Table of Contents
Advertisement
Chapter 6: Analyzer Operation
Acid
The solution must be acidified to a pH 2 to convert IC to CO
and to ensure that CO
produced in the Reactor is
2
2
properly expelled from the Gas-Liquid Separator. Since the concentration of the acid reagent is 3M to 6M, a
setting of 1% is adequate for most samples. However, if the sample is highly basic or contains a large
concentration of pH buffers, increase the acid percentage appropriately. To determine the correct setting for
those kinds of samples, increase the acid percentage until further increases do not result in higher measured
values.
Oxidizer
For most samples, an oxidizer percentage of 15% results in accurate measurements regardless of the range.
However, there are samples that benefit from lower or higher settings. If the sample is known to contain less
than about 1 ppm of NPOC or TOC, then the oxidizer can be set to a lower percentage. It can be set to 0% if the
sample is saturated with dissolved oxygen from exposure to the air. The dissolved oxygen usually is sufficient as
an oxidizer, and the precision of the measurements may be better than when the oxidizer setting is left at 15%.
Samples that contain large concentrations of oxidizable inorganic species require the oxidizer setting to be
greater than 15%. For example, high concentrations of organics in saturated sodium chloride brines have been
found to require oxidizer percentages as high as 30% or more. For best shelf life, the oxidizer should be kept out
o
of sunlight and maintained at 15 - 25
C. See also step
7
in
"Step 12: Perform a Test Analysis" on page
102.
Repetitions
Set the number of repetitions to the number of measurements to make on a Grab sample, Online, or Check
Standard measurement. The maximum number of repetitions is 20.
Rejects
You may opt to have the first few measurements on a Grab sample or Check Standard omitted from the
calculation of the average concentration and RSD. This is the number of rejects, and it must be set to at least
one measurement less than the selected number of repetitions.
Repeat Criteria
For Grab Sample Analysis, use Repeat Criteria to allow the Analyzer to follow configurable logic to determine
the number of repetitions to run. If selected to ON, you will be able set the maximum number and minimum
number of repetitions for the vial. The number of reps will be determined by the InnovOx depending on what you
enter for the RSD criteria. If you enter 7 Max Reps and 2 Min Reps, the Analyzer will run at least two repetitions
and compare the calculated RSD to the RSD criteria entered. If the calculated RSD is less than the RSD criteria,
the Analyzer will stop analysis on the vial and move to the next step in the protocol. If the calculated RSD is
higher than the RSD criteria, the Analyzer will run one more repetition and recalculate the RSD. The number of
reps used to calculated the RSD will be the Min Reps value in consecutive order. If the Analyzer continues to not
GE Analytical Instruments ©2016
145 of 270
DLM 68100-09 EN Rev. A
Advertisement
Table of Contents
