Sulphite (Free) Test Kits

Titrimetric Kits

Range MDL Method Type Kit Cat. No. Refill
2 - 20 ppm as SO3 2.0 ppm Iodometric Titrets K-9602
5 - 50 ppm as SO3 5.0 ppm Iodometric Titrets K-9605
10 - 100 ppm as SO3 10 ppm Iodometric Titrets K-9610
50 - 500 ppm as SO3 50 ppm Iodometric Titrets K-9650
10 - 100 ppm as SO2 10 ppm Ripper (Sulphite in Wine) Titrets K-9610W*

CHEMetrics offers test kits employing the well-known Iodometric and Ripper Methods 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 (* except for Sulphite in Wine which contains 10 tets).

The Iodometric Method (Sulphite)

CHEMetrics' sulphite test kits employ the iodometric chemistry in which sulphite is titrated with iodide-iodate titrant in an acid solution using a starch indicator. Thiosulphate will titrate as sulphite. Sulphamic acid is added to the sample to prevent interference from nitrite. Results are expressed as ppm (mg/l) SO3.

References:
ASTM D 1339-84, Sulphite Ion in Water, Test Method C.
APHA Standard Methods, 22nd ed., Method 4500-SO3 2- B - 2000.
USEPA Methods for Chemical Analysis of Water and Wastes, Method 377.1 (1983).

The Ripper Method (Sulphite in Wine)

CHEMetrics' sulphite in wine test kit is based on the Ripper method, which the wine industry has used for years as a standard for rapid sulphite analysis. Sulphite is titrated with an iodide-iodate solution, using a starch end point indicator. Phosphoric acid is used to adjust the pH of the sample. Results are quantified using direct-reading titration cells. The test determines free sulphite as ppm (mg/l) SO2.

Results for this test kit are acceptable for white wines (although they can have an error of up to 10 ppm). This test kit is not recommended for use with red wines or white wines containing ascorbic acid or tannin. These wines often give false high test results.

References:
ASTM D 1339-84, Sulphite Ion in Water, Test Method C.
APHA Standard Methods, 22nd ed., Method 4500-SO3 2- B -2000.
USEPA Methods for Chemical Analysis of Water and Wastes, Method 377.1 (1983).

Titrets Technology

CHEMetrics Titrets employ reverse titration technology, meaning that the premixed and premeasured iodide-iodate titrant is in the ampoule, and the sample and starch indicator is drawn in a little at a time from the sample cup. The amount of sample required to reach the endpoint is proportional to the sulphite concentration of the sample, which is shown on the scale on the side of the ampoule.

Applications

Sulphite is not usually present in surface waters. If sulphite is discharged in effluents or from domestic wastewaters, it readily oxidises to form sulphate. Sodium sulphite is the most common form of sulphite and is an excellent reducing agent with applications as an oxygen scavenger. Sulphite concentrations in boiler and process waters must be monitored routinely to avoid overtreatment. Waste treatment plants that use sulfur dioxide to remove excess chlorine must monitor their effluents for sulphite.

Sulphites have been used for centuries to sanitize and preserve foods. They are used worldwide in the wine industry as antioxidant and antimicrobial agents. However, sulphites have been identified as causative agents in certain allergic reactions suffered by asthmatics. As a result, both the FDA and the Bureau of Alcohol, Tobacco, and Firearms in the USA and EU food labelling legislation have mandated that sulphites in foods and beverages, at levels of 10 ppm or higher, be identified on the label.


Site Map | Impressum | Terms of Use | Links © 2012-2019 Galgo T: 01442 876817