ISO 14403-1-2012 pdf free download

ISO 14403-1-2012 pdf free download.Water quality — Determination of total cyanide and free cyanide using flow analysis (FIA and CFA) — Part 1:Method using flow injection analysis (FIA)
Qualité de l’eau — Dosage des cyanures totaux et des cyanures libres par analyse en flux (FIA et CFA) — Partie 1. Méthode par analyse avec injection de flux (FIA).
4.2 Interferences by sulfide, sulfite, nitrite, and carbonyl compounds
Interferences by sulfide start at 20 mg/i. If a drop of the sample on lead acetate test paper indicates the presence of sulfide, treat an additional 25 ml of the stabilized sample (pH >12) to that required for the cyanide determination with powdered lead carbonate.
Lead sulfide precipitates if the sample contains sulfide.
Repeat this operation until a drop of the treated sample solution does not darken the lead acetate test paper.
Filter the solution through a dry filter paper into a dry beaker, and from the filtrate measure the sample to be used for analysis. Avoid a large excess of lead and a long contact time in order to minimize loss by complexation or occlusion of cyanide on the precipitated material.
Aldehydes and ketones can, under certain conditions, absorb cyanide by nucleophilic addition. To avoid this interference ethylenediamirie can be added to the sample.
Interference by nitrite occurs above concentrations of 2 mg/I and can be avoided by addition of sulfamic acid (6.8) to the buffer (pH 3,8) for the gas diffusion method (6.20.1).
Sulfite interferes above concentrations of 1 mg/I.
4.3 Other Interferences
Particulate matter In the sample can lead to clogging of the transport tubes and Interferes with the photometric measurement. Particles of diameter >0,1 mm should be removed by filtration.
Thiocyanate can slightly interfere and lead to positive bias (9.3.2). Significant interferences can arise from cyanide impurities in thiocyanate (6.16).
5 Principle
5.1 Determination of total cyanide
Complex-bound cyanide is decomposed by UV light at pH 3,8. A UV-B lamp (emission maximum >310 nm to 400 nm) and a digestion coil of perfluoro (ethylene/propylene) (FEP) or polytetrafluorethylene (PTFE) is used to filter off UV light with a wavelength <290 nm thus preventing the conversion of thiocyanate into cyanide. A hydrolytic treatment in a thermoreactor (85 °C) assists the decomposition.
The hydrogen cyanide present at pH 3.8 is separated by diffusion at 30 °C to 40 °C across a hydrophobic membrane. Hydrogen cyanide is absorbed in a sodium hydroxide solution.
The absorbed cyanide is then determined by the reaction of cyanide with chloramine-T to cyanogen chloride. This reacts with pyridine-4-carboxylic acid and 1,3-dimethylbarbituric acid to give a red dye.ISO 14403-1-2012 pdf free download.