How does the Astro/1950+ TOC analyzer perform sample analysis?

Document ID

Document ID TE9117

Version

Version 1.0

Status

Status Published

Published Date

Published Date 12/13/2017
Question
How does the Astro/1950+ TOC analyzer perform sample analysis?
Summary
Astro 1950+ principle of operation
Answer
The analysis takes place in a two-stage process:
First, the TIC is removed by acidification prior to the analysis, leaving an inorganic-free sample.
Secondly, the analyzer converts the carbon in the sample to CO2 in a
low temperature UV reactor. An IR detector measures the CO2, which is
proportional to the carbon concentration in the sample.
This TOC measurement is sometimes referred to as NPOC.
The following shows a block diagram of the measurement process:



Acidification: The sample is acidified with phosphoric
acid in the TIC sparger. This converts the
inorganic carbon to CO2. This CO2 is removed
from the sample at the GLS and is
vented to the atmosphere. The sample,
which now contains only organic carbon,
is pumped from the TIC sparger to
the UV reactor for further analysis. (Only
TOC analysis requires acidification. If you
are measuring TC, your analyzer will not
acidify the sample.)
 
Oxidation: The sample is combined with carrier gas
and sodium persulfate. These additions
promote oxidation in the UV reactor. The
reactor converts the carbon in the sample
to CO2. The CO2 is again removed from
the sample at the GLS. Instead of being
vented, however, it is routed
to the IR detector.
 
Measurement: The IR detector measures the CO2. The
CO2 concentration is proportional to the
carbon concentration in the sample.

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