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Ripper Method
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<h2 id="chemical-equilibria">Chemical Equilibria</h2> <p>The first reaction of iodine with SO2 and water is as follows: </p><p>SO2+I2+2H2O→H2SO4+2HI </p><p>As the reaction proceeds, all available SO2 will be consumed and the starch indicator added to the solution will bind with the unconsumed iodine, turning the solution black. </p><p>The second step of the reaction requires pretreating with solution with NaOH to release bound SO2. The reaction with iodine can then be done. </p><p>HSO3−⇌H2SO3⇌SO2 </p> <h2 id="applications">Applications</h2> <p>The Ripper Method is commonly used in wine making applications as SO2 is often added to wine to maintain its freshness and the concentration needs to be determined. The technique is not precise and is prone to systematic error as well. This limits its use, despite being a fast and inexpensive test.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Ripper M (1898) Die Schwelflige Saure im Wein und deren Bestimmung. J Praia Chem 46: 428-73. <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Free and Total Sulfur Dioxide (SO2) in wine (Ripper method) by automatic titration" (PDF). Archived from the original (PDF) on 2023-07-15. <a href="https://web.archive.org/web/20230715160129/https://assets.fishersci.com/TFS-Assets/LPD/Application-Notes/Free%20and%20total%20sulfur%20dioxide%20SO2%20in%20wine%20by%20automatic%20titration.pdf" target="_blank">https://web.archive.org/web/20230715160129/https://assets.fishersci.com/TFS-Assets/LPD/Application-Notes/Free%20and%20total%20sulfur%20dioxide%20SO2%20in%20wine%20by%20automatic%20titration.pdf</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Measuring free sulfur dioxide" (PDF). Archived from the original (PDF) on 2016-04-14. <a href="https://web.archive.org/web/20160414212024/http://gencowinemakers.com/docs/Measuring%20Free%20Sulfur%20Dioxide.pdf" target="_blank">https://web.archive.org/web/20160414212024/http://gencowinemakers.com/docs/Measuring%20Free%20Sulfur%20Dioxide.pdf</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Vahl, J. M.; Converse, J. E. (1980). "Ripper procedure for determining sulfur dioxide in wine: Collaborative study". Journal of the Association of Official Analytical Chemists. 63 (2): 194–9. PMID 7430025. <a href="https://pubmed.ncbi.nlm.nih.gov/7430025/" target="_blank">https://pubmed.ncbi.nlm.nih.gov/7430025/</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> </ol>