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.

Abstract: A method of determining the proportion of cyanide in a sample, comprising the following steps: (i) Add the sample to be analysed to a sensor molecule that is selected from cobryrinic acid hepta C1-4 alkyl esters of the Formula I in which X is CN, R3 is H, and R1 and R2 are OCH3; (ii) Subject the sample to UV-vis spectroscopic analysis in the range 450-700 nm; (iii) Determine the free cyanide concentration from the equation (i) C=(A?0.058)/0.104??(i) in which C is the free cyanide concentration and A is A=A581/A527 the ratio of the absorbances at 581 and 527 nm, the equation (i) having been derived from a calibration curve that is a plot of A ratios calculated at 0-1 mg/L CN? with a constant 46 nmol of sensor compound. The method provides a particularly accurate assessment of cyanide concentration in an unknown sample.