Page 15 - 3_Chemical industry

Sum parameter – Total Organic Carbon

TOC – Determination in ammonia or

ammonium salt solutions
SCA-130-307

Basic chemicals may contain organic ■ Sample preparation
contaminants polluting end products. This is The ammonium nitrate solution was diluted
why quality control of the reactants is a must. with ultrapure water to a ratio of 1:10. Dilution
was carried out manually in a 50 mL
In the TOC determination of ammonia water volumetric flask under addition of several
or concentrated ammonium salt solutions, drops of concentrated sulfuric acid (25%).
various issues must be considered. Ammonia
and some ammonium salts are alkaline. The Compound
catalyst and combustion tube are sensitive to (Concen- Dilution Conc.
alkaline media and are subjected to tration)
increased wear. 1 : 10 diluted
Ammonium (5 ml / 50 ml)
nitrate add. 1-2 drops Approx.
solution Sulfuric acid until 4%
(40%) pH<7 (Note:
generation of heat)

Calibration of the TOC-L system was
executed using the automatic dilution function
in the range of 0.5 mg/L to 10 mg/L.

The solutions should, therefore, be acidified
and possibly be diluted.

The decomposition during oxidation of the
ammonium or ammonia proceeds to
completion without the formation of residues
on the catalyst. Therefore, it is not necessary
to use a high-salt kit.
Fig. Multi-point calibration
In the case described below, the NPOC with dilution function
content of a 40% ammonium nitrate solution
was determined. The required detection limit
was < 10 mg/L.