Environmental Express SimpleDist - Ammonia Nitrogen Distillation

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SimpleDist® Micro Heating Block: Operation & Instruction Manual Distillation Methods
Ammonia Nitrogen Distillation with the
SimpleDist® Micro Heating Block
1.0 Scope and Application
1.1 This method follows both Standard Methods 4500-NH3 titled Nitrogen (Ammonia) and
US EPA Method 350.1 titled Determination of Ammonia Nitrogen by Semi-Automated
Colorimetry. These methods are applicable to the determination of ammonia nitrogen
in drinking, ground, surface, and saline waters, domestic and industrial wastes, and
soils.
1.2 The standard applicable range is 0.01 to 2.0 mg/L NH
3
as N. Higher concentrations can
be determined by sample dilution.
2.0 Summary of Method
2.1 A sample is buffered at pH 9.5 with borate buffer to decrease hydrolysis of cyanates
and organic nitrogen compounds. It is then distilled into one of two catch solutions.
Boric acid is used when nesslerization or titration are used for analysis or sulfuric acid
when the phenate method or ion-selective electrode method are used for analysis. The
distillate is then analyzed by one of the methods listed above.
2.2 Reduced volume versions of this method that use the same reagents and molar ratios
are acceptable provided they meet the quality control and performance requirements
stated in the method.
2.3 Limited performance-based method modications may be acceptable provided they
are fully documented and meet or exceed method requirements.
3.0 Interferences
3.1 Cyanate, which may be encountered in certain industrial efuents, will hydrolyze to
some extent even at the pH of 9.5 at which distillation is carried out.
3.2 Residual chlorine must be removed by pretreatment of the sample with sodium
thiosulfate or other reagent before distillation.
4.0 Chemicals Required: Distillation Only
4.1 Ammonia-free water
4.2 Borate buffer solution
4.2.1 For unpreserved samples - Add 964 mL reagent water to a 1 L ask. Add in
2.17 g sodium tetraborate (Na
2
B
4
O
7
); stir until dissolved. Add 36 mL 0.1 M
NaOH (4g NaOH/L).
4.2.2 For preserved samples - Add 964 mL reagent water to a 1 L ask. Add in 2.17 g
sodium tetraborate (Na
2
B
4
O
7
); stir until dissolved. Add in 22 g NaOH pellets;
stir until dissolved.
4.3 Boric acid trapping solution (0.13M) - Add 995 mL reagent water to a 1 L ask. Add in
8.0 g boric acid (H
3
BO
3
); stir until dissolved.