Titrets Instructions

References: ASTM D 1339-84, Sulfite Ion in Water, Test Method C.
APHA Standard Methods, 20th ed., p. 4-173, method 4500 - SO₃^{2 -} B (1998).
USEPA Methods for Chemical Analysis of Water and Wastes, method 377.1 (1983).

Sulfites have been used for centuries to sanitize and preserve foods. They are used worldwide in the wine industry as antioxidant and anti-microbial agents. However, sulfites recently have been identified as causative agents in certain allergic reactions suffered by asthmatics. As a result, the FDA and the Bureau of Alcohol, Tobacco and Firearms have mandated that sulfites in foods and beverages, at levels of 10 ppm or higher, be identified on the label.

Although regulations are based on the amount of total sulfite (the sum of the free and bound forms), wine makers, bottlers and others associated with the industry are primarily interested in the amount of free sulfite in the wine or must. The combination of sulfite with aldehydes or pigments, which are naturally present, may reduce the effectiveness of the additive.

The Titrimetric Method CHEMetrics’ sulfite test kits are based on the "Ripper" method, which has long been used by the wine industry as a standard for rapid sulfite analysis. Sulfite 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 sulfite as ppm (mg/L) SO₂.

Results from this test kit are acceptable for dry white wines although they can have an error of up to 10 ppm. The test is not recommended for use with red wines, or white wines containing ascorbic acid or tannin. These wines often give false high-test results. As a rule, a test result of greater than 40-ppm free sulfite for any wine should be considered suspect and an alternative sulfite determination method should be employed.

The test is affected by the same interferences as the Ripper method. These include Botrytis, tannin pigments, and ascorbic acid.

Titrets^® simplify titration tests just as CHEMets^® and Vacu-vials^® simplify colorimetric tests.

How to use Titrets^®: for fast, simple, titration tests.

Each Titret™ contains a carefully measured quantity of titrant sealed under vacuum. The sealed tip is fitted with a miniature valve that is used to control the flow of sample into the ampoule as the analyst performs what is known as a "reverse titration."

Sample is drawn into the ampoule in small increments (with mixing) while the analyst watches for the color change, which signals the end-point of the titration. When that change occurs, the ampoule is placed in an upright position and the test result is read opposite the location of the liquid level, using a scale printed on the side of the tube.

The entire process requires only a minute or two and avoids all the equipment hassle and clean up associated with ordinary titration.

HOW TO USE Titrets^®

ATTACH VALVE	INSERT Titret into Titrettor^TM	TITRATE	READ