The Griess test is an

analytical chemistry Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separati ...

test which detects the presence of

nitrite The nitrite polyatomic ion, ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name ...

ion in

solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Soluti ...

. One of its most important uses is the determination of nitrite in

drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, a ...

. The Griess

diazotization Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. General properti ...

reaction, on which the Griess reagent relies, was first described in 1858 by

Peter Griess Johann Peter Griess (6 September 1829 – 30 August 1888) was an industrial chemist and an early pioneer of organic chemistry. Griess was influential in the formation of modern dyes, first formulating the diazotization reaction of arylamines. Li ...

.Peter Griess (1858
"Vorläufige Notiz über die Einwirkung von salpetriger Säure auf Amidinitro- und Aminitrophenylsäure,"
(Preliminary notice of the reaction of nitrous acid with picramic acid and aminonitrophenol), ''Annalen der Chemie und Pharmacie'', 106: 123–125. The test has also been widely used for the detection of

nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...

s (N-

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

= 5+), which are a common component of

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...

s, as they can be reduced to nitrites (N-

= 3+) and detected with the Griess test.

Method

Nitrite is detected and analyzed by the formation of a red pink colour upon treatment of a nitrite-containing sample with the Griess reagent, which consists of two components in an acidic solution: an

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine In organic chemistry, an aromatic amine is an organic compound consisting of an aroma ...

derivative and a coupling agent. The most common arrangements use

sulfanilamide Sulfanilamide (also spelled sulphanilamide) is a sulfonamide antibacterial drug. Chemically, it is an organic compound consisting of an aniline derivatized with a sulfonamide group. Powdered sulfanilamide was used by the Allies in World War II ...

and N-(1-naphthyl)ethylenediamine: a typical commercial Griess reagent contains 0.2% N-(1-naphthyl)ethylenediamine dihydrochloride, and 2%

in 5%

phosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, w ...

. This diamine is used in place of the simpler and cheaper

1-naphthylamine 1-Naphthylamine is an aromatic amine derived from naphthalene. It can cause bladder cancer (transitional cell carcinoma). It crystallizes in colorless needles which melt at 50 °C. It possesses a disagreeable odor, sublimes readily, and turn ...

because the latter is a potent carcinogen and moreover the diamine forms a more polar and hence a much more soluble dye in acidic aqueous medium. Other aniline derivatives that have been used include

sulfanilic acid Sulfanilic acid (4-aminobenzenesulfonic acid) is an organic compound with the formula H3NC6H4SO3. It is an off-white solid. It is a zwitterion, which explains its high melting point. It is a common building block in organic chemistry."Sulphanili ...

, nitroaniline, and ''p''-aminoacetophenone. : The Griess test involves two subsequent reactions. When sulfanilamide is added, the nitrite ion reacts with it in the Griess diazotization reaction to form a

diazonium salt Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. General properti ...

, which then reacts with N-(1-naphthyl)ethylenediamine in an

azo coupling In organic chemistry, an azo coupling is an organic reaction between a diazonium compound () and another aromatic compound that produces an azo compound (). In this electrophilic aromatic substitution reaction, the aryldiazonium cation is the ...

reaction, forming a pink-red

azo dye Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C-N=N ...

. Using a spectrophotometer, it is possible to quantitatively determine the nitrite concentration. The detection limit of the Griess test generally ranges between 0.02 and 2 μM, depending on the exact details of the specific components used in the Griess reagent.

Forensics

The test was used in

forensics Forensic science, also known as criminalistics, is the application of science to criminal and civil laws, mainly—on the criminal side—during criminal investigation, as governed by the legal standards of admissible evidence and crimina ...

for many years to test for the traces of

nitroglycerine Nitroglycerin (NG), (alternative spelling of nitroglycerine) also known as trinitroglycerin (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless, oily, explosive liquid most commonly produced by nitrating ...

Caustic soda Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alka ...

is used to break down sample containing

to produce nitrite ions. The test involves the taking of a

sample Sample or samples may refer to: Base meaning * Sample (statistics), a subset of a population – complete data set * Sample (signal), a digital discrete sample of a continuous analog signal * Sample (material), a specimen or small quantity of s ...

with ether and its division into two bowls. Caustic soda is added to the first bowl followed by the Griess reagent; if the solution turns pink within ten seconds, this indicates the presence of nitrites. The test itself is positive if, after adding only Griess reagent to the second bowl, the solution there remains clear. The convictions of

Judith Ward The M62 coach bombing, sometimes referred to as the M62 Massacre, occurred on 4 February 1974 on the M62 motorway in northern England, when a 25-pound (11 kg) Provisional Irish Republican Army (IRA) bomb hidden inside the luggage locker ...

and the

Birmingham Six The Birmingham Six were six Irishmen who were each sentenced to life imprisonment in 1975 following their false convictions for the 1974 Birmingham pub bombings. Their convictions were declared unsafe and unsatisfactory and quashed by the Cou ...

were assisted by

Frank Skuse Frank Skuse (born ca. 1934) is a British former forensic scientist for the North West Forensic Laboratories based in Chorley, Lancashire. His flawed conclusions, eventually discredited, contributed to the convictions of Judith Ward and the Birmingha ...

's flawed interpretation of Griess test results.

References

Chemical tests Forensic techniques {{forensics-stub

Method

Forensics

See also

References