vinmetrica SC-100A User manual

SC-100A manual 1Version 3.1c
Vinmetrica SC-100A™
User Manual
The Vinmetrica SC-100A is a simple and robust device that provides high accuracy in determination of
sulfite (SO2) levels in wine. These are essential parameters to control in the effort to make high quality
wines.
Materials provided in the kit:
1. Vinmetrica SC-100A SO2 controller unit (Part number SC100A-1)
2. SO2 Electrode (Part number SC-100-3), blue polycarbonate housing
3. SO2 Reagent set (Part number SC-100-2):
SO2 Titrant solution (0.0156N)
Acid Reagent (2M HCl)
Reactant solution
4. One 5 mL syringe
5. Two 3 mL polyethylene transfer pipettes
6. One 25 mL serological pipette
7. One 100 mL polypropylene beaker
Things you will need:
1. Two standard AA batteries (alkaline type).
2. Distilled water, which usually can be found at most grocery stores (aka purified water (by
deionization)).
3. (Optional) It’s handy to have a wash bottle for rinsing. Rinse bottle available from Vinmetrica
(Part number SC-100-17).
4. (Optional) Sodium Hydroxide solution, 1N concentration (for total SO2). Available from
Vinmetrica (Part number SC-100-7)
5. (Optional) Deluxe Lab Accessory Kit which includes: magnetic stirrer, burette (10mL or 25mL),
lab support stand, double burette clamp, rinse bottle and electrode holder. Available from
Vinmetrica (Part Number SC-300-9)
Figure 1. The SC-100A instrument

SC-100A manual 2Version 3.1c
Why Test for SO2?
Testing for sulfite (SO2) is crucially important for making sure your wine does not spoil by
oxidation or from microbial growth. By monitoring your SO2 levels, you can make adjustments when
needed, especially before starting primary fermentation, after malolactic fermentation has completed,
after racking or when ready to bottle. To correctly adjust sulfite, you need values for your current free
SO2 level and your wine's pH. The SC-100A analyzer will help measure your current free SO2. You
will need to obtain a value for your pH.
The key parameter in protecting your wine is molecular SO2 which for most wines should be at
0.5 to 0.8 ppm (mg/L) following secondary fermentation. This in turn depends on the free SO2 (it can
also be referred to as "unbound" SO2) and the pH. Overall, you can reach your target molecular SO2 by
measuring and adjusting your free SO2 levels and considering your wine's particular pH. See Table 1.
Table 1. Free SO2concentrations necessary to attain 0.8 mg/L molecular SO2 at a designated pH.
Free SO2(ppm)
13
16
21
26
32
40
50
63
79
99
125
pH
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
4.0
We recommend using a sulfite calculator for determining how much sulfite to add to your wines
after taking a sulfite measurement with the SC-100A SO2 Analyzer. Winemaker Magazine's Sulfite
Calculator at https://winemakermag.com/1301-sulfite-calculator can walk you through the process. See
Appendix B for more information on how to adjust your wine for sulfite.
Theory of operation:
Sulfite (SO2): The SC-100A, with the SO2 electrode and reagents provided, can be used to determine
sulfite (or SO2) levels in wine, musts, and other samples. It relies on the Ripper titration based on the
quantitative reaction of the SO2 with iodine (generated during the titration) which oxidizes the SO2 in
the sample under acid conditions.
SO2 + I2 + H2O  2I- + SO3 + 2H+ reaction of SO2 and iodine
When all the SO2 is titrated at the endpoint, excess iodine appears in solution. This is detected as
current with the SO2 electrode and signaled by audible and visual indicators. The endpoint is much
more sensitive than the starch color change commonly employed for Ripper titration, and it is sharp
and clear, even when titrating red wines and musts. From the known concentration of the titrant and its
volume required to reach the endpoint, the free SO2 is simply calculated.

SC-100A manual 3Version 3.1c
Setup
Setting up the SC-100A for the first time:
1. The SC-100A (Figure 1) runs on two standard AA batteries (alkaline cells recommended). To
insert the batteries, open the battery housing on the bottom of the back of the unit by removing the
two screws and gently prying off the lid. Install the batteries, then close the housing. If desired,
you can prop the unit up using its folding stand.
2. Low Battery Detection: When the battery level is getting low, the instrument shows a low battery
icon on the upper left side of the display but continues to operate without impairment to any
function. Replace the batteries as soon as practicable. When the battery level drops too far, the
instrument does not operate. It rapidly flashes the low battery icon for 3.0 seconds, beeps and
shuts itself off.
3. Auto Shut-off: The SC-100A shuts off after 30 minutes. If this happens unexpectedly, just press
the POWER button to resume from where you were.
4. The SO2 electrode is attached via the BNC connector protruding from the top. To ensure proper
function, ensure the BNC is tightened around the SO2 electrode termination. (Figures 2 & 3).
5. SO2 Electrode: Remove any protective cover from the electrode tip (most electrodes are shipped
without one). Put the electrode on its side, or hang it from an electrode stand if you have one. The
SO2 electrode is sturdy with its plastic housing, but do take care not to let things touch or strike
the platinum wires; they are somewhat fragile and will break if bent and straightened repeatedly.
Electrode care: When done, always rinse with DI water and let air dry. There is no need to store
any electrode in any kind of solution, and the protective cap should not be replaced.
Figure 2. Attach the SO2
electrode to the BNC connector
on the SC-100A.
Figure 3. Be sure the SO2
electrode attachment is secure
by twisting and securing it into
place.

SC-100A manual 4Version 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 SO2 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 SO2 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 SO2 in a standard 25 mL wine sample.] If using a
burette, us the syringe to dispense the SO2 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!

SC-100A manual 5Version 3.1c
solution with an “A” and the pipette for the Reactant solution with an “R”. If they do get
contaminated rinse them off with distilled water and let air dry. Caution: the Acid reagent is
corrosive and can cause damage to clothing, skin and eyes. All of the reagents are not to be
ingested. We recommend use of laboratory safety glasses and latex or nitrile gloves during
this procedure. If any solutions contact skin or eyes, flush with plenty of water.
5. Rinse the electrode briefly with distilled water before inserting it into your wine sample.
6. If you are stirring manually, begin now; use a constant moderate
swirling motion. If the electrode is not held in a stand, hold it against
the side of the beaker with one finger and grasp the beaker with the
remaining fingers so that the two move together. (Figure 7).
7. If you are using the magnetic stirrer, place the bar in the beaker, place
the beaker on top of the magnetic stirrer, and turn the magnetic stirrer
on. Be sure the stir bar will not strike the electrode in the next step.
Insert the electrode into the titration beaker so that the tip is
completely submerged to just above the circulation gaps (cutouts at
the tip of the electrode) but above the level of the stir bar
(approximately a half an inch from the bottom of the titration
beaker). If you are using the Electrode Holder, adjust it to a similar
level. You may add up to 20 mL water if needed.
8. Verify that the current is less than 50 and the green (“PROCEED”) LED is lit. If the current is
greater than this, and/or the red (“STOP”) LED is lit and the buzzer sounds, your sample has less
than 2 ppm SO2 and there is no need to proceed.
9. Titrate the sample by adding the SO2 Titrant dropwise from the syringe or burette (Figure 7), being
sure to note the starting volume mark on the syringe or burette. Try to accomplish the titration as
rapidly as possible (in 3 minutes or less), but be careful near the endpoint so as not to overrun. Be
sure to maintain stirring or swirling throughout the entire procedure.
10. During the titration, the LCD display will show transient currents, the red STOP LED will briefly
illuminate, and the beeper will sound (“beep-beep!”). These transient indicators will last longer
and longer as you approach the endpoint. Take the endpoint as the first addition of Titrant that
causes the display to exceed 50, and the red LED and beeper to stay on, for longer than 15 seconds
(or a count of 20 “beep-beeps”). It is important to maintain stirring or swirling to detect the
endpoint well. Read the endpoint volume off of the syringe or burette. This is your final volume.
11. Calculate the volume of titrant used “V” (using the syringe or burette: Starting volume minus final
volume, e.g.: V = 5.0 mL - 3.5 mL = 1.5 mL).
Figure 7. Manual stirring
technique. Hold the electrode
against the side of the titration
beaker and swirl gently; add SO2
Titrant with other hand.

SC-100A manual 6Version 3.1c
12. The free SO2 content is calculated in units of parts per million (ppm) or mg/L as
ppm SO2 = 64 * V * N * 1000
Where V = mL Titrant used to reach the endpoint; N = normality of the Titrant, and S = mL
wine sample
1
. If you use 25 mL of sample as directed, and the Titrant is 0.0156 N as supplied,
then the calculation is simply
ppm Free SO2 = 20 * V (i.e. 20 times V)
Measuring Total SO2 by Titration (optional - requires 1N NaOH):
1. Place 25 mL wine or must in the titration beaker (See Figure 5).
2. Add 10ml 1N sodium hydroxide (Vinmetrica Part number SC-100-17) and mix well. Let stand
approximately 10 minutes.
3. Using the transfer pipettes, add approximately 8 mL of the Acid Reagent and 2 mL of the Reactant
solution to the vessel. Remember that if you are using the transfer pipettes in the kit, 2 mL is
marked on the side of the neck of the transfer pipette, so dispense four of these for the Acid
Reagent.
4. Proceed from step 5 in the Free SO2 procedure above. The result calculated will be total SO2,
rather than free SO2 in parts per million (ppm) or mg/L.
Finishing up:
1. Turn off the instrument and unplug the electrode.
2. Rinse the SO2 electrode and syringe with distilled water. Let air dry.
3. Store all reagents tightly capped and away from heat and sunlight.
4. Discard waste samples and solutions in accordance with local regulations. Acidic solutions can be
neutralized by slow addition of baking soda (sodium bicarbonate) with stirring until effervescence
ceases.
1
The complete equation is:
64 [mg SO2/mmol SO2 ]* V [mL] * N [meq/mL] * 1000 [mL/L]
2 [meq/mmol SO2] * S [mL]
2 * S

SC-100A manual 7Version 3.1c
WARRANTIES AND LIABILITIES
1. The materials provided in the kit, as described on pages 1 and 2 above, (“Materials”) are
warranted as follows: The SC-100A instrument, electrode and non-reagent accessories are
warranted against defects in workmanship for 24 months from date of purchase. The reagents
are warranted to perform as described herein up until any stated expiration date or 6 months
after purchase, whichever is later. THE WARRANTIES IN THESE TERMS AND
CONDITIONS ARE IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING WITHOUT LIMITATION ANY WARRANTIES OF MERCHANTABILITY,
NONINFRINGEMENT, OR FITNESS FOR A PARTICULAR PURPOSE, SAID
WARRANTIES BEING EXPRESSLY DISCLAIMED.
2. Buyer agrees that its sole and exclusive remedy against Vinmetrica shall be limited to the repair
and replacement of Materials or parts of Materials, provided Vinmetrica is promptly notified in
writing, prior to the expiration of the warranty period specified above, of any
defect. Vinmetrica’s liability for any damages due Buyer shall be limited to the purchase price
of the Materials.
3. VINMETRICA'S MAXIMUM LIABILITY FOR ALL DIRECT DAMAGES, INCLUDING
WITHOUT LIMITATION CONTRACT DAMAGES AND DAMAGES FOR INJURIES TO
PERSONS OR PROPERTY, WHETHER ARISING FROM VINMETRICA’S BREACH OF
THESE TERMS AND CONDITIONS, BREACH OF WARRANTY, NEGLIGENCE, STRICT
LIABILITY, OR OTHER TORT WITH RESPECT TO THE MATERIALS, OR ANY
SERVICES IN CONNECTION WITH THE MATERIALS, IS LIMITED TO AN AMOUNT
NOT TO EXCEED THE PRICE OF THE MATERIALS. IN NO EVENT SHALL
VINMETRICA BE LIABLE TO BUYER FOR ANY INCIDENTAL, CONSEQUENTIAL OR
SPECIAL DAMAGES, INCLUDING WITHOUT LIMITATION LOST REVENUES AND
PROFITS.
HAZARDS AND TOXICITY
All Materials offered by Vinmetrica are intended for use by individuals who are familiar with
laboratory procedures and their potential hazards. The Materials contain chemicals which may be
harmful if misused. Due care should be exercised with all Materials to prevent direct human contact.
Glassware can break and chemicals can splash during experiments; Always use safety glasses. We
strongly recommend using nitrile or latex gloves and wearing long pants, long sleeves and closed toed
shoes. Keep out of reach of children.
6084 Corte Del Cedro Suite 105, Carlsbad CA 92011
www.vinmetrica.com [phone] [e-mail]
Copyright 2010-20. Sportsman Consulting, LLC DBA Vinmetrica. All rights reserved.

SC-100A manual 8Version 3.1c
Appendix A - Test Mode
Test Mode provides various special functions that may be useful in testing the device, for example, if
troubleshooting is necessary.
•Test Mode is entered when the POWER button is pressed longer than 2 seconds while turning the
instrument on. Remove the pH electrode if it is attached.
•Test Mode is organized into sections. Press the POWER button briefly to move to the next section.
After the last section, Test Mode restarts the first.
•Combinations of the yellow MODE LEDs are illuminated to indicate the section number as
shown in the table below.
•The Stop LED (red) is illuminated when an error is detected by the instrument The Proceed LED
(green) is illuminated to indicate no error detected. The green LED does not guarantee proper
functioning; it only indicates that no problem could be automatically detected. The user should
make careful observations to discern proper operation.
•To exit Test Mode, hold the POWER button down (5-10 seconds) until the instrument shuts off.
If the device does not shut off after 10 seconds of holding down the button, move to the next
section by releasing, then pressing again the POWER button briefly; then try to exit again.
Yello
w
LED
s
Section
Equipment Required
Description
1. Version
None.
The version number of the instrument
software is displayed.
2. Burn-in
None
The instrument goes through a
continuous “burn-in” cycle, exercising
relay, sound, LEDs, and display.
3. pH
pH probe or precision
voltage source. Do
not exceed +/- 0.5 V.
[NA]
An uncalibrated pH level is shown
in two alternating parts. First, the integer
portion of pH level is shown (1 to 14).
Next, three decimal places are shown.
Readings above 14.000 are shown as "---".
Readings below 0.000 are shown as
" ___".
4. SO2
SO2 probe or SO2
probe simulator ( e.g.,
500 kOhm resistor)
The SO2 current in nanoamperes is
displayed. For values under 10, one
decimal place is shown.
5. pH
Voltage
pH probe or precision
voltage source. Do
not exceed +/- 0.5 V.
[NA]
The raw voltage output from the
instrument's pH amplifier is displayed as
X.XX volts. Readings can range from
0.00 to 4.10.

SC-100A manual 9Version 3.1c
Yello
w
LED
s
Section
Equipment Required
Description
6.SO2
Voltage
SO2 probe or
SO2 probe simulator.
The raw voltage output from the
instrument's current amplifier is
displayed as X.XX volts. (.XXX if less
than 1.00)
7.DAC Test
None.
Disconnect probe.
The Digital-Analog Converter (DAC) is
cycled through its 32 levels.
8.Battery
Voltage
Install two AA
batteries
The battery voltage is displayed as X.XX
volts.
9.Character
Set
None.
Every ASCII character (space) to ~ is
displayed. Due to the limitations of the
7-segment format, some characters are
not used by the software.
10. Number
Display
None.
The display cycles through showing
every possible digit and every decimal
point.
11.Sound
Test
None.
The beeper is turned on continuously.
12. pH CAL
values
None. [only firmware
v3.0.6 and later]
[NA]
Displays current CAL values for
pH 7 and 4, in mV. Pressing ENTER
cycles between these. If a pH CAL reset
has been done, displays CAL value for
pH 3 rather than 4.
13.
pH CAL
reset
None. [only firmware
v3.0.6 and later]
[NA]
Displays “PrESS EntEr”; Press
ENTER to reset pH CAL parameters to
default values. Message “Good CAL
rSt” then scrolls.
14.
pH DAC
Set
None. [only firmware
v3.1.2 and later]
[NA]
Displays “PH DaC Set” then
displays the DAC index for pH bias
voltage, followed by the voltage value
itself.
15. SO2
Baseline
None. Disconnect SO2
electrode [only firmware
v3.1.0 and later]
Sets baseline value for SO2 mode. Let
message scroll 5 sec., during which time
of the baseline is automatically set.
Normal values are 0.02 to 0.10
16.
TA
endpoint
None [only firmware
v3.1.2 and later]
[NA]
Displays “seT Ta PT” then
displays TA endpoint value. Press ENTER to
toggle between default of 8.2 (USA standard)
or 7.0 (European standard).

SC-100A manual 10 Version 3.1c
Appendix B - Sulfite Adjustments
Using the Winemaker Magazine Sulfite Calculator:
Winemaker Magazine's Sulfite Calculator at https://winemakermag.com/1301-sulfite-calculator
is an excellent tool for calculating how much sulfite should be added to your wine. We will briefly go
over the process here for some clarification.
1. Select a 'Preferred method of Sulfite addition:'; we recommend using a 10% solution of
Potassium metabisulfite (KMBS). [You can prepare this solution by weighing out 10g of KMBS and
dissolving it in a FINAL volume of 100 mL DI water.]
2. Next choose the wine type (red or white).
3. Enter the "volume of wine to be corrected". Choose liters or gallons; we prefer "liters" because
the answer is returned in mL.
4. Enter the wine’s pH. If you know the % Alcohol by volume and temperature, enter these also
(but you don’t have to).
5. Now input the "Current level of Free SO2" which you determined from measuring Free SO2
with the Vinmetrica SC-300.
6. Now look below to the ‘Notes:’ section. You should now see the message "1. The
recommended level of free SO2 for this type of wine, molecular SO2 & pH is: [your value] mg/L. Redo
the calculation using this value for desired free SO2 level, if required.” Enter this value in the “Desired
level of free SO2” box.
Press ‘Calculate’ to get the correct “Amount of sulfite to be added:”. The value will be in mL or fluid
ounces of 10% sulfite solution, or in grams if you use sulfite powder as your sulfite additive.
We recommend double checking your calculations. Also, be sure you are using fresh KMBS!
Once you have added the recommended amount of sulfite, stir your wine thoroughly and take another
SO2 measurement after waiting at least 30 minutes. If the measurement matches the 'Desired level of
free SO2' then you are done, otherwise make incremental additions and repeated SO2 measurements
until you reach your desired level.
Appendix C - Troubleshooting: SO2 Issues
How stable are the reagents?
The SO2reagents and the pH/TA reagents are all warranted to last for 6 months and have a
“use-by”date on the label that is 2 years from date of manufacture. Make sure they are stored tightly
capped, out of the heat and direct sunlight. And of course, these reagents will last much longer if not
cross-contaminated with each other! If the solutions become cloudy or show signs of microbial
growth, they should be replaced.

SC-100A manual 11 Version 3.1c
How can I check the accuracy of my reagents?
It’s rare that the SO2reagents go bad, but if you are concerned about it you can run the 'Ascor-
bic Acid Test' method located in the FAQ section of the website to check your SO2reagents.
https://vinmetrica.com/wp-content/uploads/2012/04/Ascorbate_stdization_procedure-500-mg.pdf
I added the calculated amount of sulfite to my wine but the numbers are still low!
This is a common occurrence with several explanations, any or all of which may be happening.
1. Make sure you are using fresh sulfite powder. Potassium metabisulfite degrades over time and
that stuff you bought 2 years ago is probably bad now!
2. Make sure that you stir your wine thoroughly when you add sulfite. If you pour a 10% solution
of KMBS into your wine, it sinks like a battleship!
3. A significant portion of the sulfite you added may have ended up ‘bound’, particularly if your
free SO2 was very low to begin with. This bound SO2 does not show up when you measure free SO2,
and it is not protecting your wine. You will need to add more sulfite until your free SO2 comes up to
the right level. Sometimes you must add two or even three times more sulfite than you first calculated.
I’m getting strange results in SO2 mode; how do I know if my instrument is
working correctly?
For SO2measurements with the SC-100A, there are several quick tests you can do to make sure
the instrument is not faulty.
1. Be sure the battery is good per the manual’s instructions.
2. Connect the electrode and put it in about 20 mL of distilled water; add about 1 ml (half a bulb
squeeze) of each of the SO2 Acid Solution and the SO2 Reactant Solution and swirl in the usual
way, keeping constant motion. The instrument may or may not indicate STOP as above. If it does
not, add a drop of the SO2Titrant solution. This should make the STOP condition occur, with a cur-
rent of 100-300 nA. [If it doesn't you may have an electrode problem; read in the next section be-
low how to fix this.] Now add one drop of a concentrated sulfite solution (1-10% is fine) and verify
that the STOP signal ends and the PROCEED light illuminates. If this test passes, your system is
detecting the titration endpoint correctly.
3. The platinum wires of your SO2electrode could be dirty (crust, debris, etc.) even though you may
not be able to see anything. First, soak the SO2electrode in your Acid Solution for about 10
minutes and rinse with DI water. Using the back edge of a pocket knife or something similar, very
gently scrape the two platinum wires, being sure not to bend or break them. Thoroughly rinse with
DI water and try your test again.

SC-100A manual 12 Version 3.1c
4. If the above tests don’t work, remove the electrode from the connector at the back of the instru-
ment. Turn on the instrument and select SO2mode. Short out the terminals on the connector, using
a paper clip or similar metal piece to touch the center hole of the connector to its outer metal
sheath. The device should indicate “STOP” with its red LED and buzzer or beeper, and the current
should go to 1999. If this does not happen there may be a problem with the instrument; contact us
for more information.
5. Finally, you can check your SO2 reagents with the ascorbic acid (vitamin C) test located on our
website https://vinmetrica.com/wp-content/uploads/2012/04/Ascorbate_stdization_procedure-500-
mg.pdf
.
Technical assistance: [email protected] tel. [phone]