SC-100A manual
4
Version 3.1c
Instrument Operation
Turn on the instrument by pressing the POWER
button briefly (Note: depressing the POWER
button
longer than two seconds at start-up will cause the instrument to enter
Test Mode;
see Appendix A). The
instrument will go through a power-up sequence. After a few seconds the display will show a value less
than 50 (usually 0.0) and the green (Proceed) LED should be on.
Procedures
Measuring Free SO
2
by Titration:
1.
Turn on the instrument and connect the electrode. The display should show a value less than 20,
usually 0.0.
2.
Fill the syringe by drawing up the SO
2
Titrant (the bottle with the blue dot)
(Figure 4). Expel bubbles and set the plunger on the syringe to a readable point,
preferably the 5.0 mL point.
This is your starting volume
. Make sure the outside
of the syringe is dry to minimize inaccuracies. [Note: the 5.0 mL setting allows
determination of up to 100 ppm SO
2
in a standard 25 mL wine sample.] If using a
burette, us the syringe to dispense the SO
2
Titrant into the top of the burette.
3.
Using the 25 mL pipette provided in the kit, place 25 mL of wine or must in the
titration beaker (Figure 5). Draw sample up to the 0 mL mark, then dispense the
sample into your titration beaker by letting the tip of the pipette touch the side of
the vessel while the sample drains.
NEVER pipette any reagents by mouth!
Also make sure the pipette you are using is completely clean before
submerging into your wine sample.
–Do not use sulfite to sanitize it! Use 25%
ethanol or other sterilent.
4.
Using the transfer pipettes, add about 2 mL Acid Solution and 2 mL Reactant solution to the
titration beaker. It is not necessary to be extremely accurate in this step; with these pipettes, 2 mL
is indicated on the neck of the pipette. Please make sure to label the pipettes to eliminate cross
contamination, this will prolong the shelf life of the reagents e.g. mark the pipette for the Acid
Figure 4.
Withdraw
the titrant from its
bottle using a clean 5
mL syringe.
Figure 5.
Dispense 25
mL of your wine into the
titration beaker using the
25 mL sampling pipette.
Make sure this is clean
before putting the pipette
into your wine container!
