Chromate (Hexavalent) Test Kits
Visual Kits
| Range | MDL | Method | Type | Test Kit | Refill |
|---|---|---|---|---|---|
| 0.0 - 1.0 & 1 - 10 ppm | 0.05 ppm | Diphenylcarbazide | CHEMets | K-2810 | R-2810 |
Photometric Kits
| Range | Method | Type | Test Kit |
|---|---|---|---|
| 0 - 3.50 ppm | Diphenylcarbazide | Vacu-vials | K-2803 |
CHEMetrics offers test kits employing the well-known Diphenylcarbazide reagent to deliver sensitivity and accuracy within two minutes or less. Based on CHEMetrics patented Self-Filling Reagent Ampoule technology. Premixed. Premeasured. Precise. Each kit contains 30 tests.
Diphenylcarbazide Method
With the chromate test method, hexavalent chromium reacts with diphenylcarbazide under acid conditions to form a red-violet colour. Results are expressed as ppm (mg/l) CrO4.
Reference:
APHA Standard Methods, 22nd ed., Method 3500-Cr B- 2009. ASTM D 1687-02, Chromium in Water, Test Method A.
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Technical Data Sheet |
Applications
Hexavalent chromium salts are used in numerous industrial processes including electroplating and the manufacture of pigments and paints. Trivalent chromium plating is more environmentally friendly and less toxic, although more expensive and more difficult to control, compared with hexavalent chromium plating.
Historically, hexavalent chromate was used extensively as a corrosion inhibitor in open and closed cooling water systems; however, alternative inhibitors have superseded chromate due to environmental and public health concerns related to chromate discharges.
Chromate is often measured in water after industrial processes to ensure it is within pollution limits. In open and closed cooling systems, chromate is measured to ensure that the correct amount of chemical is being dosed to inhibit corrosion but not so much that it is being wasted and creating unnecessarily greater toxicity.
What is Chromate?
Chromium (Cr) is a naturally occurring metal in Group 6 of the period table, which exists as 4 different stable isotopes. Chromium occurs most commonly in 3 different oxidation states +6, +3 and +2, hexavalent chromium, Cr (VI), and trivalent chromium, Cr (III), being the most abundant. Cr (III) tends to form Cr3+ cations whereas Cr (VI) tends to form chromate (CrO42-) and less commonly dichromate (Cr2O72-) oxyanions. Cr (III) compounds are insoluble in water with the exception of Cr2O3 and Cr(OH)3. Cr (VI) is 500 times more toxic than CR (III). Elemental chromium does not occur freely in nature, but most frequently occurs as chromite. Chromium salts can be found in soil and groundwaters. Chromium is a nonessential trace element for plant health but essential for animal health.