Griess reaction

The most important color reaction for nitrate esters and nitramines is based on the formation of nitrite ions (NO2 ), upon reaction of these compounds with alkahs [31,32]. The nitrite ions are then detected by the classical Griess reaction [5,6]. 

The nitrite ions are detected by the Griess reaction, starting with their reaction with an aniline derivative, such as sulfanilic acid, or sulfanilamide. The reaction is carried out in an acidic medium (e.g., acetic acid) and leads to the formation of a diazonium ion (Eq. (8)) ... 

The limit of detection of the nitrite ions by the Griess reaction, using the above-mentioned reagents, was reported [4] to be 0.05 0,g (this value refers to the N02 ions and not to the explosive which produces them). 

In the Franchimont test [42], nitramines are reduced to nitrite ions by zinc and acetic acid and then subjected to the Griess reaction. A modification of this test was used for the identification of nitramine impurities in RDX [43]. 

As part of a routine procedure, a local forensic scientist was summoned to swab the detainees hands in an attempt to find explosives traces. Fie took etheral swabs from the suspects hands. On these swabs, he applied a field test based on the Griess reaction. Two of the five tested positively on one of their hands. The suspects were then interrogated extensively and several of them signed a confession. 

As stated above, nitrate esters (such as NG or PETN) and nitramines (such as RDX or HMX), form nitrite ions under alkahne conditions and therefore can be detected by the Griess reaction. However, the Griess spot test by itself does not enable to distinguish between individual explosives within these groups. 

Another important source for false-positive results in the use of the Griess reaction for the identification of explosives is the possible presence of nitrate ions, together with some accidental reducing substances. In this situation, the nitrate ions (NOs ) could be reduced to nitrite ions (NO2 ), giving a positive result in the Griess reaction. 

Recalling the above-mentioned classification of color reactions, it is clear that in the Griess reaction atoms from the analyte are incorporated into the colored product. This leads to a higher degree of specificity compared with oxidation/ reduction reactions where only electrons (and no atoms) are transferred. 

Another field technique for screening soils for the presence of TNT, 2,4-dinitrotoluene (2,4-DNT) and RDX was reported [99]. The color reagents were KOH for TNT (red color) and sodium sulfite for 2,4-DNT (blue-purple color). In screening soil for the presence of RDX, the first step would be to remove any potential contaminants - nitrite and nitrate ions - from the soil, using an ion exchange resin. The RDX is then reduced by zinc powder and the resulting N02 ions are detected by the Griess reaction. Detection limits were estimated to be 1 mg of TNT or RDX and 2 mg of 2,4-DNT per 1 kg of soil. 

The diazonium intermediate releases molecular nitrogen (N2) to form reactive carbonium ions. If the R group is aromatic, the diazonium intermediates can be stabilized as a salt, and are widely used as intermediates in synthetic chemistry. The formation of a diazonium intermediate with sulfanilic acid by acidified nitrite, a source of nitrosonium ion, is the basis for measuring nitrite by the Griess reaction. 

Alexejevsky s Method. This depends on the reduction of chloropicrin by metallic calcium to form nitrous acid, which is detectable by the Griess reaction. ... 

Thus by means of the Griess Reaction it is possible to start with an amino compound, diazotise it and then couple up the diazo compound with an undiazotized amino compound and obtain the amino azo compound either directly or after molecular rearrangement. 

By the Griess reaction the para compound is always formed unless, in the case of the homologues of aniline, e.g. in preparing the amino azo toluenes, the para position is occupied. In this case the ortho compound results. 

Butter Yellow.—The di-methyl derivative of amino azo benzene which we have referred to in our discussion of the general method for the formation of amino azo compounds by the Griess reaction (p. 569), is also a dye known as butter yellow It is insoluble in water, but soluble in oils and, therefore, is used to color butter. 

Replacement and rearrangement without loss of nitrogen. (Griess reaction.)... 

Fig. 7.18. Low-pressure interfaces to detectors based on flow injection. (A) Interface to a photometric detector across a membrane. (Reproduced with permission of the American Chemical Society.) (B) Interface to a flow-through photometric sensor with prior derivatization by the modified Griess reaction. (Reproduced with permission of the American Chemical Society.) (C) Interface to a piezoelectric detector. P peristaltic pump, C collector, CUC clean-up column, DB debubbler, SA sulfamic acid, NEDD /V-( 1-naphthyl)ethylenediamine dihydrochloride, SV switching valve, W waste, DF displacement flask, IV injection valve, FC-PZ flow-cell-piezoelectric crystal, OC oscillator circuitry, F frequency counter, PC personal computer. (Reproduced with permission of Elsevier.)...

Nitrite is commonly determined by a colorimetric procedure using a reaction called the Griess reaction. In this reaction, the sample containing nitrite is reacted with sulfanilimide and N-(l-Napthyl) ethylenediamine to form a colored species that absorbs at 550 nm. By using an automated flow analysis instrument, the following results were obtained for standard solutions of nitrite and for a sample containing an unknown amount ... 

Sandwich techniques can also be implemented in a sequential injection analyser, as demonstrated by the spectrophotometric determination of nitrate and nitrite in natural waters [12]. The sample plug was set between two reagent plugs and the assembly was aspirated towards the holding coil of an ordinary sequential injection analyser. Two Griess reaction zones were established at both ends of the sample zone, and only one was... 

Nitrate, nitrite Soil solutions Filtration/dialysis UV-Vis 0.02-0.60, 0.01-0.75 pg mL-1 Unsegmented continuous flow system filtration/dialysis probe for sampling real-time monitoring of a leaching process Griess reaction after optional nitrate conversion to nitrite [542]... 

The nitrite ion can be detected spectrophotometrically after the separation of nitrosamines by HPLC followed by photolytic or chemical denitrosation. Postcolumn formation of an azo dye by the reaction of nitrite with a Griess-type reagent allows its spectrophotometric detection at 546 The kinetics and mechanisms of the Griess reaction have been extensively... 

Air Griess reaction Photometry 2.0-500 ngm Membrane-based gas sampling... 

The most representative example of this type of reaction is the so-called Griess reaction, originally developed for the kinetic determination of nitrite. Nitrite in a weakly acidic solution reacts with an amine (usually sulfanilic acid) to form the corresponding diazonium salt, which then couples with a naphthylamine or naphthol. This reaction can also be used for the kinetic determination of nitrate after reduction in a column, as well as for measuring other species such as sulfonamides (Bratton-Marshall reaction), and benzodiazepines and N-methylcarba-mate pesticides, the hydrolysis of which yields the corresponding benzophenones (which can be diazoti-zed) and naphthols (useful for the coupling reaction), respectively. 

Nitrite Griess reaction 1.0x10" moll" SF mixing. Nitrate can be determined using cadmium... 

A/-Methylcarbamate Griess reaction with 1-naphthol as 0.35-40 Carbaryl, carbofuran, and propoxur are... 

Sulfonamides Griess reaction 0.5-8.5 Practical problems associated with these types of reaction were avoided by using the CAR technique... 

Griess reaction W-Methyicarbamate pesticides 1- and 2-Naphthoi Mixtures of carbaryi and its hydroiysis product (1-naphthoi) and of carbofuran and propoxur can be resoived using the stopped-fiow technique Mixtures in ratios from 20 1 to 1 5 were resoived as were ternary mixtures with carbaryi... 

Spectrophotometric with Griess reaction Aqueous (urine, cerebrospinal fluid, plasma, cell culture medium) Micromolar... 

Nitrogen-containing species The nitrate content in waters is usually low but can rise to appreciable levels in farming wastewater as a result of soil fertilization. Nitrite originates from the microbiological reduction of nitrate or the oxidation of ammonia. Nitrite is usually determined spectrophotometrically using the Griess reaction. Nitrate is determined by the same method after prereduction to nitrite. 

Ethyleneglycol dinitrate, pentaerythritol tetranitrate, nitroglycain, Tetryl, RDX, HMX, DNT and TNT were sqrarated on a C g column (A = 254 nm) using a 50/50 methanol/water mobile phase. Elution was complete in <10 min [181]. To enhance, sensitivity, a postcolumn Griess reaction was run (sulfanilimide and A-[naphthyl-(l)]ethylenediamine photolyzed with sample). Peak shapes and resolution were excellent. Detection limits of lOOpg were reported. 

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