Assay for dibromonitrilopropionamide

Details Assay for dibromonitrilopropionamide Assay for dibromonitrilopropionamide

1993-08-24

1995-01-17

Housel, James C.

Chemistry: analytical and immunological testing

Nitrogen containing

Cyanide or isocyanide

436106, 436166, 422 61, G01N 3315

Patent

active

053825292

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to an assay for the compound NC--C(Br).sub.2 --CONH.sub.2, i.e. dibromonitrilopropionamide (DBNPA).


BACKGROUND OF THE INVENTION

DBNPA is a biocide that is used in cooling towers, in order to control organisms such as Legionella, in paper-making, and in other aqueous environments. An object behind the invention is to monitor the level of such compounds in the water.


SUMMARY OF THE INVENTION

According to the present invention, a method of testing for the presence of DBNPA in a sample comprises adding to the sample, under alkaline conditions and in the presence of a magnesium compound, a phenolic or anilinic compound that generates a colour; and observing the resultant colour.
The invention is based on the discovery that there are many phenolic and anilinic compounds which can react with DBNPA, to generate a coloured species, in the presence of magnesium ions. The novel method is both simple and effective. A kit of the essential components can be provided.


DESCRIPTION OF THE INVENTION

The reaction is preferably conducted at a pH of 8.5 to 10, e.g. about 9. For this purpose, a buffer such as an alkali metal tetraborate (e.g. borax), Tris.HCl or Trisglycine.HCl can be used.
The magnesium ions can be provided in the form of any Mg compound that catalyses the reaction. MgCO.sub.3, as present in hard water can be used, as can MgCl.sub.2, MgSO.sub.4, Mg(NO.sub.3).sub.2 and other Mg salts. Calcium, sodium, potassium and aluminium ions apparently do not catalyse the reaction.
The assay may be affected by the presence of iron (III) or iron (II). If present, iron ions are therefore preferably removed, e.g. using a cation-exchange resin.
The phenolic or anilinic compound can be chosen, depending on the conditions, by anyone skilled in the art. It is preferably pyrocatechol, although it may be any analogous compound, e.g. of the 1,4-benzenediol/benzenediamine/aminophenol or, preferably, 1,2-benzenediol/benzenediamine/aminophenol-type. Colours given by certain such compounds are tabulated below:


______________________________________ Compound Colour ______________________________________ pyrocatechol distinctive violet (turns yellow in acid) hydroquinone relatively evanescent blue- green (3,4-dihydroxyphenyl)acetic violet acid (3,4-dihydroxyphenyl)acetamide red-purple [2-(3,4-dihydroxyphenyl)ethyl]- violet trimethylammonium chloride (3,4-dihydroxyphenyl)glycol violet 2-(3,4-dihydroxyphenyl)ethanol violet 3-methylcatechol deep purple 4-methylcatechol blue-red o-phenylenediamine red p-phenylenediamine red-orange ______________________________________
m-Phenylenediamine gives no colour, and neither does phenol, but the use of such compounds is included within the scope of this invention; a colour can be generated by the addition of an oxidising agent such as periodate. Guaiacol gives an orange colour, and isohomovanillic acid faint purple, in the presence of borax. The colour is likely to be pH-dependent, but the optimum pH can be determined simply.
In use of the method according to the invention, the colour that is generated is preferably compared with a blank of the phenolic or anilinic compound. The colour can be measured by any suitable means.
The following Examples illustrate the invention.


EXAMPLE 1

To aqueous DBNPA was added 10% v/v of Tris-HCl buffer, pH 9.1, containing a catalytic amount of MgCl.sub.2. Pyrocatechol was added in aqueous form, to a concentration of 50 .mu.g/ml. A violet colour was allowed to develop over 5 minutes, and was read at 537 nm. The colour turned yellow in acid. It also acted as an oxidation-reduction indicator, and was decolorised by SnCl.sub.2 and K.sub.3 Fe(CN).sub.6. The reading allowed quantification of the amount of DBNPA, by comparison with a pyrocatechol-containing blank.


EXAMPLE 2

The following steps were conducted: MgCl.sub.2. Mix thoroughly.


EXAMPLE 3

The following steps were carried out: cationic resin in the lithium form.
1. A method of testing for the presence of

REFERENCES:
patent: 3519711 (1970-07-01), Svigals
patent: 4761427 (1988-08-01), Segall et al.
R. I. Botto et al. Anal. Chem., 1981, 53, 2375-2376.
S. Honda et al. Anal. Chim. Acta 1983, 149, 297-303.

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