Dissolved Oxygen Measurement

Applications for dissolved oxygen measurement

Air can be regarded as having a constant percentage (approximately 20.9%) of oxygen. Wherever air comes in contact with water, the oxygen in the air will dissolve in the water. The amount of oxygen that dissolves in the water depends on many factors: whether there is adequate time and adequate mixing to fully saturate the water, the water temperature, the air pressure, the salt content of the water, and whether there are substances in the water which consume the oxygen. Since the oxygen content is important for many biological and chemical processes, measurement of the amount of oxygen actually dissolved in a water sample is of great importance.

Applications for dissolved oxygen measurement include processes where the amount of oxygen affects a reaction rate or process efficiency, or indicates an environmental condition. Some important applications include wastewater treatment, wine production, bio-reactions, and environmental water monitoring. DO instruments have the flexibility to use polargraphic and optical technology for DO measurement needs meeting regulatory requirements. Membrane oxygen electrodes are the most widely used and accepted method for real-time measurements of oxygen in water. Learn more about how Thermo Scientific instruments can help you meet your regulatory needs.

Accurate and consistent dissolved oxygen measurements

We offer an array of dissolved oxygen measurement instrumentation and accessories designed to meet your standards for performance and price. Our dissolved oxygen meters, probes, solutions, and accessories are designed to offer maximum repeatability and accuracy in your dissolved oxygen readings.

Browse our complete portfolio or let one of our experts help you make a selection.

Measuring dissolved oxygen in wine

A bottle of wine’s oxygen content has a great effect on its quality, stability, and longevity. This is why monitoring and controlling the oxygen incorporation at different stages of the wine-making and bottling process is becoming a growing concern for wineries. Although oxygen is a part of the wine’s natural aging process, adverse levels can cause discoloration to white wines and flavor degradation to both white and red varietals. To ensure the consumer is getting the highest-quality product, measuring the concentration of molecular oxygen of wine after bottling is very important.

Using an Orion Star A223 RDO/DO portable meter with an RDO optical dissolved oxygen sensor enables wineries to continually produce high-quality wines. Because the RDO sensor allows the wine to be measured directly in the bottle, dissolved oxygen measurements can be made with speed and accuracy. The speed, accuracy, and precision of the RDO sensor is equivalent or superior to current DO measurement techniques.

Measuring dissolved oxygen at high altitudes

DO solubility in saturated water at any one temperature, barometric pressure, and salinity has been measured and recorded by scientists over the years. The information has then been used in programming modern recording instruments. Water holds less oxygen at low barometric pressure (high altitude) and at high salinity.

Dissolved oxygen levels can be measured at altitudes of 4,500 meters or above sea level utilizing advanced instrumentation with particular design features. The saturated dissolved oxygen (DO) level of a water sample is dependent on a number of factors, including:

Temperature

Atmospheric pressure/altitude

Salinity

The oxygen partial pressure of the sample as measured by the DO sensor is converted into concentration terms (mg/L) by using the solubility value of oxygen at the specific atmospheric pressure, temperature, and salinity.

Advanced instrumentation, like Thermo Scientific™ dissolved oxygen meters, are designed with components that measure these factors and use them to determine readings. Thermo Scientific™ Orion™ Versa Star™, Thermo Scientific™ Orion Star™ A200 series and Orion Star A300 series dissolved oxygen meters have an internal barometer that is used to measure the exact barometric pressure at the point of measurement. No matter what your altitude, you’ll have confidence that your readings are reliable.

Meeting regulatory and compliance standards

Meeting regulatory requirements often goes hand in hand with dissolved oxygen measurements, and it’s critical that you have instruments and electrodes that allow you to stay complaint with these industry standards. Below is a list of international standards for regulatory compliance requirements for a variety of industries.

Regulatory requirements

International standards for regulatory compliance requirements: 

SM: Standard Methods for the Examination of Water and Wastewater. APHA, AWWA, WEF.

ASTM: American Society for the Testing and Materials

ISO: International Organization for Standardization

USP: United States Pharmacopeia

EP: European Pharmacopeia

China MEP: China Ministry of Environmental Protection

AOAC: Association of Official Analytical Chemists

NRCS: Natural Resources Conservation Service

PSS-78: Practical Salinity Scale of 1978

FDA: U.S. Food and Drug Administration

USDA: United Stated Department of Agriculture