Environmental Express SimpleDist - Manual (Page 16)

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SimpleDist: Operation and Instruction Manual System Operation
Total Cyanide Distillation with the SimpleDist™:
1.0 Scope and Application
1.1 This method follows US EPA method number 335.4 titled Determination of Total Cyanide by Semi-Automated
Colorimetry. It is applicable for the determination of total cyanide in drinking, ground, surface, and saline waters,
domestic and industrial wastes, and soils.
1.2 The standard range is typically 5 to 500µg/L. Lower detection limits can be achieved by using a longer path length
flow cell in the analysis step when using an automated continuous flow analyzer.
2.0 Summary of Method
2.1 The cyanide as HCN is released from metal-cyanide complexes by means of an acidic manual reflux-distillation
whereby the HCN gas that is formed is separated from the sample matrix and absorbed in a dilute solution of
sodium hydroxide. The distillate can be analyzed for cyanide by semi-automated colorimetry, manual colorimetry,
titrimetric, or
ion-selective electrode.
2.2 Reduced volume versions of this method that use the same reagents and molar ratios as in the original method are
acceptable provided they meet the quality control and performance requirements stated in the method.
3.0 Interferences
There are several known interferences with this method. A few of these are:
Aldehydes
Thiocyanates
Nitrate-nitrite Thiosulfates
Chlorine Sulfides
Some of these interferences are reduced or eliminated by the distillation process. For example, the nitrate-nitrite
interference is eliminated by addition of sulfamic acid during the distillation step. Further, the addition of magnesium
chloride, which acts as a catalyst, will promote the breakdown of refractory iron-cyanide complexes.
The reagent preparations for these two interferences will be summarized in the Reagent Preparation section. For all other
pretreatment procedures refer to the US EPA method number 335.4 and/or SW846 9010C.
4.0 Chemicals Required: Distillation Only
4.1 Sodium hydroxide
4.2 Sulfuric acid, 18N
4.3 Magnesium chloride, if refractory iron-cyanide complexes are present
4.4 Sulfamic acid – if nitrates and nitrites are present
4.5 Potassium cyanide
4.6 Potassium hydroxide
4.7 Reagent water ASTM Type II or equivalent
Note: The toxicity for each of the reagents used in this procedure are not fully documented. Treat each chemical as a potential
health hazard and limit exposure. Exercise good laboratory technique with an emphasis on safety.