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Oxygen (dissolved) Test Kits

Oxygen (Dissolved) Test Kits

Click on a catalog number in the tables below for more information or to purchase a DO test kit.

What is Dissolved Oxygen?

In bodies of water, dissolved oxygen (DO) is the form of oxygen that is available to sustain aquatic organisms but it does not include the oxygen associated with a molecule of water. Water bodies become oxygenated through various means. In the natural environment, the main source is atmospheric oxygen, however other pathways include agitation (waterfalls) and photosynthetic aquatic plants. Surface waters typically have over 8 ppm DO, but levels can be as low as 4 ppm in certain conditions. Concentrations lower than 2 ppm DO are called hypoxic. As many aquatic organisms rely on dissolved oxygen to survive, hypoxic conditions can stress or outright kill aquatic life. Fish consume DO through their gills and microorganisms consume oxygen as they feed on pollutants or decaying matter.

The concentration of dissolved oxygen is dependent on several environmental factors. Temperature, pH, season, and time of day will influence DO levels. Temperature has a very large impact, as cold water can retain more dissolved oxygen than warm water.

Wastewater treatment facilities often treat wastewater using the activated sludge process which relies on aerobic microorganisms to breakdown or oxidize excess nutrients and pollutants. Aerators inject bubbles of oxygen into waste to maintain the microorganism population. A level of at least 2 ppm DO must be maintained for this process to work.

Industrial water treatment operators monitor oxygen levels in high-pressure boilers, low-pressure boilers, and heat recovery steam generators (HRSG). At elevated temperatures, oxygen is highly corrosive to metals as it causes pitting. High-pressure boilers and deep well oil recovery equipment are particularly vulnerable to this attack. To prevent costly corrosion damage, liquids in contact with metal surfaces must be treated to mitigate oxygen concentration, usually by a combination of physical and chemical means. Deaeration can reduce the dissolved oxygen concentration of boiler feedwater from several ppm to a few ppb. Chemical reducing agents (referred to as oxygen scavengers), such as hydrazine, DEHA and sodium sulfite, may be used instead of or in conjunction with deaeration. Testing for DO can occur in feedwater or condensate depending on various factors.

Why Test for Dissolved Oxygen in Water?

DO concentration is a basic measurement for assessing the health of a body of water. Environmental groups, consulting firms, and government agencies regularly monitor aquatic ecosystems’ DO concentration to ensure they can support life. Frequent testing of dissolved oxygen in water is an effective way to catch conditions that can cause hypoxia before they can threaten aquatic life.

Industries that rely on metal systems like high-pressure boilers measure DO concentrations to prevent costly or catastrophic equipment corrosion. DO measurements also help operators determine whether they are dosing oxygen scavenger effectively to limit chemical waste.

About Our Test Kits

Two oxygen test methods are available that offer different measurement ranges:

  • The Rhodazine D method is very sensitive and measures oxygen in the part per billion (ppb) range, so it is the method of choice for boiler and condensate oxygen monitoring. The Rhodazine D dye develops a pink color in the presence of oxygen.
  • The Indigo Carmine method uses a dye which turns blue in the presence of parts per million (ppm) oxygen. This method is routinely used for monitoring oxygen in surface water for environmental monitoring.

CHEMetrics has manufactured quality DO test kits since 1969. We offer visual and instrumental options that measure in ppb ranges, perfect for high-pressure boilers, and ppm ranges for environmental applications.

CHEMetrics visual DO test kits feature CHEMets® self-filling ampoules that contain pre-measured reagent for a single test. Simply snap the ampoule directly in a sample to draw in the correct volume of sample and then compare to the supplied color standards to find the concentration.

CHEMetrics instrumental DO test kits feature Vacu-vials® ampoule technology. Vacu-vials ampoules utilize the same self-filling technology as CHEMets ampoules, but the vials have a 13mm diameter, so they are compatible with most photometers or spectrophotometers.

Click on a catalog number below for more information or to purchase a test kit.

Visual Kits

Range MDL Method Kit Catalog No. Refill Catalog No.
0-20 ppb 2 ppb Rhodazine D K-7511 R-7511
0-40 ppb 2.5 ppb Rhodazine D K-7540 R-7540
0-100 ppb 5 ppb Rhodazine D K-7599 R-7540
5-180 ppb 5 ppb Rhodazine D K-7518 R-7518
0-1 ppm 0.025 ppm Rhodazine D K-7501 R-7501
1-12 ppm 1 ppm Indigo Carmine K-7512 R-7512

Instrumental Kits

Range Method Kit Catalog No.
0-1.000 ppm Rhodazine D K-7553
0-15.0 ppm Indigo Carmine K-7513
0-15.0 ppm Indigo Carmine I-2002


The Indigo Carmine Method

References: ASTM D 888-87, Dissolved Oxygen in Water, Test Method A. Gilbert, T. W., Behymer, T. D., Castañeda, H. B., “Determination of Dissolved Oxygen in Natural and Wastewaters,” American Laboratory, March 1982, pp. 119-134.
Dissolved Oxygen test kits for environmental and drinking water applications (ppm range) employ the indigo carmine method. The reduced form of indigo carmine reacts with D.O. to form a blue product. The indigo carmine methodology is not subject to interferences from temperature, salinity, or dissolved gases such as sulfide, which plague users of D.O. meters. The results of these dissolved oxygen test kits are expressed as ppm (mg/L) O2.
The Rhodazine D™ Method

References: Developed by CHEMetrics, LLC ASTM Power Plant Manual, 1st. ed. p. 169 (1984). ASTM D 5543-15, Low Level Dissolved Oxygen in Water. Department of the Navy, Final Report of NAVSECPHILADIV Project A – 1598, Evaluation of CHEMetrics Feedwater Dissolved Oxygen Test Kit (1975).
Test kits for boiler waters and applications requiring trace levels of D.O. (ppb range) employ the Rhodazine D methodology. Developed by CHEMetrics, LLC, and approved by ASTM as the reference method for ppb D.O. determination, the Rhodazine D compound in reduced form reacts with dissolved oxygen to form a bright pink reaction product. The method is not subject to salinity or dissolved gas interferences. Oxidizing agents, including benzoquinone, can cause high results. Reducing agents such as hydrazine and sulfite do not interfere. Results are expressed as ppm (mg/L) or ppb (ug/L) O2.Low-range dissolved oxygen test kits include a special sampling tube for use with boiler feedwater. This device allows the user to break the tip of the ampoule in a flowing sample stream in order to preclude error from contamination by atmospheric oxygen.

Application Overview:  Monitoring Dissolved Oxygen in High-Pressure Boiler Systems

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