Determination of Total Nitrogen in Water Samples - Experiment Method

Running head: DETERMINATION OF TOTAL NITROGEN IN WATER SAMPLES
Determination of total nitrogen in water samples
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DETERMINATION OF TOTAL NITROGEN IN WATER SAMPLES 2
ABSTRACT
The experiment is a standard method used in the determination of organic nitrogen in water
samples, based on the Kjeldahl technique of digestion where nitrogen is converted to ammonia.
(Davis, Shokouhian, Sharma,and Minami, 2012)The experiment was done in two phases, (a)
determination of ammonia and (b) determination of organic nitrogen. The first step involved
altering the PH of the solution to eliminate unwanted compounds in water through distillation.
(Kagimoto, Taguchi, Fukumoto, and Ohno, 2010)

DETERMINATION OF TOTAL NITROGEN IN WATER SAMPLES 3
INTRODUCTION
The experiment is the most straightforward and easy way to determine the amount of
nitrogen in water. Excess nitrogen concentrations often result from factors such as fertilizer
runoff, and combustion of fuels. (Xu, Paerl, Qin, Zhu, and Gaoa, 2010) Nitrogen in water exists
as both inorganic and organic species where the inorganic forms can be nitrite and nitrates
whereas the reduced form is ammonia. The reduced forms can be in diverse complexes including
amino acids, urea, aldehydes, and ketones. Their separation is therefore difficult as they are
capable of forming the same color with the reagent used. This technique utilizes the principle of
dissociation of nitrogen to complexes like amino acids and proteins. (Chapman, Fromme, Barty
White, Kirian,Aquila, Doak,2011). Total determination of TKN together with the sum of nitrates
and nitrites is usually obtained.
Equal molar concentrations of hydroxide and persulfate ions are adapted to yield a
solution with a given PH at a distinct ration of dilution. Nitrogen oxidation to nitrate occurs with
continued digestion at alkaline condition initially present. Bisulfate ions result from the thermal
decomposition of the ions leading to a drop in PH of the reaction mixture. There is a subsequent
increase in acidity of digest mixture and phosphorus is hydrolyzed to orthophosphate. In most
cases, a column of high capacity is vital in minimizing chromatographic interferences caused by
chloride, and chlorate (via chloride oxidation). A laboratory blank is helpful in detecting
whether the interventions exist within the sample, reagents or the lab instruments.
The reagent used here consisted of:
 magnesium oxide in fine powder form
 solution of ammonium for calibration