Top 10 Titration Rules To Live By (Part 2 - Analysis)
Accurate analysis equals top-notch results.
Proper preparation prior to your analysis will help to ensure that your tests run
smoothly and accurately. Care should also be taken post-analysis to make sure that
your equipment runs optimally in the future. Taking an extra five minutes to dot your
i's and cross your t's can make a difference.
Analysis
#5 Inspect The Instrumentation Before and After Analysis
In order to make sure the results of the titrator are accurate, the instrument and
electrode should be inspected before and after analysis.
Pre-Analysis
Electrode:
The electrode is the part of the titration system that is responsible for monitoring the
titration reaction; it is critical to ensure that the electrode remains functioning as
intended. The first thing to check is the fill level of the electrolyte. This should be
topped off with the appropriate solution when it falls below one inch of the fill hole. It
is also important that the fill cap be loosened or removed during titration to allow for
the steady flow of the electrolyte into the sample which is required for electrode
stability. Always check that the electrode was stored properly before analysis. For
proper storage conditions, refer to the electrode manual or contact your sales
representative. Prior to the start of analysis, the tip of the electrode should be rinsed
with deionized water and free from debris. During analysis, the electrode should be
submerged to the appropriate depth. Some electrodes will require calibration prior to
the actual running of your titration. Check your SOP to see if that is required. If you
are unsure, please feel free to reach out to a Hanna Representative, or take a look at
our posted SOPs.
Titrant:
Before sample analysis, ensure that the titrant bottle contains enough titrant, and that
the dispensing tube is firmly seated in the liquid titrant. It is also important to check
for air bubbles in the burette and tubing. Priming your tubing to get rid of bubbles is
sometimes necessary. A simple rinse tip (a small amount of the titrant is released
through the dispensing tube) can be enough to dispel any air bubbles near the
dispensing tip.
Remember that the volume of the titrant consumed to reach an endpoint is directly
factored into results.
Hanna Tip: Nothing is worse than having a perfect titration curve,
and then find that air has been drawn up from the titrant bottle due
to insufficient titrant (take it from us!). Always check your titrant
level.
Post Analysis
Immediately following titration completion, the electrode should be lifted out of the
sample. Prolonged exposure to sample can cause damage to electrodes and shorten
their lifespan as well as affecting the electrode response, electrode noise, and affect
subsequent samples.
To prevent cross contamination, it is important that the electrode, overhead stirrer
propeller, temperature sensor (if present), and dosing tip be rinsed with deionized
water in between samples and upon workload completion. If you are working with
samples that could clog or cling to the electrodes, there are special cleaning solutions
and instructions to keep you in tip top shape.
When storing the systems for longer periods of time, the electrode fill cap should be
tightened or replaced to prevent the evaporation of the electrolyte fill solution.
Electrodes should be stored per the manual or SOP recommendations.
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