Method and kit for detection of cyanide

Abstract

A metal contamination detection system, forming part of a cyanide detection system which is especially useful when used in conjunction with a corrinoid cyanide detection system as it allows for the quick and accurate assessment of impurities that could lead to a false cyanide result, and therefore the need to remove the impurities for an accurate result or a better metals recovery.

Claims

1. A cyanide detection kit comprising: (i) a composition for detecting metal contamination comprising a solid buffer, the buffer being adapted to provide a pH of from 9-10; and (ii) a cyanide detection component comprising: at least one first colorimetric solid phase extraction device, said first device comprising a non-polar solid phase loaded with a first corrinoid compound selected from the group consisting of: a cobalamine according to formula (I), ##STR00004## a cobyrinic acid hepta Cl-4 alkyl ester derivative (II), a cobyrinic acid (III) and a cobinamide (IV), ##STR00005##

2. The cyanide detection kit according to claim 1, in which the buffer is selected from the group consisting of a N-cyclohexyl-2-aminoethanesulfonic acid (CHES) buffer, Carbonate-Bicarbonate Buffer (Carbonate), Glycine Buffer (Glycine), 2-Amino-2-Methyl-1-Propanol (AMP) buffer, 2-Amino-2-methyl-1,3-propanediol (AMPD) buffer, and combinations thereof.

3. The cyanide detection kit according to claim 2, in which the buffer is CHES.

Description

EXAMPLE 1

(1) Preparation & Employment of Solid Buffer

(2) The buffer solutions [Carbonate, Glycine, Boric Acid, AMP, AMPD, CAPSO, NaOH(as reference), CHES] were prepared in a concentration of 0.5 M and 0.25M in water and its pH is set to a value between 9.0 and 10.0 by addition of hydrochloric acid or sodium hydroxide solution. The liquid buffer was filled into plastic vials and dipped into liquid nitrogen, before the vials were closed with perforated lids. The vials were put into a lyophilizer at −83° C. and a pressure of 0.08 mbar. After 12-24 hours, the buffers have dried and were ready for use.

(3) Prior to use, 0.3 ml of the water sample to be tested for cyanide and any potential interferences is added to lyophilized buffer.

EXAMPLE 2

(4) Testing of Interfering Metal Ions

(5) The presence of selected metal ions was simulated by the addition to water of 30, 50, 80, 100, 200, 250, 300, 500 and 1000 ppm of the metal ions shown in the following table. This provided the limits of detection shown in the table.

(6) limit of detection (ppm) for each buffer system with 0.25 M

(7) TABLE-US-00002 Metal Ions Buffer Systems Ni.sup.2+ Cu.sup.2+ Fe.sup.2+ Fe.sup.3+ Co.sup.2+ Zn.sup.2+ Hg.sup.2+ Cr.sup.3+ Carbonate 250 100 200 50 200 200 100 100 Glycine 250 100 200 100 250 250 250 250 Boric Acid 250 250 250 250 250 250 500 500 AMP 250 100 80 80 80 200 100 100 AMPD 200 100 80 80 80 250 250 250 CAPSO* 250 250 250 250 250 250 250 250 NaOH 300 300 200 200 500 500 300 300 CHES 200 200 100 50 100 200 100 100 *3-(Cyclohexylamino)-2-hydroxy-1-propanesulfonic acid buffer

(8) Similar results were achieved with a higher buffer concentration of 0.5M

(9) To a sample of each of these metal ions in water was added potassium cyanide to give a CN.sup.− concentration of 1.0 ppm. These samples were then added to the dried buffer prepared in Example 1. In each case, there was a coloured or white precipitate, indicating the presence of a metal that had complexed with the CN.sup.−.

(10) Had a cyanide-containing sample, also containing any one of these metal ions, been tested by corrinoid-based cyanide detection assay, the cyanide would not have shown up and the tester would have falsely believed that no cyanide was present.

(11) The test indicates that a metal contaminant is present, and that it is necessary to remove it prior to testing for cyanide.