vinmetrica Dissolved Oxygen System User manual

Dissolved Oxygen Manual 1 Version 1.7
Vinmetrica Dissolved Oxygen System
User Manual
The Vinmetrica Dissolved Oxygen system provides a simple, accurate and affordable way to determine
oxygen concentrations in wine and other samples.
Materials provided in the kit:
1. Electrolyte Solution (PN: SC-200-13-2)
2. Sodium sulfite powder (PN: SC-200-13-1)
(for 0% Oxygen reference)
3. Vinmetrica Dissolved Oxygen (DO) probe
4. Standard measuring vial
5. One 5 mL syringe (SC-100-6)
6. Extra DO probe membrane cap (SC-200-13-3)
Things you will need:
1. Vinmetrica SC-200 or SC-300, or comparable meter with 1 mV or 0.02 pH resolution.
2. Distilled water (DI water)
3. Rinse bottle (PN: SC-100-17)
4. Small measuring spoon or spatula (e.g., Vinmetrica 0.05 g spoon, PN: RS-12)
Why Test for Dissolved Oxygen?
Dissolved oxygen (DO) has numerous effects on wine, some desirable, some definitely not.
Depending on the type of wine and its characteristics, controlled exposure to oxygen plays a beneficial
role in wine quality such as influencing color stability and suppleness. However, too much oxygen
exposure can lead to premature deterioration, browning, and acetaldehyde formation. At time of
bottling, for example, it is generally desirable to keep DO below 10% saturation. DO can then be
measured throughout the bottling process to ensure oxygen uptake is minimized. Careful management
of DO will ensure best stability and outcome for your wine.
How it works:
The electrode has an internal electrolyte solution behind a gas-permeable membrane. Oxygen in
the sample diffuses into this internal electrolyte and creates an electrochemical (“galvanic”) reaction at
the metal contact on the electrode. This is picked up by the SC-200 or -300 and displayed as a voltage
reading (firmware x.1.2 or higher), or as an apparent “pH” value, either of which can be related to the
response of known oxygen content, allowing you to determine DO as % saturation.
Figure 1. The Dissolved Oxygen Kit

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Setup
1. If attached, carefully and gently remove the black rubber cover from the end of the electrode.
Take care not to separate the two pieces of the membrane cap.
2. Electrode preparation:
a. Remove the end of the electrode (“membrane cap”) by gently unscrewing it from the bar-
rel. NOTE: Do not pull off the end cap, this may damage the membrane. This will ex-
pose the silver-gray (zinc) cylindrical anode and its shiny (silver) cathode disk at the end.
(Inorganic salt deposits can appear on the zinc anode of the probe over time. See Appendix
A for further information.)
b. Hold the membrane cap in a vertical position and fill with 0.3 mL (about 8 drops, or until
the liquid level reaches the lip at the bottom of the cap’s threads) with electrolyte. You can
use the syringe provided to do this. Ensure that no air bubbles are trapped in the electro-
lyte. Hold the electrode vertically down and screw membrane cap up until it is just finger
tight. Do not over tighten.
3. Attach the electrode to the pH meter and put it in pH mode or, if available, potential mode
(Firmware versions x.1.2 or higher, or x.2.d, where x is 2 or 3).
a. To use potential mode on a SC-200 or 300 with latest firmware version, turn instrument on
and select pH mode, then hit Mode button one more time. The pH LED should now be
blinking to indicate potential mode.
Procedures
1. Calibration: To calibrate the response of your electrode and instrument, you will determine the
values for “0% saturation” (i.e., when no oxygen is present in solution) and for “100% satura-
tion” (i.e., when the maximum amount of oxygen is present).
a. Calibrate 0% saturated DO: place about 2 mL of DI water into the measuring vial (about 2/3
full) and add about 0.5 g (less than ¼ teaspoon) of sodium sulfite powder. Swirl for 30 sec-
onds to mix. This is in effect a saturated solution and it removes all the oxygen from the wa-
ter [note: you can also make a 0% saturated DO solution by bubbling pure nitrogen through
DI water at a moderate rate for 5 minutes]. Place the electrode in the vial. Keep the solution
moving by gently rotating or swirling the vial. Wait for the value to stabilize, about 2
minutes. In potential mode, you should see a value of 0 ± 10 mV or so. If you are reading
apparent pH, you will see a value of around 6.5-7.0, depending on the previous pH calibra-
tion settings. Write down the value that you see; this is your 0%DO.
b. Calibrate 100% saturated DO: remove the electrode and rinse it thoroughly with distilled
water; gently shake off excess liquid. You can use either method below.
i. Air method (good, simplest): Allow air to freely contact the membrane. This
will make the electrode display an approximate 100% saturated DO value. Typ-
ically this is within 5 % of the next method

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ii. Oxygen-saturated water method (best, more complex): place electrode in dis-
tilled water that has been shaken for 3-5 minutes with air, or preferably, that has
a continuous stream of air bubbled through it (a cheap aquarium pump works
well).
c. Wait for the 100% saturated DO value to stabilize, again about 2 minutes. In potential
mode, you will typically see a value of 200 to 300 mV, and always greater than 150. If you
are reading apparent pH, you will see a value of around 3 to 2, and always less than 4.5.
Write down the value; this is your 100%DO.
NOTE: new versions of the DO electrode can show responses in 100% DO that exceed
+330 mV. In this case you may see an overrange reading on the display “^^^^” in Po-
tential mode. To enable a higher range, go into Test Mode (see Appendix A of your in-
strument’s manual for how to enter Test Mode) and select Section 14 (pH DAC Set).
Press the MODE button 4 times to set the DAC at level 12. Now you will be able to
read up to 430 mV.
When you are done with your DO readings, go back into Test Mode and restore the
DAC value to its previous value (normally 16) by pressing the ENTER button 4 times.
Leaving the DAC at 12 will cause errors in pH readings!
Contact Tech Support (760-494-0597) if you have any questions.
2. The measurement vial with the saturated solution of Sodium Sulfite can be capped and stored
for up to one month. If you will not be using the solution again you can rinse out the measure-
ment vial and shake out excess water. Rinse electrode with DI water.
3. Measure the sample (wine or other liquid) by either method (a.) or (b.) below. Method (a.)
avoids contact with your bulk wine or liquid, but is inherently difficult to get highest accuracy
because atmospheric oxygen rapidly enters the sample. Method (b.) is easier and accurate, but
note the CAUTION statement.
a. Take a sample of the wine to be measured. It is important to move quickly to avoid ox-
ygen in the air from reaching the wine sample. (NOTE: if available, use inert gas to
sparge the sampling area and the measuring vial to minimize entry of atmospheric oxy-
gen) Place about 2 mL of your wine into the measuring vial (about 2/3 full). Immerse
the electrode in the wine sample as in step 1 and slowly swirl the sample. OR
b. (Recommended) Insert the clean electrode directly into the wine sample (bottle, carboy,
barrel, etc.) and gently swirl. In this case you may want to clean the electrode by dip-
ping it in 20% ethanol solution to minimize contamination of your wine samples. Mini-
mize access of air during this time (sparge the head space with inert gas if possible).
[CAUTION: there is a small risk of affecting your wine by this method. Normally the
electrolyte solution will not contact your wine, and vice versa, because the membrane is
impermeable except to gases. However in the event of a leakage due to breakage or de-

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tachment of the membrane end of the electrode, a small amount of sodium salts and pro-
pylene glycol can enter your wine. The amounts are small enough that a bottle or larger
size container of wine will not become unsafe to consume, but be aware of this.]
4. Again wait for the reading to stabilize. Usually the millivolt value will drop to a lower reading
over about 1 minute, from which it may slowly start to rise again. Note the lowest reading that
you see during this time. If you are reading in pH mode, you will see the opposite effect - a low
pH reading will rise, then possibly start to decrease again - take the highest value. Table 1
shows some typical data:
Table 1. typical data in mV or pH mode (Note: your data may be different!)
Test
mV
“pH”
0%DO
+3.0
6.87
100%DO
+240
3.48
Wine sample
+36
6.39
5. Calculate DO as % of saturation as follows: Subtract the 0% DO calibration value from each
reading. Divide the subtracted value for each wine sample by the subtracted value for the 100%
Saturated DO calibration value. Multiply this by 100 to get percent saturated DO for each wine
sample, i.e.
DO, % saturation = 100 * [Wine sample – 0%DO]/[100%DO - 0%DO]
For example, from the data in Table 1:
DO, % saturation = 100 * (36-3.0)/(240-3.0) = 14%
Or = 100 *(6.39-6.87)/(3.48-6.87) = 14%.

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Reporting dissolved oxygen in mg/L :
If you prefer to get your data in units of mg/L of dissolved oxygen, you can convert your %
saturation values. You need to know what value of mg/L DO corresponds to 100% saturation DO.
This number depends on several factors, including the conductivity (or “salinity”) of the wine, its
alcohol content, temperature, and the ambient barometric pressure. For most wines, only the latter two
are significant. At room temperature (72 F or 22.5 degrees C) and ordinary air pressure (sea level on a
clear day), the saturating oxygen level is about 8.5 mg/L. For most purposes, this value will be close
enough to give you the accuracy needed to make decisions. Be aware, however that this value
decreases about 10% for every 5ºC (8ºF) increase and for every 3000 feet (1000m) of elevation
increase.
1
Once you have a value for 100% (saturating) dissolved oxygen for your wine in ambient
conditions, calculate your dissolved oxygen from the data you have.
DO, mg/L = saturating oxygen level (mg/L) x % saturation
In the above example, assuming we are at sea level and 72 degrees, the DO is 8.5 x 14% = 1.2 mg/L
Finishing Up:
1. Turn off your pH meter and rinse the vials and the electrode with DI water. Replace the black
rubber cover over the end of the electrode to prevent damage to the membrane.
2. Electrode Storage: The electrode may be stored with its tip submerged in water for a few weeks
at a time, but make sure the electrode is disconnected from the meter during storage. For long
term storage you should store the electrode dry (unscrew the membrane cap, drain the
electrolyte, rinse everything with distilled water and let dry in air).
3. Cleaning and Maintenance: After the electrode has been used for a period of time the residual
current may rise, which shows up as an increasing value of 0% DO, and/or you may see a
decrease in 100%DO values. First, try replacing the electrolyte as described on page 2 under
“Setup”. If normal responses still aren’t seen within 15 minutes, the electrode may need
servicing. To recondition the electrode, gently unscrew the membrane cap from the electrode
body and rinse the inside of the cap with DI water; allow to air dry. Soak the silver-gray
cylindrical zinc anode in 0.1N HCl (1 ml 2M HCl, or the Vinmetrica Acid Solution for SO2, in
20 ml DI water) for 15 to 20 minutes. Rinse the zinc anode with DI water, blot dry with tissue
paper. If necessary, use fine sandpaper or similar fine abrasive to remove any grey or white or
other deposits from the anode, and restore a shiny appearance. Rinse with DI water and blot dry
with clean cloth or tissue paper. Refill with fresh electrolyte and replace membrane cap as
directed in the Setup section. It may take an hour or so for normal responses to stabilize.
1
To estimate changes in saturating oxygen level with temperature and pressure, see the dissolved oxygen
calculator at http://water.usgs.gov/software/DOTABLES/ . Set the specific conductivity of the wine to 3000
microsieverts/cm. To calculate air pressure change with altitude, see http://www.altitude.org/air_pressure.php

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4. Replacing the membrane assembly: The membrane that comes in the probe has a life
expectancy of one year. However the membrane may become damaged and will need replacing.
Your kit provides an additional membrane cap. Fill the cap with fresh electrolyte and replace it
as directed in the Setup section. It may take an hour or so for normal responses to stabilize.
Additional replacement membrane caps can also be ordered from Vinmetrica, P/N SC-200-13
Technical support: [email protected] tel. [phone]
Appendix A: Troubleshooting
Over time small, white, inorganic salt deposits may appear on the Zinc (cylindrical anode) portion of
the probe. There is a quick and simple way to remove them to ensure you are getting the most accurate
reading possible with you Dissolved Oxygen probe.
1. Remove the membrane cap to expose the anode and cathode of the probe.
2. Using either medium grit sandpaper or the fine side of a nail file gently scrape away at the white
deposits on the cylindrical portion of the probe. DO NOT use the sandpaper on the shiny, silver
cathode disk at the end of the probe. Continue filing away until all the salt deposits have been
removed.
3. Give the probe a rinse and allow to dry or screw the membrane cap (with fresh electrolyte
solution) on to the end of the probe to begin testing.

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WARRANTIES AND LIABILITIES
1. The materials provided in the kit, as described on page 1 above, (“Materials”) are warranted as
follows: All reagents, powders and non-reagent accessories are warranted against defects in
workmanship for 6 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, provided storage recommendations are followed. The electrode is warranted for a period
of 1 year. 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]
Technical assistance: [email protected] tel. [phone]
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