Page 20 - 3_Chemical industry
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SCA-130-309
Automated reagent preparation eliminates The autosampler OCT-1 has a big advantage
any contamination of the reagent solutions for the measurement of aggressive matrices,
and minimizes the blank value of the because its parts are done of Teflon.
instrument.
■ Method of phosphoric acid
■ TOC determination measurement
Due to lower TOC concentration, the The concentrated phosphoric acid (85%) is
instrument is calibrated in a range of 0,1 – 1 diluted by 1:5.
mg/L. TOC determination in phosphoric acid was
carried out using the NPOC (Non-Purgeable
Organic Carbon) method. Prior to TOC
determination, neutral or alkaline samples are
acidified in order to decompose all inorganic
carbonates and bicarbonates. This step could
be omitted for phosphoric acid.
Acidification: 0%
Sparge-time: 2 minutes
Figure: Calibration of NPOC between 0,1 – 1 mg/l. Injection volume: 3000µl
Concentration of the phosphoric acid does ■ Results
not play a significant role in the
determination; it is only necessary to ensure
that the acid is not too viscous. The 85%
phosphoric acid solution was therefore diluted
1:5 with water.
The resulting 17% acid solution was
transferred into the instrument using an OCT-
1 autosampler. Abb.: Peak graph of diluted phosphoric acid(17%)
The 17% phosphoric acid solution measured
in this way resulted in a TOC concentration of
0.61 mg/L. The relative standard deviation
over three injections was 1.8%.
■ Recommended Analyser / Configuration
- TOC-V WP/WS
- OCT-1
