhexadrine	Purple red
Sugar	Brilliant yellow
Salicylic acid	Purple red
Tetracycline	Purple red
Thioridazine	Purple red
Guaifenesin	Green with purple streaks
Methapyrilene	Purple
Pyrilamine	Purple
Trifluoperazine	Orange
Triflupromazine	Orange