ISO 14403-1-2012 pdf free download.Water quality – Determination of total cyanide and free cyanide using flow analysis (FlA and CFA)—Part 1:Method using flow injection analysis (FIA).
This part of lSO 14403 specifies methods for the determination of cyanide in various types of water (suchas ground, drinking, surface, leachate, and waste water) with cyanide concentrations from 2 ugl to 500 uglexpressed as cyanide ions in the undiluted sample. The range of application can be changed by varying theoperation conditions, e.g. by diluting the original sample or using a different injection volume.
ln this part of lSO 14403, a suitable mass concentration range from 20 ug/l to 200 ug/l is described.
Seawater can be analysed with possible changes in sensitivity and adaptation of the reagent and calibrationsolutions to the salinity of the samples.
2Normative references
The following referenced documents are indispensable for the application of this document. For datedreferences, only the edition cited applies.For undated references, the latest edition of the referenced document(including any amendments) applies.
ISO 3696, Water for analytical and laboratory use— Specification and test methods
ISO 5667-3, Water quality — Sampling —Part 3: Preservation and handling of water samples
IS0 8466-1,Water quality — Calibration and evaluation of analytical methods and estimation of performancecharacteristics —Part 1: Statistical evaluation of the linear calibration function
ISO 8466-2, Water quality — Calibration and evaluation of analytical methods and estimation of performancecharacteristics — Part 2: Calibration strategy for non-linear second-order calibration functions
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1free cyanide
easily liberatable cyanide
sum of cyanide ions and the cyanide bound in weak metal cyanide complexes that liberate HCN at pH 3,8
3.2total cyanide
free cyanide (3.1), and in addition stronger metal-cyanide complex compounds, with the exception of cyanide bound ingold, platinum, cobalt, ruthenium, and rhodium complexes from which recovery can be partial
4lnterferences
4.1Interferences by oxidizing agents
Oxidizing agents such as chlorine decompose most of the cyanides. If the presence of oxidizing agents cannotbe excluded, treat the sample immediately after sampling. Test a drop of the sample with potassium iodide-starch test paper (Kl starch paper); a blue colour indicates the need for treatment. Add sodium thiosulfate,afew crystals at a time, until a drop of sample produces no colour on the indicator paper.
Carry out a holding time study at the sampling point in order to determine whether the sample is stable for thetime period for preservation and whether the preservation is effective. If this preservation is ineffective, onlinemeasurement instrumentation may be required.
4.2Interferences by sulfide,sulfite,nitrite, and carbonyl compounds
Interferences by sulfide start at 20 mg/l. lf a drop of the sample on lead acetate test paper indicates thepresence of sulfide, treat an additional 25 ml of the stabilized sample (pH >12) to that required for the cyanidedetermination 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 flter paper into a dry beaker, and from the filtrate measure the sample to beused for analysis.Avoid a large excess of lead and a long contact time in order to minimize loss by complexationor occlusion of cyanide on the precipitated material.
Aldehydes and ketones can, under certain conditions, absorb cyanide by nucleophilic addition. To avoid thisinterference ethylenediamine can be added to the sample.
Interference by nitrite occurs above concentrations of 2 mg/l 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/l.
4.3Other interferences
Particulate matter in the sample can lead to clogging of the transport tubes and interferes with the photometricmeasurement. 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 fromcyanide impurities in thiocyanate (6.16).
5 Principle
5.1Determination of total cyanide
Complex-bound cyanide is decomposed by UV light at pH 3,8.AUV-B lamp (emission maximum >310 nm to400 nm) and a digestion coil of perfluoro (ethylene/propylene)(FEP) or polytetrafluorethylene (PTFE) is usedto filter off uV light with a wavelength <290 nm thus preventing the conversion of thiocyanate into cyanide.ISO 14403-1 pdf download.