Oxidizer; Repetitions; Rejects; Repeat Criteria - GE Sievers InnovOx Operation And Maintenance Manual

Chapter 6: Analyzer Operation

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.

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
satisfy the RSD criteria, it will move to the next step in the protocol after the Max Reps number is realized and
report the final value.

Sparge

The duration of the sparging during the NPOC measurements is set. Because of the high efficiency of the
Sparging Chamber, a sparge time as short as 0.8 min. often is sufficient. The minimum sparge time is 0 min. in
NPOC mode. However, the composition of the sample can affect this. The frit in the Sparging Chamber also may
become contaminated during use, requiring longer sparge times. Therefore, the sparge can be set up to a
maximum of 30 min.
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