Sulfur Dioxide (SO2)

Parameter Selection

Application Importance of Sulfur Dioxide (SO2) in Winemaking

Early in the winemaking process winemakers add sulfur dioxide (SO2) to wine in order to inhibit bacteria and wild yeast growth, although this is typically considered only if malolactic fermentation isn’t intended. Later in the process after fermentation SO2 is added to wine as an antioxidant and for its anti-microbial properties. As an antioxidant SO2 helps preserve the color, flavor, and stability of the wine. As an antimicrobial SO2 interferes with the metabolic pathways of yeast and bacteria.

When SO2 is added to wine, a portion of it becomes immediately bound while a remaining portion is unbound SO2. The portion that is unbound is also called free SO2 and it is responsible for protecting the wine. The bound and free SO2 together are referred to as total SO2.

Free SO2 exists in two forms. The first form, bisulfite (HSO3-), is the predominant form but is relatively ineffective. The second form, molecular SO2, is the minor form and is responsible for protecting the wine. The amount of molecular SO2 available in wine is dependent upon the amount of free SO2 present and the pH. Typically 0.8 ppm of molecular SO2 provides adequate protection against bacteria growth and oxidation.

Meters

HI902 Potentiometric Titration System for Sulfur Dioxide

The HI902 is a potentiometric titration system for the measurement of Sulfur Dioxide (Air Oxidation and Ripper Methods) and other wine parameters. This meter has many features including:


  • Can be used for TA, YAN, and reducing sugar titrations
  • Available with 1 or 2 analog input boards. Each board can accept pH, ORP or ISE electrodes. Having two analog board inputs allows for the simultaneous connection of two probes.
  • Available with 1 or 2 dosing pumps. A second dosing pump can be used for:
    • Second titrant for a second parameter
  • Exchangeable Clip Lock burettes allow for quick changing to different titrants and are available in variety of sizes up to 50 ml
  • Linear or dynamic dosing of titrant with 40,000 step burette
    • Dynamic dosing allows for larger doses in the beginning of the titration and smaller as the end point is reached
    • Accurate and precise determination of titrant used
  • Logging and USB connection for data management
  • Compatible with HI921 autosampler for users with a high throughput of samples to be measured
  • Factory installation, training and service plans available
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HI902 Potentiometric Titration System for Sulfur Dioxide

The HI902 is a potentiometric titration system for the measurement of Sulfur Dioxide (Air Oxidation and Ripper Methods) and other wine parameters. This meter has many features including:


  • Can be used for TA, YAN, and reducing sugar titrations
  • Available with 1 or 2 analog input boards. Each board can accept pH, ORP or ISE electrodes. Having two analog board inputs allows for the simultaneous connection of two probes.
  • Available with 1 or 2 dosing pumps. A second dosing pump can be used for:
    • Second titrant for a second parameter
  • Exchangeable Clip Lock burettes allow for quick changing to different titrants and are available in variety of sizes up to 50 ml
  • Linear or dynamic dosing of titrant with 40,000 step burette
    • Dynamic dosing allows for larger doses in the beginning of the titration and smaller as the end point is reached
    • Accurate and precise determination of titrant used
  • Logging and USB connection for data management
  • Compatible with HI921 autosampler for users with a high throughput of samples to be measured
  • Factory installation, training and service plans available
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HI84500 Mini-Titrator for Sulfur Dioxide

The HI84500 is an application specific mini-titrator for the measurement of Sulfur Dioxide by using the Ripper Method. This meter has many features including:

  • Ready made reagents and titrants so no need for an analytical balance or laboratory glassware
  • Piston driven dosing system for precise control over the automatic dosing of titrant
  • Specialized ORP electrode with CPS Technology to prevent clogging from solids found in wine juice and must
  • Logging and USB connection for data management
  • Tutorial mode for step by step instruction when performing a titration
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Titrants & Reagents

Titrants for Potentiometric Titrators

Titrants and reagents used in sulfur dioxide titrations include sulfuric acid, sodium hydroxide, stabilized iodine, hydrogen peroxide, and potassium iodide. These titrants and reagents can be used with all potentiometric titrators that allow customized methods with differing concentrations of titrant.

  • Titrants available in different concentrations for multiple measurement ranges
  • Complete line of titrants and reagents to perform sulfur dioxide titration by either the Ripper or air oxidation methods
  • Can be used with any potentiometric titration system in which the user has control over the strength of titrant used
  • Produced to ISO 9001 standards
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Titrants for Potentiometric Titrators

Titrants and reagents used in sulfur dioxide titrations include sulfuric acid, sodium hydroxide, stabilized iodine, hydrogen peroxide, and potassium iodide. These titrants and reagents can be used with all potentiometric titrators that allow customized methods with differing concentrations of titrant.

  • Titrants available in different concentrations for multiple measurement ranges
  • Complete line of titrants and reagents to perform sulfur dioxide titration by either the Ripper or air oxidation methods
  • Can be used with any potentiometric titration system in which the user has control over the strength of titrant used
  • Produced to ISO 9001 standards
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Titrants and Reagents for Application Specific Mini-Titrator

Hanna’s application specific mini-titrator for sulfur dioxide analysis uses specific titrant and reagents. The HI84500 is the second generation mini-titrator in which the dosing system was improved. The first generation, HI84100, used a peristaltic pump to deliver the titrant while the HI84500 uses a piston style dosing pump. Each titrator uses its own specific titrants.

  • Titrants are pre-standardized and ready for use
  • Titrants available for low and high range
Shop HI84500 Titrants and Reagents > Shop HI84100 Titrants and Reagents >

Electrodes

HI3148 Wine Must ORP Electrode

There are many considerations that are used when designing an ORP electrode for a specific application. With wine juice and must there is a high solids content that can lead to the clogging of the reference junction resulting in erratic readings.

  • PTFE Sleeve Junction
    • Repels solids to reduce clogging
    • Movable to clean the ground glass beneath the PTFE sleeve
  • Double Junction design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Refillable with 3.5M KCl
    • Extends life of the electrode by being able to replenish the electrolyte fill solution as opposed to a gel filled that cannot be refilled
  • Platinum ring sensor
    • Better detection due to a larger surface area than a pin design
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HI3148 Wine Must ORP Electrode

There are many considerations that are used when designing an ORP electrode for a specific application. With wine juice and must there is a high solids content that can lead to the clogging of the reference junction resulting in erratic readings.

  • PTFE Sleeve Junction
    • Repels solids to reduce clogging
    • Movable to clean the ground glass beneath the PTFE sleeve
  • Double Junction design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Refillable with 3.5M KCl
    • Extends life of the electrode by being able to replenish the electrolyte fill solution as opposed to a gel filled that cannot be refilled
  • Platinum ring sensor
    • Better detection due to a larger surface area than a pin design
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HI3131 Laboratory ORP Electrode

The HI3131B is a standard laboratory ORP electrode that is commonly used on benchtop mV/ORP meters. The glass body is a good conduction of temperature allowing the reference cell to equilibrate with temperature of the sample. The HI3131B is a refillable ORP electrode.

  • Glass body
    • Fast thermo-equilibrium with sample
    • Easy to clean
  • BNC Connector
    • Universal connector that can be used with any meter that accepts a BNC connection
  • Refillable with 3.5M KCl
    • Extends life of the electrode by being able to replenish the electrolyte fill solution as opposed to a gel filled that cannot be refilled
  • Double Junction design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Ceramic junction
  • Platinum Pin Sensor
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HI3230 PEI Plastic Body ORP Electrode

The HI3230B is a rugged PEI plastic body ORP electrode with a universal BNC connector. The chemically resistant plastic protects protects this probe from accidental breakage. The HI3230B is gel filled so no refill solution is required.

  • Polyetherimide (PEI) plastic body
    • High grade chemically resistant plastic
    • Unbreakable
  • BNC Connector
    • Universal connector that can be used with any meter that accepts a BNC connection
  • Gel filled
    • Maintenance free with no refill solutions required
  • Double Junction design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Ceramic junction
  • Platinum Pin Sensor
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HI3230 PEI Plastic Body ORP Electrode

The HI3230B is a rugged PEI plastic body ORP electrode with a universal BNC connector. The chemically resistant plastic protects protects this probe from accidental breakage. The HI3230B is gel filled so no refill solution is required.

  • Polyetherimide (PEI) plastic body
    • High grade chemically resistant plastic
    • Unbreakable
  • BNC Connector
    • Universal connector that can be used with any meter that accepts a BNC connection
  • Gel filled
    • Maintenance free with no refill solutions required
  • Double Junction design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Ceramic junction
  • Platinum Pin Sensor
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Maintenance Solutions

ORP Test Solution

ORP test solutions are used for testing the performance of an ORP electrodes. When the ORP electrode is placed in the test solution the reading displayed will help the user know when to clean or replace the ORP electrode.


  • If the mV reading is 240 ± 20 mV this indicates the electrode is in good condition and can be used for titration
  • A mV reading of 240 ± 30 mV indicates the electrode is beginning to drift. The electrode should be cleaned and conditioned.
  • If the mV reading is greater than 240 ± 40 mV then the electrode should be replaced
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ORP Test Solution

ORP test solutions are used for testing the performance of an ORP electrodes. When the ORP electrode is placed in the test solution the reading displayed will help the user know when to clean or replace the ORP electrode.


  • If the mV reading is 240 ± 20 mV this indicates the electrode is in good condition and can be used for titration
  • A mV reading of 240 ± 30 mV indicates the electrode is beginning to drift. The electrode should be cleaned and conditioned.
  • If the mV reading is greater than 240 ± 40 mV then the electrode should be replaced
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ORP Electrode Refill Solutions

Maintaining a proper filling solution level in a refillable ORP electrode is critical to obtaining accurate and reliable ORP measurements. The solution not only provides an electrical pathway to the internal reference but maintaining an ideal level ensures there is adequate head pressure to ensure flow through the junction into the sample.

  • Solutions for both single and double junction electrodes
    • Single junction electrodes use 3.5 M KCl with silver chloride
    • Double junction electrodes use 3.5 M KCl
  • Available in a variety of sizes
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Cleaning Solutions

Maintaining a clean ORP electrode is critical to obtaining accurate and reliable measurements. This especially true for Winemakers that use an ORP electrode with a grape juice sample that has a high content of solids from the skins and pulp of a crushed grape. Hanna offers specially formulated solutions to clean the deposits and stains from a ORP electrode and the reference junction.


  • Specially formulated to remove wine deposits and stains
  • Available in 500 ml bottles or single use sachets
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Cleaning Solutions

Maintaining a clean ORP electrode is critical to obtaining accurate and reliable measurements. This especially true for Winemakers that use an ORP electrode with a grape juice sample that has a high content of solids from the skins and pulp of a crushed grape. Hanna offers specially formulated solutions to clean the deposits and stains from a ORP electrode and the reference junction.


  • Specially formulated to remove wine deposits and stains
  • Available in 500 ml bottles or single use sachets
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Storage Solutions

All combination ORP electrodes have a junction between the reference cell and sample. Different junction types have different porosities that will affect the time takes to be hydrated. Maintaining the hydration of the junction allows for a stable liquid junction potential which is critical for accurate and repeatable readings.

  • Keeps ORP junction hydrated for fast response
  • Available in 230 and 500 ml bottles
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Resources

Check out our Media Library and Knowledge Base pages specifically for wine and wine related products.