Molybdate Test Kits
What is Molybdate?
Molybdenum (Mo) is the 42nd chemical element on the periodic table and is categorized as a metal. It is not found as a pure metal naturally but is instead found as a component in other compounds. The molybdate anion consists of molybdenum in its highest oxidation state of 6 and oxygen, MoO42-. Sodium molybdate salt (Na2MoO4) is frequently used throughout the industrial water treatment and power generation industries as an anodic oxidizing corrosion inhibitor. It is used in both open-loop and closed-loop cooling water systems. In solution, molybdate anions complex with oxidized iron to form a protective film of molybdate and ferric oxide that prevents corrosion of metal components. Sodium molybdate is considered an effective, environmentally acceptable alternative to chromate treatment as it exhibits low or even negligible toxicity. Sodium molybdate is also favored in situations where phosphate or zinc discharges are restricted.
Why Test for Molybdate?
Since molybdate is a corrosion inhibitor, testing is critical to prevent damage to your system and control chemical costs. By testing the molybdate concentrations, you can ensure that the system is being dosed with enough corrosion inhibitor to prevent corrosion, such as pitting. Monitoring will also reveal when molybdate concentrations are too high so that operators can take preventative action to stop expensive chemical from being wasted. If your system relies on a molybdate based corrosion inhibitor, testing is a great way to keep costs low and prevent costly maintenance in the future.
About Our Test Kits
CHEMetrics visual molybdate water treatment 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 also offers an instrumental molybdate test kit featuring Vacu-vials® ampoule technology. Vacu-vials ampoules feature a 13mm diameter and utilize the same self-filling technology as CHEMets ampoules, so they are compatible with most photometers or spectrophotometers.
The CHEMetrics molybdate test kits use the catechol chemistry to form a yellow-orange color in direct proportion to the hexavalent molybdenum concentration.
Click on a catalog number in the tables below for more information or to purchase a molybdate water treatment test kit.
Visual Kits
| Range | MDL | Method | Kit Catalog No. | Refill Catalog No. |
|---|---|---|---|---|
| 0-7 ppm as Mo | 0.5 ppm | Catechol | K-6701 | R-6702 |
| 2-24 ppm as Mo | 2 ppm | Catechol | K-6702 | R-6702 |
| 20-200 ppm as Mo | 20 ppm | Catechol | K-6720 | R-6720 |
Instrumental Kits
| Range | Method | Kit Catalog No. |
|---|---|---|
| 0-25.0 ppm as Mo | Catechol | K-6703 |
The Catechol Method
References: G. P. Haight and V. Paragamian, Analytical Chemistry, pp. 32, 642 (1960). H. Onishi and E. B. Sandell, Photometric Determination of Trace Metals, 4th ed., Part 1, p. 295 (1978).The molybdate water treatment test kit employs the catechol chemistry. In a mildly reducing alkaline solution, catechol reacts with hexavalent molybdenum to form a yellow-orange colored chelate in direct proportion to the hexavalent molybdenum concentration. Test results are expressed in ppm (mg/L) molybdenum (Mo).