To determine total sulfur dioxide (SO₂) in dried apricots using classic laboratory approaches, two established methods are most commonly employed: the Monier–Williams steam-distillation method and a modified Kjeldahl distillation-titration technique. Both rely on releasing SO₂ from sample matrix into an absorbing solution and titrating the liberated sulfite ions, but they differ in apparatus and procedural details.

The Monier–Williams method, standardized as AOAC 990.28, uses acidified steam to volatilize free and bound sulphites from a homogenized fruit sample. The released SO₂ is swept by a carrier gas into a hydrogen peroxide solution, where it is oxidized to sulfuric acid. This solution is then titrated with standardized sodium hydroxide to a starch-indicator endpoint, yielding the SO₂ content. Setting up this system requires a round-bottom distillation flask, a steam inlet, an Allihn condenser, gas tubing to direct effluent into a receiving flask containing 3% H₂O₂, and titration glassware. Detailed schematics, reagent formulations, and calculation formulas can be found in the FSSAI Manual of Methods of Analysis of Foods (Food Additives section) and in VELP’s application notes on sulphur dioxide determination.

Alternatively, the Kjeldahl-based method adapts the traditional nitrogen-distillation apparatus for SO₂ analysis. After acid digestion of the dried apricot sample, the Kjeldahl distiller generates steam that carries SO₂ into an alkaline trap, where it is back-titrated. While this approach uses similar glassware and reagents (acid, H₂O₂, NaOH, starch indicator), it benefits laboratories already equipped for protein analysis, avoiding the need to purchase a separate Monier–Williams still. Published case studies and manufacturer technical guides (e.g., Raypa and Gerhardt Kjeldahl distillers) provide step-by-step instructions for apparatus setup, digestion conditions, and titration procedures.

For comprehensive, laboratory-ready protocols—complete with equipment lists, plumbing diagrams, reagent recipes, and sample calculation sheets—you may consult the AOAC Official Methods compendium (method 990.28), the FSSAI food additives manual, or the VELP application notes titled “Sulphites Determination in Dried Apricots” and “Determination of Low Sulphur Dioxide”. These resources offer validated procedures that ensure accurate, reproducible quantification of total SO₂ in dried fruits

attaching a document file...hope it will help

Здраствуйте попробуйте определения содержания диоксида серы (SO2) в продуктах переработки фруктов и овощей, в том числе в сухофруктах, используют, например, следующие методы, описанные в ГОСТ 25555.5-2014:

· Титриметрический с предварительной дистилляцией диоксида серы из продукта (метод А).

· Йодометрический с визуальным титрованием для светлоокрашенных жидких продуктов (метод Б).

· Кулонометрический с предварительной дистилляцией диоксида серы из продукта (метод В).

· Качественный метод обнаружения диоксида серы. Он основан на обесцвечивании йодкрахмальной индикаторной бумаги диоксидом серы, вытесненным из продукта при его подкислении.

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