Systea S.p.A.

The sample after proper filtration is pumped inside the LFA

reactor, where after injection of H2SO4 is trapped inside the

high temp heating bath for inorganic P hydrolysis. During

the hydrolysis time, the analyzer runs a complete TN test on

the same sample, by adding the oxidation reagents and

passing through a UV digestion step, to convert Nitrogen

into Nitrate by UV radiation in persulfate alkaline medium.

The nitrates formed are then reduced to nitrites by hydrazine

in alkaline solution, where copper is used as catalyst; the

nitrites react with sulphanilamide and

naphtylethylendiamine in acid solution, to form a pink

colored compound measurable at 550 nm.

The reactor is washed and then the analyzer opens the

heating bath and adds in the digested sample a proper

oxidant to convert all the organic forms of phosphorus into

orthophoshate, by the double action of potassium

persulphate and UV radiation in acid environment. The

orthophosphate formed reacts with molybdate to form

phosphomolybdate, which is finally reduced to blue

molybdenum by ascorbic acid. The coloured complex is

read at 660 or 880 nm.

The sample after proper filtration is pumped inside the LFA reactor, where after injection of H2SO4 is trapped inside the high temperature heating bath for inorganic P hydrolysis. During the hydrolysis time, the analyzer runs a complete TN test on the same sample, by adding the oxidation reagents and passing through a UV digestion step, to convert Nitrogen into Nitrate by UV radiation in persulfate alkaline medium. The nitrates formed are then reduced to nitrites by hydrazinein alkaline solution, where copper is used as catalyst; the nitrites react with sulphanilamide and naphtylethylendiamine in acid solution, to form a pink colored compound measurable at 550 nm. The reactor is washed and then the analyzer opens the heating bath and adds in the digested sample a proper oxidant to convert all the organic forms of phosphorus into orthophoshate, by the double action of potassium persulphate and UV radiation in acid environment. The orthophosphate formed reacts with molybdate to form phosphomolybdate, which is finally reduced to bluemolybdenum by ascorbic acid. The coloured complex is read at 660 or 880 nm.

 

	Total N	Total P
Measuring principle	Colorimetric, UV digestion + UV reduction to NO3	Colorimetric, acidic hydrolosis and UV digestion
Measuring range	0-5/10/20/50 mg/l as N	0-3/5/10 mg/l as P